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1.
Biomed Mater ; 15(1): 015012, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-31796648

RESUMO

Severe spinal cord injury (SCI) results in permanent functional deficits, which despite pre-clinical advances, remain untreatable. Combinational approaches, including the implantation of bioengineered scaffolds are likely to promote significant tissue repair. However, this critically depends on the extent to which host tissue can integrate with the implant. In the present paper, blood vessel formation and maturation were studied within and around implanted micro-structured type-I collagen scaffolds at 10 weeks post implantation in adult rat mid-cervical spinal cord lateral funiculotomy injuries. Morphometric analysis revealed that blood vessel density within the scaffold was similar to that of the lateral white matter tracts that the implant replaced. However, immunohistochemistry for zonula occludens-1 (ZO-1) and endothelial barrier antigen revealed that scaffold microvessels remained largely immature, suggesting poor blood-spinal cord barrier (BSB) reformation. Furthermore, a band of intense ZO-1-immunoreactive fibroblast-like cells isolated the implant. Spinal cord vessels outside the ZO-1-band demonstrated BSB-formation, while vessels within the scaffold generally did not. The formation of a double-layered fibrotic and astroglial scar around the collagen scaffold might explain the relatively poor implant-host integration and suggests a mechanism for failed microvessel maturation. Targeted strategies that improve implant-host integration for such biomaterials will be vital for future tissue engineering and regenerative medicine approaches for traumatic SCI.


Assuntos
Vasos Sanguíneos/patologia , Colágeno/química , Traumatismos da Medula Espinal/patologia , Traumatismos da Medula Espinal/terapia , Engenharia Tecidual/métodos , Alicerces Teciduais , Animais , Antígenos de Superfície/metabolismo , Materiais Biocompatíveis , Modelos Animais de Doenças , Feminino , Fibroblastos/metabolismo , Fibrose , Microcirculação , Ratos , Ratos Sprague-Dawley , Medicina Regenerativa , Medula Espinal/patologia , Proteína da Zônula de Oclusão-1/metabolismo
2.
Regen Biomater ; 6(2): 75-87, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30967962

RESUMO

Severe traumatic spinal cord injury (SCI) results in a devastating and permanent loss of function, and is currently an incurable condition. It is generally accepted that future intervention strategies will require combinational approaches, including bioengineered scaffolds, to support axon growth across tissue scarring and cystic cavitation. Previously, we demonstrated that implantation of a microporous type-I collagen scaffold into an experimental model of SCI was capable of supporting functional recovery in the absence of extensive implant-host neural tissue integration. Here, we demonstrate the reactive host cellular responses that may be detrimental to neural tissue integration after implantation of collagen scaffolds into unilateral resection injuries of the adult rat spinal cord. Immunohistochemistry demonstrated scattered fibroblast-like cell infiltration throughout the scaffolds as well as the presence of variable layers of densely packed cells, the fine processes of which extended along the graft-host interface. Few reactive astroglial or regenerating axonal profiles could be seen traversing this layer. Such encapsulation-type behaviour around bioengineered scaffolds impedes the integration of host neural tissues and reduces the intended bridging role of the implant. Characterization of the cellular and molecular mechanisms underpinning this behaviour will be pivotal in the future design of collagen-based bridging scaffolds intended for regenerative medicine.

3.
Neuroscience ; 394: 44-59, 2018 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-30342198

RESUMO

Locomotor patterns are mainly modulated by afferent feedback, but its actual contribution to spinal network activity during continuous passive limb training is still unexplored. To unveil this issue, we devised a robotic in vitro setup (Bipedal Induced Kinetic Exercise, BIKE) to induce passive pedaling, while simultaneously recording low-noise ventral and dorsal root (VR and DR) potentials in isolated neonatal rat spinal cords with hindlimbs attached. As a result, BIKE evoked rhythmic afferent volleys from DRs, reminiscent of pedaling speed. During BIKE, spontaneous VR activity remained unchanged, while a DR rhythmic component paired the pedaling pace. Moreover, BIKE onset rarely elicited brief episodes of fictive locomotion (FL) and, when trains of electrical pulses were simultaneously applied to a DR, it increased the amplitude, but not the number, of FL cycles. When BIKE was switched off after a 30-min training, the number of electrically induced FL oscillations was transitorily facilitated, without affecting VR reflexes or DR potentials. However, 90 min of BIKE no longer facilitated FL, but strongly depressed area of VR reflexes and stably increased antidromic DR discharges. Patch clamp recordings from single motoneurons after 90-min sessions indicated an increased frequency of both fast- and slow-decaying synaptic input to motoneurons. In conclusion, hindlimb rhythmic and alternated pedaling for different durations affects distinct dorsal and ventral spinal networks by modulating excitatory and inhibitory input to motoneurons. These results suggest defining new parameters for effective neurorehabilitation that better exploits spinal circuit activity.


