Researchers at the UC Irvine Reeve-Irvine Research Center have used adult human neural stem cells to successfully regenerate damaged spinal cord tissue and improve mobility in mice.
The findings point to the promise of using this type of cells for possible therapies to help humans who have spinal cord injuries. Study results appear online in the Proceedings of the National Academy of Sciences Early Edition.
In their study, Brian Cummings, Aileen Anderson and colleagues injected adult human neural stem cells into mice with limited mobility due to spinal cord injuries. These transplanted stem cells differentiated into new oligodendrocyte cells that restored myelin around damaged mouse axons. Additionally, transplanted cells differentiated into new neurons that formed synaptic connections with mouse neurons.
The ability to grow new myelin sheath would also be very beneficial to patients suffering from multiple sclerosis.
Myelin is the biological insulation for nerve fibers that is critical for maintenance of electrical conduction in the central nervous system. When myelin is stripped away through disease or injury, sensory and motor deficiencies result and, in some cases, paralysis can occur. Previous Reeve-Irvine research has shown that transplantation of oligodendrocyte precursors derived from human embryonic stem cells restores mobility in rats.
“We set out to find whether these cells would be able to respond to the injury in an appropriate and beneficial way on their own,” Cummings said. “We were excited to find that the cells responded to the damage by making appropriate new cells that could assist in repair. This study supports the possibility that formation of new myelin and new neurons may contribute to recovery.”
Coordinated walking ability was restored.
Mice that received human neural stem cells nine days after spinal cord injury showed improvements in walking ability compared to mice that received either no cells or a control transplant of human fibroblast cells (which cannot differentiate into nervous system cells). Further experiments showed behavioral improvements after either moderate or more severe injuries, with the treated mice being able to step using the hind paws and coordinate stepping between paws whereas control mice were uncoordinated.
The cells survived and improved walking ability for at least four months after transplantation. Sixteen weeks after transplantation, the engrafted human cells were killed using diphtheria toxin (which is only toxic to the human cells, not the mouse). This procedure abolished the improvements in walking, suggesting that the human neural stem cells were the vital catalysts for the maintained mobility.
The lack of need to condition the stem cells to become specific types of cells makes this a simpler approach to apply than attempts which used less differentiated human embryonic stem cells.
This study differs from previous work using human embryonic stem cells in spinal cord injury because the human neural stem cells were not coaxed into becoming specific cell types before transplantation.
If human cells can improve movement in mice the likelihood that these same cells would deliver a similar benefit in humans with spinal cord injuries seems high.
The British newspaper The Guardian reports that the stem cells came from neural tissue of aborted fetuses.
Neuroscientist Aileen Anderson and her team at the Reeve-Irvine Research Centre at the University of California, Irvine, used stem cells taken from the neural tissue of aborted foetuses. When injected into the body, they can develop into any type of nervous tissue.
Can anyone confirm this? Neither the UC Irvine press release or the press release of the company that supplied the stem cells (see below) make any mention of this fact.
The company that supplied the stem cells to the UC Irvine researchers is Palo Alto California based StemCells Inc. The StemCells Inc. press release mentions that the Christopher Reeve Foundation was one of the sources of funds for this research (bringing to mind that South Park episode where Reeve's character ate fetal brains and became extremely vigorous as a result)
PALO ALTO, Calif., (September 19, 2005) – StemCells, Inc. (Nasdaq: STEM) today announced results of a published study that demonstrates that the Company’s proprietary human neural stem cells restore the lost motor function of mice with spinal cord injuries. This study is also the first to show the causal relationship between transplanted human neural stem cells and long-term recovery of motor function: The human neural cells were subsequently ablated in some of the mice, and their improved motor function was lost.
The study was conducted by Drs. Aileen Anderson, Brian Cummings and their colleagues from the Reeve Irvine Research Center at the University of California, Irvine. It will be published today online in the Early Edition of the Proceedings of the National Academy of Sciences of the United States of America (PNAS), and will appear in the September 27, 2005 print issue. The study was funded in part by a Small Business Innovative Research Grant from the National Institute of Health (NIH) to StemCells, Inc. Support was also provided by the Christopher Reeve Foundation through its International Research Consortium on Spinal Cord Injury.
The CEO of StemCells Inc. says these are still early days. But what obstacle exists for trying out these stem cells in paralyzed humans right now?
“While we are early in our quest to find a stem cell therapy for spinal cord injury, the design of this study raises the bar for evaluating experimental cell-based therapies in this extremely debilitating medical condition,” said Martin McGlynn, President and Chief Executive Officer of StemCells. “The study clearly demonstrates that our proprietary human neural stem cells make functional new neural cells, and are responsible for the restoration of hind limb function in this animal model of spinal cord injury.”
In the StemCells Inc. press release they refer to the cells as having been isolated from "normal brain tissue".
StemCells, Inc. is a development stage biotechnology company focused on the discovery, development and commercialization of stem cell-based therapies to treat diseases of the nervous system, liver and pancreas. The Company’s stem cell programs seek to repair or repopulate neural or other tissue that has been damaged or lost as a result of disease or injury. StemCells is the first company to directly identify and isolate human neural stem cells from normal brain tissue. These stem cells are expandable into cell banks for therapeutic use, which demonstrates the feasibility of using normal, non-genetically modified cells as cell-based therapies. StemCells is the only publicly traded company solely focused on stem cell research and development and has more than 40 U.S. and 100 non-U.S. patents, as well as 100 patent applications pending worldwide.
On one hand abortion is already legal in the United States and has been for decades. So use of neural stem cell tissue from aborted fetuses does not result in more fetuses getting killed. On the other hand, abortion opponents will surely get angry at the idea of remains of aborted fetuses getting used to develop medical treatments.
Put aside the ethical considerations. Think about the medical implications. The scientific lesson here is that types of neural stem cells already exist that can at least partially and substantially repair spinal cord injury. The delivery of those cells does not require creation of a futuristic high tech artificial biochemical environment in the spine (say complex chemical gradients varying through time) or an elaborate system for controlling the migration and differentiation of the cells. Given the development of the right sort of neural stem cells a substantial amount of spinal repair becomes possible pretty easily.
The technical point here, even for abortion opponents, is that if a way to make the right sorts of neural stem cells can be found then stem cells can fix damaged spines. Granted, some people would prefer a different way to make these stem cells. I expect other ways will be found. But once stem cells can get programmed to the right epigenetic state then the cells will repair spinal cords. That's good news.
Update: Be sure to read the comments on this post. Garson Poole points to the use of premature births that die as a source of cells. This neatly sidesteps opposition to abortion. The use of organs from people who unexpectedly die is morally accepted across the political spectrum (with the exception of perhaps a couple of religious demoninations that do not oppose this choice by others). So why not the same with premature births?
|Share |||Randall Parker, 2005 September 20 12:05 PM Biotech Stem Cells|