Pre regeneráciu a rast poranených nervových vlákien bolo preskúmaných mnoho postupov, no výsledný rast axónov je často náhodný až dezorganizovaný a odráža sa na zložitejšom zotavovaní pacienta. V tejto práci boli vyrobené nové skafoldy s mikroštruktúrnymi a mechanickými vlastnosťami nervového skafoldu pomocou metódy freeze-casting. Konkrétne boli vyrobené biokeramické skafoldy na báze fosforečnanov vápenatých, oxidu titaničitého alebo oxidu zirkoničitého. Pomocou kontrolovaného rastu ľadu v jednom smere bola pripravená orientovaná mikroštruktúra. Pozorovanie pomocou skenovacej elektrónovej mikroskopie potvrdilo lineárne orientované póry (lamelárny systém), v ktorých priemerná veľkosť pórov klesala so zvyšujúcou sa rýchlosťou mrazenia. Skafoldy pripravené pomocou mrazenia v tekutom dusíku vykazovali vynikajúce mechanické vlastnosti, kde pevnosť v ohybe bola získaná v rozmedzí 10–17 MPa. Tie isté skafoldy mali vzdialenosť medzilamelamelárnych priestorov 10–30 µm, ktorých parametre sú vhodné pre nervové skafoldy. Biokompatibilita bola vyhodnotená pomocou Schwannových buniek in vitro, kde bola pozorovaná adhézia a rast v lamelárnom smere. Cytotoxické testy odhalili negatívny vplyv vyššej koncentrácie vápnika na prežitie Schwannových buniek. Pripravené skafoldy mali schopnosť tvorby apatitu na povrchu v podobe embryonálnych a nukleačných centier a apatitu samotného. Skafoldy na báze fosforečnanov vápenatých a oxidu titaničitého vykazovali sľubné regeneračné vlastnosti, konkrétne adhéziu a rast prostredníctvom pórovitej štruktúry a taktiež vynikajúce mechanické vlastnosti.

Le vieillissement entraîne plusieurs changements au niveau de la fonction musculaire qui peuvent mener à une perte de la masse musculaire et de sa fonction qu’on appelle sarcopénie. La sarcopénie entraîne une augmentation du risque de chutes et d’hospitalisations qui nuit à la qualité de vie des personnes âgées. Le vieillissement de la population représente un enjeu important au sein de la société en raison de son impact socioéconomique élevé. Plusieurs facteurs contribuent à ce déclin observé au cours du vieillissement, mais un des éléments clés qui y contribue sont des altérations de la jonction neuromusculaire (JNM). La JNM est une synapse tripartite composée de la terminaison nerveuse présynaptique, de la fibre musculaire postsynaptique et des cellules de Schwann périsynaptiques (CSPs), des cellules gliales. Les CSPs jouent un rôle essentiel dans la maintenance, la modulation de la transmission et de la plasticité synaptique et la réparation de la JNM. Plusieurs études effectuées chez le murin ont démontré que la JNM présente des altérations telles que de la dénervation, de la fragmentation du postsynaptique et des signes de modulation et de réparation gliaux au cours du vieillissement. Ces altérations contribuent aux déficits de la fonction neuromusculaire observés lors du vieillissement. La JNM humaine demeure cependant sous-étudiée, particulièrement en considérant sa structure tripartite. Afin de mieux comprendre le vieillissement neuromusculaire chez l’humain, des biopsies du Vastus lateralis ont été effectuées chez 4 jeunes adultes (23-28 ans) et 5 personnes âgées (60-75 ans) sains et actifs. Un marquage immunohistochimique a été effectué sur les biopsies afin d’identifier les trois composantes de base de la JNM et le type de fibre, puis visualiser en microscopie confocale. Des mesures fonctionnelles ont également été prélevées pour chacun des participants âgés. L’analyse des JNMs a permis de démontrer qu’une instabilité de l’innervation de même qu’une relation tripartite divergente se développe avec l’âge. Ces altérations corrèlent également avec un déficit fonctionnel. Dans l’ensemble, notre étude présente des altérations de la JNM humaine au cours du vieillissement ayant un impact sur la fonction neuromusculaire. Elle pourrait permettre de mieux comprendre les mécanismes à la base du vieillissement neuromusculaire pour développer des stratégies d’intervention thérapeutiques efficaces pour limiter l’impact du vieillissement. / Several changes occur in muscular function in aging which can lead to a loss of muscle mass and function called sarcopenia. Sarcopenia can lead to an increased risk of fall and hospitalization and to a poor quality of life. Aging of the population represents an important societal issue due to its high socioeconomic impact. Many factors contribute to the decline of muscular function seen in aging, but alterations of the neuromuscular junctions are a key element leading to sarcopenia. The NMJ is a tripartite synapse composed of the presynaptic nerve terminal, the postsynaptic muscle fiber as well as perisynaptic Schwann cells (PSC), glial cells. PSCs play a key role in maintenance, modulation of synaptic transmission and plasticity as well as repair of the NMJ. Several rodent studies have shown that the NMJ present alterations such as denervation, fragmentation of the postsynaptic and glial-related signs of modulation and repair in aging. These alterations contribute to the neuromuscular deficits observed in aging. However, the NMJ remain widely understudied, particularly when considering its tripartite structure. In order to get a better understanding of neuromuscular aging in humans, biopsies form the Vastus lateralis were performed on 4 young (23-28 years old) and 5 older (60-75 years old) healthy and physically active men. Immunohistochemistry labelling of the NMJ’s main components and type of fibers was performed and then imaged using confocal microscopy. Functional assessment was also measured for each older adult. Analysis of NMJs revealed an instability in the innervation as well as a divergent tripartite relationship in older individuals. These alterations also correlated with neuromuscular deficits. Taken altogether, our study highlights alterations of the NMJ in aging leading to altered neuromuscular function. This could lead to a better understanding of the underlying mechanisms leading to sarcopenia and to develop better therapeutic strategies to limit its impact during aging.

