Pain. 2018 Sep 3. doi: 10.1097/j.pain.0000000000001395. [Epub ahead of print]

Mesenchymal Stem Cell Exosomes as a Cell-Free Therapy for Nerve Injury-Induced Pain in Rats.

Shiue SJ¹, Rau RH², Shiue HS³, Hung YW¹, Li ZX¹, Yang KD^4,5,6, Cheng JK^7,8.

Abstract

Nerve injury-induced neuropathic pain is difficult to treat. In this study, we used exosomes derived from human umbilical cord mesenchymal stem cell (UCMSC) as a cell-free therapy for nerve injury-induced pain in rats. Isolated UCMSC exosomes range in size from 30 to 160 nm and contain CD63, HSP60 and CD81 exosome markers. After L5/6 spinal nerve ligation surgery, single intrathecal injection of exosomes reversed nerve ligation-induced mechanical and thermal hypersensitivities of rat right hindpaw at initial and well-developed pain stages. Moreover, continuous intrathecal infusion of exosomes achieved excellent preventive and reversal effects for nerve ligation-induced pain. In immunofluorescent study, lots of Exo-green-labelled exosomes could be found majorly in the ipsilateral L5 spinal dorsal horn, dorsal root ganglion, and peripheral axons, suggesting the homing ability of UCMSC exosomes. They also appeared in the central terminals or cell bodies of IB4, CGRP and NF200 sensory neurons. In addition, exosome treatment suppressed nerve ligation-induced up-regulation of c-Fos, CNPase, GFAP, and Iba1. All these data suggest the analgesic effects of exosomes may involve their actions on neuron and glial cells. Exosomes also inhibited the level of TNF-α and IL-1β, while enhanced the level of IL-10, BDNF and GDNF in the ipsilateral L5/6 DRG of nerve-ligated rats, indicating anti-inflammatory and pro-neurotrophic abilities. Protein analysis revealed the content of vascular endothelial growth factor C, angiopoitin-2 and fibroblast growth factor-2 in the exosomes. In summary, intrathecal infusion of exosomes from UCMSCs may be considered as a novel therapeutic approach for nerve injury-induced pain.