nanopolymers delivery of the bone morphogenetic protein-4 plasmid to mesenchymal stem cells promotes articular cartilage repair in vitro and in vivo

The clinical application of viral vectors for gene therapy is limited for biosafety consideration. In this study, to promote articular cartilage repair, poly (lactic-co glycolic acid) (PLGA) nanopolymers were used as non-viral vectors to transfect rabbit mesenchymal stem cells (MSCs) with the pDC316-BMP4-EGFP plasmid. The cytotoxicity and transfection efficiency in vitro were acceptable measuring by CCK-8 and flow cytometry. After transfection, Chondrogenic markers (mRNA of Col2a1, Sox9, Bmp4, and Agg) of experimental cells (MSCs being transfected with BMP-4 plasmid by PLGA nanopolymers) were increased more than those of control cells (MSCs being transfected with naked BMP-4 plasmid alone). In vivo study, twelve rabbits (24 knees) with large full thickness articular cartilage defects were randomly divided into the experimental group (MSCs being transfected with BMP-4 plasmid by PLGA nanopolymers) and the control group (MSCs being transfected with naked BMP-4 plasmid). The experimental group showed better regeneration than the control group 6 and 12 weeks postoperatively. Hyaline-like cartilage formed at week 12 in the experimental group, indicating the local delivery of BMP-4 plasmid to MSCs by PLGA nanopolymers improved articular cartilage repair significantly. PLGA nanopolymers could be a promising and effective non-viral vector for gene therapy in cartilage repair.