Durant le vieillissement, l’ensemble des fonctions de l’organisme se détériore, que ce soit aussi bien au niveau moteur que cognitif. Le vieillissement s’accompagne d’une diminution de la force, ainsi que de la masse musculaire. Des études récentes tendent à montrer que cette perte de masse musculaire que l’on appelle sarcopénie aurait pour origine un dérèglement de la jonction neuromusculaire. Les changements au niveau du présynaptique et du post synaptiques lors du vieillissement normal font l’objet de plusieurs études, mais les changements relatifs aux cellules de Schwann périsynaptique sont très peu connus. Le but de cette étude est donc d’analyser les modifications des interactions neurone-glie à la jonction neuromusculaire. Dans cette étude, nous montrons que certaines fonctions des cellules gliales de la synapse âgée sont déréglées, en particulier, le type de récepteurs activés par une stimulation nerveuse à haute fréquence. D’autre part, nos résultats montrent que les mécanismes responsables de l’augmentation de la transmission synaptique suite à cette stimulation nerveuse à haute fréquence sont altérés à la synapse âgée. Enfin, outre les modifications de la terminaison axonale et de la fibre musculaire, les cellules gliales montrent des signes de réorganisation structurelle propre à une synapse en réparation. Ces résultats montrent que le fonctionnement de la jonction neuromusculaire et a fortiori les interactions neurones-glie sont altérées lors du vieillissement normal. / Aging comes with an alteration and organism functions including cognitive and motor functions. Major weakening of the neuromuscular system occurs which includes muscle weight loss, difficulties in initiating voluntary movement and reduced muscle strength. The possible role of the alteration of the neuromuscular junction has been examined but always only considering the pre- and postsynaptic elements. However, perisynaptic Schwann cells (PSCs), glial cells at the neuromuscular junction (NMJ), play fundamental roles in the regulation of the synaptic efficacy of the NMJ as well as in its maintenance and stability. Hence, we analysed NMJ properties and their glial cells in aging. This study shows that PSCs function at the old NMJ are dysregulated. Indeed, PSCs ability to detect synaptic transmission, determined using imaging of intracellular Ca2+, was maintained in PSCs at NMJs from old mice, but the contribution of the muscarinic component was greatly reduced. On the other hand, our results using synaptic recordings are showing that a number of synaptic plasticity events known to be regulated by PSCs are reduced at NMJs of old mice. Finally, morphological NMJ reorganisation and sprouting of PSCs were also observed. These data suggest that PSC properties are consistent with the repair of the NMJ that may also result in their reduced ability in regulating synaptic efficacy.

