August 01, 2010
Replacement Joints Grown Quickly In Rabbits

It is important to remember why old cars can outlast old humans: Failed car parts can be replaced. With rare exception failed human parts can't be replaced. But a team of researchers has recently developed a way to grow replacement joints in rabbits.

A pioneering study published Online First in the Lancet has shown that failing joints can be replaced with a joint grown naturally using the host's own stem cells. The work paves the way for a future of naturally grown joints that would last longer than currently used artificial joints. The work was carried out by Professor Jeremy J Mao, and his team at Columbia University Medical Center, New York, USA, and colleagues from University of Missouri and Clemson University.

Rather than try to grow replacement parts outside the body the trend in tissue engineering is to try to create the right local conditions within the body. This would probably be harder to do when growing replacement organs since existing organs often can't be removed to make room for new organs. The existing heart or liver needs to keep functioning while the replacement is grown. Though I wonder whether a big cavity could be created in the body where replacement organs could grow. Imagine walking around with an extended gut similar to pregnant women. But rather than growing a new baby you'd be growing a new full-sized heart or kidney or pancreas.

Growth factor was used to attract the rabbits' own stem cells to very rapidly build up a new joint on implanted scaffolds.

In this proof-of-concept study, Professor Mao and colleagues removed the forelimb thigh joint of 10 rabbits, and then implanted three dimensional biomaterial scaffolds infused with growth factor. The rabbits' own stem cells were 'homed' by the growth factor to go to the location of the missing joint, and regenerated cartilage and bone in two separate layers. Just four weeks later, the rabbits were able to resume normal movements, similar to rabbits with normal functional joints. These rabbits had grown their own joint using their own stem cells, instead of stem cells harvested apart or outside of the host.

This is an amazing result. His team is going to try goats next. How many years will we have to wait before this technique is tried in humans?

Check out the pictures for how this is done.

Share |      Randall Parker, 2010 August 01 04:34 PM  Biotech Repair Joints

Black Death said at August 2, 2010 6:05 AM:

Assuming that this exciting technology is one day ready for prime time in humans, an interesting question then arises - who is going to pay for it? Government-sponsored health care programs, whether single-payer (Canada, UK) or part of a public-private system (US) are headed over the financial cliff and on to the rocks below. Most elderly people have some degenerative arthritis - will they all get joint replacements? Will people who have destroyed their livers with alcohol get new ones? How about smokers who've ruined their lungs or hearts? Now organs for them? All the more reason to save your money and plan to pay for it yourself - who wants to die on a waiting list?

Lou Pagnucco said at August 2, 2010 8:30 AM:

Hopefully, this technology will advance quickly without the typical bureaucratic impediments.

Perhaps, given the prevalence of osteoarthritis, some assembly-line mass production techniques may develop, like for cataracts. Maybe, similar approaches can repair dental ligaments, skin, bone, tooth surfaces, etc.

Black Death points out a dilemma. Especially now, with the wealth chasm growing between classes, new medical technology may not be available to all, or even most. Politicians will resort to evasion and obfuscation.

Lou Pagnucco said at August 2, 2010 8:36 AM:

I should have added one of today's directly related press releases:

Growing Organs and Helping Wounds Heal
A strong, stretchy material could provide a scaffold for growing organs or making wounds heal faster

James Bowery said at August 2, 2010 9:24 AM:

Since inflammation is a catalyst for senescence, I wonder if this might be more significant for life extension than might otherwise be apparent. It would, of course, entail early intervention in osteoarthritis and perhaps frequent replacement to really have life extensive properties.

Nick G said at August 2, 2010 9:37 AM:

I think that organ replacement is the wrong approach.

Better to prevent injury. We need to indentify the basic causes of aging. Why do 120 lb dogs get severe arthritis at age 5, and 120 lb humans at 70? Similarly, rates live 2-3 years, and bats live 50 years. Why couldn't the underlying rate of aging be reset to postpone arthritis to 170? Surely that would be far more effective and comfortable and far cheaper?

At the moment basic research into the basic causes of aging is badly underfunded: perhaps 3% of the Nat Institute on Aging (drug companies explicity say that they don't want to do such research).

100M people per year, dying preventable deaths. A far greater tragedy than anything else one can imagine.

Jim said at August 2, 2010 1:10 PM:

Ask me the money is in dogs and cats, so why not test on those first?
Replacing/repairing people's pets limbs is far more lucrative.

People might come later... though why throw the money away--- test away on animals with a near immediate return IMHO.
Work on people later when the tech is solid.

