for National Geographic News
A new study shows that human stem cells injected into mice can repair damaged spinal cords and help partially paralyzed mice walk again.
Although many questions remain unanswered, the research raises the hope of using stem cells to help people with spinal cord injuries.
"We're very excited about these stem cells," said Aileen Anderson of the Department of Physical Medicine and Rehabilitation at the University of California, Irvine. "We're really on the cusp of making some big leaps forward."
Previous research has suggested that human stem cells can help rodents recover from spinal injuries. But the new study marks the first time that scientists have shown that human stem cells make connections with the nervous systems of the mice and are thus key to recovery from spinal cord injuries.
The findings are reported today in the journal Proceedings of the National Academy of Sciences.
Stem cells are primitive cells with the power to transform into the various cells and tissues found in the human body. There are many types of stem cells, from bone marrow to fetal tissue to embryos.
For their experiment, the UC Irvine researchers used fetal brain stem cells provided by StemCells Inc., a Palo Alto, California-based company. The scientists injured the spinal cords of mice and nine days later injected them with the stem cells.
Using mice, scientists can easily mimic the damage caused to humans in a car or diving accident, making mice an excellent model to study neurological diseases.
The researchers found that the stem cells migrate up the spinal cord and develop into multiple different neural cell types, including neurons and oligodendrocytes, the cell type that forms insulating myelin sheaths around nerves.
Myelin is a nerve-fiber coating that plays a critical role in maintaining the nervous system's electrical conduction. Injuries or disease that strip away this protective layer can lead to sensory or motor deficiencies and sometimes paralysis.
"We show that these [stem] cells make connections with the nervous system of the mouse in a way that is appropriate and could mediate recovery," Anderson said. "That's a big thing."
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