I recently came across a video of a talk given by Dr. Hans Keirstead, whose work I have mentioned in a previous post. In the video, posted June 29, 2009 (almost exactly a year ago), Dr. Keirstead showcases his research on a stem cell therapy for SMA. He shows how he was able to grow functional motor neurons (proving it by showing them innervating muscle fibers) and explaining the then-current status of a proposed human trial to replace damaged tissue.
The proposed trial is for infants who suffer from Type 1 SMA. SMA (Spinal Muscular Atrophy) occurs from a malfunctioning SMN gene and the Type 1 (infantile) version is rapidly fatal. Like with a form of ALS called PMA (Progressive Muscular Atrophy), the motor neurons between the spinal cord and muscles die leaving the person paralyzed. When the diaphragm muscle is eventually denervated the person dies of respiratory failure. Regenerative medicine offers a way to replace lost tissue and restore function. In lab and animal tests it appears Dr. Keirstead has been successful. now for the next step.
There seem to be good reasons to try this in SMA infants. I am going to be coldly blunt but I beg the reader to take a breath and stay with me. First, the infants are going to die very soon so the trial length is short; you will see quick benefit or have rapid access to post-mortem tissue (also the reason Neuralstem included late-stage ALS patients in its trial). Because of the infants small size, the grafted neurons don’t have far to go to innervate muscle. In an adult such as myself motor neurons would have to grow a bit over a meter to reach fingers and toes. Even the phrenic nerve (the “money” nerve in neurodegenerative disease) would need to grow nearly half a meter to innervate my diaphragm muscle. Nerves grow slow so that could take as much as two years (for the more distal muscles). Infant bodies are still also in a rapid growth mode which may assist the grafts (mentioned in the Stanford study in a previous post). I could also guess that an immature immune system may be beneficial for anti-rejection purposes (pure speculation on my part). Time is in critically short supply in SMA (and ALS) so having short trial lengths is crucial. June 22, 2010 update on program progress.
Because SMA is so similar to ALS, if this trial goes well it would be huge news for PALS. In fact, ALS is the next disease in line for this treatment. With this program and the concurrent ongoing programs by Brainstorm, TCA, and Neuralstem either soon to be or currently in trial, I have great hope for regenerative medicine.
As always I invite responsible comments or questions.