Assuntos
Locomoção , Neurônios Aferentes/fisiologia , Robótica , Medula Espinal/fisiologia , Raízes Nervosas Espinhais/fisiologia , Vias Aferentes/fisiologia , Animais , Estimulação Elétrica , Membro Posterior/inervação , Membro Posterior/fisiologia , Neurônios Motores/fisiologia , Ratos Wistar
4.
Brain Behav Immun ; 74: 96-105, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30071254

RESUMO

The prevalence of obesity has increased at an alarming rate during past decades. Obesity is associated with pathophysiological disorders that can evolve and increase the risk of heart disease, diabetes and hypertension. While the impact of diabetes on post-operative recovery is now known, the consequences of obesity on post-operative pain remain much less explored. Here, we show that obesity affects post-operative pain resolution and leads to a chronic pain state in mice. Several mechanisms were identified as implicated in the prolonged post-operative pain. Indeed, we found that following a hind paw incision, high fat diet prolonged glial cell activation in the spinal cord. It also altered the expression of neurotrophins and increased inflammatory and endoplasmic reticulum stress markers in both central and peripheral nervous systems. Moreover, we show that a dietary intervention, leading to weight reduction and decreased inflammation, was able to restore normal pain sensitivity in mice suffering from chronic pain for more than 10 weeks. In conclusion, our data demonstrate that obesity is responsible for pain chronicization. This is clearly of importance in a clinical post-operative setting.


Assuntos
Limiar da Dor/fisiologia , Dor Pós-Operatória/dietoterapia , Animais , Astrócitos/metabolismo , Dieta Hiperlipídica/efeitos adversos , Hiperalgesia/metabolismo , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Crescimento Neural/efeitos dos fármacos , Neuroglia/metabolismo , Obesidade/metabolismo , Obesidade/fisiopatologia , Dor Pós-Operatória/fisiopatologia , Medula Espinal/metabolismo
5.
J Tissue Eng Regen Med ; 12(11): 2125-2137, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30044547

RESUMO

The reconstruction of peripheral nerve injuries is clinically challenging, and today, the autologous nerve transplantation is still considered as the only gold standard remedy for nerve lesions where a direct nerve coaptation is not possible. Nevertheless, the functional merits of many biomaterials have been tested as potential substitutes for the autologous nerve transplant. One of the strategies that have been pursued is the combination of bioengineered nerve guides with cellular enrichment. In this present study, we combined the previously evaluated collagen-based and microstructured nerve guide Perimaix with olfactory ensheathing cell enrichment. Rat sciatic nerve defects of 20 mm were either bridged by a cell-seeded or nonseeded nerve guide or an autologous nerve transplant. Animals were monitored for 12 weeks for structural and functional parameters. Seeded cells survived on Perimaix, and following implantation aligned along the microstructured Perimaix framework. Axonal densities within the cell-seeded nerve guides were higher than in the nonseeded nerve guides and were comparable to the autograft. Additionally, cell-seeding had local beneficial effects on myelination within the nerve guide, as myelin sheath thickness was enhanced when compared with the empty scaffold. Nevertheless, for bridging the nerve gap of 20 mm, both the cell-seeded as well as nonseeded scaffolds were equally efficient regarding the functional outcome, which did not differ between the autograft, seeded or nonseeded groups. Our data demonstrate that olfactory ensheathing cell enrichment has local effects on nerve regeneration in combination with the Perimaix nerve guide. Surprisingly, for traversing the lesion gap, additional cell-seeding is not crucial.


