Erythropoietin inhibits ferroptosis and ameliorates neurological function after spinal cord injury

Ferroptosis is one of the critical pathological events in spinal cord injury.Erythropoietin has been reported to improve the recovery of spinal cord injury.However,whether ferroptosis is involved in the neuroprotective effects of erythropoietin on spinal cord injury has not been examined.In this study,we established rat models of spinal cord injury by modified Allen’s method and intraperitoneally administered 1000 and 5000 IU/kg erythropoietin once a week for 2 successive weeks.Both low and high doses of erythropoietin promoted recovery of hindlimb function,and the high dose of erythropoietin led to better outcome.High dose of erythropoietin exhibited a stronger suppressive effect on ferroptosis relative to the low dose of erythropoietin.The effects of erythropoietin on inhibiting ferroptosis-related protein expression and restoring mitochondrial morphology were similar to those of Fer-1(a ferroptosis suppressor),and the effects of erythropoietin were largely diminished by RSL3(ferroptosis activator).In vitro experiments showed that erythropoietin inhibited RSL3-induced ferroptosis in PC12 cells and increased the expression of xCT and Gpx4.This suggests that xCT and Gpx4 are involved in the neuroprotective effects of erythropoietin on spinal cord injury.Our findings reveal the underlying anti-ferroptosis role of erythropoietin and provide a potential therapeutic strategy for treating spinal cord injury.

Endothelial progenitor cell-conditioned medium promotes angiogenesis and is neuroprotective after spinal cord injury

Endothelial progenitor cells secrete a variety of growth factors that inhibit inflammation, promote angiogenesis and exert neuroprotective effects. Therefore, in this study, we investigated whether endothelial progenitor cell-conditioned medium might have therapeutic effectiveness for the treatment of spinal cord injury using both in vitro and in vivo experiments. After primary culture of bone marrow-derived macrophages, lipopolysaccharide stimulation was used to classically activate macrophages to their proinflammatory phenotype. These cells were then treated with endothelial progenitor cell-conditioned medium or control medium. Polymerase chain reaction was used to determine mR NA expression levels of related inflammatory factors. Afterwards, primary cultures of rat spinal cord neuronal cells were prepared and treated with H2O2and either endothelial progenitor cell-conditioned medium or control medium. Hoechst 33258 and propidium iodide staining were used to calculate the proportion of neurons undergoing apoptosis. Aortic ring assay was performed to assess the effect of endothelial progenitor cell-conditioned medium on angiogenesis. Compared with control medium, endothelial progenitor cell-conditioned medium mitigated the macrophage inflammatory response at the spinal cord injury site, suppressed apoptosis, and promoted angiogenesis. Next, we used a rat model of spinal cord injury to examine the effects of the endothelial progenitor cell-conditioned medium in vivo. The rats were randomly administered intraperitoneal injection of PBS, control medium or endothelial progenitor cell-conditioned medium, once a day, for 6 consecutive weeks. Immunohistochemistry was used to observe neuronal morphology. Terminal deoxynucleotidyl transferase-mediated d UTP nick-end labeling assay was performed to detect the proportion of apoptotic neurons in the gray matter. The Basso, Beattie and Bresnahan Locomotor Rating Scale was used to evaluate the recovery of motor function of the bilateral hind limbs after spinal cord injury. Compared with the other two groups, the number of axons was increased, cavities in the spinal cord were decreased, the proportion of apoptotic neurons in the gray matter was reduced, and the Basso, Beattie and Bresnahan score was higher in the endothelial progenitor cell-conditioned medium group. Taken together, the in vivo and in vitro results suggest that endothelial progenitor cell-conditioned medium suppresses inflammation, promotes angiogenesis, provides neuroprotection, and promotes functional recovery after spinal cord injury.