Characterization of Primary Mesenchymal Stem Cell Chondrogenic Differentiation Potential in Hyaluronic Acid-Albumin Hydrogel

Objective: A currently investigated approach for the treatment of cartilage damage focuses on the use of biomaterials that can support the endogenous stem cell regeneration of the damaged tissue, in order to avoid the drawbacks involved with cell transplantation strategies. This study aimed to investigate the ability of the hyaluronic acid-albumin based hydrogel to support viability, proliferation and chondrogenic differentiation of synovial mesenchymal stem cells, as a potential strategy for endogenous stem cell regeneration treatment of articular cartilage defects. Methods: Cell viability and proliferation were analyzed by fluorescent activated cell sorting, using DAPI staining for viability and EdU staining for proliferation. The retention of mesenchymal stem cell specific immunophenotype during culture and its modulation during chondrogenesis were analyzed using fluorescent activated cell sorting. Chondrogenic differentiation was verified by reverse transcription polymerase chain reaction for the expression of genes associated with chondrogenesis. Finally, histology and medium analysis were performed to evaluate glycosaminoglycan content in the samples. Cells from different donors were included to evaluate donor variability. Results: Primary synovial cells in the hydrogel were viable up to 28 under both expansion and chondrogenic culture conditions. Synovial mesenchymal stem cells can proliferate in the hyaluronic acid-albumin hydrogel when cultured with platelet derived growth factor-BB (PDGF-BB) but not with fibroblast growth factor-2 (FGF-2). Primary synovial mesenchymal stem cells can chondrogenically differentiate in the hydrogel as confirmed by chondrogenic gene expression analysis, produced glycosaminoglycans in the culture medium and histology. Finally, primary synovial mesenchymal stem cell CD90 and CD73 marker expression in the hyaluronic acid-albumin hydrogel was gradually lost during expansion, while during chondrogenesis both markers expression was retained but the CD90+/CD73+ cells decreased over time. Conclusions: In vitro evaluation of the hyaluronic acid-albumin hydrogel indicates that it is a promising candidate biomaterial for supporting endogenous stem cell regeneration of cartilage defects.