Neuropathic pain is a type of chronic pain caused by injury or dysfunction of the nervous system, without effective therapeutic approaches. Mesenchymal stromal cells (MSCs), through their paracrine action, have great potential in the treatment of this syndrome. In the present study, the therapeutic potential of MSC-derived conditioned medium (CM) was investigated in a mouse model of neuropathic pain induced by partial sciatic nerve ligation (PSL). PSL mice were treated by endovenous route with bone marrow-derived MSCs (1 × 106), CM, or vehicle. Gabapentin was the reference drug. Twelve hours after administration, neuropathic mice treated with CM exhibited an antinociceptive effect that was maintained throughout the evaluation period. MSCs also induced nonreversed antinociception, while gabapentin induced short-lasting antinociception. The levels of IL-1β, TNF-α, and IL-6 were reduced, while IL-10 was enhanced on sciatic nerve and spinal cord by treatment with CM and MSCs. Preliminary analysis of the CM secretome revealed the presence of growth factors and cytokines likely involved in the antinociception. In conclusion, the CM, similar to injection of live cells, produces a powerful and long-lasting antinociceptive effect on neuropathic pain, which is related with modulatory properties on peripheral and central levels of cytokines involved with the maintenance of this syndrome.

Diabetic neuropathy is a frequent complication of diabetes. Symptoms include neuropathic pain and sensory alterations—no effective treatments are currently available. This work characterized the therapeutic effect of bergenin in a mouse (C57/BL6) model of streptozotocin-induced painful diabetic neuropathy. Nociceptive thresholds were assessed by the von Frey test. Cytokines, antioxidant genes, and oxidative stress markers were measured in nervous tissues by ELISA, RT-qPCR, and biochemical analyses. Single (3.125–25 mg/kg) or multiple (25 mg/kg; twice a day for 14 days) treatments with bergenin reduced the behavioral signs of diabetic neuropathy in mice. Bergenin reduced both nitric oxide (NO) production in vitro and malondialdehyde (MDA)/nitrite amounts in vivo. These antioxidant properties can be attributed to the modulation of gene expression by the downregulation of inducible nitric oxide synthase (iNOS) and upregulation of glutathione peroxidase and Nrf2 in the nervous system. Bergenin also modulated the pro- and anti-inflammatory cytokines production in neuropathic mice. The long-lasting antinociceptive effect induced by bergenin in neuropathic mice, was associated with a shift of the cytokine balance toward anti-inflammatory predominance and upregulation of antioxidant pathways, favoring the reestablishment of redox and immune homeostasis in the nervous system. These results point to the therapeutic potential of bergenin in the treatment of painful diabetic neuropathy.

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Chemotherapy-induced neuropathy is a disabling pain condition resulting from chemotherapy for cancers. Up to now, no drug is available to cure chemotherapy-induced neuropathy. In the present study, we describe the structural design, synthesis, chemical and pharmacological characterization of 15 thiazolidinones, a class of potential analgesic compounds. The synthesis of new thiazolidinones was achieved by using the thiazolidinone heterocyclic as main structural pharmacophoric group and varying the substituents attached to the phenyl near to the iminic bond. The analgesic potential of the compounds was investigated in a mice model of oxaliplatin-induced neuropathic pain, using von Frey, rota-rod and open-field tests. Except for compound 14, these thiazolidinones exhibited antinociceptive property without causing motor impairment. Thiazolidinones 12, 15 and 16 displayed a dose-dependent antinociceptive effect, with similar efficacy and enhanced potency than gabapentin, the gold standard drug used for neuropathic pain. In addition, the antinociceptive activity of 16 lasted longer than gabapentin. The antinociceptive effect of thiazolidinones was prevented by GW9662, a PPARγ antagonist. The main antinociceptive compounds exhibited positive Lipinski's index, predicting their oral bioavailability. In conclusion, the structural design performed here led to the identification of new compounds endowed with potent antinociceptive activity, potentially useful to treat chemotherapy-induced neuropathic pain.

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