Recombinant human erythropoietin prevents motor neuron apoptosis in a rat model of cervical sub-acute spinal cord compression

Abstract

The objective of the study was to investigate the effects of recombinant human erythropoietin (rhEPO) in a rat model of cervical sub-acute spinal cord compression. 80 Wistar rats were randomly divided into 4 groups. Rats in the sham group (Group A, n = 5) underwent surgical procedures without cervical spinal cord compression; while rats in other groups were subjected to the spinal compression process. In the control group (Group B, n = 25), rats received an i.v. injection of 1 mL saline at day 7 post-surgery. Rats in the low-dose group (Group C, n = 25) and the high-dose group (Group D, n = 25) were treated with rhEPO at 500 units/kg body-weight and 5000 units/kg, respectively, via intravenous injection at day 7 post surgery. Limb motor function was scored by Basso–Beattie–Bresnahan (BBB) standards at 3, 7, 14, 21 and 28 days post-surgery. The distribution and quantities of EPO and its receptor (EPO-R) in the compressed segment of the spinal cord were detected by immunohistochemistry. Motor neuron apoptosis in the spinal cord was evaluated using TUNEL staining and flow cytometry at the indicated time points. Finally, IL-8, TNF-α, IL-6, and IL-1β levels in the compressed cervical spinal cord were determined by ELISA within the lesion epicenter at each time point post-surgery. The data suggest that expression of EPO-R was significantly increased following sub-acute cervical spinal cord compression; Groups C and D exhibited better BBB scores at all observed time points compared with the control group ( p < 0.01). Using TUNEL staining and FCM, we observed that rhEPO profoundly inhibited motor neuron apoptosis in the spinal cord at day 21 ( p < 0.01). Additionally, treatment with rhEPO halted the elevation of inflammatory cytokines. rhEPO administration decreased motor neuron apoptosis in the cervical spinal cord, improved motor functions and reduced the inflammatory response in a sub-acute cervical spinal cord compression model. Moreover, sustained treatment with low doses of rhEPO revealed a positive therapeutic effect.