According to lead author Dr. Stephen Davies, assistant professor of neurosurgery at Baylor College of Medicine in Houston the rats were given immature immune system support cells called astrocytes and this resulted in a 40-percent rise in nerve-fiber growth at the site of the injury in only eight days.
The results of the research is published in the April 26 in the open-access Journal of Biology. The Christopher Reeve Foundation has partly funded this research.
Stem cell technology for the repair of the central nervous system in humans has been the focus of several studies over many years. This study has shown advances in the use of that technology. Stem cells have the ability to respond to signals in tissue to become cells of that particular type of tissue.
Stem cells can be either of adult or embryonic origin. Adult stem cells are derived from the body's tissue or organs whereas embryonic stem cells are derived from eggs fertilized in vitro.
Davies explains that the body normally creates scar tissue to prevent infection during any injury including a spinal cord injury. However this mechanism can have disastrous consequences on the spinal cord because scars inhibit nerve-fiber regeneration thereby leading to paralysis and other problems.
And for this very reason transplanting adult stem cells into an injured spinal cord does not encourage nerve growth. .
This led the Davies team to think of signaling cells similar to stem cells known as the glial-restricted precursors, or GRPs, to become a particular type of embryonic astrocyte which was considered to have a remarkable ability of repairing embryonic spinal cord. This in turn was considered for transplantation into adult spinal cord injuries that could inhibit scarring while encouraging nerve growth at the same time.
For this purpose a specific type of astrocyte support cell was generated from the GRPs, discovered by cell biologist Margot Mayer-Proschel of the University of Rochester Medical Center.
It was observed that rats given this specialized astrocyte cell showed less scar tissue and nerve damage in contrast to the control group, which was transplanted with un-cultured cells. Amazingly their locomotion improved to such an extent that they could walk completely normally within two weeks of the treatment
In addition it was observed that the brains of these rats also demonstrated improvement. This was unusual because degeneration of neurons often occurs with spinal cord injuries due to the degeneration of their nerve fibers running down the spinal cord. However with the astrocyte transplant up to 80 percent of nerve degeneration was suppressed.
Dr. Wise Young, a neuroscientist and director of Rutgers University`s W.M. Keck Center for Collaborative Neuroscience has been a pioneer in treating spinal-cord injury. He has organized clinical trials in China, where the influence of umbilical-cord blood stem cells in the central nervous system is planned.
According to Young 'The paper shows very compelling data for moving GRPs to clinical trial as soon as compatible human cells can be obtained.'
However Davies points out that the lack of availability of stem-cell lines in the United States was a big hurdle to be crossed as hundreds of thousands of the GRP cells would be required to act in a person.
Young still remains optimistic that the day was not too far when scientists would be able to make any cell into a stem cell.
In the future Davies hopes to use the new technology to repair central nervous system injuries in people, as well as other neurodegenerative diseases.