MINNEAPOLIS / ST. PAUL (January, 13 2008) – University of Minnesota researchers have created a beating heart in the laboratory.
By using a process called whole organ decellularization, scientists from the University of Minnesota Center for Cardiovascular Repair grew functioning heart tissue by taking dead rat and pig hearts and reseeding them with a mixture of live cells. The research will be published online in the January 13 issue of Nature Medicine.
“The idea would be to develop transplantable blood vessels or whole organs that are made from your own cells,” said Doris Taylor, Ph.D., director of the Center for Cardiovascular Repair, Medtronic Bakken professor of medicine and physiology, and principal investigator of the research.
Lots of people have dodgy hearts that need replacement.
Nearly 5 million people live with heart failure, and about 550,000 new cases are diagnosed each year in the United States. Approximately 50,000 United States patients die annually waiting for a donor heart.
While there have been advances in generating heart tissue in the lab, creating an entire 3-dimensional scaffold that mimics the complex cardiac architecture and intricacies, has always been a mystery, Taylor said.
It seems decellularization may be a solution – essentially using nature’s platform to create a bioartifical heart, she said.
The problem with decellularization is that you need a dead heart to start with. But perhaps studies on the extracellular matrix will lead to ways to make a purely synthetic extracellular matrix.
Decellularization is the process of removing all of the cells from an organ – in this case an animal cadaver heart – leaving only the extracellular matrix, the framework between the cells, intact.
After successfully removing all of the cells from both rat and pig hearts, researchers injected them with a mixture of progenitor cells that came from neonatal or newborn rat hearts and placed the structure in a sterile setting in the lab to grow.
The results were very promising, Taylor said. Four days after seeding the decellularized heart scaffolds with the heart cells, contractions were observed. Eight days later, the hearts were pumping.
Growth of replacement hearts, as great as it would be, is not the ideal way to solve heart disease. Better to be able to send in gene therapy and/or cell therapy to repair the existing heart while it still beats. But even once such treatments become available some will still need replacement hearts due to sudden trauma.
Grown replacement parts will some day make body repair as commonplace as car repair.
A British research team led by the world's leading heart surgeon has grown part of a human heart from stem cells for the first time. If animal trials scheduled for later this year prove successful, replacement tissue could be used in transplants for the hundreds of thousands of people suffering from heart disease within three years.
Sir Magdi Yacoub, a professor of cardiac surgery at Imperial College London, has worked on ways to tackle the shortage of donated hearts for transplant for more than a decade. His team at the heart science centre at Harefield hospital have grown tissue that works in the same way as the valves in human hearts, a significant step towards the goal of growing whole replacement hearts from stem cells.
Yacoub thinks his team might be able to grow a complete heart within 10 years. That's 2017. So if you need a new heart in 2025, no problem - at least if you can afford it. But if full replacement hearts become possible by, say, 2020 (add a few years for complications along the way) then why won't all the other organs follow shortly thereafter? By the year 2030 should anyone in an industrialized country die from internal organ failure? It seems totally avoidable.
Next throw in some stem cell therapies that repair blood vessels and muscles. We''ll also need therapies to repair immune cells. That will leave the last great rejuvenation frontier: the brain. Can't replace that. Need to repair the existing cells. Brain rejuvenation is the hardest challenge of all. For that we'll need excellent gene therapy and nano repair devices. I hope many of us do not become too brain aged and dumb before such therapies become available.
Here's hope for those suffering from anterior cruciate ligament tears.
CHARLOTTESVILLE, Va., Feb. 19, 2007 - A research team led by Cato T. Laurencin, M.D., Ph.D., at the University of Virginia Health System has created a synthetic matrix on which the ACL (anterior cruciate ligament) can be regenerated effectively for treatment of ACL tears.
This is an important discovery, because the ACL, the stabilizing ligament that connects the thighbone to the legbone, usually does not heal after it is torn during sports or other injuries. The ACL unravels like an unbraided rope when torn, making healing difficult. More than 200,000 people in the United States suffer this rupture each year.
"This is the first tissue-engineered matrix for ACL to demonstrate such substantial neo-ligament formation, in terms of both vascularity and collagen formation," said Dr. Laurencin, Chairman of the UVa Department of Orthopaedic Surgery and leader of the team. "We tested one synthetic matrix with actual ACL cells from our animal model and one without these cells. While both systems encouraged the ingrowth of neo-ligament tissue, matrices with seeded cells performed particularly well in this study."
Dr. Laurencin concluded that the ACL replacement with ACL cells had a robust functional tissue outcome in the rabbits that received this matrix.
Tissue engineering doesn't get as much attention as stem cell research. But we need tissue engineering advances as much as we need stem cell research advances.
Note the researchers used a machine developed for the textile industry.
The team grew ligament tissue after first weaving together strands of biodegradable polyester using a machine originally designed for textile production. This material, called polylactide, naturally dissolves in the body over time.
Every industry that develops technology for manipulating small pieces of matter potentially could produce technology also useful for biological manipulations. We see this with gene chips and microfluidic devices developed as spin-offs of the computer semiconductor industry. But we also see scientists using ink jet printers to deposit cells for tissue engineering.
Laurencin's team seeded the woven polylactide structure with cells taken from rabbits' anterior cruciate ligaments and cultured them in a dish for two days. Finally, they surgically replaced whole anterior cruciate ligaments in another group of rabbits with the polylactide scaffold material, attaching it to the joint in the same way as a normal ligament.
Twenty-four hours later, the rabbits could already bear their own weight on their knees, and showed fairly normal mobility.
We need the ability to build and grow replacement parts for our bodies. With these parts most chronic, painful, and debilitating diseases will become curabel. Eventually full body rejuvenation will become possible.
A Newcastle University team in England has grown mini-livers from umbilical cord stem cells.
Scientists have grown an artificial liver that is set to revolutionise the medical world, it was revealed today.
A team based at Newcastle University have grown a tiny liver, believed to be the first of its kind in the world.
Using stem cells taken from umbilical cords, Dr Nico Forraz and Professor Colin McGuckin made the breakthrough.
The two scientists also took a trip to Houston, Texas, to work with scientists at Nasa.
And using some skills they learned at Nasa they were able to make the miniature livers, which can now be used for drug and pharmaceutical testing, eradicating the need to test on animals and humans.
They think they are 10 years to being able to grow a full liver.
Dr Forraz said: "We have taken a little bit of umbilical cord blood, and then it is all about enhancing things that already exist.
"We cannot build a fullsized liver yet. That will take about 10 years. But this is the first important step.
"We expect this to really take off in the next 18 months or so.
Livers are relatively simpler things to grow than 3 dimensionally more complex structures such as hearts and kidneys. So I'm expecting we'll see replacement livers before replacement hearts or kidneys.
As it stands, the mini organ can be used to test new drugs, preventing disasters such as the recent 'Elephant Man' drug trial. Using lab-grown liver tissue would also reduce the number of animal experiments.
Within five years, pieces of artificial tissue could be used to repair livers damaged by injury, disease, alcohol abuse and paracetamol overdose.
And then, in just 15 years' time, entire liver transplants could take place using organs grown in a lab.
These scientists intend to commercialize their work with their company ConoStem.
Liver replacement has applications beyond liver cirrhosis. First off, some people die from liver failure brought on by the trauma of accidents. Also, liver cancer is another kind of liver failure which kills people. Liver cancer cases that are now inoperable will become operable when it becomes possible to remove an entire liver and replace it with a new one.
For a number of types of organs replacement to treat cancer might end up saving more lives than replacement due to accidents and other diseases. Got pancreatic cancer? Replace it. Got kidney cancer? Replace it. Advances in testing will allow identification of a growing portion of all cancers before metastasis. If a cancer is still contained within a single organ then an excellent solution might some day be to just replace that whole organ. Though other ways to cure cancer might eventually avoid the need for this approach.
We can develop the technology to grow replacement parts for just about every part of the body and this can be accomplished within the lifetimes of most of the people reading this. So why aren't we trying much harder? Government research funding for stem cells and tissue engineering should be at least an order of magnitude larger.
The University of Pittsburgh Medical Center and biotech company Revivicor are attempting to revive efforts to genetically engineer pigs to make organs for xenotransplantation into humans. Writing for the Pittsburgh Tribune-Review Luis Fabregas covers a lot of territory in a survey of the UPMC-Revivicor efforts. Human trials for some types of transplants might be just a few years off.
Momentum is building for two promising projects.
One is using insulin-making pig islets to bolster the insulin levels of people with type 1 diabetes, something routinely done in at least one hospital in Mexico City. In the last five years, about 40 patients at Children's Hospital of Mexico have received the pig islet transplants. Some of them have significantly reduced their insulin intake, said spokeswoman Isis Casanova.
