Читать книгу The SAGE Encyclopedia of Stem Cell Research - Группа авторов - Страница 331

In order to utilize stem cells in the regeneration of cartilage, tendons, and ligaments, a cell line needs to be identified that differentiates into these connective tissues. Mesenchymal stem cells (MSCs), also known as bone marrow stromal stem cells, marrow-isolated adult multipotent inducible cells, multipotent adult progenitor cells, and mesenchymal adult stem cells, were recognized as non-hematopoietic stem cells with the ability to differentiate into a number of connective tissue cells, including chondrocytes (cartilage), tenocytes (tendons and ligaments), osteocytes (bone), myocytes (muscle), and adipocytes (fat).

The Mesenchymal and Tissue Stem Cell Committee of the International Society for Cellular Therapy had proceeded to standardize MSCs based on the following three criteria: (1) must adhere to plastic when maintained in standard culture conditions; (2) must express the surface proteins CD105, CD73, and CD90 in greater than 95 percent of the culture and lack the expression of CD45, CD34, CD14, or CD11b, CD79α or CD19, and HLA-DR in greater than 95 percent of the culture; (3) must differentiate to osteoblasts, adipocytes, and chondroblasts in vitro. Since the identification of these chondrocyte and tenocyte progenitors, scientists have now been able to extract mesenchymal stem cells not only from bone marrow but also from adipocytes, umbilical cord blood, periodontal ligament, peripheral blood, and synovial fluid, among others.

In addition to the ability of the mesenchymal stem cells to differentiate into a large number of connective tissues, MSCs have an immunosuppressive effect toward the immune effector cells: CD4+ and CD8+ T lymphocytes, Natural Killer (NK) cells, B lymphocytes, monocytes, and dendritic cells. This immunosuppressive effect is integral to the MSCs’ ability to decrease the rate that the implanted stem cells are rejected, via graft-versus-host disease. A decrease in the graft-versus-host disease would increase the likelihood of a successful transplant.