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OBJETIVO: avaliar o efeito das neuregulinas 1-alfa e 1-beta na regeneração de nervos ciáticos de camundongos C57BL/6J, adultos, machos, através da técnica de tubulização. MÉTODOS: Utilizaram-se 18 animais, divididos em 3 grupos, implantando-se prótese de polietileno em falhas de 4,0 mm no nervo ciático esquerdo: grupo 1 contendo apenas colágeno purificado (Vitrogen®); grupo 2, colágeno associado a neuregulina 1-alfa; grupo 3 com colágeno e neuregulina 1-beta. O grupo controle foi formado por 6 segmentos de nervos ciáticos direitos. Após 4 semanas, os animais foram sacrificados; extraiu-se segmento do ponto médio do nervo regenerado no interior das próteses, padronizaram-se cortes histológicos e confecção das lâminas para análise histomorfométrica. Confrontaram-se os resultados estatisticamente. RESULTADOS: Os animais tratados com neuregulinas tiveram maior número de axônios mielinizados, com diferença estatisticamente significante quando comparados ao grupo colágeno. Não houve diferença estatística entre os grupos de neuregulinas 1-alfa e 1-beta. CONCLUSÃO: a adição de neuregulinas proporcionou aumento significativo do número de fibras mielinizadas. / PURPOSE: To evaluate the effect of neuregulins 1-alpha and 1-beta on the regeneration the sciatic nerves of male adult C57BL/6J mice, using the tubulization technique. METHODS: Eighteen animals were used, divided into three groups. A polyethylene prosthesis was implanted in a 4.0 mm defect of the left sciatic nerve, as follows: group 1 containing only purified collagen (Vitrogen®); group 2, collagen with neuregulin 1-alpha; group 3, collagen with neuregulin 1-beta. The control group was formed by six segments of right sciatic nerves. Four weeks later, the animals were sacrificed. A segment from the midpoint of the nerve regenerated inside the prostheses was extracted, histological sections were standardized and slides were made up for histomorphometric analysis. The results were statistically compared using the Tukey multiple comparisons test and Students t test. RESULTS: The animals treated with neuregulins had greater numbers of myelinized axons, with a statistically significant difference in relation to the collagen-only group. There was no statistical difference between the neuregulin 1-alpha and 1- beta groups. CONCLUSION: It was concluded that the addition of neuregulins provided a significant increase in the number of myelinized fibers.

Orientador: Vânia Niéto Brito de Souza / Resumo: A infecção pelo Mycobacterium leprae (ML) estimula um processo de desdiferenciação e proliferação das células de Schwann (SCs) que pode contribuir para a disseminação do bacilo. Os macrófagos (MOs) são células efetoras da resposta imune que promovem a eliminação de patógenos, entretanto, na hanseníase são colonizados pelo ML. Sabe-se que os MOs podem apresentar uma polarização funcional na qual os MOs M1 apresentam características pró-inflamatórias e microbicidas enquanto os MOs M2 atuam na reparação tecidual e possuem perfil anti-inflamatório. SCs infectadas pelo ML produzem mediadores capazes de interferir com a função dos MOs aumentando sua sobrevida e promovendo sua migração. Embora diferentes programas funcionais tenham sido observados em MOs de pacientes com formas polares da hanseníase a influência de SCs nesse processo não é sabida. Neste estudo avaliamos se SCs infectadas pelo ML podem interferir na polarização de MOs murinos derivados de medula óssea. Para tanto, culturas primárias de SCs murinas foram infectadas experimentalmente com bacilos viáveis e cocultivadas com MOs. Nossos resultados indicam que a produção de óxido nítrico foi baixa nas culturas de MOs após a infecção com o bacilo, mas mostrou-se aumentada nas coculturas de MOs e SCs infectadas pelo ML. A infecção com ML não induziu produção significante das citocinas IL-6, IL-10 e TNF em culturas de MOs e SCs, entretanto, a interação entre MOs e SCs infectadas com o bacilo resultou em aumento na produção de... