Researches from different fields around the world are searching for both new sources of biomaterials and potential hepatocytes in order to supply drug tests, cell therapies, and cell transplantation as alternative therapeutic support to liver diseases and injuries. Placenta may be eligible as a new model in tissue engineering due to its rich extracellular matrix (ECM) and availability after birth. Placental scaffolds were produced by decellularization with 0.01, 0.1 and 1% SDS, and 1% Triton X-100 which were valued by means of structure and composition. Afterwards, placental scaffolds were co-cultured with mouse embryonic fibroblasts in a tridimensional (3D) rotating system. Placental scaffolds presented a well-preserved acellular ECM containing 9.42 ± 5.2 ng dsDNA per mg of ECM. Weak collagen I of the natives clearly appears in decellularized ECM while the collagen III, once well observed in native placenta, it was absent on scaffolds. This interesting observation may have been due to the solubilization SDS-induced of the collagen III fibrils during decellularization. Fibronectin was well-observed in placental scaffolds whereas laminin and collagen IV were strongly stained. Recellularized with fibroblasts by a 3D culture system, placental scaffolds showed potential for repopulation, with cells adhered throughout its acellular ECM. Placental scaffolds were then newly recellularized, aiming now for differentiation of mouse embryonic stem cells into hepatic cells. In a protocol of 23 days, it was simulated major events of liver embryonic development by adding growth factors. As result, a high index of cells adhered, proliferated and migrated throughout outer and inner scaffolds ECM surface. Absence of Oct4 and Nanog showed that Activin A and Wnt3a (d0-6) induced primitive endoderm fate, and negative label for Foxa2 and Sox17 representing BMP4 and FGF2 (d6-10) differentiation-induced generating definitive endoderm cells. Also, FGF1, FGF4 and FG8b (d10-14) induced hepatoblast phenotype cells, that were observed positive for AFP and CK7 markers. Finally, HGF and FS-288 (d14-23) induced to hepatocyte-like cells, positive for CK18 and Alb markers. The hepatocyte-like cells functional aspects were observed by glycogen storage. Though a heterogeneous cell hepatic lineage was confirmed, mouse placental scaffolds shown a useful model to support recellularization with simultaneous differentiation into hepatic fate simulating phases of embryonic development. / Pesquisas de diferentes campos ao redor do Mundo estão em busca de novas fontes tanto de biomateriais, quanto de potenciais hepatócitos, a fim de suprir testes de drogas, terapias celulares e transplante de células, como suporte terapêutico alternativo para doenças e lesões hepáticas. Placentas podem ser elegíveis como um novo modelo em Engenharia Tecidual em decorrência de sua rica matriz extracelular (ECM), e disponibilidade após o nascimento. Os scaffolds placentários foram produzidos por decelularização com SDS 0,01, 0,1 e 1% e Triton X-100 1%, os quais foram avaliados por meio da estrutura e composição. Posteriormente, os scaffolds placentários foram co-cultivados com fibroblastos embrionários de camundongos em um sistema rotativo tridimensional (3D). Os scaffolds placentários apresentaram uma MEC acelular bem conservada, contendo 9,42 ± 5,2 ng/dsDNA/mg/MEC. O fraco colágeno I nos nativos aparece claramente na MEC descelularizada, enquanto o colágeno III bem visível na placenta nativa estava ausente nos scaffolds. Esta observação interessante pode decorrido da solubilização das fibrilas de colágeno III, induzida pelo SDS durante a decelularização. A fibronectina foi bem observada nos scaffolds placentários, enquanto a laminina e o colágeno IV estiveram fortemente marcados. Recelularizados com fibroblastos por um sistema de cultura 3D, os scaffolds placentários mostraram potencial para repovoamento, com células aderidas ao longo de sua MEC acelular. Os scaffolds placentários foram então novamente recelularizados, visando agora a diferenciação de células tronco-embrionárias de camundongos em células hepáticas. Em um protocolo de 23 dias, foram simulados os grandes eventos do desenvolvimento embrionário do fígado, pela adição de fatores de crescimento. Como resultado, um alto índice de células aderiu, proliferou e migrou através das superfícies externa e interna dos scaffolds. A ausência de Oct4 e Nanog demostraram que o Activin A e o Wnt3a (d0-6) induziram o destino endoderma primitivo, e a marcação negativa para Foxa2 e Sox17 representaram a geração de células endodermais definitivas pela diferenciação induzida por BMP4 e FGF2 (d6-10). Ainda, FGF1, FGF4 e FG8b (d10-14) induziram células do fenótipo hepatoblasto, que foram observadas positivas para os marcadores AFP e CK7. Finalmente, HGF e FS-288 (d14-23) induziram as células hepatocyte-like, positivas para os marcadores CK18 e Alb. The hepatocyte-like cells functional aspects were observed by glycogen storage. Though a heterogeneous cell hepatic lineage was confirmed, mouse placental scaffolds shown a useful model to support recellularization with simultaneous differentiation into hepatic fate simulating phases of embryonic development. Os aspectos funcionais das células hepatocyte-like foi observada pelo armazenamento de glicogênio. Embora uma linhagem hepática formada por células heterogêneas tenha sido confirmada, os scaffolds placentários de camundongos se mostraram um modelo útil para sustentar a recelularização com simultânea diferenciação em destino hepático, simulando fases do desenvolvimento embrionário.

