Photobiomodulation-driven cardiomyogenic differentiation and endothelial vascularization: A dual approach with Aloe...

Cardiomyogenic differentiation plays a critical role in cardiac tissue engineering. It enables the transformation of precursor cells into functional cardiomyocytes capable of contraction and pumping. This study investigates the synergistic effects of Aloe vera (AV) and photobiomodulation (PBM) on cardiomyogenic differentiation in rat cardiomyoblast cell line derived from embryonic ventricular heart tissue (H9C2). It also examines the vascularization potential of primary rat cardiac microvascular endothelial cells (CMECs). Given their natural interaction in cardiac tissue, H9C2 and CMECs were co-cultured at a 6:1 ratio. Cytotoxicity assays established 10 mg/mL AV as a safe concentration, with cell viabilities exceeding 80 % across both monocultures and co-cultures. In the culture, PBM was applied every other day for 10 days, using a polychromatic light source (600-1200 nm) placed 20 cm away from the cells, at an irradiance of 0.04 W/cm² for 3 min per day. Neither AV nor PBM negatively affected cell viability. Fluorescence imaging indicated enhanced alignment and nuclear fusion in H9C2 cells, suggesting cardiomyogenic differentiation, particularly under combined AV-PBM treatment. Moreover, both AV and AV-PBM treatments significantly improved CMECs vascularization potential by day 14. RT-qPCR revealed a 7-fold and 9-fold increase in FGF2 gene expression following PBM and AV-PBM treatment, respectively. Anti-von Willebrand factor staining and imaging confirmed that CMECs formed lumen-like structures beneath H9C2 cells under all treatment conditions. These results demonstrate that the combined application of AV and PBM effectively promotes cardiomyogenic differentiation in H9C2 cells and enhances CMEC-mediated vascularization. This suggests a promising strategy for optimizing biosignaling and tissue integration in cardiac tissue engineering.