An efficient ex vivo expansion of adult mesenchymal stem cells in scaffolds

Tissue engineering utilizing mesenchymal stem cells (MSCs) in combination with scaffolds presents promising alternative therapies for bone defects. Because of their low numbers in adult tissues, most clinical applications of MSCs depend on isolation followed by ex vivo expansion. The development of methods to obtain sufficient quantities of MSCs, and to improve their safety and functionality, could dramatically facilitate their use in clinical applications in regenerative medicine. A number of papers have demonstrated stimulatory effects of growth factors on proliferation and differentiation of MSCs in culture. It is important to understand the biological effects of factors that regulate MSC activity. This review will discuss the effects of growth factors on MSCs and their mechanisms of action with respect to the efficient ex vivo expansion of MSCs for regeneration of hard tissue such as bone.