The need for tissue and organ replacements cannot be satisfied by autograft and allografts alone. The purpose of this study was to investigate the feasibility of electrospinning a blend of polydioxanone and fibrinogen to produce an engineered tissue scaffold. Fiber diameter and pore size of blends were characterized, as well as mechanical strength. Cell proliferation assays for 1 and 7 day cultures were preformed, and a histological evaluation was performed to determine how favorable the various blends were to cell infiltration and proliferation. Some ratios of blends were identified that contained both acceptable mechanical properties and properties that facilitated cell infiltration. These findings pave the way for future refinement and use of these scaffolds for a variety of tissue engineered targets.

Le polydioxanone est un polymère cristallin et bioabsorbable qui a été développé pour une utilisation médicale, spécifiquement pour la réalisation de points de sutures. Il présente une meilleure combinaison de propriétés mécaniques (souplesse, résistance et extensibilité) par rapport à d'autres fibres synthétiques. Ce polymère a fait fobjet de plusieurs études fondamentales qui visaient à en connaître plus sur ses propriétés physico-chimiques. Au cours de nos travaux, nous avons utilisé deux techniques expérimentales, soit la diffraction des rayons X et la microspectroscopie Raman, afin de caractériser quantitativement l'orientation des chaînes dans la fibre et obtenir des informations sur leur conformation dans la phase cristalline. Parallèlement, des méthodes de simulation moléculaire ont été utilisées pour l'étude de la structure cristalline et le repliement des chaînes. La diffraction des rayons X a été employée pour déterminer la période de la fibre et son degré d'orientation. Les clichés de diffraction des rayons X nous ont permis d'identifier directement la valeur de la période de fibre, qui est la réciproque de la distance entre les strates de taches de diffraction observées. Le coefficient de distribution d'orientation P₁₀₀ cham est calculé à partir de l'intensité des taches de diffraction des plans (hkl). Les résultats obtenus indiquent que la valeur de la période de fibre, ou paramètre de maille V est différente de celle attendue pour une conformation entièrement trans coplanaire, ceci indiquant que la conformation de la chaîne n'est pas trans. La valeur de P₁₀₀cham montre que les chaînes dans la fibre sont hautement alignées suivant l'axe de cette dernière et que la distribution des cristaux est unimodale. La spectromicroscopie Raman a été utilisée pour déterminer quantitativement l'orientation des groupements carbonyle dans la fibre. Les paramètres d'ordre P200 et P400 ont été déterminés à partir de la variation de l'intensité de la bande C=0 avec la polarisation de la radiation. Ces paramètres d'ordre ont permis de déterminer la distribution d'orientation la plus probable de la bande C=0. Les résultats indiquent que les groupements carbonyle possèdent une distribution d'orientation gaussienne et sont orientés principalement de façon perpendiculaire à l'axe de la fibre. Une étude des conformations possibles a de plus été menée par la méthode Monte-Carlo. Avec les informations obtenues par les méthodes expérimentales, nous avons proposé une conformation probable des chaînes dans la forme cristalline, soit (tgttg). D'autres études de simulation de la cristallisation ont été effectuées par dynamique moléculaire en utilisant les logiciels Insight // et Discover, dans le but d'obtenir un aperçu des conformations, d'empilements et des repliements des chaînes qui peuvent être présents dans la phase cristalline. Les résultats obtenus montrent que les chaînes ont tendance à former des hélices. Différents repliements des chaînes ont été observés, composés chacun d'une à deux unités de répétition, qui peuvent correspondre à une chaîne adjacente impliquée dans le repliement suivant les différentes plans cristallographiques. Les résultats obtenus au cours de nos travaux ont permis de mieux comprendre l'organisation structurale du polydioxanone. Les travaux effectués ont mis en évidence que la diffraction des rayons X et la spectromicroscopie Raman sont des techniques bien adaptées pour l'étude de la structure cristalline et l'orientation moléculaire des fibres. L'analyse conformationnelle et la dynamique moléculaire sont deux méthodes qui donnent de l'information sur les conformations possibles des chaînes, la