INTRODUÇÃO: O nervo facial desempenha um papel importante em diversas funções fisiológicas no organismo, no entanto, distúrbios funcionais desse nervo podem também afetar a psique do indivíduo, provocando mudanças significativas na autoimagem, interferindo no rendimento profissional e piorando a qualidade de vida. Lesões graves do nervo facial (neurotmeses) mesmo quando tratadas precocemente apresentam resultados funcionais pobres. Com a recente descoberta das células-tronco, as células multipotentes do estroma mesenquimal indiferenciadas (CMEMi) ou diferenciadas em células com fenótipo de células de Schwann (CMEMd) podem ser uma alternativa melhor para o tratamento de lesões graves do nervo facial. OBJETIVOS: Avaliar a melhora funcional e histológica do ramo mandibular do nervo facial após neurotmese e implantação das CMEMi e CMEMd. MÉTODOS: Em 48 ratos Wistar realizou-se a neurotmese do ramo mandibular direito do nervo facial com a formação de um hiato de 3mm e a tubulização (conduíte de silicone) da região do nervo lesada. Foram criados quatro grupos de acordo com o método de reparo: conduíte de silicone vazio (grupo A, grupo controle); conduíte de silicone com gel acelular (grupo B); conduíte de silicone com gel acelular e CMEMi (grupo C), e conduíte de silicone com gel acelular e CMEMd (grupo D). Um quinto grupo, grupo N, foi criado a partir de segmentos do nervo normal para a avaliação histológica. Os resultados funcionais foram avaliados com o estudo de condução nervosa e os histológicos por avaliação qualitativa e quantitativa dos segmentos proximais e distais. RESULTADOS: Na avaliação funcional, após 6 semanas, os grupos C e D apresentaram amplitudes maiores que os grupos A e B (p<0,001). O grupo C apresentou duração menor que os grupos A, B e D (p<0,001). Na avaliação qualitativa dos segmentos proximais, houve pouca diferença entre os grupos, já nos segmentos distais, as diferenças dos grupos A e B em relação aos grupos C e D foram bem evidentes, no entanto, em ambos os segmentos, o grupo C foi o que mais se aproximou do nervo normal. Na avaliação histológica quantitativa do segmento proximal, não houve diferença no número total e na densidade axonal entre os grupos (p0,169), somente nos diâmetros axonais dos grupos A e B quando comparados ao nervo normal (p<0,001). No segmento distal, o número e a densidade axonal do grupo C foram maiores que os do grupo A e B (p=0,001) e iguais as do grupo D (p=0,711), porém, em todos os grupos, número e a densidade axonal foram menores que do grupo N (p0,003). Não houve diferença na média dos diâmetros entre os grupos operados (p0,007), somente quando comparados com o grupo N (p<0,001). CONCLUSÕES: As CMEMi assim como as CMEMd beneficiaram a regeneração do ramo mandibular do nervo facial de ratos Wistar, contudo, as CMEMi apresentaram resultados funcionais e histológicos melhores que as CMEMd / INTRODUCTION: Facial nerve performs an important function in different physiological activities in the organism, however, functional disturbances of such nerve may also attack a persons mind, causing expressive changes in their self-image, interfering in professional life and aggravating their quality of life. Severe lesions in the facial nerve (neurotmesis) present poor functional results even when early treated. With recent discovering of the stem cells, undifferentiated multipotent stem cell (uMSC) from mesenchymal stroma or differentiated to Schwann cell-like (dMSC) can be a better perspective to treat severe lesion of the facial nerve. OBJECTIVES: The objective of this study is to evaluate the functional and histological improvement of the mandibular branch after neurotmesis and implantation of the uMSC and dMSC. METHODS: The neurotmesis of the right mandibular branch of the facial nerve with a 3mm gap formation and tubulization (silicone tubing) of the wounded nerve area was performed in 48 Wistar rats. Four groups were divided according to the restoration method: empty silicone tubing (group A, control group); silicone tubing with non-cell gel (group B); silicone tubing with non-cell gel and uMSC (group C) and silicone tubing with non-cell gel and dMSC (group D). A fifth group (N) was created from the normal nerve segments to perform histological evaluation. The nerve conduction study evaluated the functional results; quantity and quality evaluation of the distal and proximal segment evaluated the histological results. RESULTS: After six weeks, regarding functional evaluation, groups C and D presented larger amplitude than groups A and B (p<0.001). Group C presented lesser duration than groups A, B and D (p<0.001). There was little difference among the groups in the quality evaluation of the proximal segments; on the other hand, the differences in groups A and B in relation to groups C and D were quite expressive in the distal segments. However, group C, in both segments, was the one that came closer to the normal nerve. Regarding quantity histological evaluation of the proximal segment, there was no difference in the total number and in the axonal density among the groups (p0.169); there was difference only in the axonal diameters in groups A and B when compared to normal nerve (p<0,001). Regarding distal segment, axonal density and number, in group C, were higher than in group A and B (p=0.001) and the same as in group D (p=0,711), but number and axonal density were lesser than in group N (p0,003). There was no difference in the diameter average among the operated groups (p0.007), when only compared to group N (p<0.001). CONCLUSION: Both uMSC and dMSC benefited regeneration of the mandibular branch of the facial nerve in Wistar rats, although uMSC presented better functional and histological results

