Of Paralyzed Mice and Men

It sounds too good to be true but British writer, Graham Smith, writing September 13 in the British journal Mail Online, reports that a gel containing stem cells, when applied to the site of a spinal cord injury in rats, produced an “astonishing degree” of nerve growth. He reported that treated animals which were previously paralyzed experienced “significant” functional improvement and were able to move all the joints of their affected legs. The gel was made by embedding neural stem cells in a mixture of blood clotting protein and growth chemicals.

The lead researcher is Professor Mark Tuszynski, M.D. Ph.D. from the Department of Neurosciences, University of California at San Diego. Smith quoted Tuszynski as saying, “Using this method, after six weeks the number of axons (nerve fibers) emerging from the injury site exceeded by 200-fold what had ever been seen before. The axons also grew ten times the length of axons in any previous study, and, importantly, the regeneration of these axons resulted in significant functional improvement.”

In the study report, published in the journal Cell, Tuszynski said that there is good reason to believe the new technique may also work in humans. Bradley J. Fikes, of the San Diego North County Times, quoted Tuszynski as saying that the early-stage neural stem cells grew new axonal connections across the injury and re-established significant mobility, something that has not been done before. Both rat and human neural stem cell transplants restored function. Tuszynski said the rats were treated a week following their injury, which is a clinically relevant model for human therapy.

The transplanted cells improved mobility on a 21-point scale, from 1.5 after their spinal cords were severed to 7 after the treatment. “They become new cells of the spinal cord that can form a new relay across the injury site, ” Tuszynski said. “It’s functional based on an improved motor outcome in the injured rats, and based on the transmission of electrical impulses across the injury site.”

The human neural stem cells were obtained from two difference sources; a line of human embryonic stem cells, and one of human fetal spinal cord cells, Tuszynski said.

Additional studies will be needed before the technique is considered safe enough to use on people, he said. The treatment must be tested on larger animals, such as pigs, and the animals must be followed after treatment for long periods of time to see if there are any dangerous side effects. Tuszynski recently received a $4.6 million grant from the California Institute for Regenerative Medicine, which was founded to fund stem cell research when voters approved Proposition 71 in 2004.