déformation induite par la cristallisation et le repliement des chaînes. bable de la bande C=0. Les résultats indiquent que les groupements carbonyle possèdent une distribution d'orientat gaussienne et sont orientés principalement de façon perpendiculaire à l'axe de la fibre. Une étude des conformations possibles a de plus été menée par la méthode Monte-Carlo. Avec les informations obtenues par les méthodes expérimentales, nous avons proposé une conformation probable des chaînes dans la forme cristalline, soit (tgttg). D'autres études de simulation de la cristallisation ont été effectuées par dynamique moléculaire en utilisant les logiciels Insight // et Discover, dans le but d'obtenir un aperçu des conformations, d'empilements et des repliements des chaînes qui peuvent être présents dans la phase cristalline. Les résultats obtenus montrent que les chaînes ont tendance à former des hélices. Différents repliements des chaînes ont été observés, composés chacun d'une à deux unités de répétition, qui peuvent correspondre à une chaîne adjacente impliquée dans le repliement suivant les différentes plans cristallographiques. Les résultats obtenus au cours de nos travaux ont permis de mieux comprendre l'organisation structurale du polydioxanone. Les travaux effectués ont mis en évidence que la diffraction des rayons X et la spectromicroscopie Raman sont des techniques bien adaptées pour l'étude de la structure cristalline et l'orientation moléculaire des fibres. L'analyse conformationnelle et la dynamique moléculaire sont deux méthodes qui donnent de l'information sur les conformations possibles des chaînes, la déformation induite par la cristallisation et le repliement des chaînes.

Implanted biomaterials often induce inflammation that frequently leads to the foreign body response, fibrosis, and the failure of the implant. Thus, it is important to evaluate how cells interact with materials to promote a more regenerative response. It is critical to determine how to modulate the response of tissue resident innate immune cells, as they are among the first cells to interact with implanted materials. Among tissue resident innate immune cells are mast cells, which are inflammatory sentinels that degranulate and orchestrate the fate of other cell populations, such as monocytes/macrophages and lymphocytes. Mast cells have also been reported to play a vital role in the foreign body response of implanted biomaterials as well as angiogenesis. The goal of this study was to determine how to modulate mast cell responses to electrospun scaffolds by altering scaffold architecture and composition to promote anti-inflammatory and regenerative cell-scaffold interactions. Scaffold architecture was manipulated by changing either fiber diameter or pore diameter and mast cell responses were mediated by endogenous and exogenous DAMPs (i.e. IL-33 and LPS, respectively). Particularly in response to IL-33, scaffolds with increased fiber and pore diameter promoted less inflammatory cytokine and chemokine release while increasing angiogenic cytokine release. Additionally, taking scaffolds that promoted increased inflammatory cytokine expression and increasing the pore diameter alone dampened inflammatory cytokine expression. The next question we wanted to answer was how might the degradative byproducts of scaffolds alter mast cell inflammatory responses. Given the widespread use of polylactic acid, we decided to investigate this question using lactic acid as a degradative byproduct. In the presence of physiologically relevant levels of lactic acid, IL-33- and IgE-mediated inflammatory cytokines and chemokines are suppressed, while angiogenic cytokines are enhanced. This response was shown to be pH- and MCT1-dependent and was recapitulated in primary human skin mast cells as well as in vivo. In summary, scaffold architecture and the presence of select polymer degradative byproducts have the potential of selectively suppressing inflammatory cytokines and enhancing angiogenic cytokines.