INTRODUÇÃO: As lesões traumáticas graves do nervo facial, relativamente frequentes no cotidiano do otorrinolaringologista, mesmo que reparadas com as melhores técnicas microcirúrgicas, apresentam recuperação funcional extremamente limitada acarretando grande impacto na motricidade facial e, consequentemente, na qualidade de vida dos pacientes. OBJETIVOS: Avaliar a recuperação funcional (eletroneuromiografia), histológica (quantitativa e qualitativa) e imunohistoquímica do ramo mandibular do nervo facial de ratos obtidas após autoenxerto combinado a transplante de células-tronco multipotentes de polpa dentária indiferenciadas (CTPD). Seguiu-se comparação com os resultados anteriormente obtidos pelos mesmos pesquisadores e utilizando mesma técnica cirúrgica após transplante de células-tronco de medula óssea indiferenciadas (CTMOi) e diferenciadas em Schwann-like (CTMOd). Realizou-se autoenxerto no ramo mandibular do nervo facial de ratos para reparo de GAP de 5mm provocado por duas neurotmeses sequenciais, reimplantação do próprio fragmento retirado, sendo o mesmo envolvido por tubo de ácido poliglicólico (Grupo A) e preenchido com gel acelular de lâmina basal purificada, com transplante de CTPD (grupo B). Após seis semanas, os animais foram sacrificados e as análises realizadas. RESULTADOS: Observou-se que, seis semanas após a cirurgia, os animais do grupo tratado com células-tronco apresentaram valores médios de amplitude do potencial de ação muscular composto (PAMC) (CTPD 3,79±1,74mV; CTMOd 2,7±0,53mV; CTMOi 1,81±0,77mV) estatisticamente superiores ao grupo controle (0,75±0,46mV, p < 0,001). Os diâmetros axonais médios, também, foram significativamente maiores nos grupos tratados com células-tronco (CTPD 3,04±0,49?m; CTMOd 3,5±0,16?m; CTMOi 3,15±0,32?m) do que no grupo controle (2,13±0,07?m), com valor de p < 0,001. A densidade axonal foi estatisticamente superior no grupo controle (0,021±0,003axônios/um2) quando comparada aos grupos tratados (CTPD 0,014±0,004 axônios/um2; CTMOd 0,017±0,003axônios/?m2; CTMOi 0,015±0,002axônios/um2, p=0,004).Ao ensaio de imunofluorescência, no grupo tratado com CTPD, observou-se células positivas para lamina humana A/C e para S100, evidenciando, assim, a presença de células humanas com fenótipo de Schwann no segmento distal do nervo analisado. No grupo tratado com CTMOi houve marcação em beta-galactosidade, mas não em S100, confirmando a presença de células exógenas, porém não diferenciadas em Schwann. Já no grupo tratado com CTMOd demonstrou a presença de células exógenas com fenótipo de Schwann ao observar a comarcação pelos marcadores beta-galactosidase e S100, mantendo, assim, o mesmo fenótipo do observado in vitro. CONCLUSÃO: Conclui-se que, segundo critérios funcionais e histológicos, a regeneração do ramo mandibular do nervo facial de ratos foi superior quando associada ao transplante de CTPD comparativamente ao controle. O grupo tratado com CTPD apresentou melhores resultados funcionais e parâmetros histológicos similares aos obtidos com CTMOi e CTMOd. Nos três grupos tratados com células-tronco, as células exógenas foram observadas após 6 semanas de experimento, com evidência de integração ao tecido neural e evidência de diferenciação in vivo para o fenótipo de Schwann apenas no grupo tratado com CTPD / INTRODUCTION: Traumatic lesions of the facial nerve, relatively frequent of the daily routine of the otorhinolaryngologist, even if when repaired with the best microsurgical techniques, have limited functional recovery causing great impact on facial motricity, consequently, on patients\' quality of life. OBJECTIVES: The purpose of this study was to evaluate the functional and histological recovery (quantitative and qualitative) and immunohistochemistry of the mandibular branch of the facial nerve of rats obtained after autograft combined with transplantation of multipotent undifferentiated dental pulp stem cells (DPSC). We compared the results obtained previously by the same researchers and using the same surgical technique after transplantation of undifferentiated bone marrow stem cells (uBMSC) and differentiated to Schwann cell-like (dBMSC). METHODS: A 5mm gap in the mandibular branch of the facial nerve was perfomed by two sequencial neurotmesis, followed by autograft with reimplantation of the removed fragment itself, tubulization with a polyglycolic acid tube (Group A) and transplantation with DPSC (group B). After six weeks, the animals were sacrificed and analyzes performed. RESULTS: Six weeks after surgery, the animals in the stem cells group had mean values of the amplitude of the compound muscle action potential (CMAP) (DPSC 3.79±1.74mV; dBMSC 2.7±0,53mV; uBMSC 1.81±0.77mV) statistically higher than the control group (0.75±0.46mV, p < 0.001). Medium axon diameters were also significantly higher in the stem cells treated groups (DPSC 3.04±0.49um, dBMSC 3.5±0.16um, uBMSC 3.15± 0.32um) than in the control group (2.13±0.07um), with a value of p < 0.001. The axonal density was statistically higher in the control group (0.021±0.003axons/um2) when compared to the treated groups (DPSC 0.014±0.004 axons/?m2, dBMSC 0.017±0.003 axons/?m2, uBMSC 0.015±0.002 axons/um2, p=0.004). In the immunofluorescence