Introduction: The administration of stem cells holds promise as a potential therapy for spinal cord injury (SCI). Mesenchymal stem cells have advantages for clinical applications, since they can be easily obtained, are suitable for autologous transplantation and have been previously shown to induce regeneration of the spinal cord in experimental settings. Here we evaluated the feasibility, safety and potential efficacy of autologous transplantation of mesenchymal stem cells in subjects with chronic complete SCI. Method: We conducted a phase I, non-controlled study in 14 subjects of both genders aging between 18 to 65 years, with chronic traumatic SCI (>6 months), at thoracic or lumbar levels, classified as American Spinal Injury Association (ASIA) A - complete injury. Baseline somatosensory evoked potentials (SSEP), spinal magnetic resonance imaging (MRI) and urodynamics were assessed before and after treatment. Pain rating was performed using the McGill Pain Questionnaire and a visual analogue score scale. Bone marrow-derived mesenchymal stem cells were cultured and characterized by flow cytometry, cell differentiation assays and G-band karyotyping. Mesenchymal stem cells were injected directly into the lesion following laminectomy and durotomy. Results: Cell transplantation was an overall safe and well-tolerated procedure. All subjects displayed variable improvements in tactile sensitivity and eight subjects developed lower limbs motor functional gains, principally in the hip flexors. Seven subjects presented sacral sparing and improved American Spinal Injury Association impairment scale (AIS) grades to B or C – incomplete injury. Nine subjects had improvements in urologic function. One subject presented changes in SSEP 3 and 6 months after mesenchymal stem cells transplantation. Statistically significant correlations between the improvements in neurological function and both injury size and level were found. Conclusion: Intralesional transplantation of autologous mesenchymal stem cells in subjects with chronic, complete spinal cord injury is safe, feasible, and may promote neurological improvements. Trial registration: ClinicalTrials.gov NCT01325103 – Registered 28 March 2011

Diabetic neuropathy (DN) is a frequent and debilitating manifestation of diabetes mellitus, to which there are no effective therapeutic approaches. Mesenchymal stem/stromal cells (MSC) have a great potential for the treatment of this syndrome, possibly through regenerative actions on peripheral nerves. Here, we evaluated the therapeutic effects of MSC on spinal neuroinflammation, as well as on ultrastructural aspects of the peripheral nerve in DN-associated sensorial dysfunction. C57Bl/6 mice were treated with bone marrow-derived MSC (1 × 106), conditioned medium from MSC cultures (CM-MSC) or vehicle by endovenous route following the onset of streptozotocin (STZ)-induced diabetes. Paw mechanical and thermal nociceptive thresholds were evaluated by using von Frey filaments and Hargreaves test, respectively. Morphological and morphometric analysis of the sciatic nerve was performed by light microscopy and transmission electron microscopy. Mediators and markers of neuroinflammation in the spinal cord were measured by radioimmunoassay, real-time PCR, and immunofluorescence analyses. Diabetic mice presented behavioral signs of sensory neuropathy, mechanical allodynia, and heat hypoalgesia, which were completely reversed by a single administration of MSC or CM-MSC. The ultrastructural analysis of the sciatic nerve showed that diabetic mice exhibited morphological and morphometric alterations, considered hallmarks of DN, such as degenerative changes in axons and myelin sheath, and reduced area and density of unmyelinated fibers. In MSC-treated mice, these structural alterations were markedly less commonly observed and/or less pronounced. Moreover, MSC transplantation inhibited multiple parameters of spinal neuroinflammation found in diabetic mice, causing the reduction of activated astrocytes and microglia, oxidative stress signals, galectin-3, IL-1β, and TNF-α production. Conversely, MSC increased the levels of anti-inflammatory cytokines, IL-10, and TGF-β. The present study described the modulatory effects of MSC on spinal cord neuroinflammation in diabetic mice, suggesting new mechanisms by which MSC can improve DN.

Pain corresponds to the most frequent reason for visits to physicians, and its control by conventional drugs is accompanied by several side effects, making treatment difficult. For this reason, new chemical entities derived from natural products still hold great promise for the future of drug discovery to pain treatment. The objective of this study was to evaluate the antinociceptive and anti-inflammatory profiles of p-cymene (PC), a monocyclic monoterpene, and its possible mechanisms of action. Mice treated acutely with PC (25, 50, or 100 mg/kg, i.p.) were screened for carrageenan-induced hyperalgesia and the inflammatory components of its cascade (30-180 min), carrageenan-induced pleurisy (4 h), and tail-flick test (1-8 h). Also, we observed the PC effect on the generation of nitric oxide by macrophages and the activation of neurons in the periaqueductal gray (PAG) by immunofluorescence. PC reduced (p < 0.001) the hyperalgesia induced by carrageenan, TNF-α, dopamine, and PGE2. PC decrease total leukocyte migration (100 mg/kg: p < 0.01), neutrophils (50 and 100 mg/kg: p < 0.05 and 0.001), and TNF-α (25, 50, and 100 mg/kg: p < 0.01, 0.05, and 0.001, respectively), besides reducing NO production (p < 0.05) in vitro. PC produced antinociceptive effect in tail-flick test (p < 0.05), which was antagonized by naloxone, naltrindole, nor-BNI, and CTOP, and increased (p < 0.001) the number of c-Fos-immunoreactive neurons in PAG. These results provide information about the anti-hyperalgesic and anti-inflammatory properties of PC suggesting a possible involvement of the opioid system and modulating some pro-inflammatory cytokines.

Background and purpose:  Protein kinase (PK) A and the ε isoform of PKC (PKCε) are involved in the development of hypernociception (increased sensitivity to noxious or innocuous stimuli) in several animal models of acute and persistent inflammatory pain. The present study evaluated the contribution of PKA and PKCε to the development of prostaglandin E₂ (PGE₂)‐induced mechanical hypernociception.Experimental approach:  Prostaglandin E₂‐induced mechanical hypernociception was assessed by constant pressure rat paw test. The activation of PKA or PKCε was evaluated by radioactive enzymic assay in the dorsal root ganglia (DRG) of sensory neurons from the hind paws.Key results:  Hypernociception induced by PGE₂ (100 ng) by intraplantar (i.pl.) injection, was reduced by i.pl. treatment with inhibitors of PKA [A‐kinase‐anchoring protein St‐Ht31 inhibitor peptide (AKAPI)], PKCε (PKCεI) or adenylyl cyclase. PKA activity was essential in the early phase of the induction of hypernociception, whereas PKC activity was involved in the maintenance of the later phase of hypernociception. In the DRG (L4‐L5), activity of PKA increased at 30 min after injection of PGE₂ but PKC activity increased only after 180 min. Moreover, i.pl. injection of the catalytic subunit of PKA induced hypernociception which was markedly reduced by pretreatment with an inhibitor of PKCε, while the hypernociception induced by paw injection of PKCε agonist was not affected by an inhibitor of PKA (AKAPI).Conclusions and implications:  Taken together, these findings are consistent with the suggestion that PKA activates PKCε, which is a novel mechanism of interaction between these kinases during the development of PGE₂‐induced mechanical hypernociception.