Characterization of the cell secretomes from undifferentiated and chondro-induced stem cells

Abstract

Background: Articular cartilage is an essential part of the skeletal system. It provides a frictionless surface for smooth pain-free articulation and limits the load applied to subchondral bone during joint movement. Articular cartilage is an avascular and aneural tissue without lymphatic vessels. Due to this unique nature, articular cartilage has poor self-repair capacity. Therefore, minor cartilage defect often leads to Osteoarthritis (OA). OA is considered one of the most common forms of arthritis and a major cause of physical disability amongst non-hospitalized adults, particularly in the aging population. Various treatment methods have been developed, but all bear limitations. Cellular therapy, where mesenchymal stem cells are used to reconstruct articular cartilage has shown encouraging results. Aim: In this study, we have compared the chondrogenic potential of mesenchymal-like stem cells (MSCs) from Hoffa fat pad (HFP) and umbilical cords (UC). Scaffold-free 3D cultures were used to induce chondrogenic differentiation and final tissue products were checked by histological and biochemical assays. Proteomic analyze of HFPSC secretome was used to check changes in inflammatory and immune-modulatory responses before and after differentiation. Results: Isolated cells were plastic-adherent, highly proliferative and expressed surface markers according to MSCs phenotype. The mean GAG/DNA ratio was very similar for both HFPSCs and MCSCs. Cartilage spheroids of HFPSCs showed more intense alcian blue staining than MCSCs and had better cartilage-like morphology. Proteomics analyze of the supernatant of HFPSCs showed no differences in expression of inflammatory immune-modulatory molecules between monolayers and 3D cultures. Conclusion: We have demonstrated that MSCs can be isolated from HFP and UC. HFPSCs showed greater chondrogenic potential and had morphological resemblance with native cartilage. Protein analysis of the supernatants showed extracellular matrix components and regulatory proteins during 3D cultures. Although, classical pro-inflammatory mediators were not identified by LC.MS/MS, more sensitive protein approaches should be used to get more certain results.