Assuntos
Regeneração Tecidual Guiada/métodos , Bainha de Mielina/transplante , Regeneração Nervosa , Nervo Isquiático , Engenharia Tecidual/métodos , Animais , Autoenxertos , Axônios/fisiologia , Feminino , Regeneração Tecidual Guiada/instrumentação , Ratos , Ratos Endogâmicos Lew , Nervo Isquiático/fisiologia , Nervo Isquiático/transplante
6.
Stem Cell Rev Rep ; 13(4): 499-512, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28509260

RESUMO

Oligodendrocyte progenitor cells (OPCs) play a pivotal role in both health and disease within the central nervous system, with oligodendrocytes, arising from resident OPCs, being the main myelinating cell type. Disruption in OPC numbers can lead to various deleterious health defects. Numerous studies have described techniques for isolating OPCs to obtain a better understanding of this cell type and to open doors for potential treatments of injury and disease. However, the techniques used in the majority of these studies involve several steps and are time consuming, with current culture protocols using serum and embryonic or postnatal cortical tissue as a source of isolation. We present a primary culture method for the direct isolation of functional adult rat OPCs, identified by neuron-glial antigen 2 (NG2) and platelet derived growth factor receptor alpha (PDGFrα) expression, which can be obtained from the adult spinal cord. Our method uses a simple serum-free cocktail of 3 growth factors - FGF2, PDGFAA, and IGF-I, to expand adult rat OPCs in vitro to 96% purity. Cultured cells can be expanded for at least 10 passages with very little manipulation and without losing their phenotypic progenitor cell properties, as shown by immunocytochemistry and RT-PCR. Cultured adult rat OPCs also maintain their ability to differentiate into GalC positive cells when incubated with factors known to stimulate their differentiation. This new isolation method provides a new source of easily accessible adult stem cells and a powerful tool for their expansion in vitro for studies aimed at central nervous system repair.


Assuntos
Células-Tronco Adultas/metabolismo , Separação Celular , Oligodendroglia/metabolismo , Medula Espinal/metabolismo , Células-Tronco Adultas/citologia , Animais , Antígenos/metabolismo , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Oligodendroglia/citologia , Fator de Crescimento Derivado de Plaquetas/metabolismo , Proteoglicanas/metabolismo , Ratos , Ratos Sprague-Dawley , Medula Espinal/citologia
7.
Neurosci Lett ; 653: 113-119, 2017 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-28533177

RESUMO

The differential pharmacological responsiveness of cephalic and extra-cephalic neuropathic pain has been proposed to relate to distinct mechanisms that may involve neuroinflammatory reactions mediated by glial cells. Astrocytes are particularly important for neuronal sensitization in neuropathic pain, in part through modulation of glutamatergic transmission. Because the metabotropic glutamate receptor 5 (mGluR5) is involved in the astrocytic regulation of the glutamatergic system, we investigated modifications of its expression in models of cephalic versus extra-cephalic neuropathic pain. Adult male rats underwent unilateral chronic constriction injury (CCI) of either the infraorbital nerve (ION) or the sciatic nerve (SN). Seven days later, mGluR5 and the astrocyte marker GFAP (glial fibrillary acidic protein) were overexpressed and appeared localized mainly in the superficial lamina of the trigeminal nucleus in CCI-ION and the spinal cord dorsal horn in CCI-SN rats. In addition, colocalization of GFAP and mGluR5 strongly suggested an increase of astrocytic mGluR5 expression in nerve-injured rats compared to sham animals. The present data show an upregulation of astrocytic mGluR5 in central structures in both CCI-ION and CCI-SN. This suggests that the pharmacological modulation of mGluR5 could be a new approach to reduce both cephalic and extra-cephalic neuropathic pain.


