Gong, P. | Search bioRxiv

bioRxiv2019

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

1.Background/AimsRadiotherapy 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. MaterialsBMSCs 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)- genes. ResultsBMSC 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-) 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- and IL-6 were lower in group D than in group B. ConclusionThis 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.

cell biology↗

bioRxiv2019

Changes in spinal cord hemodynamic reflect modulation of spinal network with different parameters of epidural stimulation

In this study functional ultrasound (fUS) imaging has been implemented to explore the local hemodynamic response induced by electrical epidural stimulation and to study real-time in vivo functional changes of the spinal cord, taking advantage of the superior spatiotemporal resolution provided by fUS. By quantifying the hemodynamic and electromyographic response features, we tested the hypothesis that the transient hemodynamic response of the spinal cord to electrical epidural stimulation could reflect modulation of the spinal circuitry and accordingly respond to the changes in parameters of electrical stimulation. The results of this study for the first time demonstrate that the hemodynamic response to electrical stimulation could reflect functional organization of the spinal cord. Response in the dorsal areas to epidural stimulation was significantly higher and faster compared to the response in ventral spinal cord. Positive relation between the hemodynamic and the EMG responses was observed at the lower frequencies of epidural stimulation (20 and 40 Hz), which according to our previous findings can facilitate spinal circuitry after spinal cord injury, compared to higher frequencies (200 and 500 Hz). These findings suggest that different mechanisms could be involved in spinal cord hemodynamic changes during different parameters of electrical stimulation and for the first time provide the evidence that functional organization of the spinal cord circuitry could be related to specific organization of spinal cord vasculature and hemodynamic.\n\nSignificance StatementElectrical epidural stimulation (EES) has been successfully applied to control chronic refractory pain and was evolved to alleviate motor impairment after spinal cord injury, in Parkinsons disease, and other neurological conditions. The mechanisms underlying the EES remain unclear, and current methods for monitoring EES are limited in sensitivity and spatiotemporal resolutions to evaluate functional changes in response to EES. We tested the hypothesis that the transient hemodynamic response of the spinal cord to EES could reflect modulation of the spinal cord circuitry and accordingly respond to the changes in parameters of EES. The proposed methodology opens a new direction for quantitative evaluation of the spinal cord hemodynamic in understanding the mechanisms of spinal cord functional organization and effect of neuromodulation.

neuroscience↗