Semaphorin 3a reduces the side effects of radiation on BMSCs by reducing ROS

1. Background/Aims Radiotherapy does not only kill tumor cells but also impairs the function of adjacent tissues, especially bone metabolism by damaging bone marrow stromal stem cells (BMSCs). This study aimed to investigate the effect of semaphorin 3a (Sema3a) on BMSCs exposed to 2 Gy radiation. Materials BMSCs were divided into four groups, namely, group A (0 Gy), group B (2 Gy), group C (0 Gy + Sema3a), and group D (2 Gy + Sema3a). A Cell Counting Kit-8 kit, Alizarin-Red and Oil-Red-O staining, alkaline phosphatase activity kit, and dichlorodihydro-fluoresce in diacetate were used to test cell proliferation, cell cycle, osteogenic ability, adipogenic ability, and the level of reactive oxygen species (ROS), respectively, in each group. Real-time PCR was performed to test the expression of osteogenic (osteocalcin and Runt-related transcription factor 2), adipogenic (peroxisome proliferator-activated receptor gamma), interleukin (IL)-6, and tumor necrosis factor (TNF)-α genes. Results BMSC proliferation, osteogenic differentiation, and the number of cells undergoing division (S+G2 phase of the cell cycle) were found to be lower in group B than in group A. and the cellular levels of ROS, adipogenic differentiation, and expression of inflammatory factors (IL-6 and TNF-α) were higher in group B than in group A. Furthermore, osteogenic differentiation ability was higher in group D than in group B, and adipogenic differentiation ability, cellular levels of ROS, and gene expression of TNF-α and IL-6 were lower in group D than in group B. Conclusion This study demonstrated that 2 Gy radiation could decrease the osteogenic differentiation ability of BMSCs and increase their adipogenic differentiation ability by increasing the production of ROS. However, Sema3a could reduce these side effects by decreasing the levels of ROS.