Researchers at Children's Hospital of Pittsburgh, led by Dr. Massimo Trucco, have been testing pig islets in small monkeys since 2004.
Another project would use pig hearts in people with severe heart failure instead of mechanical pumps.
By Revivicor's own estimates, the market for pig organs could be worth at least $6 billion.
The intensity of UPMC's efforts, including discussions between Revivicor and the U.S. Food and Drug Administration, suggest UPMC is poised to begin human clinical trials within two or three years.
Revivicor's pigs have been genetically modified to not produce alpha-1-galactose sugar which causes human immune rejection. Much more could be done along those lines to make pig organs more like human organs in order to enhance compatibility. This strikes me as a direction that ought to get huge amounts of funding.
Pigs have a virus incorporated into their genomes called porcine endogenous virus (PERV) which could potentially infect humans. But such viruses could be knocked out of pigs genetically engineered for organ production. At the same time, a variety of human genes could get transplanted into pigs to make them have immune systems, livers, and other organs more like humans. It is a lot of work. All the more reason to start doing in sooner and on a greater scale.
Every day that goes by your organs all get one day older and closer to failure. If we start trying a lot harder now many of us could get youthful organs transplanted from pigs when our own organs get old and start to fail. Time's a wasting. Time is wasting our body parts and making them slowly break down. We ought to develop the means to repair and replace old human body parts.
The promise of xenotransplantation:
ATLANTA -- Islet cell xenotransplantation presents a promising near-term solution to the critically low islet cell supply for humans suffering from type 1 diabetes, according to researchers from the Emory Transplant Center, the Yerkes National Primate Research Center of Emory University and the University of Alberta, Canada. The Emory/Yerkes researchers successfully transplanted and engrafted insulin-producing neonatal porcine islet cells harvested by the University of Alberta researchers into diabetic rhesus macaque monkeys, restoring the monkeys' glucose control and resulting in sustained insulin independence. This research, published in the February 26 advanced online edition of Nature Medicine, also examines the effectiveness of a costimulation blockade-based regimen developed at Emory proven to have fewer toxic side effects than currently used immunosuppressive regimens, and provides essential answers to the possibility of cross-species viral transmission, a common concern of xenotransplantation use in humans.
If we had a much larger effort aimed at implementing all the Strategies for Engineered Negligible Senescence (SENS) there'd be a lot more money available for genetically engineering pigs to become more immuno-compatible with humans. That would make xenotransplantation a lot easier.
We need replacement parts. We should be trying much harder to develop them.
In a major step towards understanding prostate disease, Melbourne scientists have grown a human prostate from embryonic stem cells.
A study published in the March edition of Nature Methods describes how human embryonic stem cells were developed into human prostate tissue equivalent to that found in a young man, in just 12 weeks.
Hey, I want to grow a new prostate and replace mine before mine gets old enough to cause really serious problems. The idea of getting youthful replacement parts becomes more appealing with every passing year.
We should be able to get replacement parts that last longer than the originals. Not every man gets BPH or prostate cancer. Once DNA sequencing is cheap and large numbers of people get their medical histories and DNA sequences compared scientists will identify large numbers of genetic variations that contribute to disease risk. My guess is DNA sequencing will get cheap before replacement organs become feasible. So we'll know what to change. One's own DNA might still be used for making replacement parts (reduces immuno-rejection problems). But gene therapy to patch our DNA (rather like software patches) with the best sequences for reducing specific disease risk will fix it to make it last longer.
For making organs last longer there's a step beyond using best existing genetic variations: Develop genetic sequences that are better than any that have evolved naturally. For example, move all the genes now found in the mitochondria (which have about 15,000 genetic letters of code) into the nucleus where they will be better protected from free radical damage.
The researchers expect a more immediate benefit from their work in the form of prostate cells that can be studied for showing how prostates deteriorate and become diseased.
The study was co-authored by Dr Renea Taylor from Monash University's Immunology and Stem Cell Laboratories, PhD researcher Ms Prue Cowin from the Monash Institute of Medical Research and other Australian and US researchers.
Dr Taylor said the discovery would allow scientists to monitor the progression of the prostate from a normal to a diseased state.
"We need to study healthy prostate tissue from 15-25 year old men to track this process," she said. "Understandably, there is a lack of access to samples from men in this age group, so to have found a way we can have an ongoing supply of prostate tissue is a significant milestone.
"As nearly every man will experience a problem with their prostate, we're very excited about the impact our research will have."
Although prostate cancer is the most common cancer in men, the impact of benign prostate disease (BPH) is equally significant - up to 90 percent of men will have BPH by the time they're 80. BPH is not usually life-threatening, but has a dramatic impact on quality of life.
My guess is that a lot of men with ambivalent feelings about embryonic stem cells who have benign prostate hyperplasia (i.e. difficulty urinating - which also increases the odds of kidney failure btw) are going to resolve those ambivalent feelings in favor of embryonic stem cells if they can get offered replacement prostates that solve their problem.
The cells were planted into mice after being treated in ways that instructed the cells to become prostate tissue.
"We grew the prostate tissue by 'telling' the embryonic stem cells how to become a human prostate gland. We then implanted the cells into mice, where they developed into a human prostate, secreting hormones and PSA; the substance in the blood used to diagnose prostate disease,'' Ms Cowin said.
We really need the ability to grow whole replacement organs. These ladies have taken a big step in that direction. But additional problems must also be solved to grow organs in the right three dimensional shape and ideally to do that in a human body. Mice are obviously too small to grow replacement organs for humans and present problems with disease transfer as well.
Needed replacement bone pieces can be grown in a special layer on the surface of other bones.
An international team of biomedical engineers has demonstrated for the first time that it is possible to grow healthy new bone reliably in one part of the body and use it to repair damaged bone at a different location.
The research is described in a paper titled 'In Vivo Engineering of Organs: The Bone Bioreactor' published online by the Proceedings of the National Academy of Sciences.
Researchers from Imperial College London, the Massachusetts Institute of Technology and Vanderbilt University hope their discovery, which takes advantage of the body's natural wound-healing response, will transform treatments for serious bone breaks and diseases.
New Zealand White rabbits were used to test this procedure. The researchers successfully transferred the bone to another location in the rabbits to repair a bone injury at the other location.
The periosteum layer on the outside of bones has stem cells which can be coaxed into growing replacement bone.
This new research, however, takes a new approach that has proven to be surprisingly simple. Long bones in the body are covered by a thin outer layer called the periosteum. The layer is a little like scotch tape: the outside is tough and fibrous but the inside is covered with a layer of special pluripotent cells which, like marrow cells, are capable of transforming into the different types of skeletal tissue. Because of this, Dr Stevens and her colleagues decided to create the bioreactor space just under this outer layer.
They created the space by making a tiny hole in the periosteum and injecting saline water underneath. This loosened the layer from the underlying bone and inflated it slightly. When they had created a cavity the size and shape that they wanted, next the researchers removed the water and replaced it with a gel that is commercially available and approved by the FDA for delivery of cells within the human body. They chose the material because it contained calcium, a known trigger for bone growth. Their major concern was that the bioreactor would fill with scar tissue instead of bone, but that didn't happen. Instead, it filled with bone that is indistinguishable from the original bone.
Here is the really cool part: This approach might work for growing replacement tissue for organs such as the liver and pancreas.
"This research has important implications not only for engineering bone, but for engineering tissues of any kind," said researcher Robert S. Langer, Institute Professor at the Massachusetts Institute of Technology and a pioneer in the field of tissue engineering. "It has the potential for changing the way that tissue engineering is done in the future."
The scientists intend to proceed with the large animal studies and clinical trials necessary to determine if the procedure will work in humans and, if it does, to get it approved for human treatment. At the same time, they hope to test the approach with the liver and pancreas, which have outer layers similar to the periosteum.
While some organ fail too quickly to allow patients to grow new organs to replace them for some types of organ failure the decline of organ function takes months or years and the problem is diagnosed long before the organ reaches an advanced stage of failure. Plus, advances in embedded nanosensors will lead to much earlier identification of failing organs to provide even more time to grow replacements. Therefore the ability to grow replacement organs within one's own body using one's own cells (which will not suffer from immune rejection) would have great value.
An essential component in Strategies for Engineered Negligible Senescence (SENS) is the replenishment of adult stem cell reservoirs in the body with youthful adult stem cells. Imagine then a two stage process for rejuvenation of organs. First, add youthful stem cells to an existing old organ. Then induce the growth of a new replacement organ in a layer created on the surface of the existing organ. Then once the replacement organ develops to full size remove the old organ.
