Recent advances in bone regeneration: The role of adipose tissue-derived stromal vascular fraction and mesenchymal stem cells

The management of large bone defects, atrophic nonunions, and other conditions with poor bone formation presents a formidable challenge to the treating physician, as all available techniques of bone reconstruction have drawbacks. Recent advances in stem cell biology, specifically adipose tissue-derived mesenchymal stem cells (ASCs) and adipose tissue stromal vascular fraction (SVF), have opened up new horizons by providing a reliable and abundant source of stem cells with osteogenic potential that can be used in various bone tissue engineering techniques. In this review, several aspects related to the use of ASCs are addressed, such as harvesting and processing of adipose tissue, advantages of ASCs over bone marrow-derived mesenchymal stem cells, mechanism of action and safety of ASCs, and factors affecting the differentiation of ASCs. Published reports on the use of ASCs in critical size defects, nonunions, and distraction osteogenesis are also reviewed. Innovative trends in stem cell research on musculoskeletal pathologies are highlighted, with special emphasis on the increasing evidence that the direct application of freshly prepared SVF processed from adipose tissue into the bone defect to be treated without a prior differentiation or an ex vivo expansion and culture is possible. This highly promising approach may lead to the development of a one-step intraoperative cell therapy.