Assuntos
Astrócitos/metabolismo , Nervo Maxilar/lesões , Neuralgia/metabolismo , Células do Corno Posterior/metabolismo , Receptor de Glutamato Metabotrópico 5/metabolismo , Nervo Isquiático/lesões , Núcleos do Trigêmeo/metabolismo , Animais , Proteína Glial Fibrilar Ácida/metabolismo , Imuno-Histoquímica , Ligadura , Masculino , Ratos Sprague-Dawley , Regulação para Cima
8.
Exp Neurol ; 293: 62-73, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28359740

RESUMO

Vasoactive intestinal peptide (VIP) is one of the neuropeptides showing the strongest up-regulation in the nociceptive pathway after peripheral nerve injury and has been proposed to support neuropathic pain. Nevertheless, the story may be more complicated considering the known suppressive effects of the peptide on the immune reactivity of microglial cells, which have been heavily implicated in the onset and maintenance of pain after nerve injury. We here used mice deficient in VIP and the model of spared nerve injury, characterized by persistent tactile hypersensitivity. While tactile hypersensitivity developed similarly to wild type mice for the ipsilateral hindpaw, only transgenic mice showed a mirror-image tactile hypersensitivity in the contralateral hindpaw. This exacerbated neuropathic pain phenotype appeared to be mediated through a local mechanism acting at the level of the lumbar spinal cord as a distant nerve lesion in the front limb did not lead to hindpaw hypersensitivity in VIP-deficient mice. Innocuous tactile hindpaw stimulation was found to increase a neuronal activation marker in the bilateral superficial laminae of the lumbar dorsal horn of VIP-deficient, but not wild type mice, after SNI. A deeper study into the immune responsiveness to the nerve lesion also proved that VIP-deficient mice had a stronger early pro-inflammatory cytokine response and a more pronounced microglial reactivity compared to wild type controls. The latter was also observed at four weeks after spared nerve injury, a time at which bilateral tactile hypersensitivity persisted in VIP-deficient mice. These data suggest an action of VIP in neuropathic states that is more complicated than previously assumed. Future research is now needed for a deeper understanding of the relative contribution of receptors and fiber populations involved in the VIP-neuropathic pain link.


Assuntos
Hiperalgesia/etiologia , Hiperalgesia/genética , Inflamação Neurogênica/etiologia , Inflamação Neurogênica/genética , Traumatismos dos Nervos Periféricos/complicações , Peptídeo Intestinal Vasoativo/deficiência , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Feminino , Lateralidade Funcional/genética , Regulação da Expressão Gênica/genética , Proteína Glial Fibrilar Ácida/metabolismo , Hiperalgesia/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas dos Microfilamentos/metabolismo , Neuralgia/etiologia , Inflamação Neurogênica/metabolismo , Medição da Dor , Proteínas Proto-Oncogênicas c-fos/metabolismo , Fatores de Tempo , Peptídeo Intestinal Vasoativo/genética
9.
Exp Neurol ; 286: 1-11, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27641322

RESUMO

Tactile hypersensitivity is one of the most debilitating symptoms of neuropathic pain syndromes. Clinical studies have suggested that its presence at early postoperative stages may predict chronic (neuropathic) pain after surgery. Currently available animal models are typically associated with consistent tactile hypersensitivity and are therefore limited to distinguish between mechanisms that underlie tactile hypersensitivity as opposed to mechanisms that protect against it. In this study we have modified the rat model of spared nerve injury, restricting the surgical lesion to a single peripheral branch of the sciatic nerve. This modification reduced the prevalence of tactile hypersensitivity from nearly 100% to approximately 50%. With this model, we here also demonstrated that the Regulator of G protein Signaling 4 (RGS4) was specifically up-regulated in the lumbar dorsal root ganglia and dorsal horn of rats developing tactile hypersensitivity. Intrathecal delivery of the RGS4 inhibitor CCG63802 was found to reverse tactile hypersensitivity for a 1h period. Moreover, tactile hypersensitivity after modified spared nerve injury was most frequently persistent for at least four weeks and associated with higher reactivity of glial cells in the lumbar dorsal horn. Based on these data we suggest that this new animal model of nerve injury represents an asset in understanding divergent neuropathic pain outcomes, so far unravelling a role of RGS4 in tactile hypersensitivity. Whether this model also holds promise in the study of the transition from acute to chronic pain will have to be seen in future investigations.


