Effect of the physicochemical properties of pure or chitosan-coated poly(L-lactic acid)scaffolds on the chondrogenic differentiation of mesenchymal stem cells from osteoarthritic patients.

Due to the attractive properties of poly(L-lactic acid) (PLLA) and chitosan (CHT) for tissue engineering applications, this study is aimed at analyzing the chondrogenic potential of human bone marrow-derived mesenchymal stem cells (BM-MSCs) derived from osteoarthritic (OA) patients, in pure or CHT-coated PLLA, using different coating methodologies. Although PLLA scaffolds coated in one-step (PLLA-CHT1) yielded CHT smooth pellicles filling the PLLA macropores, a two-step strategy resulted in a CHT fiber-like thin coating covering PLLA pore walls (PLLA-CHT2). Both strategies led to the incorporation of similar content of CHT and a two-fold increase in the scaffold's water uptake capacity, providing elastic moduli values comparable to the ones found for human articular cartilage. After confirming OA-derived BM-MSCs, metabolic activity in the scaffolds, the chondrogenic potential was tested at 30 and 60 days, in a chondrogenic differentiation medium. PLLA scaffolds improved the chondrogenic differentiation of BM-MSCs, regarding cell pellet conventional culture and presented a typical cartilage zonal distribution, although was not able to revert a terminal differentiation. In PLLA-CHT1, on a short term, a rather heterogeneous tissue was formed, with confined areas of either slower cell infiltration or a faster maturation, with enhanced chondrogenic phenotype. In PLLA-CHT2, a similar tissue to PLLA was obtained, albeit on the long term, these scaffolds helped to maintain a hyaline-like phenotype and prevented the advance of the hypertrophic process. These results demonstrate the importance of the scaffolds microenvironment on the cellular events of chondrogenesis.