Macrophages Promote Nerve Regeneration in Peripheral Nerve Injury

A special class of white blood cell could offer insights regarding ways to spur regeneration in two of the most devastating and stubborn forms of nerve damage – those to the brain and spinal cord.


In a study published earlier this month in the Journal of Neuroscience, Case Western Reserve University School of Medicine’s Richard Zigmond, PhD, and his research group report on a telling discovery involving the impact of these white blood cells – called macrophages – on peripheral nerve regeneration. The findings point to new frontiers for research regarding opportunities to encourage new growth of injured peripheral and central nervous system fibers.


Scientists have long known that macrophages support regeneration by digesting fragments of the degenerating nerve fibers and “clearing the way” for new growth. When a nerve fiber is cut, the part of the fiber distant from the cell body that contains the nucleus degenerates, but the cell body survives and regenerates a new fiber.


In 1995, Zigmond and his team found that macrophages not only surround injured nerve fibers, but also surround the cell bodies of these fibers. The cells’ impact on fibers was clear, but until now researchers had not been able to identify macrophages’ role with regard to cell bodies. After all, cell bodies do not degenerate.


The new study involves two mutant mouse strains in which macrophages do not enter the region of nerve cell bodies. This absence, the researchers found, correlated with a striking defect in regrowth of the fiber from the cell body in response to nerve injury.


Zigmond’s team next will seek to understand precisely how the macrophages impact cell bodies, knowledge that could guide future therapeutic applications.


Founded in 1843, Case Western Reserve University School of Medicine is the largest medical research institution in Ohio and is among the nation's top medical schools for research funding from the National Institutes of Health. The School of Medicine is recognized throughout the international medical community for outstanding achievements in teaching. The School's innovative and pioneering Western Reserve2 curriculum interweaves four themes--research and scholarship, clinical mastery, leadership, and civic professionalism--to prepare students for the practice of evidence-based medicine in the rapidly changing health care environment of the 21st century. Nine Nobel Laureates have been affiliated with the School of Medicine.

Annually, the School of Medicine trains more than 800 MD and MD/PhD students and ranks in the top 25 among U.S. research-oriented medical schools as designated by U.S. News & World Report's "Guide to Graduate Education."

The School of Medicine is affiliated with University Hospitals Cleveland Medical Center, MetroHealth Medical Center, the Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and the Cleveland Clinic, with which it established the Cleveland Clinic Lerner College of Medicine of Case Western Reserve University in 2002.

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Jessica Studeny