The Self-Healing Brain?

Jack Parent Photo: Martin Vloet

University of Michigan neurologist Jack M. Parent, M.D., is fascinated by how primitive neural cells called neuroblasts respond to acute brain injuries. In a series of experiments with laboratory rats, Parent found that neuroblasts multiply and form neural chains that move across the brain to the injury site in an attempt to form new neurons. Understanding how this self-repair mechanism works could someday help physicians reduce brain damage from strokes or neurodegenerative diseases.

“There is some cue in common that activates neural development and growth. We don’t know what it is, but we are looking for candidate molecules — growth factors or neurotrophic factors — that stimulate the proliferation and migration of precursor cells,” says Parent, an assistant professor of neurology in the U-M Medical School.

Until recently, scientists believed the mammalian adult central nervous system — the brain and spinal cord — was incapable of generating new neurons from adult stem cells, a process known as neurogenesis. But now scientists know that precursor cells in a part of the brain called the subventricular zone or SVZ continue to produce new neurons throughout life for the brain’s olfactory bulb, which processes scent. Another area of the brain called the dentate gyrus also generates neuroblasts, which form neurons in the hippocampus — the section of the brain involved in learning, memory and regulating emotions. “Many other sites in the brain’s cortex contain neural progenitor cells, but they never develop into neurons,” Parent adds.

Parent cautions that, while his results are intriguing, many years of research at the molecular level and in animals will be necessary before human clinical trials could even be considered. “It’s not enough to stimulate the development of neuroblasts in human brains and hope they do what you want them to do,” Parent says. “There can be harmful consequences.”

Parent’s research is supported by the National Institute for Neuro-logical Disorders and Stroke of the National Institutes of Health and the Parents Against Child-hood Epilepsy Foundation. His research collaborators include Daniel Lowenstein, M.D., from Harvard Medical School and Donna Ferriero, M.D., and Zinaida Vexler, Ph.D., of the University of California-San Francisco Medical School.

—SFP

Read the complete story at:
www.med.umich.edu/opm/newspage/2002/neuralstem.htm

See Parent’s home page at:
www.med.umich.edu/neuro/parent.htm