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Mycobacterium leprae (ML) infection stimulates dedifferentiation and proliferation of Schwann cells (SCs) that may contribute to the spread of the bacillus. Macrophages (MOs) are effector cells of the immune response that promote the elimination of pathogens, however, in leprosy they are colonized by ML. It is known that MOs can present a functional polarization in which M1 MOs show pro-inflammatory and microbicidal activities while M2 MOs act in tissue repair presenting an anti-inflammatory profile. SCs infected by ML produce mediators able to interfere with MOs function, increasing their survival and promoting their migration. Although different functional programs have been observed in MOs from patients with polar forms of leprosy, the influence of SCs in this process is not known. In this study we evaluated whether SCs infected with ML could interfere in the polarization of murine MOs derived from bone marrow. For this purpose, primary cultures of murine SCs were experimentally infected with viable bacilli and co-cultivated with MOs. Our results indicate that nitric oxide production was low in cultures of MOs after infection with the bacillus, but it was increased in the co-cultures of MOs and ML-infected SCs. The infection with ML did not induce significant production of IL-10, TNF and IL-6 in cultures of MOs and SCs, however, the interaction between MOs and ML infected-SCs resulted in increased production of cytokines, mainly IL-10, inducing a decrease in the TNF/IL-10 ... (Complete abstract click electronic access below) / Mestre

Orientador: Alexandre Leite Rodrigues de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-09T22:46:07Z (GMT). No. of bitstreams: 1 Pierucci_Amauri_D.pdf: 4256178 bytes, checksum: fe35fc60e55f7ea9104ff8bf2bc809f5 (MD5) Previous issue date: 2007 / Resumo: A regeneração periférica é um fenômeno intrincado que envolve diferentes tipos celulares, dentre os quais as células de Schwann são os componentes celulares não neurais mais importantes. Após a lesão periférica, as células de Schwann proliferam e, juntamente com os macrófagos, participam na fagocitose dos fragmentos de mielina e dos axônios em degeneração. Essas auxiliam na orientação axonal em direção ao órgão alvo através da formação das bandas de Büngner. Ainda, atuam no rearranjo dos componentes da matriz extracelular do microambiente do nervo lesado, bem como na produção de vários fatores neurotróficos, entre eles, o fator neurotrófico do nervo (NGF), fator neurotrófico derivado do cérebro (BDNF), fator neurotrófico de crescimento ciliar (CNTF), visando à manutenção, desenvolvimento e regeneração dos neurônios após a lesão. As lesões nervosas que acometem no nervo periférico podem ser resultado de traumas como esmagamento, transecção parcial ou completa do nervo. Quando ocorre a transecção completa do nervo, há a perda de continuidade e forma-se uma fenda entre o coto proximal e o coto distal. No sentido de reparar-se o nervo lesionado, foram desenvolvidas diversas técnicas, incluindo-se o emprego de autoenxertos, próteses tubulares não absorvíveis e inertes (polietileno) e biorreabsorvíveis (biomateriais). Essas últimas têm a vantagem de sustentarem o inicio do processo regenerativo, orientando o brotamento axonal em direção ao coto distal, além de serem degradadas à medida que o nervo cresce em diâmetro. Podem ainda ser confeccionadas com as dimensões, formatos e porosidade desejados. Devido às características positivas destas próteses reabsorvíveis, a importância das células de Schwann e dos componentes da matriz extracelular, o presente trabalho tem como objetivos estudar a influência dos biomateriais poli L-ácido láctico e poli caprolactona sobre a expressão, pelas células de Schwann, das cadeias a1, a2 e ß1 que compõem as lamininas tipo I e II, bem como a expressão de colágeno tipo IV, através do emprego das técnicas de imunohistoquímica realizadas após a tubulização e imunocitoquímica através da cultura purificada de células de Schwann sobre os diferentes biomateriais. Além disso, avaliamos o comportamento das células de Schwann sobre os biomateriais, através da microscopia eletrônica de varredura. Já o resultado da regeneração axonal foi estudado através de uma análise morfológica pela microscopia de luz, microscopia eletrônica de transmissão e morfometria dos nervos regenerados. Comparando-se estruturalmente os tubos confeccionados pelo método de extrusão e solvente, pôde-se observar que o último apresentava espessura reduzida em comparação às próteses confeccionadas pelo método de extrusão. Ainda, a transparência dos tubos, ora propostos em nossa metodologia, influenciou positivamente durante o processo de implantação da prótese na tubulização. Após a regeneração, observou-se que