Assuntos
Hiperalgesia/etiologia , Traumatismos dos Nervos Periféricos/complicações , Proteínas RGS/metabolismo , Regulação para Cima/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Análise de Variância , Animais , Benzotiazóis/farmacologia , Biofísica , Proteínas de Ligação ao Cálcio/metabolismo , Modelos Animais de Doenças , Estimulação Elétrica , Feminino , Lateralidade Funcional , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Hiperalgesia/metabolismo , Hiperalgesia/patologia , Proteínas dos Microfilamentos/metabolismo , Limiar da Dor/efeitos dos fármacos , Limiar da Dor/fisiologia , Traumatismos dos Nervos Periféricos/metabolismo , Pirimidinas/farmacologia , Proteínas RGS/antagonistas & inibidores , Proteínas RGS/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Corno Dorsal da Medula Espinal/efeitos dos fármacos , Corno Dorsal da Medula Espinal/metabolismo , Fatores de Tempo , Regulação para Cima/efeitos dos fármacos
10.
Cell Mol Life Sci ; 73(7): 1413-37, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26768693

RESUMO

Dental stem cells are an emerging star on a stage that is already quite populated. Recently, there has been a lot of hype concerning these cells in dental therapies, especially in regenerative endodontics. It is fitting that most research is concentrated on dental regeneration, although other uses for these cells need to be explored in more detail. Being a true mesenchymal stem cell, their capacities could also prove beneficial in areas outside their natural environment. One such field is the central nervous system, and in particular, repairing the injured spinal cord. One of the most formidable challenges in regenerative medicine is to restore function to the injured spinal cord, and as yet, a cure for paralysis remains to be discovered. A variety of approaches have already been tested, with graft-based strategies utilising cells harbouring appropriate properties for neural regeneration showing encouraging results. Here we present a review focusing on properties of dental stem cells that endorse their use in regenerative medicine, with particular emphasis on repairing the damaged spinal cord.


Assuntos
Polpa Dentária/citologia , Traumatismos da Medula Espinal/terapia , Transplante de Células-Tronco , Animais , Humanos , Fatores de Crescimento Neural/metabolismo , Receptores de Fator de Crescimento Neural/metabolismo , Medicina Regenerativa , Células-Tronco/citologia
11.
Pain Res Manag ; 2016: 9703036, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28115879

RESUMO

Background. Capsaicin, one of several capsaicinoid compounds, is a potent TRPV1 agonist. Topical application at high concentration (high concentration, >1%) induces a reversible disappearance of epidermal free nerve endings and is used to treat peripheral neuropathic pain (PNP). While the benefit of low-concentration capsaicin remains controversial, the 8%-capsaicin patch (Qutenza®, 2010, Astellas, Netherlands) has shown its effectiveness. This patch is, however, costly and natural high-concentration capsaicinoid solutions may represent a cheaper alternative to pure capsaicin. Methods. In this retrospective study, 149 patients were screened, 132 were included with a diagnosis of neuropathic pain, and eighty-four were retained in the final analyses (median age: 57.5 years [IQR25-75: 44.7-67.1], male/female: 30/54) with PNP who were treated with topical applications of natural high-concentration capsaicinoid solutions (total number of applications: 137). Indications were postsurgical PNP (85.7%) and nonsurgical PNP (14.3%) (posttraumatic, HIV-related, postherpetic, and radicular PNP). Objectives. To assess the feasibility of topical applications of natural high-concentration capsaicinoid solutions for the treatment of PNP. Results. The median treated area was 250 cm2 [IQR25-75: 144-531]. The median amount of capsaicinoids was 55.1 mg [IQR25-75: 28.7-76.5] per plaster and the median concentration was 172.3 µg/cm2 [IQR25-75: 127.6-255.2]. Most patients had local adverse effects on the day of treatment, such as mild to moderate burning pain and erythema. 13.6-19.4% of the patients experienced severe pain or erythema. Following treatment, 62.5% of patients reported a lower pain intensity or a smaller pain surface, and 35% reported a sustained pain relief lasting for at least 4 weeks. Conclusion. Analgesic topical treatment with natural high-concentration capsaicinoid is feasible and may represent a low cost alternative to alleviate PNP in clinical practice.