Goats... how short sighted is that--
when veterinarians would be lining up to get that tech today (like what Lasik did for Optometrists).

Randall Parker said at August 2, 2010 5:18 PM:

Nick G,

Slowing down aging is harder than organ replacement. Even if we knew how to genetically reprogram our cells to last longer the easiest way to do that is to reprogram a few cells and then grow those cells up into whole organs.

Also, most people already have a substantial chunk of aging that has happened to their bodies. With aging populations come higher average ages. As of 2009 the median male age in the United States is 35.4 years and for women 38 years. The overall median age in Germany is 44.3 years. Check out all the median ages at that latter link. In the industrialized countries people are already mostly middle aged or later.

Every person reading this is going to be 10 years older before technologies for substantially slowing aging will be available.


Good point about pets. A lot of useful clinical experience on joint rejuvenation could be racked up using pets real soon.

Randall Parker said at August 2, 2010 5:26 PM:

James Bowery,

Inflammation: This is one of the reasons I eat olives daily. Olives down-regulate genes for inflammation.

Senescent cells: We need a way to tell them to commit suicide. This would make room for healthier cells to take their place.

Tylwyth Waff said at August 2, 2010 10:40 PM:
Though I wonder whether a big cavity could be created in the body where replacement organs could grow.
It's called a "uterus," although when it doesn't have a head, we call it an "axlotl tank."
Nick G said at August 3, 2010 8:31 AM:


Those are good thoughts - I'm not suggesting we abandon this kind of organ replacement research - we'll certainly need much better repair methods. I'm simply suggesting that we're badly suboptimizing our research dollars by neglecting basic aging research. Calorie restriction appears to work almost immediately in simple organisms, and apply to almost all froms of aging-related degeneration, suggesting something very basic and powerful. Aging research would be likely to bear fruit for almost every branch of medicine, and for almost every degenerative disease. For instance, we spend $1B on Alzheimer's research, and $30M on basic aging research. This badly, badly suboptimal.

Also, slowing down aging may be harder than organ replacement, and the easiest method may be to reprogram a few cells and then grow those cells up into whole organs. We simply don't know yet what will be easiest or work the best - we haven't done the research.

Nick G said at August 3, 2010 10:45 AM:

Let me put finer point on that: individual diseases are sexier, and have constituencies. For instance, one of the founders of Google is personally spending $50M on Parkinson's research simply because he has a genetic risk of getting it - that's just one small part of many funding sources for that disease. The same thing is true for many other diseases: breast cancer, Muscular Dystrophy, you name it.

Meanwhile, basic aging research is geting only $30M in total. This is incredibly suboptimal.

Randall Parker said at August 3, 2010 7:34 PM:

Nick G,

I would agree there's too much going into specific diseases. However, if I could shift the focus I would shift it toward developing capabilities. We need better capabilities for measuring and manipulating what goes on in cells and organisms. We need automated miniature devices and sensors and microscopic chemical factories under digital control.

Nick G said at August 4, 2010 9:21 AM:


That's a great idea. Still, I think the suboptimal level investment in basic aging research is incredibly important. Thirty years ago I expected to be much more relaxed about getting old than I am. I'm beginning to fear that when I am 80 years old, that I will be suffering from growing disabilities and facing a short life expectancy.

It angers me that the medical establishment is moving like molasses - researchers and companies seem to much more afraid of failure than they are of success, thus they focus on uncontroversial research and incremental improvements. Further, they truly seem to be afraid of finding solutions to medical problems, and therefore hurting their careers or profitability. This, too, is motive to aim for tiny incremental improvements in order to extend life of their products. They develop me-too drugs to extend their patents. They look for treatments and drugs that they can sell for people's lifetimes: the mantra for cancer, for instance, is making cancer a chronic disease, rather than a killer. How about just curing it??

Again, a 120 lb dog begins to suffer from all the ailments of aging at 5 years, while humans don't see the same until they are 10x as old. Why the difference? Why is no one looking??

Matt said at August 14, 2010 7:18 PM:

Interesting discussions.

The new research sounds promising.

I injured my left hip 4 years ago (age 26), and I'm in pain every day. Dang, I don't want an implant, despite the fact I hear they're pretty damn good these days (and will probably get even better..). I'd rather become a human guinea pig and take part in stem cell trials.

Is Suspended Animation possible, or is it still within the realms of science-fiction? That would be ideal, wake up in the year 2070, when people will be getting diagnosed with cancer and having a laugh and a joke about it with their doctor - "Eh? You've got cancer again?? Jeez what are you like. Here take these, and I don't want to see you back here again"

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