o número de fibras regeneradas no interior dos tubos derivados das membranas de PCL foi significantemente maior, 30 e 60 dias após tubulização. Ainda, uma intensa marcação com S-100, colágeno tipo IV e laminina foi observada no nervo regenerado no interior das próteses, em cujos grupos utilizaram-se os biomaterias (PCL e PLLA). De fato, a imunomarcação demonstrou que os biomateriais e o microambiente no interior dos tubos foram capazes de estimular positivamente as células de Schwann em resposta à lesão nervosa periférica. Em conjunto, nossos resultados evidenciam que os tubos de PCL e PLLA derivados da membrana podem ser considerados um método alternativo na preparação de próteses tubulares visando o reparo do nervo periférico / Abstract: The present study proposed a new approach to produce tubular conduits designed for peripheral nerve repair. In this sense, membranes of PLLA and PCL were obtained after solvent evaporation and wrapped around a mandrel. The effectiveness of the nerve regeneration was compared with polyethylene and PCL extruded prosthesis 30 and 60 days after surgery. The comparison between extrusion and solvent tubes cleared shown structural differences which were directly proportional to the hardness and transparency. An important factor to be considered is that the fiber counting indicated that solvent PCL tubes provided a significantly greater number of axons 30 days after repair. Sixty days after operation, the greatest regenerative performance was obtained with PCL, regardless the method of construction of the tube. An intense labeling against S-100, type IV collagen and laminin could be observed in the tissue obtained from solvent PCL and PLLA groups, indicating that such constructions are able to positively stimulate Schwann cell responses. Overall, the present results provide evidence that solvent conduits may be regarded as an alternative preparation method for tubular prosthesis aiming peripheral nerve regeneration. In the in vitro study, PCL and PLLA solvent polymers were used for culturing purified of Schwann cells. The imunolabeling revealed an up-regularion of the expression of collagen IV, laminin I, laminin II and S-100 by the Schwann cells, showing that biodegradable polymers enhance the activity of such cells, positively influencing the peripheral nerve regeneration process / Doutorado / Anatomia / Mestre em Biologia Celular e Estrutural

Orientador: Francesco Langone / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-09T17:39:09Z (GMT). No. of bitstreams: 1 Hussein_Fernanda_M.pdf: 13730743 bytes, checksum: 0ded9b4ee837e3040ae51d3a2c5d6b02 (MD5) Previous issue date: 2007 / Resumo: As células tronco são células indiferenciadas capazes de se auto replicar e de se diferenciar em diversos tipos celulares maduros com funções especializadas. As células tronco de medula óssea são particularmente interessantes por serem células multipotentes, ou seja, geram células de diversos tecidos, são de fácil obtenção através da aspiração da medula óssea femural e eliminam os problemas de rejeição por ser possível realizar transplante autólogo.As células de Schwann são um dos tipos celulares mais importantes do Sistema Nervoso Periférico (SNP). Elas são uma fonte de sinais para a geração e desenvolvimento dos nervos periféricos, da mielinização e, ainda, auxiliam na regeneração axonal no caso de lesões tanto do SNP quanto do SNC. Os estudos enfocando a indução da diferenciação de células progenitoras a tipos celulares específicos desejados estão em seus passos iniciais. Já são conhecidos diversos fatores que favorecem o desenvolvimento de um determinado tipo celular a partir de células progenitoras in vitro. Contudo, permanecem desconhecidos os fatores intrínsecos ao organismo que induzem esse processo. Faz-se necessário portanto que se investigue, ainda in vitro, porém sem manipulações exógenas e mimetizando o microambiente corpóreo, quais fatores endógenos são os responsáveis pela deflagração do processo de diferenciação. Neste sentido, o Meio Condicionado por células de Schwann mostrou exercer efeitos importantes sobre as células mesenquimais de medula óssea, promovendo sua proliferação e possivelmente induzindo o processo de diferenciação nestas células. Ainda, a Eletroforese 2DE comparativa mostrou uma similaridade maior entre CS e CMMO do que com as CMMO cultivadas em MC, indicando que esta última poderia estar sofrendo