Assuntos
Capsaicina/análogos & derivados , Capsaicina/administração & dosagem , Neuralgia/diagnóstico , Neuralgia/tratamento farmacológico , Medição da Dor/efeitos dos fármacos , Administração Tópica , Adulto , Idoso , Antipruriginosos/administração & dosagem , Antipruriginosos/química , Estudos de Coortes , Composição de Medicamentos , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor/métodos , Soluções Farmacêuticas/administração & dosagem , Soluções Farmacêuticas/química , Estudos Retrospectivos
12.
Eur J Neurosci ; 43(3): 404-16, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26296589

RESUMO

Many bioartificial nerve guides have been investigated pre-clinically for their nerve regeneration-supporting function, often in comparison to autologous nerve transplantation, which is still regarded as the current clinical gold standard. Enrichment of these scaffolds with cells intended to support axonal regeneration has been explored as a strategy to boost axonal regeneration across these nerve guides Ansselin et al. (1998). In the present study, 20 mm rat sciatic nerve defects were implanted with a cell-seeded microstructured collagen nerve guide (Perimaix) or an autologous nerve graft. Under the influence of seeded, pre-differentiated mesenchymal stromal cells, axons regenerated well into the Perimaix nerve guide. Myelination-related parameters, like myelin sheath thickness, benefitted from an additional seeding with pre-differentiated mesenchymal stromal cells. Furthermore, both the number of retrogradely labelled sensory neurons and the axon density within the implant were elevated in the cell-seeded scaffold group with pre-differentiated mesenchymal stromal cells. However, a pre-differentiation had no influence on functional recovery. An additional cell seeding of the Perimaix nerve guide with mesenchymal stromal cells led to an extent of functional recovery, independent of the differentiation status, similar to autologous nerve transplantation. These findings encourage further investigations on pre-differentiated mesenchymal stromal cells as a cellular support for peripheral nerve regeneration.


Assuntos
Diferenciação Celular , Células-Tronco Mesenquimais/citologia , Regeneração Nervosa , Traumatismos dos Nervos Periféricos/cirurgia , Alicerces Teciduais/química , Animais , Células Cultivadas , Colágeno/química , Feminino , Regeneração Tecidual Guiada , Transplante de Células-Tronco Mesenquimais , Bainha de Mielina/metabolismo , Ratos , Ratos Endogâmicos Lew , Nervo Isquiático/fisiologia , Nervo Isquiático/transplante , Alicerces Teciduais/efeitos adversos
13.
Neuromodulation ; 19(1): 38-46, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26449748

RESUMO

OBJECTIVES: Investigate whether electrical stimulation of the spinal cord adapted to trigger locomotor patterns additionally influences dorsal horn networks. MATERIALS AND METHODS: An in vitro model of isolated neonatal rat spinal cord was used to repetitively deliver electrical stimuli to lumbar dorsal roots and record from homolateral lumbar dorsal roots and ventral roots. RESULTS: Repetitive electrical lumbar dorsal root stimulation can affect both locomotor rhythms derived from ventral neuronal circuits and activity from dorsal neuronal circuits. CONCLUSION: These data suggest that neuro-electrostimulation protocols can simultaneously activate functionally distinct spinal neuronal circuits.


Assuntos
Potenciais de Ação/fisiologia , Rede Nervosa/fisiologia , Corno Dorsal da Medula Espinal/fisiologia , Medula Espinal/anatomia & histologia , Raízes Nervosas Espinhais/fisiologia , Animais , Animais Recém-Nascidos , Biofísica , Estimulação Elétrica , Técnicas In Vitro , Modelos Lineares , Ratos , Ratos Wistar , Medula Espinal/fisiologia , Fatores de Tempo
14.
Tissue Eng Regen Med ; 13(5): 585-600, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30603440

RESUMO

The implantation of bioengineered scaffolds into lesion-induced gaps of the spinal cord is a promising strategy for promoting functional tissue repair because it can be combined with other intervention strategies. Our previous investigations showed that functional improvement following the implantation of a longitudinally microstructured collagen scaffold into unilateral mid-cervical spinal cord resection injuries of adult Lewis rats was associated with only poor axon regeneration within the scaffold. In an attempt to improve graft-host integration as well as functional recovery, scaffolds were seeded with highly enriched populations of syngeneic, olfactory bulb-derived ensheathing cells (OECs) prior to implantation into the same lesion model. Regenerating neurofilament-positive axons closely followed the trajectory of the donor OECs, as well as that of the migrating host cells within the scaffold. However, there was only a trend for increased numbers of regenerating axons above that supported by non-seeded scaffolds or in the untreated lesions. Nonetheless, significant functional recovery in skilled forelimb motor function was observed following the implantation of both seeded and non-seeded scaffolds which could not be correlated to the extent of axon regeneration within the scaffold. Mechanisms other than simple bridging of axon regeneration across the lesion must be responsible for the improved motor function.

