Details:
National MS Society-supported
investigators led by Steven A. Goldman, MD, PhD, of Cornell University
Medical College, have reported the discovery and isolation of a population
of immature ("progenitor") myelin-making cells
(oligodendrocytes) in the brains of adult humans. These cells have the
potential to repair myelin that has been destroyed by MS, and possibly to
aid in the recovery of function.
Reporting
in the November 15 issue of The Journal of Neuroscience, the
investigators describe having found that the oligodendrocyte progenitor
cells are surprisingly abundant in adult brain matter, and are capable of
dividing to produce new oligodendrocytes. Most adult human brain cells do
not divide.
This
is the first demonstration that such cells can be stimulated to divide and
give rise to new oligodendrocytes.
Background
Throughout
the 1990s, researchers had been searching for oligodendrocyte progenitor
cells in the human brain. Oligodendrocyte progenitor cells had been found
in the rat brain in the 1970s and 1980s. Immature oligodendrocytes had
been found in human brain tissue, but none of these had been capable of
dividing. Researchers had begun to conclude that oligodendrocyte
progenitor cells capable of dividing did not exist in the adult human
brain. But by using surgically removed samples of adult human brain
tissue, combined with newly developed techniques of molecular cell
identification and separation, Goldman and colleagues were able to refute
this notion and for the first time, segregate a population of dividing
oligodendrocyte progenitors in adult brain.
The
Study
In
this study, reported in the November 15 issue of The Journal of
Neuroscience, adult human brain cells were obtained from brain matter
that was removed from eight patients ranging in age from 24 to 65 years
old, who underwent surgery for a variety of disorders. The investigators
used a technique they had developed and tested in animal brain cells to
separate living progenitor cells from the larger brain cell population.
The
investigators identified a discrete population of oligodendrocyte
progenitor cells, which they estimated to represent about four percent of
the population of cells in the in the white matter of the brain. They then
segregated the progenitor cells, and demonstrated that they were capable
of dividing, "more or less on demand," says Goldman.
What
the Study Means
This
study shows that oligodendrocyte progenitor cells exist within the adult
human brain and are capable of dividing. Furthermore, this study describes
a method for the isolation and actual purification of these cells,
potentially in large numbers. This raises the possibility that patients
with MS might someday be treated either by transplanting oligodendrocyte
progenitor cells, or by stimulating the patients' own oligodendrocyte
progenitor cells to divide and produce new cells. Treatments might also be
devised that combine elements of both approaches.
Dr.
Goldman's team is currently conducting studies to determine whether
transplanted oligodendrocyte progenitor cells will be able to produce
replacement myelin on nerve fibers whose myelin has been destroyed.
Studies will also be needed to determine whether stimulating the growth of
new oligodendrocytes from progenitor cells that exist within a patient's
brain will remyelinate damaged neurons.
The
National MS Society is actively funding these and other efforts to find
ways to repair myelin and nerve cells that have been destroyed by multiple
sclerosis, with the hope of restoring nerve function.
