Mesenchymal stromal cells: Basics, classification, and clinical applications

The discovery, isolation, characterization and differentiation of stem cells have significantly changed the global scenario of medicinal use of these cells for diseases for which conventional drugs are of limited therapeutic potential. The presence of stem cells in virtually every multicellular organism suggests that these cells probably have a major role to play throughout the lifetime of the organism for performing specialized functions that are biologically demanded from time to time for normal development and survival. Stem cells are classified as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells. Mesenchymal stromal cells (MSCs) are adult stem cells originally identified in mouse bone marrow, have now been discovered in many species and can be isolated from human and animal sources. Human MSCs (hMSCs) are multipotent, non-hematopoietic stromal cells which have the ability to differentiate into variety of cell types, including osteoblasts, chondrocytes, myocytes, adipocytes, cardiomyocytes, endothelial cells, hepatocytes and neural cells. These cells are identified by adherence to plastic surfaces under normal culture conditions and exhibit fibroblast-like morphology. The cultured MSCs express cell surface markers including CD29, CD44, CD49a-f, CD51, CD73, CD105, CD106, CD166, and Stro-1 and lack the expression of CD14, CD19, CD34, CD45 and HLA-DR surface molecules. Because of their immunosuppressive, anti-inflammatory properties and ability to secrete paracrine factors, hMSCs have emerged with a great potential in the field of tissue engineering and regenerative medicine and promise to be a liable source for therapeutic applications. This review article provides an overview on classification, sources and importance of mesenchymal stromal cells with an emphasis on its clinical applications. Brief updates on production technology and currently available cell therapy products have been described.