Adipose-Derived Mesenchymal Stromal Cells: A Tool for Bone and Cartilage Repair

Abstract

The osteogenic and chondrogenic differentiation ability of adipose-derived mesenchymal stromal cells (ASCs) and their potential therapeutic applications in bone and cartilage defects are reported in this review. This becomes particularly important when these disorders can only be poorly treated by conventional therapeutic approaches, and tissue engineering may represent a valuable alternative. Being of mesodermal origin, ASCs can be easily induced to differentiate into chondrocyte-like and osteocyte-like elements and used to repair damaged tissues. Moreover, they can be easily harvested and used for autologous implantation. A plethora of ASC-based strategies are being developed worldwide: they include the transplantation of freshly harvested cells, in vitro expanded cells or predifferentiated cells. Moreover, improving their positive effects, ASCs can be implanted in combination with several types of scaffolds that ensure the correct cell positioning; support cell viability, proliferation and migration; and may contribute to their osteogenic or chondrogenic differentiation. Examples of these strategies are described here, showing the enormous therapeutic potential of ASCs in this field. For safety and regulatory issues, most investigations are still at the experimental stage and carried out in vitro and in animal models. Clinical applications have, however, been reported with promising results and no serious adverse effects.

Keywords: adipose-derived mesenchymal stromal cells; bone; cartilage; chondrogenic differentiation; osteochondral defects; osteogenic differentiation; regenerative medicine; scaffolds; stem cells; tissue engineering.

Figure 1

Schematic drawing showing main steps of harvesting and treatments of adipose-derived mesenchymal stromal cells (ASCs) for bone and cartilage repair. After liposuction procedures, fat tissue in the lipoaspirate can be mechanically disrupted (A) to obtain micro fat particles (nanofat) containing ASCs and other cell types (lymphocytes, pericytes, vascular endothelial cells and vascular smooth muscle cells). Lipoaspirate can be digested and centrifuged (B) to obtain a pellet (stromal vascular fraction, SVF) containing ASCs that can be expanded and undergo osteogenic or chondrogenic differentiation. Nanofat particles, SVF cells, expanded ASCs or predifferentiated ASCs can be directly implanted or included in scaffold-assisted treatments.