The transfection efficiency of photosensitizer-induced gene delivery to human MSCs and internalization rates of EGFP and Runx2 genes

To improve the transfection efficiency of non-viral gene vectors to human mesenchymal stem cells (hMSCs), a photosensitizer (PS)-induced gene delivery system was designed by using pheophorbide-a (pheo-a) as a PS. In FACS results, this system showed excellent gene transfection efficiency depending on irradiation power. The result was strongly supported by western blot and real-time quantitative PCR (RT-qPCR) assays. The protein and mRNA expression of enhanced green fluorescent protein (EGFP) in hMSCs treated with 0.9 J/cm2 irradiation increased 9.8- and 8.7-fold compared with non-irradiated hMSCs, respectively. Furthermore, the internalization of PEI/pDNA complexes in hMSCs was enhanced by light irradiation even under conditions that inhibited endocytosis. The hemolytic activity of PS with irradiation (0.9 J/cm2) significantly increased to 55%. Thus, PS with light irradiation facilitated both the internalization and endosomal escape of gene complexes. For osteogenic induction, the Runt-related transcription factor 2 (Runx2) gene was transferred to hMSCs via PS-induced transfection. Von Kossa staining indicated that Runx2 overexpression significantly enhanced the osteogenesis of hMSCs. Therefore, this PS-induced gene delivery method has potential value for stem cell therapy via gene delivery.