We still need the ability to grow organs outside of a human body. However, for those cases where replacement organs can grow inside one's body we might gain the ability to grow organs much sooner by use of this "in vivo bioreactor" approach.
Using human embryonic stem cells and a mixture of tissue types a group of researchers has found a way to grow replacement muscle tissue which has blood vessels.
CAMBRIDGE, Mass.--For years, a major obstacle has dashed the hopes of creating "replacement parts" for the human body: the lack of an internal, nourishing blood system in engineered tissues. Without it, thicker tissues can't thrive, which has confined tissue engineering's practical application to thin skin, which can recruit blood vessels from underlying tissue.
Now, researchers in Institute Professor Robert Langer's lab at MIT have used a novel cocktail of cells to coax muscle tissue to develop its own vascular network, a process called pre-vascularization. When implanted in living mice and rats, these tissues integrated more robustly with the body's own tissues than similar implants without blood vessels.
This approach should work with other tissue types.
"What's even more exciting than being able to make skeletal muscles for reconstructive surgery or to repair congenitally defective muscles, for instance, is that this a generic approach that can be applied towards making other complex tissues. It could allow us to do really wonderful things," says collaborator Daniel Kohane, an affiliate at MIT and assistant professor of pediatrics at Harvard Medical School.
The researchers published their work in Nature Biotechnology, available online in advance on June 19, 2005. An accompanying News and Views commentary says this "landmark paper" provides "a compelling demonstration of the benefits of pre-vascularization for engineering larger pieces of tissue."
"When I came to work with Bob Langer for my postdoc, it was my dream to vascularize a tissue," recalls first author Shulamit Levenberg, who is now on the faculty of the biomedical engineering department at Technion in Haifa, Israel where she completed these studies. She chose to tackle muscles, since they depend on blood vessels interspersed with muscle fibers and also serve as a model for highly vascularized organs such as the liver, heart, and lung.
The researchers used three cell types: myoblasts, endothelial cells, and fibroblasts. Some of the endothelial cells formed the needed blood vessels.
Levenberg theorized she needed to combine three cell types: myoblasts that form muscle fibers; endothelial cells that independently self-organize into vessel tubes; and fibroblasts that are the precursors for the smooth muscle cells that stabilize the vessel amidst the tissue's gooey extracellular matrix. "No one had tried a 3-D tri-culture scaffold before. It's hard enough to work with one cell type, let alone three!" explains senior author Langer, who is a pioneer in tissue engineering.
The VEGF mentioned here is a Vascular Endothelial Growth Factor, a hormone that causes blood vessels to form. The process of blood vessel formation is called angiogenesis. Angiogenesis has come to be well understood as a result of Harvard cancer researcher Judah Folkman's decades of pursuit of anti-angiogenesis compounds as an approach to stopping cancer tumor growth. The field of tissue engineering therefore benefits from insights developed by cancer researchers.
In vitro experiments validated Levenberg's hypothesis: "The endothelial cells formed vessels, recruited the fibroblasts, and differentiated them into smooth muscle cells," she says. "The differentiated fibroblasts expressed the angiogenic growth factor, VEGF, which further stimulated vessel growth." The constructs measured 5mm by 5mm by 1mm.
Note the use of human embryonic stem cells to make endothelial cells. My guess is that work was done in Israel.
For implantation in living animals, the lab used immunodeficient mice and rats that would not reject the human-derived endothelial cells. At the beginning of the project, Levenberg had isolated endothelial cells from human embryonic stem cells – a first. Human derivation is key for clinical use to avoid an immune rejection.
The animal studies progressed in stages. First, the researchers implanted a muscle construct under the skin, then inserted one within a leg muscle, and finally replaced a piece of a rat's abdominal muscle with a construct, simulating a situation applicable to trauma victims, for instance. Later tissue staining showed that the implants' vessels grew into the host tissue and the host's vessels grew into the constructs.
But what good are blood vessels if they don't deliver the goods – blood? Using two non-invasive live imaging techniques (labeled lectin injected into the tail vein and a luminescent luciferase-based system), the researchers could watch the host's blood flow into the engineered vessels. About 41% of the constructed vessels became perfused with the hosts' blood, meaning they functioned in the living body. "That's pretty good for a first try," Levenberg asserts.
Importantly, twice as many of the cells survived in the tri-culture implants compared to implants without endothelial cells. "The myoblasts also became even longer tubes when implanted, and they began to align themselves with the host's muscle fibers," Levenberg recounts.
"This tri-culture system shows a whole new way of creating a vascular network in the tissue," summarizes Langer. "We've also demonstrated another powerful use of human embryonic stem cells."
In addition to Kohane, Levenberg and Langer collaborated with Patricia D'Amore and Diane Darland at The Schepens Eye Research Institute, Evan Garfein at Brigham and Women's Hospital, Robert Martin of MIT's Division of Comparative Medicine, Richard Mulligan of Children's Hospital and Harvard Medical School, Clemens van Blitterswijk at Twente University in the Netherlands, and present and former MIT graduate students Mara Macdonald Jeroen Rouwkema.
The discovery of an approach which causes the growth of blood vessels in bioengineered organs lifts a major obstacle in the way of tissue engineering. If tissue engineers can cause cells to build vascular networks then the construction of larger three dimensional pieces of tissue becomes possible.
One of the 7 Strategies for Engineered Negligible Senescence (SENS) is the introduction of replacement cells. I think the category should be worded a bit more broadly since we have parts that are not even cells (e.g. heart valves). Also, while some of those replacement parts will be delivered as cell types injected into the body for many organ failure problems we will need to grow replacement organs. That requires the development of an additional set of capabilities for doing tissue engineering to create three dimensional structures. This latest result is a very helpful step in that direction.
Muscle cells are one of the types of cells that have lost the ability to divide. Biologists call such cells post-mitotic because normal cell division is called mitosis. Knock out of the p38 gene in rats and mice allows muscle cells to divide.
It has long been believed that after initial development, the heart muscle cells can no longer proliferate. The new findings demonstrate that by eliminating a brake that halts the division of the muscle cells, researchers can then trigger the proliferation of the cells by adding specific cardiac growth factors.
The researchers will publish their findings in the May 15, 2005, issue of the journal Genes & Development. The paper was published online on May 3.
The research team was led by Howard Hughes Medical Institute investigator Mark T. Keating at Children's Hospital Boston and Harvard Medical School. Keating and his colleagues collaborated with researchers from the University of California, Los Angeles and Boehringer Ingelheim Pharmaceuticals in Ridgefield, Conn.
“There has been a longstanding controversy going back more than a hundred years about whether cardiomyocytes (cardiac muscle cells) in adult mammals have the capacity to proliferate,” said Keating. “While there have been occasional studies indicating this possibility, the dogma has been that they can't.” According to Keating, researchers thought that once an animal's heart has fully developed, cardiomyocytes lose the molecular plasticity that allows them to divide.
Whenever you read a scientist claim that some cell type X can't be made to do something that another cell type Y can do translate that statement into "We do not yet know how to make cell type X act like cell type Y". Cells in your body are like different computers running the same computer program. The different copies of the computer program may be in different states. But it is inevitable that ways will be found to get cells in one state to change into the state that another cell type uses. This wil be achieved for just about any pairs of cell types that exist in the body (exceptions being red blood cells that have lost their DNA and egg and sperm cells that no longer have full copies of their DNA).
The researchers accomplished their feat by knocking out a gene in rat cells for a protein called p38.
In their studies, Keating and his colleagues explored whether an enzyme called p38 acted as a brake on proliferation of adult cardiomyocytes. Although p38 is known to be involved in regulating cell division, very little is understood about its possible role in cardiomyocytes, said Keating.
In their experiments, the researchers explored whether knocking out p38 activity in cultures of rat cardiomyocytes could induce proliferation. The researchers found that knocking out p38 in the cell cultures of both infant and adult rats — in the presence of a cardiomyocyte growth factor protein called FGF1 — induced DNA synthesis, an important component in cell proliferation.
They also found other indications that the p38-knockout cells were undergoing mitotic proliferation. For example, they found that the proliferating cells dedifferentiated, meaning they temporarily lost the characteristics of mature heart muscle cells and reverted to a more fetal type of proliferating cell. Additional genetic studies of p38 inhibition showed that it regulates genes thought to be critical for cardiomyocyte proliferation.
Importantly, they found that the cardiomyocytes lacking p38 activity could continue to proliferate through many rounds of cell division in the presence of FGF1. “The fact that we could show that were multiple rounds of division is important, because clinical regeneration of cardiac muscle would require the cells to divide again and again,” said Keating.