assay, cells positive for human laminA/C and for S100 were observed in the DPSC-treated group, thus evidencing the presence of human cells with Schwann cells phenotype in the distal segment of the nerve analyzed. In the group treated with uBMSC there was beta- galactosidase, but not in S100, confirming the presence of exogenous but undifferentiated cells. In the group treated with dBMSC, the presence of exogenous cells with Schwann cells phenotype was observed by observing the comarcation by beta-galactosidase and S100 markers, thus maintaining the same phenotype as that observed in vitro. CONCLUSION: According to functional and histological criteria, the regeneration of the mandibular branch of the facial nerve of rats was superior when associated with the DPSC transplant compared to the control. The DPSC treated group had better functional results and histological parameters similar to those obtained with uBMSC and dBMSC. In the stem cells-treated groups, exogenous cells were observed after 6 weeks of experiment with evidence of neural tissue integration and evidence of in vivo differentiation for the Schwann cells phenotype only in the DPSC-treated group

INTRODUÇÃO: As lesões traumáticas graves do nervo facial, relativamente frequentes no cotidiano do otorrinolaringologista, mesmo que reparadas com as melhores técnicas microcirúrgicas, apresentam recuperação funcional extremamente limitada acarretando grande impacto na motricidade facial e, consequentemente, na qualidade de vida dos pacientes. OBJETIVOS: Avaliar a recuperação funcional (eletroneuromiografia), histológica (quantitativa e qualitativa) e imunohistoquímica do ramo mandibular do nervo facial de ratos obtidas após autoenxerto combinado a transplante de células-tronco multipotentes de polpa dentária indiferenciadas (CTPD). Seguiu-se comparação com os resultados anteriormente obtidos pelos mesmos pesquisadores e utilizando mesma técnica cirúrgica após transplante de células-tronco de medula óssea indiferenciadas (CTMOi) e diferenciadas em Schwann-like (CTMOd). Realizou-se autoenxerto no ramo mandibular do nervo facial de ratos para reparo de GAP de 5mm provocado por duas neurotmeses sequenciais, reimplantação do próprio fragmento retirado, sendo o mesmo envolvido por tubo de ácido poliglicólico (Grupo A) e preenchido com gel acelular de lâmina basal purificada, com transplante de CTPD (grupo B). Após seis semanas, os animais foram sacrificados e as análises realizadas. RESULTADOS: Observou-se que, seis semanas após a cirurgia, os animais do grupo tratado com células-tronco apresentaram valores médios de amplitude do potencial de ação muscular composto (PAMC) (CTPD 3,79±1,74mV; CTMOd 2,7±0,53mV; CTMOi 1,81±0,77mV) estatisticamente superiores ao grupo controle (0,75±0,46mV, p < 0,001). Os diâmetros axonais médios, também, foram significativamente maiores nos grupos tratados com células-tronco (CTPD 3,04±0,49?m; CTMOd 3,5±0,16?m; CTMOi 3,15±0,32?m) do que no grupo controle (2,13±0,07?m), com valor de p < 0,001. A densidade axonal foi estatisticamente superior no grupo controle (0,021±0,003axônios/um2) quando comparada aos grupos tratados (CTPD 0,014±0,004 axônios/um2; CTMOd 0,017±0,003axônios/?m2; CTMOi 0,015±0,002axônios/um2, p=0,004).Ao ensaio de imunofluorescência, no grupo tratado com CTPD, observou-se células positivas para lamina humana A/C e para S100, evidenciando, assim, a presença de células humanas com fenótipo de Schwann no segmento distal do nervo analisado. No grupo tratado com CTMOi houve marcação em beta-galactosidade, mas não em S100, confirmando a presença de células exógenas, porém não diferenciadas em Schwann. Já no grupo tratado com CTMOd demonstrou a presença de células exógenas com fenótipo de Schwann ao observar a comarcação pelos marcadores beta-galactosidase e S100, mantendo, assim, o mesmo fenótipo do observado in vitro. CONCLUSÃO: Conclui-se que, segundo critérios funcionais e histológicos, a regeneração do ramo mandibular do nervo facial de ratos foi superior quando associada ao transplante de CTPD comparativamente ao controle. O grupo tratado com CTPD apresentou melhores resultados funcionais e parâmetros histológicos similares aos obtidos com CTMOi e CTMOd. Nos três grupos tratados com células-tronco, as células exógenas foram observadas após 6 semanas de experimento, com evidência de integração ao tecido neural e evidência de diferenciação in vivo para o fenótipo de Schwann apenas no grupo tratado com CTPD / INTRODUCTION: Traumatic lesions of the facial nerve, relatively frequent of the daily routine of the otorhinolaryngologist, even if when repaired with the best microsurgical techniques, have limited functional recovery causing great impact on facial motricity, consequently, on patients\' quality of life. OBJECTIVES: The purpose of this study was to evaluate the functional and histological recovery (quantitative and qualitative) and immunohistochemistry of the mandibular branch of the facial nerve of rats obtained after autograft combined with transplantation of multipotent undifferentiated dental pulp stem cells (DPSC). We compared the results obtained previously by the same researchers and using the same surgical technique after transplantation of undifferentiated bone marrow stem cells (uBMSC) and differentiated to Schwann cell-like (dBMSC). METHODS: A 5mm gap in the mandibular branch of the facial nerve was perfomed by two sequencial neurotmesis, followed by autograft with reimplantation of the removed