Heart failure is the main cause of death for both men and women in the United States. The only proven treatment for patients with heart failure is heart transplantation. The goal of this research is to create patches of tissue that could mimic the function of the native heart to repair the damaged portions of the heart. In this study, whole porcine hearts were decellularized to create a 3D construct that was recellularized with cardiomyocytes (CM) differentiated from human induced pluripotent stem (IPS) cells. At day 4 of differentiation, IPS-derived CMs were implanted onto cardiac extracellular matrix (cECM) and ten days after recellularization, the cells started to beat spontaneously. After implantation, the progenitor CMs continued to proliferate and populate the cECM. A live/dead assay showed the potential of the cECM as a scaffold suitable for recellularization. Confocal microscopy images were taken to evaluate the organization of the cells within the matrix and the impact of the cECM on the growth and maturation of the CMs. Representative cardiac Troponin T (cTNT) and vimentin immunostaining images of CMs derived from iPSCs, on cECM and on standard cell culture plates showed that the cECM allowed the cells to organize and form fibrils with the fibroblasts, compared with CMs cultured in regular culture plates. The timeline of implantation of the cells was a key factor for the development of the heart tissue constructs. Progenitor CMs seeded onto cECM showed better organization and the ability to penetrate 96 µm deep within the collagen fibers and align to them. However, mature CMs seeded onto the matrix showed a disorganized network with very reduced interaction of CMs with fibroblasts, forming two different layers of cells; CMs on top of fibroblasts. In addition, the depth of penetration of the mature CMs within the matrix was only 20 µm. To evaluate the impact of the addition of support cells to the CM monolayer cultures, CMs were co-cultured with human umbilical vein endothelial cells (HUVEC) and it was demonstrated that at ratios of 2:1 HUVEC:CM the beating rate of the CMs was improved from 20 to 112 bpm, additionally, the CM monolayer cultures showed a more synchronized beating pace after the addition of HUVECs. Pharmacological stimulation was performed on CM monolayer cultures using norepinephrine as a stimulator and the results showed that the beating pace of the CMs was improved to 116 bpm after 5 minutes of drug exposure. For future studies, inosculation of the tissue constructs could be performed with the incorporation of membrane proteins to understand the mechanotransduction of the cells. As a preliminary study, the action of dual claudins was evaluated with HUVEC cultures and the results showed the potential of these membrane proteins in the healing of the damaged cell membrane.

La technologie des cellules souches et les sciences de biomatériaux ont obtenu des grands progrès au cours des dernières décennies et sont devenues plus populaires dans le monde. Les chercheurs cherchent à étudier et à évaluer les différentes sources de cellules et de biomatériaux qui, en combinaison, peuvent fournir une plateforme d’ingénierie tissulaire produite à grande échelle et à bas prix, pour être utilisée aux tests de médicaments, aux thérapies cellulaires et transplantations, dans le but de fournir un soutien thérapeutique aux blessures et à la régénération des tissus endommagés. En général, les trois constituants les plus importants de l’ingénierie tissulaire sont : le choix du type cellulaire, la source du biomatérial (charpente), la création et le maintien d’un lieu favorable à la formation des tissus. Lorsque ces trois constituants sont gérés avec succès, le microenvironnement cellulaire in vitro est plus similaire à ce que la cellule est exposée in vivo, en permettant que la croissance et la différenciation cellulaire survient de façon plus fiable et efficace. Le placenta bovin décellularisé a démontré avoir une riche matrice extracellulaire, des vaisseaux bien développés, étant un biomatérial à haute disponibilité et à bas prix. Mais, on ne sait pas si les charpentes placentaires ont le potentiel d’être repeuplés avec des cellules souches mésenchymateuses (MSC) dérivées du tissu adipeux, et ce processus s’appelle recelularisation. Encore, on ne sait pas si les charpentes placentaires ont la capacité d’offrir, après recelularisation, un ambient approprié pour différencier ces cellules en différentes lignées. Ainsi, afin de fournir des informations sur la capacité du complexe MSC – charpente placentaire à être utilisé avec succès dans l’ingénierie tissulaire, les objectifs de cette thèse ont été : étudier le potentiel des charpentes placentaires bovins en offrir un soutien à la recelularisation par