We wouldn't want to have p38 permanently knocked out in our heart muscle cells. The heart muscle cells might grow too much and possibly even become cancerous. Also, p38 might serve some other as yet undiscovered purposes. But this result demonstrates that the process by which cells become unable to divide (post-mitotic) is reversible.
The scientists also raised mice with the p38 gene knock-out.
“As a result of these experiments, we felt quite confident that we could induce cardiomyocytes to proliferate, at least in vitro,” said Keating. “However, an in vitro system is quite artificial, and there could be many reasons why it would not be relevant in vivo.” So, in further experiments in collaboration with co-author Yibin Wang and his colleagues at UCLA, the researchers tested whether a genetic knockout mouse lacking p38 would show evidence of cardiomyocyte proliferation. Those experiments did yield significant evidence for such proliferation, said Keating.
Keating says a drug that would temporarily knock out p38 activity might enable heart repair after a heart attack. If heart cells could temporarily be given the ability to divide they could grow replacements for lost cells.
“These findings represent the first step toward showing that drugs that eliminate p38 activity could reduce scar tissue formation and enhance cardiac regeneration after cardiac injury,” said Keating. The formation of scar tissue in damaged hearts is the major reason myocardial infarctions lead to subsequent abnormalities and compromised heart function, he said.
A drug aimed at knocking out p38 might also induce regular muscles to grow. But for an old person who has lost a lot of muscle cells throughout the body due to aging such a side effect might even be a benefit. But does p38 also prevent other types of cells from dividing? If a drug that suppresses p38 activity also caused, for example, nerve cells to divide then that would be a very problematic side effect.
Adult and embryonic stem cells are the other major alternatives being investigated for replacing lost heart muscle cells. But if existing muscle cells can be induced to divide they'd offer a few advantages. Most notably, they are already located where the replacement cells are needed. Also, as compared to adult stem cells their DNA might be in better shape because they haven't been dividing for decades collecting errors on each cell division. Though muscle cell DNA does accumulate damage.
We need complete understanding and mastery of the mechanisms which govern cell division both to replenish lost cells and also to cure cancer and other diseases which are caused by excessive cell division. This latest report provides yet another piece of the puzzle.
The Norwegian team used a micro-surgery technique to cut out a small section of the developing spinal cord within the chicken egg.
Human haematopoietic stem cells (hHSCs) from bone marrow were then implanted into the damaged area.
The eggs were incubated before the embryos were removed, and spinal cord slices containing human cells dissected out and analysed.
These neurons were found to be very functional and even have the ability to send signals to other neurons.
Put human haematopoietic stem cells into the right environment and they will become neurons.
Senior researcher Joel C. Glover, of the Institute of Basic Medical Science at the University of Oslo, in Norway said, "We found that bone marrow stem cells did make neurons in the environment of the regenerating embryonic [chick] spinal cord."
There are a number of types of neurons. While the news reports on this study do not say what types of neurons were produced I'm going to guess that they were cholinergic. Parkinson's Disease sufferers need dopaminergic neurons. However, getting the bone marrow stem cells to turn into any kind of neuron is probably the bigger obstacle to get past than getting them to turn into a particular type of neuron. So this result is good news for Parkinson's sufferers.
The key to the success of this model lies in as-yet-unidentified compounds within the quickly developing "microenvironment" of the embryonic spinal cord, said Paul Sanberg, a professor of neurosurgery and director of the University of South Florida's Center for Aging and Brain Repair.
Sanberg, an expert in this kind of research, believes that if scientists can identify those compounds, they might then be able to use them as a kind of cellular fertilizer -- encouraging adult stem cells to generate into human neurons.
Sanberg also commented that since chicken eggs are used on a massive scale to make vaccines (notably influenza vaccine - and that method is too slow to handle deadly pandemics btw) that the infrastructure and considerable experience already exists for using chicken embryos to make suitable cell types for therapeutic purposes.
The ability to take an adult stem cell type and turn it into a differentiated cell type which it does not normally become is strongly suggestive that adult stem cells can be made quite pliable if only scientists can discover the right combinations and concentrations of growth factors to change them. I've always expected this to be the case. But the question has always been just how hard will the search turn out to be to discover the compounds and techniques for converting adult stem cells into a larger range of cell types? Perhaps experiments with chick embryos will provide the means to more rapidly discover how to change the differentiation state of adult stem cells.
While the use of human embryonic stem cells (hESCs) remains morally objectionable in some quarters it is important to note that the use of hESCs may still be a faster approach for the development of some forms of cell therapies. However, even if hESC research is slowed by political opposition it is my very strong expectation that for any therapy that can be developed using hESCs eventually a way will be found to provide an equivalent therapy using adult stem cells instead.
One other point is too often missed in the adult versus embryonic stem cell debate: A larger research effort (meaning more money) would accelerate either of these approaches. I wish as much effort would go into pushing for increased stem cell research funding (even if that funding would come with strings attached with regard to use of hESCs) as currently goes into arguing about hESC research. Lots of questions about stem cells can be answered with research into animal models and lots of progress can be made with adult stem cell research.
An Israeli research team at the Weizmann Institute of Science in Rehovot, Israel has discovered that tissues can be transplanted from organs in developing pig embryos to produce functioning organs in mice if the tissues are extracted from pig embryo organs during an optimal time window that is specific to each organ. (same article here)
Scientists at the Weizmann Institute of Science have determined distinct gestational time windows for the growth of transplanted pig embryonic liver, pancreas and lung precursor tissue into functioning organs in mice. These findings -- appearing this week in PNAS online Early Edition -- could help enhance the chances for successful implementation of embryonic pig tissue in the treatment of a wide spectrum of human diseases.
The study, led by Prof. Yair Reisner of the Institute's Immunology Department, involved the extraction of embryos from sows at various stages of pregnancy and implantation of organ-committed cell tissue into immunodeficient mice. His novel approach did not involve the growth of any tissue in culture. The analysis of embryonic-tissue at various gestational ages revealed a unique pattern of growth and differentiation for each organ.
The potential of embryonic pig tissues as a new source for organ transplantation in humans has been advocated for more than two decades. Transplant too early, however, and the risk is undifferentiated embryonic tissue that can develop into undesirable and possibly malignant tissue, a type of tumor known as "teratoma." Transplant too late and the risk is that the tissues will have reached the stage where they have been marked with certain identifiers that trigger rejection by the new host.
The study demonstrated that maximal liver growth and function were achieved at the earliest teratoma-free gestational age (four weeks). The growth and functional potential of the pancreas occurred later (six weeks) and its optimal transplant age limit was defined by a decline in the insulin- secreting capacity beyond 10 weeks gestational age. Development of mature lung tissue containing essential respiratory system elements was observed at a relatively late gestational age. The sequence of transplanted organ development paralleled that of normal embryonic development in which the liver and pancreas precede the lungs.
"Disappointing results in past transplantation trials may be explained, at least in part, by these results," explains Reisner. Early studies that attempted to cure diabetic patients by implantation of pig embryonic pancreas, made use of late gestation tissue which is now shown to be inferior compared to the optimal six weeks gestational time.
In previous studies, Reisner's group demonstrated that transplanted human and pig kidney embryonic tissue could grow into miniature, functioning human or pig kidneys inside a mouse. His novel approach was a matter of timing: gestational age proved to be the key to successful kidney growth from transplanted embryonic tissue.
Some pretty simple knowledge (the optimal time to take the cells from each organ) may make possible trans-species organ cell transplants (a.k.a. xenotransplantation).
The key is to take cells from an organ during the period soon after it has started to form.
Growing new organs in humans from embryonic pig tissues may be feasible, researchers report, but the cells need to come from specific stages of an embryo's development. Using pig tissue to replace human organs could help patients with diseases such as diabetes, Parkinson's disease, and liver failure, but researchers have so far faced a challenge of balance. On the one hand, stem cells taken from very early in an embryo's development tend to develop tumors after transplantation, whereas tissue from adult organs face rejection by the recipient's immune system. Taking cells from an embryonic organ soon after it has begun to form may strike the ideal balance. To investigate the best time to harvest embryonic cells, Yair Reisner and colleagues took embryonic pig tissue that had begun to form particular organs at various developmental stages and transplanted them into mice. The researchers studied three types of organs--liver, pancreas, and lung--and found unique growth patterns. Optimal time windows were clearly seen for each organ. The authors say these findings may help in part to explain the failure of previous transplantation trials of pancreatic islets in diabetic patients.
This research was sponsored by a American-Israeli tissue transplantation biotech company called Tissera.