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-03T13:36:36Z No. of bitstreams: 1 anelieseholetzdetoledolourenco.pdf: 1031352 bytes, checksum: 854cb00affac32d268ed966a87b7d1bb (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-03T19:01:14Z (GMT) No. of bitstreams: 1 anelieseholetzdetoledolourenco.pdf: 1031352 bytes, checksum: 854cb00affac32d268ed966a87b7d1bb (MD5) / Made available in DSpace on 2017-04-03T19:01:14Z (GMT). No. of bitstreams: 1 anelieseholetzdetoledolourenco.pdf: 1031352 bytes, checksum: 854cb00affac32d268ed966a87b7d1bb (MD5) Previous issue date: 2009-07-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Realizou-se uma investigação clínica com o intuito de verificar a efetividade da incorporação da tenda e do arco de polidioxanona à técnica do tracionamento coronal do retalho - sem o uso de membrana de Regeneração Tecidual Guiada - no recobrimento das recessões gengivais Classe I e II de Miller pós-tratamento ortodôntico.Quarenta e nove recessões gengivais (16 pacientes) foram avaliadas antes e após o procedimento cirúrgico (0, 7, 30, 60, e 120 dias). Registrou-se o Nível da Recessão Gengival (NRG), a Profundidade do Sulco Gengival (PSG) e a Altura da Mucosa Ceratinizada (AMC). Durante o procedimento cirúrgico, fios de polidioxanona foram inseridos em pequenos orifícios realizados na crista óssea interradicular (não se adicionou uma membrana de Regeneração Tecidual Guiada) e o retalho foi tracionado coronalmente para recobrimento das recessões. A análise estatística realizada utilizou o teste não paramétrico de Wilcoxon. Ao término do acompanhamento verificou-se que em 48 casos, o nível final da recessão gengival foi menor que o inicial (NRG: 2,55 mm+-1,11/dia 0; 0,34 mm+-0,65/dia 120 – p=0.0001); a profundidade final do sulco gengival mostrou-se idêntica à inicial em 47 casos (PSG: 0,99 mm+-0,71/dias 0 e 120 – p=1) e que a altura final da mucosa ceranitizada foi maior que a original em 46 casos (AMC: 2,38 mm+-0,76/dia 0; 3,18 mm+- 0,90/dia 120 – p=0.0001). Concluiu-se que, a incorporação da tenda e do arco de polidioxanona à técnica do tracionamento coronal do retalho - sem o uso de membrana de Regeneração Tecidual Guiada - permite o recobrimento das recessões gengivais Classe I e II de Miller pós-tratamento ortodôntico, não havendo formação de sulco gengival aumentado, permitindo ainda, aumento da faixa de mucosa ceratinizada. / This study evaluates the clinical effectiveness of a polydioxanone tend and arch - with no use of Guided Tissue Regeneration membrane - in a root coverage method for Miller Class I and II gingival recessions after orthodontics treatment. Forty-nine gingival recessions (in 16 patients) were observed before and after the surgical procedure (0, 7, 30, 60, and 120 days). The gingival recession level (NRG), the sulcus probing depth (PSG) and the Keratinized Mucosa Width (AMC) were registered. During the surgery, polydioxanone tend and arch were inserted in little holes in osseous crest (there was not Guided Tissue Regeneration membrane addition) and the flap was coronally positioned in order to cover the gingival recessions. Statistical analysis was performed with the non-parametric Wilcoxon test. The results could showed that in 48 cases, the final gingival recession was smaller than the initial level (NRG: 2,55 mm+-1,11/dia 0; 0,34 mm+-0,65/dia 120 – p=0.0001); the sulcus probing depth showed the same values at the beginning and at the end of experiment in 47 cases (PSG: 0,99 mm+-0,71/dias 0 e 120 – p=1) and the keratinized mucosa width was greater at day 120 than at day 0 in 46 cases (AMC: 2,38 mm+-0,76/dia 0; 3,18 mm+- 0,90/dia 120 – p=0.0001). The conclusion was that the addition of a polydioxanone tend and arch to the coronally positioned flap - with no use of a Guided Tissue Regeneration membrane – allow the root coverage of Miller Class I and II gingival recessions, with no formation of deeper gingival sulcus, still allows increasing in a keratinized mucosa width.

The objective of this research project was to evaluate the mechanical, morphological, and permeability properties of electrospun blends of polydioxanone and poly(lactic acid) for application as vascular grafts. Mechanical analysis was performed by uniaxial tensile testing to examine the peak load, peak stress, elastic modulus, and strain at break of the fibrous materials. The morphological characteristics of the polymer blends were analyzed using phase contrast microscopy, scanning electron microscopy, and image analysis software. Scanning electron microscopy and image analysis software were used to assess fiber diameter and pore size of electrospun scaffolds. Scaffold permeability measurements were also used to calculate fiber diameter and pore size, and the values were compared to those obtained using image analysis. The material property results acquired from the research suggest that the electrospun polymer blends have potential for use in vascular graft applications.

