An effective erythropoietin dose regimen protects against severe nerve injury-induced pathophysiological changes with improved neural gene expression and enhances functional recovery

Authors
PK Govindappa, MAH Talukder, AA Gurjar, et al

Lab
Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science (CORTS), The Pennsylvania State University College of Medicine, Hershey, PA, USA

Journal
International Immunopharmacology

Abstract
The functional recovery following non-severing peripheral nerve injury (PNI) is often incomplete. Erythropoietin (EPO) is a pleiotropic hormone and it has been shown to protect peripheral nerves following mild and even moderate severity injuries. However, the effectiveness of EPO in severe PNI is largely unknown. In this study, we sought to investigate the neuroprotective effect of a new dose regimen of EPO in severe sciatic nerve crush injury (SSCI). Adult male mice (8 animals/group) were randomly assigned to sham (normal saline, 0.1 ml/mouse), SSCI (normal saline, 0.1 ml/mouse) and SSCI with EPO (5000 IU/kg) groups. SSCI was performed using calibrated forceps for 30 sec. EPO or normal saline was administered intraperitoneally immediately after the SSCI and at post-injury day1 and 2. The functional recovery after injury was assessed by sciatic function index (SFI), von Frey Test (VFT), and grip strength test. Mice were euthanized on day 7 and 21 and nerves at injury/peri-injury site were processed for gene (quantitative real-time PCR) and protein (immunohistochemistry) expression analysis. EPO significantly improved SFI, VFT, and hind limb paw grip strength from post-injury day 7. EPO demonstrated significant regulatory effects on mRNA expression of inflammatory (IL-1beta and TNF-alpha), anti-inflammatory (IL-10), angiogenesis (VEGF and eNOS), and myelination (MBP) genes. The protein expression of IL-1beta, F4/80, CD31, NF-kappaB p65, NF-H, MPZ, and DHE (redox-sensitive probe) was also significantly modulated by EPO treatment. In conclusion, the new dose regimen of EPO augments sciatic nerve functional recovery by mitigating inflammatory, anti-inflammatory, oxidative stress, angiogenesis, and myelination components of SSCI.

BIOSEB Instruments Used:
Grip strength test (BIO-GS3)