Behold the chimera… But before that, behold the angry mob cursing at whoever shut down the clinical trial inching toward a solution for mending damaged spinal cord tissue. That trial, previously under way at the Shepherd Center in Atlanta, used human study subjects to test a stem cell treatment shown in the laboratory to give spine-damaged rats the ability to walk again. The implications of the trial for many physically disabled individuals were breathtaking. However, Geron, the company behind the research, had laid out $150 million to get the program as far as the first year of the human trial with no promise of a payback. With resources dwindling, the organization moved to cut its losses. In November 2011, after having initiated treatment on four human subjects, Geron announced the study was over.
It’s hard to blame Geron. It has to make payroll like everyone else. With the project now on life support, though, Geron reports it is seeking partners who can afford to float the trial financially and keep it moving forward. The situation seems hopeful but, in my estimation, unlikely.
Not all is gloom and doom for spinal cord injury research this year, however. Some recent developments are, in fact, downright encouraging. The first positive sign is that the shutdown of the Shepherd Center study forces us to recognize the United States government finally did right by the medical community. Specifically, the FDA gave its full blessing to the Geron trial and, in so doing, made it the first ever government-approved embryonic stem cell trial on human subjects in this country. Could it be the FDA has taken notice that stem cell research may offer real tools to battle conditions that ultimately show up as big ticket items on the national health care tab? If so, this is an ideal time to introduce a second bit of good news that may foretell another leap forward: a new chimera monkey, tailor-made for spinal cord injury research.
In medical research jargon, “chimera” typically refers to a genetically modified lab animal, such as a mouse engineered with a specific gene missing so that conditions such as Parkinson’s disease or diabetes might be easily studied. Rodent chimeras have been generally good for medical science, but come with vexing limitations. For one, it turns out spinal cord-injured rodents are naturally predisposed to better recovery of locomotion than humans, which can skew the results of how a test subject responds to a spinal cord treatment. A treatment that enables rodents to walk may do nothing at all for humans. Another difficulty in working with rodent models is that rats don’t live nearly as long as humans, which makes translating the long-term effects of stem cell transplants from rat models into humans dicey. These problems diminish when researchers utilize an animal whose physiology closely resembles our own, and has a lifespan of a couple of decades rather than a couple of years.
Recently, the Oregon National Primate Research Center (ONPRC) announced it had successfully created the world’s first chimeric monkeys, cobbled together with early-stage stem cells taken from up to six different rhesus monkeys, rather than the standard two-parent configuration. Good news for the research community. Shoukhrat Mitalipov, PhD, the man behind the newly minted primates, explains in a recent Reuters interview that the creatures were created to deepen the understanding of stem cells and to gauge whether stem cells for humans can develop into mature functional tissues. In a separate news release Mitalipov points out stem cell therapies offer promise as a way to replace damaged nerve cells among individuals paralyzed as the result of a spinal cord injury. “As we move stem cell therapies from the lab to clinics and from the mouse to humans, we need to understand what these cells do and what they can’t do, and also how cell function can differ in species,” Mitalipov notes.
Science now has a bold new primate that can kick research into high gear. This, coupled with the government’s less timid posture toward using humans in embryonic stem cell trials, could nicely position spinal cord injury research in 2012. One great unknown lingers: will embryonic stem cell research survive the coming presidential election? It would be tragic if the favorable conditions outlined here collapse under the pen of a president bent on vetoing embryonic stem cell research out of existence. I am not suggesting a specific candidate for your vote, nor am I suggesting you keep the guy already in office. What I insist on, however, is that you discover which candidate is likely to keep this research moving forward and which is likely to kill it. The information is out there—find it. Then cast your vote for yourself, and for your patients.
Editor’s Note: Look for an exciting new digital edition of Rehab Management beginning with our March issue.
—Frank Long
