Researchers at the San Raffaele Hospital (Milan, Italy) published unexpected results of studies in which immature nerve cells (adult mouse neural stem cells) injected into the blood of mice with MS-like disease were able to suppress the immune attacks that damage the brain and spinal cord tissues. The study is being reported by Drs. Stefano Pluchino, Gianvito Martino and colleagues in the July 14, 2005 issue of Nature. These findings, if confirmed, suggest that neural stem cells that reside in the adult brain may not only serve as replacement cells for tissue repair, but in some circumstances may also protect the brain from inflammation. Further research is needed to address multiple issues involved in translating such experiments into finding ways to fight the immune attack and protect and repair brain tissues in people with MS.

In recent years, scientists have been exploring ways to repair the damage of brain and spinal cord tissues during the course of the immune attack in MS. Evidence suggests that the body successfully repairs some myelin damaged in MS, but not enough to keep up with its loss. Research has shown that adult brains contain stem cells – also known as precursors or progenitors – that might serve as replacement cells. It has been hoped that, given the right signals, these may be stimulated to grow into viable new tissue. The search for these signals is an active area of research. Another possibility being explored is cell transplantation.

Studies involving transplantation of immature myelin-making cells (oligodendrocyte precursors) have been to some degrees successful in rodent models, triggering recovery of function and restoring nerve conduction. However, such repair has only been successful in isolated areas of the brain, whereas MS and MS-like diseases in animal models involve lesions scattered throughout the brain and spinal cord. Finding a way to introduce potential replacement cells that can migrate throughout the central nervous system and home in on damaged areas has presented a significant hurdle in this field.

The San Raffaele Hospital team and others have been investigating transplantation of neural stem cells, which have the potential to develop into various types of brain cells – including nerve cells and myelin-making cells – and which appear capable of expanding their numbers extensively, and moving to distant sites of injury within the brain. In 2003, they reported that neural stem cells transplanted into mice with an MS-like disease were able to migrate to multiple areas of myelin and nerve fiber damage in mice with an MS-like disease, repair this damage, and restore clinical function. (Nature 2003;422:688-694). In the current study, the team attempted to define the mechanisms responsible for the migration of these cells into the brain and to sites of injury. This study was funded in part by the National MS Society (USA), the Myelin Project, the Italian MS Foundation and the Italian Minister of Health.

From National MS Society via ScienceBlog