Mesenchymal stem cell

A mesenchymal stem cell (MSC) is a multipotent cell found in the stroma, the supporting connective tissue, of many organs, including bone marrow, fat and the umbilical cord. It is distinct from the blood-forming stem cells that share the marrow. In the laboratory, MSCs are defined by how they behave: they stick to plastic culture dishes, grow as spindle-shaped cells resembling fibroblasts, carry a typical set of surface markers and can be coaxed into osteoblasts (bone), chondrocytes (cartilage) and adipocytes (fat). The name refers to mesenchyme, the loose embryonic tissue, mostly from the mesoderm, that gives rise to connective tissues.

Alexander Friedenstein first described them in the 1960s and 1970s as marrow cells that formed colonies in culture and made bone when transplanted. In the marrow they help build the niche that supports hematopoietic stem cells. Many scientists now prefer the name mesenchymal stromal cells, because cultured populations are mixed and few of the cells have been shown to renew themselves in the body, and reports that they can turn into heart muscle, liver or nerve cells remain disputed.

MSCs are studied widely in regenerative medicine, both for repairing bone and cartilage and for their ability to calm immune responses, for example in graft-versus-host disease after transplants. Most such uses are still experimental.