Inhibition of neuropathic hyperalgesia by intrathecal bone marrow stromal cells is associated with alteration of multiple soluble factors in cerebrospinal fluid

Injury-induced neuropathic pain remains a serious clinical problem. Recent studies indicate that bone marrow stromal cells (BMSCs) effectively attenuate chronic neuropathic pain in animal models. Here, we examined the therapeutic effect of intrathecal administration of BMSCs isolated from young (1-month-old) rats on pain hypersensitivity induced by tibial nerve injury. Cerebrospinal fluid (CSF) was collected and analyzed to examine the effect of BMSC administration on the expression of 67 soluble factors in CSF. A sustained remission in injury-induced mechanical hyperalgesia was observed in BMSC-treated rats but not in control animals. Engrafted BMSCs were observed in spinal cords and dorsal root ganglia at 5 weeks after cell injection. Injury significantly decreased the levels of six soluble factors in CSF: intercellular adhesion molecule 1 (ICAM-1), interleukin-1β (IL-1β), IL-10, hepatocyte growth factor (HGF), Nope protein, and neurogenic locus notch homolog protein 1 (Notch-1). Intrathecal BMSCs significantly attenuated the injury-induced reduction of ICAM-1, IL-1β, HGF, IL-10, and Nope. This study adds to evidence supporting the use of intrathecal BMSCs in pain control and shows that this effect is accompanied by the reversal of injury-induced reduction of multiple CSF soluble factors. Our findings suggest that these soluble factors may be potential targets for treating chronic pain.