Impact of TGF-β family-related growth factors on chondrogenic differentiation of adipose-derived stem cells isolated from lipoaspirates and infrapatellar fat pads of osteoarthritic patients.

The success of cell-based approaches for the treatment of cartilage defects requires an optimal autologous cell source with chondrogenic differentiation ability that maintains its differentiated properties and stability following implantation. The objective of this study was to compare the chondrogenic capacity of mesenchymal stem cells (MSCs) isolated from lipoaspirates (ASCs) and the infrapatellar fat pad (IFPSCs) of osteoarthritic patients and treated with transforming growth factor (TGF)-β family-related growth factors. Cells were cultured for 6 weeks in a 3D pellet culture system with the chimeric activin A/bone morphogenic protein (BMP)-2 ligand (AB235), the chimeric nodal/BMP-2 ligand (NB260) or BMP-2. To investigate the stability of the new cartilage, ASCs-treated pellets were transplanted subcutaneously into severe combined immunodeficiency (SCID) mice. Histological and immunohistochemical assessment confirmed that the growth factors induced cartilage differentiation in both isolated cell types. However, reverse transcription-quantitative PCR results showed that ASCs presented a higher chondrogenic potential than IFPSCs. In vivo results revealed that AB235-treated ASCs pellets were larger in size and could form stable cartilage-like tissue as compared to NB260-treated pellets, while BMP-2-treated pellets underwent calcification. The chondrogenic induction of ASCs by AB235 treatment was mediated by SMAD2/3 activation, as proved by immunofluorescence analysis. The results of this study indicated that the combination of ASCs and AB235 might lead to a cell-based cartilage regeneration treatment.