Adipose Derived Cells and Tissues for Regenerative Medicine

Adipose tissue is now recognized as a complex organ serving endocrine, immune, and metabolic functions. Adipose depots are composed of mature adipocytes as well as stromal vascular fraction (SVF) cells, a heterogeneous population of B and T lymphocytes, endothelial cells, macrophages, pericytes, smooth muscle, and stromal cells that can be isolated by enzymatic digestion. When placed into culture medium, a subset of the SVF cells can adhere to the plastic surface and expand in number. This latter population, known as "adipose-derived stromal/stem cells" (ASC), exhibits trilineage (adipo-, chondro-, osteo-) differentiation potential. There are currently more than 180 clinical studies underway worldwide exploring the regenerative medical application of SVF cells and ASC in a range of medical conditions. Plastic surgeons have a particular interest in the use of autologous fat and SVF enhanced fat for cosmetic and reconstructive surgical procedures. Orthopedic and craniofacial surgeons have begun to use ASC to treat bone and musculoskeletal defects with success. Furthermore, studies are underway to exploit the immunomodulatory function of ASC to treat immune-mediated disorders such as Crohn's disease. Indeed, it is postulated that adipose tissue and cells modulate tissue regeneration and inflammatory responses through their secretion of paracrine factors. Continued advances in this emerging field will require harmonization of international standards and guidelines defining the release criteria as well as the safety and efficacy of adipose-derived cells and tissues. Currently, there are no accepted standard guidelines for autologous fat harvesting technique, processing, or method of injection. Close collaboration between academia, industry, and regulatory authorities will be necessary to ensure that adipose-derived products are affordable and quality controlled throughout the globe.