Cartilage regeneration via small molecule induced rat bone marrow mesenchymal stem cells on natural biomaterials

Cartilage is an avascular and aneural tissue that has low self-repair capacity upon damages resulted from diseases and injuries. Current orthopaedic treatments have some limitations such as donor site morbidity, and inadequate mechanical and functional properties of the newly formed tissue compared to native tissue. In this context, cartilage tissue engineering can offer an alternative solution to overcome the limitations of conventional orthopaedic treatments. In this study, natural biomaterials Locust bean gum (LBG), Xanthan gum (XG) and Mastic Gum (MG) were combined to form cryogel scaffolds for cartilage tissue engineering. The LBG-XG and LBG-XG-MG cryogels were physically, mechanically, and chemically characterized. The results demonstrated the macro-porous, and interconnected pore structures of the cryogels and sustained release of the small molecule Kartogenin (KGN) from cryogels to induce chondrogenic differentiation. Furthermore, these cryogels showed similar mechanical properties with the native cartilage tissue and other polysaccharide-based cryogels in the literature. According to cell viability analysis, rat bone marrow mesenchymal stem cells (RBM-MSCs) were able to attach, grow, and proliferate inside the cryogels. The cryogels having concentrations of 3 percent (w/v) - 1:1 (w/w) LBG-XG and 3 percent (w/v) - 1:1 (w/w) LBG-XG + 5 mg/mL MG were selected with respect to the results of characterizations and cell viability analysis. Further in vitro stainings and quantitative real time polymerase chain reaction analysis revealed that RBM-MSCs produced cartilage specific matrix molecules and expressed cartilage specific genes inside the selected cryogels. In vivo studies were performed in an ectopic rat model to test the chondrogenic differentiation. The RBM-MSCs were differentiated into chondrocyte like cells in KGN-loaded cryogels after 4 and 8 weeks of implantation. All these results showed that LBG-XG and LBG-XG-MG cryogels have a potential to be used in cartilage tissue engineering.