Other labs are working on making pigs genetically more compatible with humans by transferring human genes into pigs in order to grow up organs that are highly compatible with humans. See my previous posts "Human Genes Put Into Pig Sperm"and "Genetically Engineering Pigs for Xenotransplantation" for some details. The promise of the genetic engineering approaches is that potentially fully grown organs could be transferred from pigs to humans. Such transfers of fully formed organs might require immunosuppressive drugs to make them compatible. Whereas the transfer of starter cells from early embryo proto-organs may provide greater immunocompatibility.
The obvious advantage of transferring fully formed organs is that they can be used to save people's lives in cases of acute organ failure. When the liver or another vital organ has stopped working entirely there is not enough time to transfer some cells and wait for those cells to grow up into a complete organ. Full sized organs are needed to deal with emergencies. However, in cases where an organ is failing slowly the ability to gradually grow a replacement alongside of it offers the potential for a more immunocompatible replacement.
My guess is that in the future both the use of starter cells to grow replacement organs in a human body and the transfer of fully grown xenotransplants will become commonly used treatments for organ failures. These treatments might even be used in a complementary fashion. Get an emergency full sized xenotransplant organ with immunosuppressive drugs to meet an immediate emergency need and then once the patient is stabilized and healthy transfer in some more immunologically compatible cells to grow yet another organ that will serve as the permanent replacement.
In the longer run it seems reasonable to expect the development of techniques that allow the growth of full sized immunologically compatible organs. Alternatively, full sized organs will be grown up and then immune system modification therapies will be developed that will be able to adjust an immune system to teach it that a transplant organ should be treated as native tissue.
Human embryonic stem cells (hESCs) have previously been converted into many different cell types including a number of nerve cell types. But until now no lab has been successful in converting hESCs into motor neurons. Motor neurons are the nerve cells that run down the spinal cord to send messages to muscle cells to cause muscles to contract. Your body won't motor around without motor neurons to order your muscles to push you along. Suffer from an injury that cuts your motor neurons in your spine and you'll find yourself desiring some replacement motor neurons about as soon as you regain consciousness and are apprised of you tragic predicament. Well, University of Wisconsin-Madison scientists Su-Chun Zhang and Xue-Jun Li have found a sequence of growth factors and other chemicals that can be allied to hESCs to turn them into motor neurons. (also found here)
MADISON - After years of trial and error, scientists have coaxed human embryonic stem cells to become spinal motor neurons, critical nervous system pathways that relay messages from the brain to the rest of the body.
The new findings, reported online today (Jan. 30, 2005) in the journal Nature Biotechnology by scientists from the University of Wisconsin-Madison, are important because they provide critical guideposts for scientists trying to repair damaged or diseased nervous systems.
Motor neurons transmit messages from the brain and spinal cord, dictating almost every movement in the body from the wiggling of a toe to the rolling of an eyeball. The new development could one day help victims of spinal-cord injuries, or pave the way for novel treatments of degenerative diseases such as amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease. With healthy cells grown in the lab, scientists could, in theory, replace dying motor neurons to restore function and alleviate the symptoms of disease or injury.
Much sooner in the future, the advance will allow researchers to create motor neuron modeling systems to screen new drugs, says study leader Su-Chun Zhang, an assistant professor of anatomy and neurology in the Stem Cell Research Program at the Waisman Center at UW-Madison.
Scientists have long believed in the therapeutic promise of embryonic stem cells with their ability to replicate indefinitely and develop into any of the 220 different types of cells and tissues in the body.
But researchers have struggled to convert blank-slate embryonic stem cells into motor neurons, says Zhang. The goal proved elusive even in simpler vertebrates such as mice, whose embryonic stem cells have been available to scientists for decades.
There is a fairly small window in time during which developing embryo cells possess the capacity to turn into motor neurons.
One reason scientists have had difficulty making motor neurons, Zhang believes, may be that they are one of the earliest neural structures to emerge in a developing embryo. With the ticking clock of development in mind, Zhang and his team deduced that there is only a thin sliver of time - roughly the third and fourth week of human development - in which stem cells could be successfully prodded to transform themselves into spinal motor neurons.
I think it is inevitable that methods will be found to dedifferentiate (i.e. make less specialized or less committed to a single purpose) both adult stem cell types and fully specialized cell types (e.g. liver cells or skin fibroblast cells) to turn these cells back into less differentiated stem cells and even all the way back into embryonic stem cells. So for the production of motor neurons we will not always be limited to starting with embryonic stem cells to pass them through that 2 week window in early embryonic development during which embryonic stem cells can be converted into motor neurons. In fact, compounds that cause cellular dedifferentiation have already been found. I expect many more techniques for dediffentiating cells will be found.
Think of cells as enormously complex state machines. Currently it is much easier (though not easy in an absolute sense) to coax cells to switch from the embryonic state into other states. The reason for this is pretty obvious: Cells in the embryonic state must be capable of transitioning through a series of steps into all the other states (e.g. to the state that heart muscle cells are in or the state that liver cells are in or the state that insulin-secreting Pancreatic Isles of Langerham cells are in) because embryos develop to produce cells in all those states. They must have that capacity or else a full organism couldn't develop starting from an embryo. However, just because there are some cell state transitions that do not happen under normal conditions of development that doesn't mean that those transitions can't be made to happen with the right (and waiting to be discovered) sequences of hormones, growth factors, gene therapies, and other stimuli.
Just because some day we will have methods to turn non-embryonic cell types into all other cell types that does not mean that avoidance of the use of hESCs in developing therapies has no future cost in terms of the health of some fraction of the human population. There is a very real possibility that hESCs can be developed for some therapeutic uses faster than other cell types can be developed for all uses. My guess is that at least for some purposes hESCs will be ready to provide treatments faster than adult stem cell types can be coaxed to do the same. We will see more research results such as this paper offering the possibilty of a cell therapy treatment for which the development of alternative non-hESC based cell therapy treatments are a more distant prospect.
Zhang's group had to use precise timings of changes in the biochemical cocktails fed to the cells to produce the desired outcome.
In addition to the narrow time frame, it was also critical to expose the growing stem cells to an array of complex chemical cocktails. The cocktails constitute naturally secreted chemicals - a mix of growth factors and hormones - that provide the exact growing conditions needed to steer the cells down the correct developmental pathway. "You need to teach the [embryonic stem cells] to change step by step, where each step has different conditions and a strict window of time," says Zhang. "Otherwise, it just won't work."
To differentiate into a functional spinal motor neuron, the stem cells advanced through a series of mini-stages, each requiring a unique growing medium and precise timing. To start, the Wisconsin team generated neural stem cells from the embryonic stem cells. They then transformed the neural cells into progenitor cells of motor neurons, which in turn developed in a lab dish into spinal motor neuron cells.
Note that this group had to try many different compounds and timings to find a recipe that worked. Greater automation of lab equipment is accelerating and will continue to accelerate this kind of work by increasing the rate at which different chemical cocktails can be tried in searches for techniques to turn various cell types into other cell types. So I expect the rate of advance of stem cell research of all kinds to accelerate regardless of the likely outcomes of political debates about human embryonic stem cell research.
Bioengineering researchers at the University of California, San Diego have invented a process to help turn embryonic stem cells into the types of specialized cells being sought as possible treatments for dozens of human diseases and health conditions. Sangeeta Bhatia and Shu Chien, UCSD bioengineering professors, and Christopher J. Flaim, a bioengineering graduate student, described the cell-culture technique in a paper published in the February issue of Nature Methods, which became available online on Jan. 21.
It is very likely this technique would be useful in testing proteins for their ability to turn non-embryonic stem cells into other cell types as well.
To find out what would work they had to develop the means to automatically test many different combinations and concentrations of proteins.
“We kept the other factors constant and developed a miniaturized technique to precisely vary extracellular matrix proteins as a way to identify which combinations were optimal in producing differentiated cells from stem cells,” said Bhatia. She, Chien, and Flaim described in their paper a technique that enabled them to identify the precise mix of proteins that optimally prompted mouse embryonic stem cells to begin the differentiation process into liver cells. Bhatia, Chien, and Flaim designed the technique with other cell biologists in mind so that any of them could duplicate it with off-the-shelf chemicals and standardized laboratory machinery. “We think other researchers could easily use this technique with any other tissue in mouse, or human, or any other species,” said Bhatia.
They adopted an existing machine that delivers tiny volumes of DNA and made it deliver protein instead.
In their experiments, the UCSD researchers took advantage of the knowledge that the extracellular matrix in liver is comprised primarily of just five proteins. They applied spots of all 32 possible combinations of the five proteins as engineered niches onto the surface of gel-coated slides, and then added mouse embryonic stem cells to the niches. After the cells were allowed to grow, the researchers assayed their progression into liver cells. “We looked at all the combinations at once,” said Bhatia. “Nobody has done this combinatorial approach before.”
