Cell Transplant Tested as Treatment for Nerve Pain in Mice
WEDNESDAY May 23, 2012 -- A new study in mice suggests that scientists may someday be able to treat nerve pain by transplanting embryonic nerve cells to restore a broken nervous system.
There are plenty of caveats. It's not clear if the treatment will work in humans, and its cost and possible side effects are unknown. Still, there's potential for researchers to make a difference for people with nerve pain. The condition, also known as neuropathic pain, can make parts of the body ultra sensitive to touch and can be difficult to treat.
"Nothing that gets rid of the pain works for a long period of time," said study co-author Allan Basbaum, chair of the department of anatomy at the University of California, San Francisco. "The problem is that even if drugs sort of work, they work everywhere in the body and inevitably have adverse side effects like sedation and mental clouding."
Nerve pain can strike a variety of types of patients, from those who have had shingles or undergone chemotherapy to those with diabetes. Scientists think certain nerve cells become damaged or lost, and lose the ability to regulate the pain signals that go to the brain, Basbaum said.
That's why a light touch, which the nervous system would normally regard as nothing to worry about, can explode in the brain as severe pain as nerve cells fail to dampen the sensation. In the new study, Basbaum and colleagues injected embryonic nerve cells into the spinal cords of mice in an attempt to repair their broken nerves.
Some of the cells developed into neurons. Within four weeks, the mice lost their hypersensitivity. Basbaum said the findings show "unequivocally" that the cells integrated into the nervous system of the mice.
The next step is to inject human embryonic nerve cells into mice that are genetically engineered to not reject human tissue. "We want to do the groundwork to learn how to handle human cells," Basbaum said.
The ultimate goal is to test the treatment in humans, Basbaum said. "But if the cells don't integrate as they do in the mouse, or the cells don't survive, then it doesn't work."
He said the potential cost of the procedure isn't known. Any work with human embryonic cells could create controversy because they're derived from human embryos. However, scientists are trying to find alternative ways to develop the cells.
Laura Stone, an assistant professor at McGill University's Alan Edwards Center for Research on Pain in Montreal, praised the study.
The research "demonstrates that transplantation of cells into the spinal cord could be used as a strategy perhaps not only in chronic pain but in spinal cord injury or other neurodegenerative disorders," she said.
Still, the treatment that worked in mice might not work in humans. Even if it does, an available treatment for people would be "many, many years away," Stone added.
In the big picture, however, "there has been an enormous amount of progress in the last 20 years on understanding basic mechanisms underlying chronic pain in general and neuropathic pain in particular," Stone said. "We as a field have identified many new possible drug targets that were unknown just a few years ago."
The study appears in the May 24 issue of the journal Neuron.
For more on back pain, try the U.S. National Library of Medicine.
Posted: May 2012