The therapeutic effects of transferring remote ischemic preconditioning serum in rats with neuropathic pain symptoms.

BACKGROUND AND OBJECTIVES: Neuropathic pain is defined as pain caused by damage to the nerve as a result of a lesion or disease. It has been shown that ischemic preconditioning exerts a protective role in various tissue injuries; however, the effect of transplantation of remote ischemic preconditioning serum (RIPCs) on neuropathic pain symptoms has not been studied. The aim of this project is to investigate the effect of RIPCs transfusion by different routes of administration on neuropathic pain symptoms. Our secondary aim was to demonstrate the role of Schwann cells in the regeneration of sciatic nerve injury and to evaluate the change in the number of glial cells in the spinal cord dorsal horn.

METHODS: The sciatic nerve partial ligation method was used to induce neuropathic pain. Changes in neuropathic pain symptoms were assessed by measuring thermal hyperalgesia and mechanical allodynia. To determine the possible therapeutic site, alterations in the number of spinal cord lumbar posterior horn microglia and astrocytes were evaluated by ionized calcium-binding adapter molecule 1 (iba1) and glial fibrillary acidic protein (GFAP) immunostaining. Myelin basic protein immunohistochemistry was also used to assess Schwann cell immunoreactivity in the sciatic nerve.

RESULTS: In rats that underwent partial sciatic nerve ligation, neuropathic pain symptoms developed on average on day 12 and persisted up to day 21 (p < 0.0001). RIPCs administered intravenously for five days reduced thermal hyperalgesia more than intraperitoneal and subcutaneous administration (p < 0.05). Both central glial cells appear to play a role in the effect of RIPCs. RIPCs treatment increases Schwann cell remyelination.

CONCLUSIONS: Our results showed that intravenously administered RIPCs remarkably improved the neuropathic pain symptoms, thermal hyperalgesia and mechanical allodynia. Further studies are needed to evaluate the role of RIPCs transfusion on glial cells.