fragment itself, tubulization with a polyglycolic acid tube (Group A) and transplantation with DPSC (group B). After six weeks, the animals were sacrificed and analyzes performed. RESULTS: Six weeks after surgery, the animals in the stem cells group had mean values of the amplitude of the compound muscle action potential (CMAP) (DPSC 3.79±1.74mV; dBMSC 2.7±0,53mV; uBMSC 1.81±0.77mV) statistically higher than the control group (0.75±0.46mV, p < 0.001). Medium axon diameters were also significantly higher in the stem cells treated groups (DPSC 3.04±0.49um, dBMSC 3.5±0.16um, uBMSC 3.15± 0.32um) than in the control group (2.13±0.07um), with a value of p < 0.001. The axonal density was statistically higher in the control group (0.021±0.003axons/um2) when compared to the treated groups (DPSC 0.014±0.004 axons/?m2, dBMSC 0.017±0.003 axons/?m2, uBMSC 0.015±0.002 axons/um2, p=0.004). In the immunofluorescence assay, cells positive for human laminA/C and for S100 were observed in the DPSC-treated group, thus evidencing the presence of human cells with Schwann cells phenotype in the distal segment of the nerve analyzed. In the group treated with uBMSC there was beta- galactosidase, but not in S100, confirming the presence of exogenous but undifferentiated cells. In the group treated with dBMSC, the presence of exogenous cells with Schwann cells phenotype was observed by observing the comarcation by beta-galactosidase and S100 markers, thus maintaining the same phenotype as that observed in vitro. CONCLUSION: According to functional and histological criteria, the regeneration of the mandibular branch of the facial nerve of rats was superior when associated with the DPSC transplant compared to the control. The DPSC treated group had better functional results and histological parameters similar to those obtained with uBMSC and dBMSC. In the stem cells-treated groups, exogenous cells were observed after 6 weeks of experiment with evidence of neural tissue integration and evidence of in vivo differentiation for the Schwann cells phenotype only in the DPSC-treated group

INTRODUÇÃO: O nervo facial desempenha um papel importante em diversas funções fisiológicas no organismo, no entanto, distúrbios funcionais desse nervo podem também afetar a psique do indivíduo, provocando mudanças significativas na autoimagem, interferindo no rendimento profissional e piorando a qualidade de vida. Lesões graves do nervo facial (neurotmeses) mesmo quando tratadas precocemente apresentam resultados funcionais pobres. Com a recente descoberta das células-tronco, as células multipotentes do estroma mesenquimal indiferenciadas (CMEMi) ou diferenciadas em células com fenótipo de células de Schwann (CMEMd) podem ser uma alternativa melhor para o tratamento de lesões graves do nervo facial. OBJETIVOS: Avaliar a melhora funcional e histológica do ramo mandibular do nervo facial após neurotmese e implantação das CMEMi e CMEMd. MÉTODOS: Em 48 ratos Wistar realizou-se a neurotmese do ramo mandibular direito do nervo facial com a formação de um hiato de 3mm e a tubulização (conduíte de silicone) da região do nervo lesada. Foram criados quatro grupos de acordo com o método de reparo: conduíte de silicone vazio (grupo A, grupo controle); conduíte de silicone com gel acelular (grupo B); conduíte de silicone com gel acelular e CMEMi (grupo C), e conduíte de silicone com gel acelular e CMEMd (grupo D). Um quinto grupo, grupo N, foi criado a partir de segmentos do nervo normal para a avaliação histológica. Os resultados funcionais foram avaliados com o estudo de condução nervosa e os histológicos por avaliação qualitativa e quantitativa dos segmentos proximais e distais. RESULTADOS: Na avaliação funcional, após 6 semanas, os grupos C e D apresentaram amplitudes maiores que os grupos A e B (p<0,001). O grupo C apresentou duração menor que os grupos A, B e D (p<0,001). Na avaliação qualitativa dos segmentos proximais, houve pouca diferença entre os grupos, já nos segmentos distais, as diferenças dos grupos A e B em relação aos grupos C e D foram bem evidentes, no entanto, em ambos os segmentos, o grupo C foi o que mais se aproximou do nervo normal. Na avaliação histológica quantitativa do segmento proximal, não houve diferença no número total e na densidade axonal entre os grupos (p0,169), somente nos diâmetros axonais dos grupos A e B quando comparados ao nervo normal (p<0,001). No segmento distal, o número e a densidade axonal do grupo C foram maiores que os do grupo A e B (p=0,001) e iguais as do grupo D (p=0,711), porém, em todos os grupos, número e a densidade axonal foram menores que do grupo N (p0,003). Não houve diferença na média dos diâmetros entre os grupos operados (p0,007), somente quando comparados com o grupo N (p<0,001). CONCLUSÕES: As CMEMi assim como as CMEMd beneficiaram a regeneração do ramo mandibular do nervo facial de ratos Wistar, contudo, as CMEMi apresentaram resultados funcionais e histológicos melhores que as CMEMd / INTRODUCTION: Facial nerve performs an important function in different physiological activities in the organism, however, functional disturbances of such nerve may also attack a persons mind, causing expressive changes in their self-image, interfering in professional life and aggravating their quality of life. Severe lesions in the facial nerve (neurotmesis) present poor functional results even when early treated. With recent discovering of the stem cells, undifferentiated multipotent stem cell (uMSC) from