Bhatia, Chien, and Flaim reported that either collagen-1 or fibronectin had strongly positive effects on the differentiation of the stem cells they tested. Unexpectedly however, when both collagen-1 and fibronectin were combined in one niche, the liver cell differentiation process was subtly inhibited. “You would not predict that from the customary cell biology experiments,” said Bhatia. “By using this combinatorial technique we were surprised to find many interesting interactions, and we were able to tease out the effects of each protein, alone and in combination with others.”
Cell biologists have not performed such combinatorial assays for other desired cell types because they had no practical way to do so. Bhatia, Chien, and Flaim seized on the unique ability of so-called DNA spotting machines to deliver tiny volumes of liquid, about one trillionth of a liter per spot. The spotting machines, which cost about $20,000, have become common fixtures at most research universities, but the innovation reported today in Nature Methods involved using such a machine to spot solutions of proteins rather than DNA. The UCSD researchers also refined other parameters so that the technique would be reproducible in other research laboratories.
The more important story here is not the discovery of particular protein combinations that make stem cells differentiate into liver cells. What will be more valuable in the longer run is the ability to apply their technique to more combinations of proteins to convert embryonic and other cell types into various desired cell types. With better tools the rate of progress can accelerate by orders of magnitude. This is yet another example of the general trend toward the development of techniques that are accelerating the rate of advance of biomedical research.
Here is a stem cell therapy, just now entering practical clinical use, that is great because illustrates the future of medicine: it fixes the underlying problem. Make the problem stop happening. A person's own cells extracted from muscle can strengthen bladder muscles and cure incontinence.
CHICAGO - Austrian researchers are successfully treating incontinent women with the patient's own muscle-derived stem cells. The findings of the first clinical study of its kind were presented today at the annual meeting of the Radiological Society of North America (RSNA).
"Urinary incontinence is a major problem for women, and for an increasing number of men," said Ferdinand Frauscher, M.D., associate professor of radiology at the Medical University of Innsbruck and the head of uroradiology at University Hospital. "We believe we have developed a long-lasting and effective treatment that is especially promising because it is generated from the patient's own body."
The stem cells are removed from a patient's arm, cultured in a lab for six weeks, and then injected into the wall of the urethra and into the sphincter muscle. The result is increased muscle mass and contractility of the sphincter and a thicker urethra. Many patients have no urinary leakage within 24 hours after the 15- to 20-minute outpatient procedure.
Stress incontinence affects nearly 15 million people — primarily women — around the world. It occurs when the urethra narrows or becomes otherwise abnormal, or when the sphincter muscles that help open and close the urethra become weak or diminished, causing urine leakage when an individual exercises, coughs, sneezes, laughs or lifts heavy objects.
Twenty females, ages 36 to 84, who were experiencing minor to severe stress incontinence participated in the research. Muscle-derived stem cells were removed from each patient's arm and cultured, or grown, using a patented technique that yielded 50 million new muscle cells (myoblasts) and 50 million connective tissue cells (fibroblasts) after six weeks. When implanted into the patient under general or local anesthetia, the new stem cells began to replicate the existing cells nearby. One year after the procedure, 18 of the study's 20 patients remain continent.
"These are very intelligent cells," Dr. Frauscher said. "Not only do they stay where they are injected, but also they quickly form new muscle tissue and when the muscle mass reaches the appropriate size, the cell growth ceases automatically."
Since the stem cells must be in contact with urethra and sphincter tissue for the procedure to work, a major factor in the success of this treatment was the development of transurethral three-dimensional ultrasound. "With real-time ultrasound, we are able to see exactly where the new cells must be placed," Dr. Frauscher said.
This treatment is a far greater economic value because it is of similar cost to existing treatments but works better because it actually fixes the cause of the problem.
Dr. Frauscher said the cost of the stem cell procedure was comparable to two popular treatments for incontinence: the long-term purchase and use of absorbents, such as adult diapers, and collagen injections, which show improvement during the first six months but often result in symptoms returning after a year. Dr. Frauscher also said the stem cell treatment appears to be more successful with women at this time. For men, incontinence is often caused by prostate surgery, which may result in scar tissue formation, where the stem cells do not grow very well. In men without scar tissue stem cell therapy seems to work as well as in women, Dr. Frauscher said.
Think about the economic value of stem cell treatments. Our problem in the United States isn't that we spend $1.6 trillion (as of 2002 - surely higher now) per year on medical care. Our problem is that so much of that care does not really fix the underlying causes of various medical conditions. Imagine medical treatments were capable of fixing everything that breaks just as auto mechanics can fix cars. Imagine you could therefore live in perfect health. Then I for one would not complain if that takes 15+% of the GDP.
Curiously, the one woman who gained no benefit from the procedure was 84 years old. One plausible explanation for the failure in her case is that her muscle stem cells are too old to form vigorous muscle cells.
The treatment is now being given to many more women beyond the original trial group.
The team is currently treating eight to 10 women per week and long waiting lists are building up.
This treatment is about to become more widely available.
Frauscher, head of uroradiology at University Hospital in Innsbruck, Austria, said his team has plans to start using this technique at other centers. "Next year we will start in three centers in Austria, two in Germany, one in Switzerland and one in the Netherlands," he said. "We are also planning to perform this in the USA."
The needed cells were extracted from the muscle cells and grown up by a company called InnovaCell. They claim to use some patented processes to accomplish this.
What I find great about this report is that it shows that stem cell therapies that really fix what is wrong are moving into regular clinical practice. Stem cell therapies are not some distant prospect. They are happening now and every year that goes by from here on out we will have more stem cell therapies that successfully treat more diseases and disorders.
The tricked eggs divide for four or five days until they reach 50 to 100 cells – the blastocyst stage. These blastocysts should in theory yield stem cells, but because they are parthenogenetic – produced from the egg only – they cannot be viewed as a potential human life, says Karl Swann of the University of Wales College of Medicine in Cardiff, UK.
An enzyme which is normally present in sperm and involved in fertilization was isolated and applied to eggs with no sperm in sight.
Swann’s team tricked the eggs into dividing by injecting phospholipase C-zeta (PLC-zeta), an enzyme produced by sperm that Swann discovered two years ago with Cardiff colleague Tony Lai.
It sounds like Swann's group is repeating with human eggs a process he already demonstrated with mouse eggs a couple of years ago.
This brings up a question I raised in the context of possibly being able to some day isolate pluripotent stem cells from the blood of pregnant women: Will religiously motivated opponents of human embryonic stem cell research (hESC) find this latest technique to be an objectionable way to get cells to use to study embryo development or to induce cells to become organs? After all, there is no fertilization by a sperm (and, as we all know, Every Sperm is Sacred) to trigger the hypothesized moment of ensoulment. So are these cells ethically acceptable for stem cell research?
Biological scientists are going to continue to come up with new ways of manipulating cells that make them hard to place into traditional categories based on their origins. Either the religious folks are going to adopt a definition of human life as beginning at conception or they are going to have to define a cell as the beginning point of life by use of a still-to-be-elucidated statement of epigenetic state of an embryonic cell. If they go the latter route they are going to have to wait till science advances far enough that it can describe the epigenetic state (which will likely be a range of states) that can come into existence right after fertilization and then apply that definition to all other cells that have one of those states regardless of how it got there.
A new study finds surgery to transplant an ovary to the upper arm is feasible and preserves hormonal function in women undergoing treatment for cervical cancer. The report details the technical procedure and outcome of only the second successful human ovarian autotransplantation in the world. The study will be published in the December 15, 2004 issue of CANCER, a peer-reviewed journal of the American Cancer Society. A free abstract of this study will be available via the CANCER News Room upon online publication.
While treatment for cervical cancer, including systemic chemotherapy and regional administration of ionizing radiation, improves survival and cure rates, it can also cause permanent ovarian failure. Since cervical cancer is diagnosed during reproductive years, ovarian failure can be a severe blow to a patient's quality of life. While protecting a patient's fertility has often been studied, there have been no effective options.
Hormonal regulators, such as gonadotropin-releasing hormone, have demonstrated ovarian protection in rats but conflicting data in nonhuman primates. Cryopreservation of embryos has been successful, but there have been no reported successful cryopreservation and transplantation of oocytes or primordial follicles, which are necessary for future fertility. Attempts at ovarian tissue autograft or xenograft without blood vessel anastamoses in animal models and human cases have been promising but hampered by large follicle loss due to ischemia. However, animal models with anastamoses have demonstrated success, but there has been only one prior successful human autotransplant.
