"Coculture-Driven Mesenchymal Stem Cell-Differentiated Articular Chondrocyte-Like Cells Support Neocartilage Development"
Mesenchymal stem cells (MSCs) are an attractive source for repair and regeneration of tissue or organ defects. Transplantation of MSCs into defective knee joints to restore cartilage function has yielded some success, although they have yet to pass the pre-clinical and phase I stages towards proper therapeutic use (Koga et al.). A greater understanding of in vivo MSC differentiation mechanisms could aid the widespread use of MSCs through the precise control of cell lineage during in vitro differentiation. Several bioactive agents, such as transforming growth factor-b (TGF-b), insulin-like growth factor-1 (IGF-1), bone morphogenetic protein-2 (BMP-2), and basic fibroblast growth factor (FGF-2), are essential for the chondrogenic differentiation of MSCs (Heng et al.). The mode of delivery of these factors to MSCs has been scrutinised using gradual delivery through means such as gene therapy (Pagnotto et al.) and polymeric vehicles for molecule release (Macdonald et al. and Shah et al.) which have been posited to more closely replicate in vivo conditions (Macdonald et al.). However, an easier method may be the co-culture of MSCs with primary chondrocytes which would secrete proteins such as TGF-b, IGF-1, BMP-2 and FGF-2 slowly over time at physiological concentrations. This has now been studied in detail by researchers from the laboratory of Gilda A. Barabino at the Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, USA and published in Stem Cells Translational Medicine. The researchers found that co-culture mediated differentiation of MSCs with chondrocytes led to the development of robust neocartilage in a three-dimensional agarose system that resisted hypertrophic maturation and calcification (Yang, Lee and Barabino).