um processo de diferenciação celular, diferentemente das CS e das CMMO / Abstract: Bone marrow mesenchymal stem cells (BMMSC) are capable to differentiate into several cell types. The differentiation depends on culture media molecules signaling. In this study we investigated the effect of Schwann cell conditioned media on BMMSC morphology and molecular phenotype. Schwann cells (SC) were isolated from adult Wistar rats sciatic nerve (Glia, 17: 327-338, 1996) and were cultivated in DMEM plus 10% FBS (D10). Every 48 hours the SC conditioned media (CM) were collected and stored at -80°C. The BMMSC were isolated from adult Wistar rats femur bone marrow (PNAS, 95:3908-3913,1995). BMMSC were maintained in D10. Subsequently, they were cultivated in CM for 7, 14 and 21 days. After 14 days in CM it was detected changes on the BMMSC typical flattened morphology to the SC bipolar morphology. The frequency of these changes increased after 21 days. These changes have been followed by changes on immunoreactivity and S100b protein localization on BMMSC. Before they were cultivated in CM, the BMMSC showed low immunoreactivity to S100b protein on cytoplasm. Culture in CM generated a S100b label gradual increase and it was found in nuclear compartment. Only the nucleous was S100b labeled, after 21 days. On the other hand, the bipolar morphology cells showed cytoplasmatic and nuclear S100b+. These findings agree with Deloume et al. (Mol. Cell. Neurosci. 27:453-465, 2004) about the S100b immunolabelling during the differentiation of glial progenitor cells into oligodendrocytes. Our results suggest that molecules present in CM are capable of inducing phenotypes changes related with the S100b expression and it roles on differentiation of BMMSC into SC. Moreover, 2DE electrophoresis shown a extent similarity between SC and BMMSC. This result suggests that the BMMSC cultivated in CM could be in a differentiation process / Mestrado / Fisiologia / Mestre em Biologia Funcional e Molecular

OBJETIVO: avaliar o efeito das neuregulinas 1-alfa e 1-beta na regeneração de nervos ciáticos de camundongos C57BL/6J, adultos, machos, através da técnica de tubulização. MÉTODOS: Utilizaram-se 18 animais, divididos em 3 grupos, implantando-se prótese de polietileno em falhas de 4,0 mm no nervo ciático esquerdo: grupo 1 contendo apenas colágeno purificado (Vitrogen®); grupo 2, colágeno associado a neuregulina 1-alfa; grupo 3 com colágeno e neuregulina 1-beta. O grupo controle foi formado por 6 segmentos de nervos ciáticos direitos. Após 4 semanas, os animais foram sacrificados; extraiu-se segmento do ponto médio do nervo regenerado no interior das próteses, padronizaram-se cortes histológicos e confecção das lâminas para análise histomorfométrica. Confrontaram-se os resultados estatisticamente. RESULTADOS: Os animais tratados com neuregulinas tiveram maior número de axônios mielinizados, com diferença estatisticamente significante quando comparados ao grupo colágeno. Não houve diferença estatística entre os grupos de neuregulinas 1-alfa e 1-beta. CONCLUSÃO: a adição de neuregulinas proporcionou aumento significativo do número de fibras mielinizadas. / PURPOSE: To evaluate the effect of neuregulins 1-alpha and 1-beta on the regeneration the sciatic nerves of male adult C57BL/6J mice, using the tubulization technique. METHODS: Eighteen animals were used, divided into three groups. A polyethylene prosthesis was implanted in a 4.0 mm defect of the left sciatic nerve, as follows: group 1 containing only purified collagen (Vitrogen®); group 2, collagen with neuregulin 1-alpha; group 3, collagen with neuregulin 1-beta. The control group was formed by six segments of right sciatic nerves. Four weeks later, the animals were sacrificed. A segment from the midpoint of the nerve regenerated inside the prostheses was extracted, histological sections were standardized and slides were made up for histomorphometric analysis. The results were statistically compared using the Tukey multiple comparisons test and Students t test. RESULTS: The animals treated with neuregulins had greater numbers of myelinized axons, with a statistically significant difference in relation to the collagen-only group. There was no statistical difference between the neuregulin 1-alpha and 1- beta groups. CONCLUSION: It was concluded that the addition of neuregulins provided a significant increase in the number of myelinized fibers.

