The Future Role of Mesenchymal Stem Cells in Tissue Repair and Medical Therapeutics: Realities and Expectations

Mesenchymal Stem Cells (MSCs); which were first described by Alexander Fridenstein in the 1960s; are heterogeneous, non-hematopoietic, adult multipotent stromal progenitor cells that are capable of self-renewal and differentiation into various cell types [1-8]. They can be isolated from various sources including: Bone Marrow (BM) which is the main source, peripheral blood, umbilical cord blood, amniotic fluid, placenta, Adipose Tissue (AT), dental pulp, synovial fluid, salivary glands, liver, lung, skin and skeletal muscles [1-10]. MSCs have the following distinguishing features: adherence to the plastic vessel; capacity to different into osteoblasts, adipocytes and chondrocytes; and being characteristically positive for CD105, CD73, and CD90 and characteristically negative for CD45, CD34, CD11b, CD14, CD19, CD79a, and human leukocyte antigen (HLA)-DR on flow cytometry [1,3,4,11-16]. However, under certain circumstances, MSCs obtained from BM, AT, and other sources may express CD34 surface markers [5-8,17]. Additionally, MSCs do not express significant histocompatibility complexes and immune stimulating molecules. Consequently, they escape immune surveillance and their clinical utilization in transplantation is not associated with graft rejection [10].