15.
Br J Pharmacol ; 172(22): 5333-46, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26478461

RESUMO

BACKGROUND AND PURPOSE: Regulators of G protein signalling (RGS) are major determinants of metabotropic receptor activity, reducing the lifespan of the GTP-bound state of G proteins. Because the reduced potency of analgesic agents in neuropathic pain may reflect alterations in RGS, we assessed the effects of CCG 63802, a specific RGS4 inhibitor, on pain hypersensitivity and signalling through cannabinoid receptors, in a model of neuropathic pain. EXPERIMENTAL APPROACH: The partial sciatic nerve ligation (PSNL) model in male Sprague Dawley rats was used to measure paw withdrawal thresholds to mechanical (von Frey hairs) or thermal (Hargreaves method) stimuli, during and after intrathecal injection of CCG 63802. HEK293 cells expressing CB1 receptors and conditional expression of RGS4 were used to correlate cAMP production and ERK phosphorylation with receptor activation and RGS4 action. KEY RESULTS: Treatment of PSNL rats with CCG 63802, twice daily for 7 days after nerve injury, attenuated thermal hyperalgesia during treatment. Spinal levels of anandamide were higher in PSNL animals, irrespective of the treatment. Although expression of CB1 receptors was unaffected, HU210-induced CB1 receptor signalling was inhibited in PSNL rats and restored after intrathecal CCG 63802. In transfected HEK cells expressing CB1 receptors and RGS4, inhibition of cAMP production, a downstream effect of CB1 receptor signalling, was blunted after RGS4 overexpression. RGS4 expression also attenuated the CB1 receptor-controlled activation of ERK1/2. CONCLUSIONS AND IMPLICATIONS: Inhibition of spinal RGS4 restored endogenous analgesic signalling pathways and mitigated neuropathic pain. Signalling through CB1 receptors may be involved in this beneficial effect.


Assuntos
Hiperalgesia/metabolismo , Neuralgia/metabolismo , Proteínas RGS/antagonistas & inibidores , Receptor CB1 de Canabinoide/metabolismo , Medula Espinal/metabolismo , Animais , AMP Cíclico/metabolismo , Células HEK293 , Temperatura Alta , Humanos , Ligadura , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Estimulação Física , Proteínas RGS/metabolismo , Ratos Sprague-Dawley , Receptor CB1 de Canabinoide/agonistas , Nervo Isquiático/cirurgia , Transdução de Sinais
17.
Sci Rep ; 5: 10666, 2015 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-26053681

RESUMO

Dorsal root avulsion results in permanent impairment of sensory functions due to disconnection between the peripheral and central nervous system. Improved strategies are therefore needed to reconnect injured sensory neurons with their spinal cord targets in order to achieve functional repair after brachial and lumbosacral plexus avulsion injuries. Here, we show that sensory functions can be restored in the adult mouse if avulsed sensory fibers are bridged with the spinal cord by human neural progenitor (hNP) transplants. Responses to peripheral mechanical sensory stimulation were significantly improved in transplanted animals. Transganglionic tracing showed host sensory axons only in the spinal cord dorsal horn of treated animals. Immunohistochemical analysis confirmed that sensory fibers had grown through the bridge and showed robust survival and differentiation of the transplants. Section of the repaired dorsal roots distal to the transplant completely abolished the behavioral improvement. This demonstrates that hNP transplants promote recovery of sensorimotor functions after dorsal root avulsion, and that these effects are mediated by spinal ingrowth of host sensory axons. These results provide a rationale for the development of novel stem cell-based strategies for functionally useful bridging of the peripheral and central nervous system.


