A Trial in India

| Polio Tips and Techniques

by Dr. Richard L. Bruno

A “maiden attempt” has been made by surgeons in India to implant stem cells into the spinal cords of a “handful” of children who had paralytic polio. Doctors report “encouraging” results as “one of the polio patients…is now able to move her limbs.” This experiment, which uses stem cells harvested from the children’s own bone marrow to prevent rejection, began three months ago and only has been tried on a handful of patients.

“This is just the beginning,” said surgeon D.K. Gupta. “This trial will be carried out for the next three years… on many more patients before we can draw any conclusion. But if the initial results which are so positive and encouraging can be replicated… it could be a ray of hope for polio patients as there is no cure for polio yet.”

Are stem cells the long-awaited cure for polio paralysis? Last November, I talked about using stem cells after acute spinal cord injury and in middle-aged polio survivors, but not in those who had recently been paralyzed by polio.

In someone with a recent spinal cord injury, where scarring and glial cells (the “connective tissue” of the spinal cord) have not yet filled the gap created where spinal cord axons (the long “telephone wires” that connect brain and spinal cord motor neurons, and spinal cord neurons to muscles) were cut, stem cells would fill the gap and restore the connection to allow the brain to “tell” muscles to move again.

In someone like the young Indian polio survivor, stem cells injected into the spinal cord would need to replace the motor neurons recently killed by the poliovirus and connect with the spinal cord axons that go to paralyzed muscles. As in those having a recent spinal cord injury, stem cells would need to be injected before scarring and glial cells filled the space where the poliovirus-killed motor neurons resided and before the axons connected to the paralyzed muscles wither and disappear.

Could stem cells injected into the spinal cord of the Indian child actually have made her “able to move her limbs?” The answer is a very cautious “could be.” As we’ve talked about before, when scientists “publish” their research in the media instead of in peer-reviewed medical journals, there is far too much that we don’t know. How old is the girl? How long ago did she have polio? How much muscle function had she recovered on her own? Which specific muscles began to function again? And, was the stem cell injection just a coincidence, as she would have recovered function on her own as most polio survivors do?

I am eager for these questions to be answered. Obviously, stem cell injections restoring muscle function in young polio survivors, especially those in Third World countries, would save children from a lifetime of disability, rejection and poverty. Since it is unlikely that we will ever eliminate polio, as the recent history of continued polio outbreaks in India and Afghanistan—and new outbreaks in Uzbekistan and now Russia—demonstrate. It may be more cost-effective to provide stem cell therapy for the relatively small number of individuals paralyzed polio each year and provide routine polio vaccination, rather than spending hundreds of millions of dollars trying to eradicate a 3,000 year old virus that poverty and politics, geography, theology and war are keeping alive.

Of course, polio survivors reading this want to know if stem cells will help them. Unfortunately, the answer is no. Even if stem cells injected into the spinal cord became new motor neurons, those neurons would have to send out axons to replace those that withered 50-plus years ago. Those axons would then have to find the appropriate muscles to activate by burrowing inches—and in the case of the muscles of the foot, three feet—through the tissues inside the legs to connect with muscle fi bers that remain that have not themselves been replaced by connective tissue. Finally, the brain’s motor neurons would have to be replaced by stem cells and send out new axons as well, since those neurons and their axons also withered. Brain motor neuron axons would have to burrow through the brain and spinal cord to tell the newly implanted spinal motor neurons what to do.

So, restoring muscle function in middle-aged polio survivors would require a “hat trick” of creating new spinal cord motor neurons, new brain motor neurons plus axons from the brain to the spinal cord and then from the spinal cord to the muscles, a far too daunting task of tunneling!

Dr. Richard Bruno is Chairperson of the International Post-Polio Task Force.