Les cellules gliales qui forment les segments de myéline du système nerveux périphérique (SNP) sont appelées cellules de Schwann. Elles assurent aux nerfs un soutien fonctionnel et permettent une conduction rapide et efficace de l'influx nerveux. Cette fonction requiert une communication réciproque entre les neurones et les cellules gliales qui les entourent. Une perturbation de cette interaction entraine le plus souvent une situation pathologique comme les neuropathies périphériques dont la plus connue est la maladie de Charcot-Marie-Tooth. Cependant, les mécanismes qui conduisent à ces pathologies sont encore peu connus et leur compréhension demande au préalable l'élucidation des mécanismes physiologiques qui contrôlent le développement du SNP. Ce travail a consisté en l'analyse de nouvelles fonctions des gènes ndrg4 et elmo1, dans le développement du système nerveux périphérique, chez le poisson zèbre. Nous avons montré que ndrg4 (n-myc downstream regulated gene) est un facteur neuronal qui régule le développement de la myéline périphérique en contrôlant le regroupement des canaux sodiques aux nœuds de Ranvier et l'expression de la mbp. Ndrg4 semble moduler l'échange vésiculaire entre les axones et les cellules de Schwann, en contrôlant l'expression de certaines protéines de relargage vésiculaire comme SNAP25, membre du complexe SNARE.Ce travail décrit par ailleurs une nouvelle fonction de elmo1 (engulfment and cell motility 1) dans le développement du SNP du poisson zèbre, où il favorise la survie des neurones dans lesquels il est exprimé. Nous avons montré qu'elmo1 protège les neurones de l'apoptose et que cette fonction est contrôlée par la voie nétrine1/unc5b en amont de Rac1. De ce fait, elmo1 est requis pour le développement du ganglion de la ligne latérale postérieure et des axones qui en émergent pour donner un système nerveux fonctionnel. Ainsi, ces travaux contribuent à une meilleure connaissance du développement du SNP et élucident pour la première fois une nouvelle voie de signalisation requise pour la survie des neurones dans le SNP. / The glial cells that form myelin segments in the peripheral nervous system (PNS) are called Schwann cells (SCs). They provide functional support for nerves and allow a fast and efficient conduction of the action potentials. This requires a bilateral communication between axons and the associated glial cells. Disruption of this interaction often leads to peripheral neuropathies e.g. Charcot-Marie-Tooth disease. However, the mechanisms underlying these diseases remain poorly known and their understanding requires, at first, the elucidation of the physiological mechanisms responsible for PNS development. This work consists of a functional analysis of two genes, ndrg4 and elmo1, in the PNS development, using the zebrafish model. We showed that the neuronal factor ndrg4 (n-myc downstream regulated gene 4) regulates nodes of Ranvier organization and mbp expression along the Posterior Lateral Line nerve (PLLn). This is achieved, most likely, by the ability of ndrg4 to modulate vesicular exchange between axons and SCs. Indeed, the expression of some key proteins involved in vesicle docking and release such as SNAP25, a member of the SNARE complex, are significantly dependent on ndrg4.Moreover, this work describes a novel role for neuronal elmo1 (engulfment and cell motility 1) in PNS development by promoting neuronal survival within the PLL ganglion. We showed that elmo1 has protective role against apoptosis and that its function is controlled by the netrin1/unc5b signalling upstream of Rac1 and independently of macrophages role in apoptotic clearance. Therefore, elmo1 is required for the proper development of the PLL ganglion and the axonal development of the PLLn. Thus, this study further contributes to our understanding of PNS development and unravels a novel molecular pathway required for neuronal survival in the PNS.

