Mesenchymal stem cells (MSC) are a well-characterized population of adult stem cells. They are capable of renewing themselves through cell division and can differentiate into multi-lineage cells; including fat, cartilage, bone, tendons, and muscle mature cells. The developmental plasticity of MSC has generated tremendous interest because of the potential use of mesenchymal stem cells in regenerative medicine to replace damaged tissues. MSC cultured without serum in the presence of transformation growth factors will differentiate into chondrocytes. MSC cultured in serum with ascorbic acid and dexamethasone will differentiate into osteoblasts. Among the different applications of MSC, is the possibility of transplanting them in an injured site or assembling them in a biomimetic scaffold to generate appropriate tissue constructions. Rat mesenchymal stem cells are a valuable tool to study and understand the cell differentiation processes.