Human mesenchymal stem cells: progenitor cells for cartilage, bone, fat and stroma.

Bone marrow provides the rich milieu necessary to maintain myeloid and lymphoid progenitor cells throughout the life of an organism. At least two stem cell populations have been identified in marrow, the hematopoietic stem cell (HSC) and the mesenchymal stem cell (MSC). The HSC has been characterized in many ways, but much remains to be learned about its intrinsic potential and interactions with other cells of the marrow environment. We have studied the human stem cell population for mesenchymal tissues that resides in adult bone marrow. These MSCs potentially have the ability to differentiate to all mesenchymal cell types, including osteocytic, chondrocytic, adipocytic, myocytic, tenocytic, and also dermal and stromal lineages (1, 2). We have sought to understand the potential role(s) that MSCs play in healthy individuals and their response to trauma, disease or aging.