In this second successful human trial, C. Hilders, M.D., Ph.D., and a gynecologic surgical team of the Leiden University Hospital, The Netherlands developed a new method of ovarian autotransplantation to preserve ovarian function in a woman treated for cervical cancer. This method does not require developing a donor site with an implant over several months and utilizes a donor site that is easily accessible to noninvasive monitoring and has suitable vasculature.
Autotransplantation of a healthy ovary into the upper arm using brachial vessels to establish blood supply resulted in a functional ovary. Blood flow to and from the ovary was adequate to maintain cyclical follicular growth as verified by ultrasound and clinical examination. Moreover, the surgery did not result in additional operating time.
The authors conclude, "it seems likely that ovarian autotransplantation will be a realistic goal to achieve for women facing cancer, treated by high dose pelvic radiation, to preserve reproductive and hormonal function, thereby substantially improving the quality of life post-treatment."
Note that this is a case of autotransplantation, meaning transplantation between locations in the same body. However, the approach taken here opens up the possibility of temporary transplantation of ovaries between people as well. One can imagine a woman with cervical cancer asking all her friends to volunteer for tissue type compatibility testing so that one of them can keep an ovary alive for her during some more severe form of cancer treatment where the use of chemotherapy would pose a hazard to the ovary even if the organ was placed on the woman's own arm.
But ovary transplants onto arms is still mighty inconvenient and obviously a temporary measure. Another future possibility is that cryopreservation techniques might be improved enough to make cryopreservation a viable option. Cryopreservation would be useful as a way to allow a woman to more reliably reproduce in her late 30s, 40s, and even later ages. Take just one ovary out of a woman when she is, say, 20 years old, cryopreseve it for 20 years, and then transplant it back into the woman to serve as a much younger ovary. This might not only raise the fertility of middle aged women but might also reduce the rate of birth defects for women who reproduce later in life since a cryopreserved ovary would presumably produce a younger egg that would be less likely to contain genetic mutational damage.
Since growth of replacement ovaries will most likely become feasible in two or three decades the long term cryopreservation of ovaries is likely at most to be a transitional technique. Better to just grow a new pair of ovaries for a woman in her late 30s and throw in some genetic engineering to remove a few harmful genetic variations that she doesn't want to pass on to her kids along with adding a few genetic variations that she does want to pass along (e.g. I predict natural blondness will be incredibly popular).
However, there is another potential use of organ cryopreservation: provide a supply of key organs in event of traumatic injury. Combine the ability to grow replacement organs with the ability to freeze them. Anyone with enough money and fear of death from injury could have organs grown from their own starter cells to ensure immunocompatibility Then in event of an injury an organ could be thawed and transplanted to supply a heart, liver, or other needed replacement part.
Even cryopreservation for emergency replacement organs is likely to be a transitional technology at most. If immuno-suppressive techniques improve enough then it will not be necessary to store emergency replacement organs for each individual. If each replacement organ can be made compatible with a large range of people then a much smaller stock of recently grown organs could be constantly replenished to provide replacements to the small subset of the population that needs them. In that scenario organs there would still be a place for organs that are grown for individuals since people will want to replace organs as they age as part of a regular maintenance regime of rejuvenation therapies.
My guess is that by the time tissue engineering techniques have advanced far enough to make routine growth of replacement organs possible immunosuppression techniques will allow a fairly small stocks of organs to serve as the sources of emergency replacement organs. If there is a cost in terms of general suppressed immune response for such an approach then the emergency organs will be used to keep a patient alive until a custom and fully immune compatible organ can be grown up to provide a more compatible replacement for the temporary and less compatible organ.
There is of course one other option worth mentioning: artificial organs. Artificial heart technology is maturing with a number of promising products under development. The CardioWest Temporary Total Artificial Heart won US FDA approval in October 2004.
The CardioWest Temporary Total Artificial Heart (TAH) on Monday became the only device of its kind to be approved by the U.S. Food and Drug Administration.
"This takes the CardioWest TAH off of the Medicare 'experimental list,'" said University of Arizona cardiothoracic surgeon Dr. Jack G. Copeland, who led the study of the device. "It's a huge relief to know that 19 years of work with the device has been officially recognized and that a technology that we believed in has now been released for use by others."
The CardioWest TAH is not being pitched as a permanent solution but rather a tool to use to strengthen a body so that eventual donor heart transplantation has better odds of success.
Then there are cyborg-like bioartificial organs that blend artificial parts with human cells. A bioartificial kidney has recently been tested successfully at the University of Michigan.
ANN ARBOR, Mich. -- The first test in humans of a bioartificial kidney offers hope of the device's potential to save the lives of people with acute renal failure, researchers at the University of Michigan Health System report.
While the phase I/II study was designed primarily to look at the safety of using this device on humans, the results also suggest improvement in kidney function. The patients enrolled in the trial faced an average 86 percent likelihood of dying at the hospital. Six of those 10 patients survived more than 30 days after treatment with the bioartificial kidney. The study appears in the October issue of the journal Kidney International.
"These results showed this type of human adult progenitor/stem cell is well-tolerated by patients with acute renal failure, and resulted in some improvement of the patients' clinical conditions. It's a small study but it was compelling enough for us and the FDA to go forward with a full phase II study," says lead study author H. David Humes, M.D., professor of Internal Medicine at the U-M Medical School. Humes developed the renal tubule assist device, or RAD, the cell cartridge that is key to the bioartificial kidney.
The RAD is being developed for future commercial applications under license to Nephros Therapeutics Inc.
...
The bioartificial kidney includes a cartridge that filters the blood as in traditional kidney dialysis. That cartridge is connected to a renal tubule assist device, which is made of hollow fibers lined with a type of kidney cell called renal proximal tubule cells. These cells are intended to reclaim vital electrolytes, salt, glucose and water, as well as control production of immune system molecules called cytokines, which the body needs to fight infection.
Conventional kidney dialysis machines remove these important components of blood plasma, along with toxic waste products, and cannot provide the cytokine regulation function of living cells. Traditional therapy for patients with acute or chronic renal failure involves dialysis or kidney transplant, both of which have limitations.
While this device operates outside of the body its developers hope to eventually miniaturize it to allow implantation in the body for long term use.
There is a general thread running through all these reports and speculations: organs are going to become as manipulable and replaceable as auto car parts. The sooner this happens the better.
Results from a mouse study point in the direct of a future therapy to restore lost hair in humans.
Master cells nestled within hair follicles of the skin retain the ability to form new hairs as well as skin, new research reported in the September 3 issue of Cell confirms. While earlier work had suggested the presence of stem cells in skin, the new study by Howard Hughes Medical Institute investigators at Rockefeller University in New York provides the first direct evidence that cells extracted from the hair follicles of mice exhibit all of the defining features of true stem cells. The skin stem cells offer potential new methods to reverse baldness and boost wound healing in burn victims and those suffering from other skin injuries, the researchers said.
The putative skin stem cells reproduce themselves seemingly indefinitely in the laboratory, the study found. When engrafted onto the backs of hairless mice, the cells also formed stretches of skin, tufts of hair, and sebaceous glands, which secrete an oily substance known as sebum that lubricates skin and hair.
"We've identified cells within skin that bear all the characteristics of true stem cells--the ability for self renewal and the multipotency required to differentiate into all lineages of epidermis and hair," said Elaine Fuchs, cell biologist at Rockefeller University and senior author of the study. "The results demonstrate for the first time that individual cells isolated from hair follicles can be cultured in the laboratory and retain a capacity to make multiple cell types when grafted."
The researchers isolated two types of stem cells from hair follicles. (same article here)
“An important aspect of this paper was that we found we could isolate and characterize these cells by taking advantage of the cell-surface markers that we had previously identified from molecular profiling experiments,” said Fuchs. “We can now utilize similar methods to begin to compare mouse and human skin stem cells.”
The scientists' analyses of the biochemical characteristics of the isolated mouse stem cells revealed that the bulge contained two distinct populations of stem cells. One type, called “basal” cells, is active during early development. In contrast the “suprabasal” cells appear only after the first hair generation cycle. This distinction offers biologists an opportunity to compare the two groups of cells, in terms of the control that the bulge exerts over their proliferation and differentiation.
The two stem cell types appear at different stages of development.
According to Fuchs, previous studies in her laboratory and others suggested that a structure called the bulge, which is located within each hair follicle, might contain stem cells. Those studies hinted that the stem cells might provide the source of both new skin and hair follicles.
...
The scientists' analyses of the biochemical characteristics of the isolated mouse stem cells revealed that the bulge contained two distinct populations of stem cells. One type, called “basal” cells, is active during early development. In contrast the “suprabasal” cells appear only after the first hair generation cycle. This distinction offers biologists an opportunity to compare the two groups of cells, in terms of the control that the bulge exerts over their proliferation and differentiation.