mesenchymal stroma or differentiated to Schwann cell-like (dMSC) can be a better perspective to treat severe lesion of the facial nerve. OBJECTIVES: The objective of this study is to evaluate the functional and histological improvement of the mandibular branch after neurotmesis and implantation of the uMSC and dMSC. METHODS: The neurotmesis of the right mandibular branch of the facial nerve with a 3mm gap formation and tubulization (silicone tubing) of the wounded nerve area was performed in 48 Wistar rats. Four groups were divided according to the restoration method: empty silicone tubing (group A, control group); silicone tubing with non-cell gel (group B); silicone tubing with non-cell gel and uMSC (group C) and silicone tubing with non-cell gel and dMSC (group D). A fifth group (N) was created from the normal nerve segments to perform histological evaluation. The nerve conduction study evaluated the functional results; quantity and quality evaluation of the distal and proximal segment evaluated the histological results. RESULTS: After six weeks, regarding functional evaluation, groups C and D presented larger amplitude than groups A and B (p<0.001). Group C presented lesser duration than groups A, B and D (p<0.001). There was little difference among the groups in the quality evaluation of the proximal segments; on the other hand, the differences in groups A and B in relation to groups C and D were quite expressive in the distal segments. However, group C, in both segments, was the one that came closer to the normal nerve. Regarding quantity histological evaluation of the proximal segment, there was no difference in the total number and in the axonal density among the groups (p0.169); there was difference only in the axonal diameters in groups A and B when compared to normal nerve (p<0,001). Regarding distal segment, axonal density and number, in group C, were higher than in group A and B (p=0.001) and the same as in group D (p=0,711), but number and axonal density were lesser than in group N (p0,003). There was no difference in the diameter average among the operated groups (p0.007), when only compared to group N (p<0.001). CONCLUSION: Both uMSC and dMSC benefited regeneration of the mandibular branch of the facial nerve in Wistar rats, although uMSC presented better functional and histological results

Peripheral nerve injuries occur with high incidence and often result in profound and permanent impact on the life of patients and on healthcare expenditure. Schwann cells (SC) play a promoting role in peripheral nerve regeneration providing physical and neurotrophic support that aids axon re-growth. However, these beneficial properties are not exploitable in nerve tissue engineering due to the difficulties in SC harvesting and expansion in culture. Adult stem cells derived from bone marrow (BM-MSC) and from adipose tissue (ASC) can be differentiated in SC-like cells and be used as SC substitutes in bioengineered nerve conduits for the improvement of peripheral nerve regeneration. Pharmacological intervention approaches for the treatment of nerve injury are still not clinically available. Nevertheless, γ-Aminobutyric acid (GABA) receptors have been recently suggested as a putative target for such purpose. GABA is the main inhibitory neurotransmitter of the adult brain and interacts with two different receptor types. However, both GABA-A and GABA-B receptor types are functionally expressed also in SC, where they are involved in the regulation of SC physiology and in the development of the peripheral nervous system (PNS).The aim of this thesis was to characterise the GABAergic system of BM-MSC and ASC differentiated into a SC-like phenotype and to evaluate changes in the expression levels following differentiation. Moreover, the effect of specific GABA receptor ligands on cell proliferation and neurotrophic potential of differentiated stem cells were assessed. Using reverse transcriptase polymerase chain reaction, western blot analysis and immunohistochemistry we demonstrated that adult stem cells express several subunits of both GABA-A and GABA-B receptor systems such as GABA-B1a, GABA-B1b and GABA-B2, as well as GABA-A α2 and GABA-A β3. Expression levels and cellular localisation were comparable with adult and neonatal SC cultures used as positive controls, and protein expression levels for some of the subunits changed following glial differentiation. Interestingly, stimulation of GABA receptors with specific agonists influenced stem cell proliferation in two opposite ways. Baclofen, a GABA-B receptor agonist decreased proliferation of SC and differentiated ASC (dASC), but not of SC-like BM-MSC (dBM-MSC). By contrast, muscimol, a GABA-A receptor agonist, increased proliferation in SC and in both dASC and dBM-MSC. This suggests that GABAergic signalling could be a potential player in the mechanisms regulating stem cell differentiation and proliferation as reported in SC. Finally, baclofen treatments on SC and dASC modulated the expression levels and the release of the neurotrophins BDNF and NGF, which are key actors in the processes involved with peripheral nerve regeneration. Although further studies will be needed to clarify the role of GABA receptors in the PNS, the presence of functional GABA receptors on SC-like adult stem cells could represent an exploitable pharmacological target to modulate stem cell physiology and improve their neurotrophic potential for peripheral nerve regeneration.