Assuntos
Axônios/fisiologia , Células-Tronco Embrionárias Humanas/fisiologia , Regeneração Nervosa/fisiologia , Células Receptoras Sensoriais/fisiologia , Traumatismos da Medula Espinal/fisiopatologia , Raízes Nervosas Espinhais/fisiologia , Células-Tronco/fisiologia , Animais , Gânglios Espinais/fisiologia , Humanos , Masculino , Camundongos , Medula Espinal/fisiologia
18.
Neurosci Res ; 95: 78-82, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25697394

RESUMO

Spinal glial reactivity has been strongly implicated in pain that follows peripheral nerve injury. Among the many therapeutic agents that have been tested for anti-allodynia through immune modulation is the atypical methylxanthine propentofylline. While propentofylline shows a potent anti-allodynia effect after nerve transection injury, we here demonstrate that, when propentofylline is used intrathecally at the effective immune-modulatory dose, allodynia after rat nerve crush injury is completely preserved. Microglial/macrophage Iba-1 and astrocytic GFAP expression, increased in the dorsal horn of nerve crushed animals, was, however, effectively attenuated by propentofylline. Effective modulation of spinal glial reactivity is, thus, no assurance for anti-allodynia.


Assuntos
Hiperalgesia/metabolismo , Hiperalgesia/psicologia , Neuroglia/efeitos dos fármacos , Neuroglia/metabolismo , Corno Dorsal da Medula Espinal/metabolismo , Xantinas/administração & dosagem , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Feminino , Proteína Glial Fibrilar Ácida/metabolismo , Hiperalgesia/tratamento farmacológico , Injeções Espinhais , Proteínas dos Microfilamentos/metabolismo , Compressão Nervosa , Neuralgia/tratamento farmacológico , Neuralgia/metabolismo , Limiar da Dor/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Recuperação de Função Fisiológica/efeitos dos fármacos , Nervo Isquiático/lesões , Corno Dorsal da Medula Espinal/efeitos dos fármacos
19.
Exp Neurol ; 263: 91-101, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25311268

RESUMO

Vasoactive intestinal peptide (VIP) has potent immune modulatory actions that may influence the course of neurodegenerative disorders associated with chronic inflammation. Here, we show the therapeutic benefits of a modified peptide agonist stearyl-norleucine-VIP (SNV) in a transgenic rat model of amyotrophic lateral sclerosis (mutated superoxide dismutase 1, hSOD1(G93A)). When administered by systemic every-other-day intraperitoneal injections during a period of 80 days before disease, SNV delayed the onset of motor dysfunction by no less than three weeks, while survival was extended by nearly two months. SNV-treated rats showed reduced astro- and microgliosis in the lumbar ventral spinal cord and a significant degree of motor neuron preservation. Throughout the treatment, SNV promoted the expression of the anti-inflammatory cytokine interleukin-10 as well as neurotrophic factors commonly considered as beneficial in amyotrophic lateral sclerosis management (glial derived neuroptrophic factor, insulin like growth factor, brain derived neurotrophic factor). The peptide nearly totally suppressed the expression of tumor necrosis factor-α and repressed the production of the pro-inflammatory mediators interleukin-1ß, nitric oxide and of the transcription factor nuclear factor kappa B. Inhibition of tumor necrosis factor-α likely accounted for the observed down-regulation of nuclear factor kappa B that modulates the transcription of genes specifically involved in amyotrophic lateral sclerosis (sod1 and the glutamate transporter slc1a2). In line with this, levels of human superoxide dismutase 1 mRNA and protein were decreased by SNV treatment, while the expression and activity of the glutamate transporter-1 was promoted. Considering the large diversity of influences of this peptide on both clinical features of the disease and associated biochemical markers, we propose that SNV or related peptides may constitute promising candidates for amyotrophic lateral sclerosis treatment.


Assuntos
Esclerose Lateral Amiotrófica/patologia , Anti-Inflamatórios/farmacologia , Medula Espinal/efeitos dos fármacos , Superóxido Dismutase/efeitos dos fármacos , Peptídeo Intestinal Vasoativo/farmacologia , Esclerose Lateral Amiotrófica/metabolismo , Animais , Western Blotting , Modelos Animais de Doenças , Humanos , Imuno-Histoquímica , Fármacos Neuroprotetores/farmacologia , Ratos , Ratos Sprague-Dawley , Ratos Transgênicos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Medula Espinal/metabolismo , Medula Espinal/patologia , Superóxido Dismutase/biossíntese , Superóxido Dismutase/genética , Superóxido Dismutase-1
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