Transplanted stem cells can improve Motor skills in injured rats
FRIDAY, Aug. 30 (HealthDayNews) — Japanese researchers are reporting yet another advance in the repair of damaged body parts using fetal stem cells.
This one could be big because it involves spinal cords, experts say.
The researchers showed for the first time that when stems cell from a rat fetus were transplanted into the spinal cord of injured rats, the cells actually formed synapses, or new connections with existing cells.
New connections mean the cells are being integrated into the normal circuitry of the spinal cord. In other words, the spinal cord is healing.
The result was improved motor capabilities in the injured rats, according to the study published in the Sept. 15 special issue on stem cells in the Journal of Neuroscience Research.
“What the researchers showed in a very elegant way is that the transplanted cells actually make new synapses with existing cells, and that the existing cells also project and make contact with the transplanted cells,” says Jean de Vellis, a professor of neurobiology and director of the Mental Retardation Research Center at the University of California, Los Angeles. “That reciprocity has never been shown before.”
Developing treatments for humans with spinal-cord injuries is probably still years away, but de Vellis believes medicine is getting ever closer.
“This is a very, very hopeful sign that we can achieve partial or even eventually full recovery of the spinal cord,” says de Vellis, who also is editor and chief of the Journal of Neuroscience Research.
Because of their potential to develop into virtually any cell in the body, embryonic and fetal stem cells have become the focus of much research attention. They’ve been tested for their potential to replace cells destroyed in the brain of people with Parkinson’s disease and epilepsy with some success.
However, in many cases the transplanted cells have failed to make the new connections, says Sandra Hill-Felberg, a research instructor at Tulane University’s department of medicine.
“This paper showed you actually get synapses,” Hill-Felberg says. “Most research papers have not gotten that far.”
The team of researchers from Keio University School of Medicine in Japan extracted stem cells from a 14 day-old rat fetus. The type of stem cells they extracted are called neural progenitor cells, which are genetically programmed to later develop into various kinds of nervous system cells.
From the tissue of that one fetus, the researchers than grew enough additional cells in a laboratory to transplant into 450 rats — a feat in itself.
Previous stem cell research has been hampered because some cells that multiply in vitro look normal but they don’t behave like normal cells when they are transplanted, de Vellis says.
“This article is one of the first to better demonstrate a method of multiplying stem cells in vitro that seem to be, at the finest level of structure, normal,” he says.
The Japanese researchers then created a contusion in the spinal cords of hundreds of female rats. The injury didn’t cause paralysis, but interfered with the rats’ coordination and strength, Hill-Felberg explains.
Nine days after the injury, the researchers injected stem cells near the injury site in some of the rats. The others became the control group for comparison.
The nine-day timetable was chosen because previous research has shown that’s the time when the injury site is most hospitable to a transplantation, de Vellis says. At that point, the body reaches its peak production of growth factor around the injury site, part of the body’s attempt to heal itself.
In the future, the hope is that people with older injuries could also be helped by stem cell transplants by also injecting them with growth factor before the transplant, de Vellis says.
Five weeks after the transplant, the rats were tested for their ability to retrieve food pellets from cubbyholes. Thirteen of the 15 transplanted rats were able to eat more than five pellets, compared to 8 of 13 rats from one control group, and 8 of 17 from another.
The rats that didn’t get the transplant showed abnormal limb movements and difficulty directing their paw to the food pellet “target.” The transplanted rats had some of these deficiencies, but at a much lower frequency, according to the study.
Hill-Felberg says she would have liked to see additional tests of the motor skills in the rats that could either confirm the post-transplant improvement or, conversely, show its limitations.
And, she notes, the researchers had to transplant a “huge volume” of cells relative to the size of the rats’ spinal cord. Hill-Felberg says she is concerned injecting an equivalent volume of cells into humans could cause further injury.
Before trying this in humans, lots of additional research needs to be done to determine if there is a better way of delivering the cells than injecting them into the injury site.
“It’s a huge difference jumping from a really small little creature like a rat to a human,” Hill-Felberg says. “A lot of time we find that what you can do in a mouse or a rat just doesn’t work in people.”
What To Do
The National Spinal Cord Injury Association has information about support groups, employment, housing and recreation for people with spinal cord injuries. Or check out the Spinal Cord Injury Information Network.
SOURCES: Jean de Vellis, Ph.D., editor and chief of the Journal of Neuroscience Research, and professor, neurobiology, and director, Mental Retardation Research Center, University of California, Los Angeles; Sandra Hill-Felberg, Ph.D., research instructor, Tulane University department of medicine, New Orleans; Sept. 15, 2002, Journal of Neuroscience Research
By Jennifer Thomas
Copyright © 2002 ScoutNews, LLC. All rights reserved.
Last updated 8/30/2002.