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In der Entwicklung des peripheren Nervensystems formen Schwannzellen eine Myelinscheide um Axone mit einem Durchmesser von mehr als 1 μm durch die Bildung multipler kompakter Membranschichten. Voraussetzung einer optimalen Nervenleitgeschwindigkeit ist dabei ein physiologisches Verhältnis der Dicke der Myelinscheide zu dem jeweiligen Axondurchmesser. Eine zentrale Rolle spielt dabei der axonale EGF-like growth factor NRG1 Typ III, der ErbB2/3- Rezeptoren der Schwannzelle bindet. Der PI3K-AKT-Signalweg ist ein bekannter intrazellulärer Effektor des ErbB2/3-Rezeptors und wurde bereits mit dem Prozess der Myelinisierung in Verbindung gebracht. Um die spezifische Funktion des PI3K-AKT-Signalwegs in Schwannzellen zu erforschen, generierten wir mit Hilfe des Cre/LoxP-Systems Mausmutanten, die eine zellspezifische Inaktivierung des Gens Phosphatase and Tensin Homolog (Pten) in myelinisierenden Gliazellen aufweisen (Pten-Mutanten). Der Verlust der Lipidphosphatase PTEN führte zu einer Anreicherung ihres Substrates, des second messenger Phosphatidyl-(3,4,5)-Trisphosphat (PIP3), und damit zu einer gesteigerten Aktivität des PI3K-AKT-Signalwegs in den Schwannzellen der Pten-Mutanten. Wir beobachteten in den Pten-Mutanten eine ektopische Myelinisierung von unmyelinisierten C- Faser-Axonen sowie eine Hypermyelinisierung von Axonen bis 2 μm Durchmesser. Bei Axonen über 2 μm Durchmesser kam es zu Myelinausfaltungen und fokalen Hypermyelinisierungen (Tomacula) anliegend an Regionen des unkompakten Myelins (Paranodien und Schmidt- Lantermann-Inzisuren). Weiterhin bildeten die mutanten Remak-Schwannzellen unkompakte Membranwicklungen um nicht-myelinisierte C-Faser-Axone und um Kollagenfaserbündel aus („Remak-Myelin“). Sowohl in den Regionen unkompakten Myelins als auch in Remak- Schwannzellen konnte eine erhöhte Aktivität des PI3K-AKT-Signalwegs nachgewiesen werden. Vermutlich setzt die Anreicherung von PIP3 mit Überaktivierung des PI3K-AKT-Signalwegs in den mutanten Gliazellen einen zellautonomen Prozess der Umwicklung von Axonen in Gang. Die zusätzliche Bildung von „Remak-Myelin“ um Kollagenfasern, die keine Membranoberfläche besitzen, weist darauf hin, dass dieser Prozess nicht von einer bidirektionalen axo-glialen Kommunikation abzuhängen scheint. Die beobachteten Tomacula und Myelinausfaltungen zeigten Ähnlichkeiten mit Mausmodellen für hereditäre Neuropathien des Menschen, wie HNPP und CMT4B. Wir vermuten, dass PTEN im unkompakten Myelin unkontrolliertes Membranwachstum verhindert und dass eine gestörte Balance von Phosphoinositiden einen Pathomechanismus von tomaculösen Neuropathien darstellt. Somit identifizieren wir den PI3K-AKT-Signalweg als ein mögliches Ziel zukünftiger Therapiekonzepte für hereditäre Neuropathien des Menschen.