Adipogenic differentiation of murine bone marrow mesenchymal stem cells induced by visible light via photo- induced biomodulation

Background: Bone marrow mesenchymal stem cells (BM-MSCs) are undifferentiated cells that can proliferate and differentiate into specialized cells for tissue self-repair. Low-level laser (LLL) can induce biomodulatory effects such as cellular proliferation, differentiation, and migration. We investigated the biomodulatory effects of the photoactive compound chloroaluminum phthalocyanine nanoemulsion (AlClPc/NE) on the adipogenic differentiation of BM-MSCs, when combined with LLL (AlClPc/NE-LLL). Methods: The BM-MSCs used in this work were isolated from green fluorescent protein-positive (GFP(+)) C57BL6 mice. Cells were first treated with AlClPc/NE, a well-designed photoactive nano-drug and were then subjected to in vitro expansion, morphological and immunophenotypic characterization, and cellular cytotoxicity analysis. Subsequently, BM-MSCs were induced to differentiate into adipocytes by photo-induced biomodulation with AlClPc/NE-LLL. Results: Our results showed that the isolated cell population was consistent with murine BM-MSCs. The cellular cytotoxicity analysis revealed that the optimal nanoemulsion dose to induce BM-MSC biomodulation was 5.0 mu mol/L. Twenty-four hours following treatment with AlClPc/NE, BM-MSC were subjected to visible light irradiation of 20 mJ/cm(2) at 670 nm. Six days after photo-induced biomodulation, cells maintained high GFP expression level, and expressed detectable mRNA levels of adipogenic genes (lipoprotein lipase and PPAR gamma); formation of lipid vacuoles was observed, and the cells did not show any tumorigenic potential in vivo. Conclusions: Our results indicated that photo-induced biomodulation via visible light using AlClPc/NE and LLL can induce adipogenic differentiation of murine BM-MSCs. Therefore, cell therapy with BM-MSCs and photoinduced biomodulation may contribute to the development of new therapeutic strategies that are faster and more effective than traditional methods to trigger MSC differentiation.