Kartogenin-loaded liposomes coated with alkylated chondroitin sulfate for cartilage repair

Cartilage loss is a common clinical problem, which leads to significant pain, dysfunction, and even disability. As a result, there is growing interest in using small, non-protein molecules to protect or repair cartilage. Kartogenin (KGN), a small hydrophobic molecule, shows chondroprotective and chondrogenic properties. In this study, we embedded KGN in liposomes, and the whole system was stabilized by covering it with n-octadecylated (at two different substitution degrees) chondroitin sulfate (CS) derivatives. We investigated the interactions of empty liposomes and KGN-loaded liposomes with both CS derivatives using various physicochemical techniques, which revealed that hydrophobically modified CSs can interact with both neutral lipid membrane and negatively charged loaded-KGN lipid membrane. The cytotoxicity and chondrogenic properties of the polysaccharides and liposome-CS formulations of KGN were analyzed towards mesenchymal stem cells (MSCs). The results showed that the alkylated CS exhibited cytotoxic properties. The higher substituted CS self-assembles into stable nanoaggregates that can form a corona on the surface of liposomes, eliminating the overall cytotoxicity of this polymer. However, all tested chondrogenic markers' expression levels are enhanced for KGN-loaded liposomes and coated by lower substituted CS. Furthermore, the undesirable hypertrophy effect for this formulation significantly decreased compared to pure polymeric derivative.