|
MUSCLE MENDERS
Bone marrow cells can help repair
damaged muscular tissue, says Biplab Das
To date, bone marrow cells have been hailed for their unique contribution to blood. But now, we may have something more to appreciate marrow cells. A research team from Italy says that those cells aid the recovery of damaged muscle. To patients of muscular dystrophy, a disease in which the victim's muscles degenerate, this is something, which could provide a new lease of life.
Developmental biologist Giulio Cossu from the University of Rome teaming up with molecular biologist Giuliana Ferrari and Fulnio Mavilio of the San Raffaele Telethon Institute for Gene Therapy in Milan shows that bone marrow cells can migrate to damaged muscle and grow into new muscle cells in mice. This finding dislodges the existing idea that muscle seeks help of neighbouring cells to repair its injury and is not rescued by cells from bone marrow.
The scientists got the first inkling of bone marrow repairing damaged muscle nearly two years ago. They conducted experiments to find out if fibroblasts - a special kind of cells - could grow into muscular tissue.
They later injected the forelimb muscle of mice with fibroblasts purified from various tissues. Controls were injected with other types of cells, including bone marrow devoid of fibroblasts, with a prospect of muscle precursor cells. They chemically induced muscle damage in all the mice. Those mice that received bone marrow without the fibroblasts showed better results. By this time, two other research teams, those of Arnold Caplan at Case Western Reserve University in Cleveland and Darmin Prockop at Allegheny University of Health Sciences in Philadelphia, manipulated stromal cells - the support cells of the marrow - to become precursor muscle cells in lab dishes.
To make this happen in animals, Manilio and Ferrari badly needed a sensitive system to monitor the fate of bone marrow cells. A research team in Paris had developed a strain of transgenic mice with a marker gene capable of turning cell nuclei blue in muscle cells. Armed with this information, the Italian trio could identify the development of bone marrow cells destined to become muscle.
Mice that received bone marrow carrying the marker gene were exposed to irradiation to get their own bone marrow destroyed. After several weeks, the same mice were given toxic injection into their forelimbs to damage the muscle there. Two weeks elapsed and Ferrari noticed regrowth of muscle with blue nuclei of bone marrow cells at the damaged site.
However, despite the significance of the finding, experts point out that victims of muscular dystrophy would lack the functioning satellite cells present in the experimental mice.
To overcome this, researchers are trying out experiments on mice suffering from the same genetic defect as people with
Duchenne-type muscular dystrophy to verify the effectiveness of bone marrow cells.
|
