Pig cells may help restore spinal cords

A study published by scientists at the Yale Center for Neuroscience and Regeneration Research suggests the inner lining of a pig’s nose could be used as a treatment for spinal cord injury or disease.

The results of an experiment conducted several months ago showed that damaged monkey spinal cords repaired themselves when the pig cells were transplanted to the affected area. Led by Center Associate Director Jeffery Kocsis, a team of scientists is currently working to ascertain whether these results were due to the successful transplantation of pig olfactory cells or if the spinal cords repaired themselves independent of the transplanted cells.

Lakshmi Bangalore, the scientific liaison officer at the center, said pig cells were used because they can produce myelin — the fatty tissue that insulates nerve fibers in the central nervous system and helps transmit signals along nerves with speed and efficiency. A spinal cord injury usually does not kill neurons, but damages the myelin surrounding them so that nerves can no longer function properly, she said. In the group’s study, transplanted cells from genetically engineered pigs caused a regeneration of myelin around the damaged nerve cells, which restored their ability to transmit information throughout the nervous system.

Bangalore said the research has significant implications for the treatment of multiple sclerosis.

“MS is caused by a lack of myelin, and, after transplanting these cells into damaged areas, we did see regeneration and remylenation,” she said. “Right now we’re just trying to learn as much as possible.”

Associate research scientist Karen Lankford said the center has recently begun to transplant nerve cells from a monkey’s leg into its own spinal cord. This process differs from the original pig cell transplantation, she said, because now, instead of transferring cells from one species to another, the cells taken from one animal are put back into the same individual.

Lankford said this process has an even greater significance than the cross-species transplantation, as it relates to the eventual treatment of humans.

“Ideally, you’d want to use a person’s own cells,” she said. “Even though the pig cells are genetically engineered, they’re still a foreign cell that could possibly be rejected.”

Kocsis said that so far, it appears that the monkey cells require the transplanted pig cells in order to regenerate myelin.

In contrast, damaged cells within a rat’s spinal cord will spontaneously undergo a process of self-repair and will remyelinate themselves without the transplantation of any other cells.

“This process of self-repair doesn’t occur in humans, and we haven’t seen any self-repair in the primates that we have been studying,” Kocsis said. “The potential is there, but they don’t normally repair on their own.”

Kocsis said further research at the center is directed toward determining whether or not the spines of other animals can be stimulated to regenerate by progenitor cells — cells that are slightly more differentiated and specialized than stem cells. He said the research team is also testing to learn if young progenitor cells can be introduced into the central nervous system to facilitate remyelination.

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