Schwann cells (SCs) are crucial for peripheral nerve development and regeneration; however, the intrinsic regulatory mechanisms governing post-injury responses are poorly understood. Activation and deacetylation of nuclear factor-κB (NF- κB) in SCs have been implicated as prerequisites for peripheral nerve myelination. Using GFAP-IκBα-dn mice, in which NF- κB transcriptional activation is inhibited in SCs, we found no discernable differences in the quantity or structure of myelinated axons in adult facial nerves. Following crush injury, axonal regeneration was impaired at 31 days and greatly improved at 65 days in GFAP-IκBα-dn mutants. Compact re-myelination and sensory fiber organization were significantly compromised at 31 days and restored by 65 days. Together, these data indicate that NF- κB activation in SCs is dispensable for peripheral nerve myelination in adults, but required for early re-myelination and axonal regeneration. SC myelination during development and following injury in adult mice may hinge on different transcriptional cascades; these findings may offer new therapeutic avenues for PNS and CNS regeneration.

The transplantation of primary Schwann cells (SC) has been shown to improve nerve regeneration. However, to monitor the survival of transplanted cells within the host, a stable labelling method is required. The in vitro characteristics of green fluorescent protein labelled SC (GFP SC) and their effects in an in vivo peripheral nerve injury model were investigated.   The GFP-SC were readily visualised ex vivo and stimulated significantly better axonal regeneration compared to controls. Clinical use of autologous SC for the treatment of nerve injuries is of limited use due to difficulty in obtaining clinically useful numbers. However, bone marrow mesenchymal stem cells (MSC) can trans-differentiate into SC like cells (dMSC). The in vitro and in vivo differentiation of MSC was explored, and the study extended to include the easily-accessible adipose stem cells (ASC).  In vitro, glial growth factor stimulated MSC express S100, a SC marker, and its expression is maintained following in vivo transplantation.  Similarly, untreated MSC transplanted in vivo also expressed S100, which indicates glial differentiation in response to local cytokines and growth factors. Using an in vitro model, comprising dMSC or dASC co-cultured with adult dorsal root ganglia (DRG) neurons, the capacity of the dMSC and SC like differentiated ASC (dASC) to promote axon myelination was verified: both cell types expressed transcripts for protein zero, peripheral myelin protein-22 and myelin basic protein. The potential of stem cells in nerve repair may be limited by innate cellular senescence or donor age affecting cell functionality thus it was essential to determine the effects of donor age on morphology and functionality of stem cells.  The proliferation rates, expression of senescence markers (p38 and p53) and the stimulation of neurite outgrowth from DRG neurons by stem cells isolated from neonatal, young or old rats were very similar. However, the distribution and ultrastructure of mitochondria in dMSC and dASC from young and old rats were quite different, and seem to indicate physiological senescence of the aged cells.  Given the wide-ranging influence of Notch signalling in cell differentiation, including the neural crest to a glial cell type switch, and self-renewal in mammals, its role in the differentiation of stem cells to SC was investigated. The mRNA for notch-1 and -2 receptors were expressed in the dASC, blockage of notch signaling did not affect the neurotrophic and myelination potential of dASC.  In conclusion, these findings show that GFP labelling has no deleterious effect on SC survival and function. MSC and ASC differentiated into glial-type cells acquire SC morphology, and express characteristic SC markers, and the differentiation process was independent of the Notch signaling pathway. Also, following transplantation into a nerve gap injury dMSC improve regeneration. This study established that following co-culture with DRG neurons, dMSC and dASC were able to express peripheral myelin proteins.  Also, the functional bioactivity of these cells is independent of the donor animal age. Finally, although the glial lineage differentiated aged cells characterized in this study expressed markers typical of senescence they retained the potential to support axon regeneration.

Schwann cells are the glial cells of the peripheral nervous system. When transplanted into the injured central or peripheral nervous systems they promote repair. Traditionally Schwann cells have been isolated from the sciatic nerve, creating nerve-SC. An alternative Schwann cell source is from the differentiation of skin-derived precursors (SKPs), stem cells found in the skin, to Schwann cells (SKP-SC). SKP-SC have shown enhanced regenerative ability compared to nerve-SC. This study compares nerve-SC with SKP-SC at the functional and gene expression level to determine their degree of similarity and find their sources of variance. The functional ability of both Schwann cell types appeared similar. Their gene expression, as assessed by microarray, was similar but not identical. Genes that differed between nerve-SC and SKP-SC may represent differences important to regeneration. The similarity of SKP-SC to nerve-SC supports the use of SKP-SC for repair, and reasons for enhanced regeneration by SKP-SC are suggested.