March 7, 2005

The body springs into action to heal a wound. Cells in the bloodstream muster to form a clot and fight infection. Researchers have long known that the infection-fighting cells are produced in the bone marrow. But recently, they discovered that cells from the bone marrow also play a role in healing wounds and maintaining normal skin.

Frank Isik, M.D., of the University of Washington Medical Center in Seattle tracked the fate of bone marrow cells by using mice whose cells were engineered to glow green under a fluorescent light. He transplanted green-glowing bone marrow cells from these mice into another set of mice, which were genetically identical except that they lacked the green fluorescent protein. He then inflicted a small wound in the skin of the transplanted mice's backs. To his surprise, as long as 6 weeks after the mice had been wounded, well after infection had ceased to be an issue, green-glowing cells derived from the bone marrow remained in their healed skin.

Probing further, Isik found that only the bone marrow-derived cells produced a particular type of collagen that is found in skin throughout the body, not just in healed wounds. This led him to conclude that cells from the bone marrow help form the tough, yet expandable, matrix of the skin. Isik now wonders whether diseases that interfere with wound healing, such as diabetes, do so because they affect bone marrow cells. In time, this line of research may reveal targets for drugs that will promote wound healing.