Evidence shows there is no ideal membrane, i.e., biocompatible, biodegradable, with adequate mechanical and physical properties that enable reorganization of periodontal tissues. Eletrospinning technique has demonstrated good processing results on scaffolds made from polymers. Nanofibrous formed by this technique have characteristics that resemble the extracellular matrix. The aim of this study was to evaluate the biocompatibility of nanofibrous polydioxanone scaffolds (PDS II®) containing metronidazole or ciprofloxacin in subcutaneous implantation model in rats Wistar. PDS II® is biocompatible polyester having various applications in the medical field. Our conceptual hypothesis considers that scaffolds with antimicrobials have similar inflammatory behavior when compared to PDS positive control. Sixty adult male rats were randomized into 6 groups: negative control (SHAM) animals with incision and surgical pocket, without scaffold; positive control (PDS) animals with PDS scaffolds; 1MET animals with one PDS scaffold containing 25%wt metronidazole; 2MET animals with two PDS scaffolds containing 25%wt metronidazole, 1CIP animals with PDS scaffolds containing 25%wt ciprofloxacin; 2CIP animals with two PDS scaffolds containing 25%wt ciprofloxacin. Animals were euthanized at 3 days (n=30) and 30 days (n=30), corresponding to initial and late inflammatory responses, respectively. Outcomes measures were the degradation of collagen fibers (Picrosirius Red and Masson´s trichrome), activity of cellular enzyme (Myeloperoxidase activity and N-acetyl-β-D-glucosaminidase activity) and local oxidative profile (reactive oxygen species, lipid peroxidation, protein carbonyl, vitamin C, catalase and reduced glutathione). Dara were analyzed statistically (p<0.05) by two-way ANOVA (treatment and time). Collectively, results show that antibiotics scaffolds have a lower inflammatory response compared to PDS group. Among the nanofibers with antibiotics, the group showed better early and late inflammatory response was 2CIP. The findings of this research suggest the potential study of these scaffolds with metronidazole and ciprofloxacin in regenerative models, able to confirm the effectiveness of these artificial matrices for periodontal regeneration. / Evidências mostram que não há membranas ideais, ou seja, biocompatíveis, biodegradáveis, com propriedades mecânicas e físicas adequadas que permitam a reestruturação dos tecidos periodontais. A técnica do eletrospinning tem demonstrado bons resultados no processamento de scaffolds confeccionados a partir de polímeros. As nanofibras formadas por esta técnica possuem características que se assemelham a matriz extracelular. O objetivo do presente estudo foi avaliar a biocompatibilidade de scaffolds nanofibrosos de polidioxonona (PDS II®) contendo metronidazol ou ciprofloxacina em modelo de implantação subcutânea em ratos Wistar. A PDS II® é um poliéster biocompatível com diversas aplicações na área médica. Nossa hipótese conceitual considerou que scaffolds com antimicrobianos teriam semelhante comportamento inflamatório quando comparados ao controle positivo PDS. Sessenta ratos machos adultos foram randomizados em seis grupos: controle negativo (SHAM) - animais com incisão e loja cirúrgica, ausentes de scaffolds; controle positivo (PDS) - animais com scaffolds de PDS, 1 scaffold PDS com 25%wt de metronidazol (1MET), 2 scaffolds PDS com 25%wt de metronidazol (2MET), 1 scaffold PDS com 25%wt de ciprofloxacina (1CIP), 2 scaffolds com 25%wt de ciprofloxacina (2CIP). Os animais foram eutanasiados em 3 (n=30) e 30 dias (n=30), correspondendo a resposta inflamatória inicial e tardia, respectivamente. Os desfechos avaliados foram degradação de fibras colágenas (Picrosírius Red e Tricrômico de Masson), atividade de enzimáticas celulares (mieloperoxidase e N-Acetil β-D-Glicosaminidase) e perfil oxidativo local [espécies reativas de oxigênio (ROS), peroxidação lipídica (LP), proteína carbolinada (PC), catalase (CAT), vitamina C (VIT.C) e glutationa reduzida (GSH)]. Os dados foram analisados estatisticamente (p<0,05) através do teste Two-way ANOVA (tratamento e tempo). Coletivamente, os resultados mostram que scaffolds com antibióticos possuem menor resposta inflamatória se comparado ao grupo PDS. Entre as nanofibras com antibióticos, o grupo que apresentou melhor resposta inflamatória inicial e tardia foi 2 CIP. Os achados desta pesquisa sugerem o potencial estudo destes scaffolds com metronidazol e ciprofloxacina em modelos regenerativos, capazes de confirmar a efetividade dessas matrizes artificiais para a regeneração periodontal.