Both isolated stem cell types can be used to grow hair.
Despite the fact that the stem cells expressed many different genes, both populations were capable of self-renewal when grown in culture, said Fuchs. The researchers also found that both types of cells — even after being cultured — produced hair follicles when grafted onto the skin of a strain of hairless mice.
“I think clinicians will be interested in the fact that both of these populations can produce hair follicles after culture,” said Fuchs. “Previously, researchers have done similar transplant experiments with dissected parts of the hair follicle. And, while they've had evidence that hair follicle structures were forming, they didn't see generation of hair.
“In contrast, in our experiments, we saw quite a density of hairs, in some cases at a density that's very similar to that of normal mouse fur,” said Fuchs. “While we are not yet able to achieve such density a hundred percent of the time, the fact that we do get such density in some cases tells us that the system is working well. We just need to tweak it to the point where we can get such results consistently,” she said.
Imagine this process repeated using human hair follicles to isolate human follicle stem cells. Those stem cells could be grown up and used to get hair growing again on bald scalps. One can also imagine a modified variation of this approach being used to develop cells that can restore hair color in aged hair follicles.
This is not the first result along these lines. See: Transplanted Stem Cells Grow Hair In Mice. However, the latest result goes further in locating, categorizing, and characterizing the stem cells found in hair follicles.
Diana W. Bianchi, M.D. of the Tufts University Sackle School of Graduate Biomedical Research has found that cells from fetuses during pregnancy cross over into mothers and become a large assortment of types of specialized cells in the mothers and persist for years.
Bianchi and her colleagues retrieved cells from the tissue samples of 10 women who had male sons and compared them to tissue samples from 11 women who had never had male offspring. The reason the researchers chose women with male offspring is that it would be easy to detect cells from male offspring because male cells carry the Y chromosome, while female cells do not.
The tissue samples were from the thyroid, cervix, liver, lymph node, intestine, spleen and gallbladder. Skin samples were also collected from 11 women in a control group.
Bianchi said that not only did they find fetal cells present in the mothers' tissue samples, but that the fetal cells had taken on the characteristics of the mother's cells.
This result is very important for the stem cell debate. (same article here)
The findings could also affect the national debate over stem cells, she said, in that they raise the possibility of obtaining stem cells, which can change into many tissues of the body, without the ethical issues involved in creating or destroying human embryos. President Bush has sharply restricted federal funding for research on human embryonic stem cells to keep the government from supporting research that he believes destroys human life.
Pregnant or previously pregnant women could potentially be a source of pluripotent stem cells.
Likewise, the author of the Tufts study, Dr. Diana Bianchi, said another potential source of stem cells is women who have been pregnant.
"Studies have virtually ignored the role of pregnancy, but women who have been pregnant potentially have cells with therapeutic potential from their fetus," she said.
It is possible that many years after a pregnancy there are no longer cells in the mother's body that are fetal and capable of becoming all cell types. But a better point at which to try to catch fetal cells from the blood stream of women would be while they are still pregnant or perhaps shortly after giving birth. If fully pluripotent stem cells can be isolated from the blood of pregnant women then this may well provide a source for such cells that will not raise religious hackles.
Back in 1996 Bianchi first found fetal cells in mothers. But those cells were blood cells only. Her finding that fetal cells are becoming other cell types strongly suggests that fetal cells that are fairly undifferentiated are crossing over into women from fetuses and then differentiating (specializing) into various adult cell types. If those fetal cells that are crossing over are capable of converting into a large variety of specialized cell types then they are quite possibly the equivalent of pluripotent embryonic stem cells.
A confirmation of this result poses what seems to me an ethical problem for the religious opponents of embryonic stem cell research. If developing embryos effectively are donating human embryonic stem cells (hESC) to mothers and literally doing cell therapy to mothers then this natural process is doing something that at least some hESC therapy opponents consider to be morally repugnant.
It will be interesting to see where the various hESC research opponents come down on this result. Will they oppose the extraction of embryonic stem cells from a mother's blood while she is pregnant. If so, on what moral basis?
My guess is that a large fraction of the hESC research opponents will decide that extraction of hESC from a mother's blood is morally acceptable. No fetus will be killed by the extraction. The cells so extracted are not cells that would go on to become a complete new human life. If a sizable portion of the religious hESC opponents can be satisfied by this approach for acquiring hESC then Bianchi's research may well lead to a method to get hESC that will open the gates to a much larger effort to develop therapies based on hESC.
Working with freshly extracted human third molars (wisdom teeth) scientists have been able to isolate stem cells that can turn into the ligament that hold teeth into place.
Scientists at the National Institute of Dental and Craniofacial Research (NIDCR), one of the National Institutes of Health, and their colleagues have isolated human postnatal stem cells for the first time directly from the periodontal ligament, the fibrous, net-like tendon that holds our teeth in their sockets.
The scientists also say these cells have "tremendous potential" to regenerate the periodontal ligament, a common target of advanced gum (periodontal) disease. This enthusiasm is based on follow up experiments, in which the researchers implanted the human adult stem cells into rodents, and most of the cells differentiated into a mixture of periodontal ligament — including the specific fiber bundles that attach tooth to bone — and the mineralized tissue called cementum that covers the roots of our teeth.
"The stem cells produced beautifully dense, regenerated tissue in the animals," said Dr. Songtao Shi, a senior author on the paper and an NIDCR scientist. "That was when we knew they had great potential one day as a treatment for periodontal disease, and we're continuing to follow up on this promise with additional animal work." The results are published in the current issue of The Lancet.
The isolated cells were able to form periodontal ligament.
After further validation of their findings, Shi said he and his colleagues decided to pursue the next big question: Could these stem cells actually form periodontal ligament and cementum when transplanted into mice?
Of the 13 transplants — each of which was derived from a distinct colony of stem cells cultured in the laboratory and loaded into a hydroxyapetite carrier — eight produced a dense mixture of cementum and periodontal ligament. Interestingly, the cells even produced fibrous structures similar to the so-called Sharpey's fibers, which insert into both cementum and bone to hold teeth in place. The other five transplants showed no signs of differentiation.
Shi said his group is now following up on this finding in larger animals. If successful, Shi said he would be eager to evaluate their regenerative ability in people with advanced periodontal disease, which can be extremely difficult to control with current treatments.
My guess is they want to extract similar cells from large non-human animals because for ethical and practical reasons it is easier to do most of the work toward developing therapies using animals before attempting trials in humans.
While the press release has just been released to announce the publishing of the results in Lancet it appears this work was done last year, a patent has already been filed on it, and the final confirming step involved putting the human cells into immunicompromised mice to form the specialized ligament cells.
The NIH announces a new technology wherein stem cells from the PDL have been isolated from adult human PDL. These cells are capable of forming cementum and PDL in immunocompromised mice. In cell culture, PDL stem cells differentiate into collagen fiber forming cells (fibroblasts), cementoblasts, and adipocytes. It is anticipated that these PDL stem cells will be useful for periodontal tissue regeneration to treat periodontal disease.
It is hard to guess when this work will translate into wide availability of human treatments. But the consensus of German stem cell researchers is that some stem cell therapies will be available within 10 years.
My guess is that there are many more sources of adult stem cells hiding in various locations of the human body waiting to be found. Expect to read many more reports of discoveries of types of adult stem cells. Each such discovery is helpful not just as a potential starting source of cells for cell thearpies but also to compare to other cell types to develop a better understanding of how cells differentiate. The more cell types scientists have to compare the better they will be able to figure out how cells control their cell types and how to intervene to alter cell types for therapeutic purposes.
Helmut Drexler of University of Freiburg, Germany and his colleagues treated sufferers of acute myocardial infarctions (i.e. heart attacks) with bone marrow stem cells and found that the bone marrow stem cells boosted the volume of blood pumped by the left ventricle of the heart.
60 patients who had undergone successful percutaneous coronary intervention (PCI; balloon angioplasty and coronary stenting) to restore coronary artery bloodflow took part in the study. Half were given bone marrow stem-cell transfer 5 days after PCI, the other half were given optimum medical therapy. Patients who had been given stem-cell transfer had around a 7% improvement in left-ventricular function compared with only a 0.7% increase for patients given medical therapy.
But he added: "Larger trials are needed to address the effect of bone marrow cell transfer on clinical endpoints, such as the incidence of heart failure and survival."
While other studies have used adult stem cells to attempt to repair damaged hearts this is the first study done using adult stem cells and a proper control group of patients. (same article here)
"What makes this notable is it's the first controlled study where they actually have a control group," said Dr. Robert Bonow, chief of cardiology and professor of medicine at Northwestern University in Chicago and past president of the American Heart Association. "In previous studies, you didn't know whether th