des cellules dérivées du tissu adipeux bovin, et aussi bien qu’évaluer la capacité de différenciation cellulaire en lignées ostéogéniques et chondrogéniques. Le premier article de cette thèse c’est une revue de la littérature qui aborde la nature des cellules souches mésenchymateuses, leurs applications en médicine régénérative, l’importance de la technologie des cellules souches dans l’industrie de l’élevage et l’utilisation de l’espèce bovine en médicine translationnelle. Le deuxième article aborde l’évaluation de la recelularisation et la différenciation cellulaire. Les placentas bovins ont été décellularisés par perfusion de SDS du vaisseau ombilical et les lignées cellulaires établies après la digestion enzymatique du tissu adipeux de six vaches et la sélection par adhésion rapide à la plaque de culture. Ensuite, les cellules ont été cultivées avec les charpentes dans un système d’agitation 2D pendant 21 jours en milieu de différenciation ou de maintenance. Lorsqu’elles sont cultivées sur la plaque de culture, les cellules isolées ont présenté morphologie similaire au fibroblaste, l’expression de CD90, CD73 et CD105, tandis qu’elles n’ont pas exprimé les marqueurs CD34 et CD45. Par ailleurs, les cellules ont été capables de se différencier en lignées chondrogéniques et ostéogeniques, en fournant des preuves de leur nature mésenchymateuse. Ensuite, quand elles ont été cultivées avec les charpentes, les cellules y ont adhéré par des projections cellulaires, établies une communication cellule-charpente et se sont proliférées, fait mis en évidence par l’analyse histologique et microscopie électronique à balayage (MEB). Après, le potentiel des cellules à se différencier en lignées ostéogéniques a été exploré, lorsqu’elles ont été cultivées avec charpente. Au cours d’une période de culture de 21 jours en milieu ostéogénique, les cellules ont proliféré et se sont différenciées de façon dépendante du temps, c’est-à-dire, à chaque semaine, la plus grande abudance de cellules a été observée, fait en évidence par la coloration des noyaux cellulaires et l’augmentation de l’intensité de la coloration pour COLLAGEN 1 (COL1), qui a aussi été exprimée par réaction quantitative en chaîne de la polymérase en temps réel (qRT-PCR). Le standard a été observé par l’analyse histologique, les accumulations généralisées de calcium a aussi été plus abondantes dans les charpentes au cours de la troisième semaine de culture, demontré par la coloration de Von Kossa. L’analyse MEB a montré que les cellules ont sécrété des structures globulaires lorsqu’elles ont été cultivées sur conditions d’induction ostéogénique, cohérentes avec la sécrétion observée par l’analyse histologique. Sur la différenciation chondrogénique, les colorants Safranine et Vert Solide ont démontré succès à la différenciation, grâce à la coloration des protéoglycanes, des cellules similaires aux chondrocytes et aux collagène type II. L’analyse MEB a montré que les cellules ont changé leur morphologie de fibroblastes en globulaires quand elles ont été cultivées avec milieu d’induction chondrogène pendant 21 jours. De plus, les complexes de cellules-charpentes ont exprimé un marqueur de la lignée cartilagineuse, COLLAGEN 2 (COL2), qui est cohérent avec les observations histologiques et MEB. Face aux résultats obtenus, cette étude a démontré que les charpentes placentaires cultivés avec des cellules dérivées du tissu adipeux ont le potentiel d’être utilisés dans l’ingénierie de tissus osseux et cartilagineux. / A tecnologia de células-tronco e as ciências de biomateriais obtiveram um grande avanço nas últimas décadas e se tornaram mais populares em todo o mundo. Pesquisadores buscam investigar e avaliar diferentes fontes de células e de biomateriais que, em combinação, possam fornecer uma plataforma de engenharia tecidual de baixo custo e produzida em larga escala, para serem utilizadas em testes de drogas, terapias celulares e transplantes, com objetivo de fornecer suporte terapêutico à lesões e regeneração de tecidos danificados. Em geral, os três componentes mais importantes da engenharia de tecidos são: a escolha do tipo de célula, a fonte do biomaterial (scaffold), criação e manutenção de um ambiente propício à formação tecidual. Quando esses três componentes são gerenciados com sucesso, o microambiente celular in vitro é mais semelhante ao que a célula está exposta in vivo, permitindo que o crescimento e diferenciação celular ocorra de maneira mais fidedigna e eficiente. A placenta bovina descelularizada demonstrou ter uma rica matriz extracelular, vasos bem desenvolvidos, sendo um biomaterial com alta disponibilidade e baixo custo. No entanto, não há informação sobre o potencial dos scaffolds placentários em serem repovoados com células-tronco mesenquimais (MSC) derivadas do tecido adiposo, processo chamado recelularização. Ainda, também não há informação sobre a capacidade dos scaffolds placentários, de após recelularização, oferecer um ambiente adequado para diferenciação dessas células em diferentes linhagens. Assim, a fim de fornecer informações sobre a capacidade do complexo MSC - scaffold placentário em ser usado com sucesso na engenharia tecidual, os objetivos desta tese foram: estudar o potencial dos scaffolds placentários bovinos em oferecer suporte para recelularização por células-tronco derivadas do tecido adiposo bovino, bem como avaliar a capacidade de diferenciação celular em linhagens osteogênica e condrogênica. O primeiro artigo desta tese trata-se de uma revisão de literatura, que discute a natureza das células-tronco mesenquimais, suas aplicações na medicina regenerativa, a importância da tecnologia com células- tronco na indústria pecuária e o uso da espécie bovina na medicina translacional. O segundo artigo consiste na avaliação da recelularização e da diferenciação celular. As placentas bovinas foram decelularizadas por perfusão de SDS do vaso umbilical e as linhas celulares estabelecidas após digestão enzimática do tecido adiposo de seis vacas e seleção por adesão rápida à placa de cultivo. Em seguida, as células foram cultivadas com os scaffolds em um sistema de agitação 2D por 21 dias em meio de diferenciação ou manutenção. Quando cultivadas na placa de cultivo, as células isoladas exibiram morfologia semelhante ao fibroblasto, expressão de CD90, CD73 e CD105, enquanto não expressaram os marcadores CD34 e CD45. Além disso, as células foram capazes de se diferenciar em linhagens condrogênicas e osteogênicas, fornecendo evidências de sua natureza mesenquimal. Posteriormente, quando cultivadas com os scaffolds, as células aderiram-se aos mesmos por projeções celulares, estabeleceram comunicação célula-scaffold e se proliferaram, fato evidenciado por análise histológica e microscopia eletrônica de varredura (SEM). Em seguida, o potencial das células em se diferenciarem em linhagem osteogênica quando cultivadas com scaffold foi avaliado. Durante um período de cultivo de 21 dias no meio osteogênico, as células se proliferaram e diferenciaram de maneira dependente do tempo, ou seja, a cada semana pode ser observado maior abundância de células, evidenciada pela coloração dos núcleos celulares e aumento da intensidade da coloração para COLAGENO 1 (COL1), que também foi expresso por reação quantitativa em cadeia da polimerase em tempo real (qRT-PCR). O mesmo padrão foi observado pela análise histológica; acúmulos generalizados de cálcio também foram mais abundantes nos scaffolds na terceira semana de cultivo, evidenciado pela coloração de Von Kossa. A análise SEM revelou que as células secretaram estruturas globulares quando cultivadas sob condições de indução osteogênica, condizente com a secreção observada pela análise histológica. Em relação à diferenciação condrogênica, os corantes Safranina e Fast Green revelaram sucesso na diferenciação, através da coloração de proteoglicanos, células semelhantes aos condrócitos e colágeno tipo II. A análise SEM mostrou que as células mudaram sua morfologia de fibroblastos para globulares quando cultivadas com meio de indução condrogênica por 21 dias. Além disso, os complexos células-scaffold expressaram um marcador de linhagem cartilaginosa, COLAGENO 2 (COL2), condizente com as observações histológicas e SEM. Considerando os resultados, este estudo demonstrou que os scaffolds placentários bovinos cultivados com células-tronco derivadas de tecido adiposo bovino possuem potencial para serem utilizados na engenharia de tecidos ósseos e cartilaginosos. / Stem cell technologies and biomaterial sciences have advanced and grown more popular all over the world. The researchers aim to investigate and evaluate different sources of cells and biomaterials that, in combination, could provide a low cost, highly scalable tissue engineering platform that could be used in drug tests, cell therapies and cell transplantation. The three most important components of tissue engineering systems in general are cell source, biomaterial source (scaffolding system), and the creation and maintenance of an environment that is conducive to tissue formation. When these three components are successfully managed, the tissue engineering treatment achieves a faithful imitation of the in vivo environment, allowing for the differentiation of cells into the desirable cell types. Decellularized bovine placenta has been demonstrated to be rich in extracellular matrix (ECM) and to have well-developed vasculature, representing a highly available, low cost, practically scalable biomaterial. However, it is not known if placental scaffolds have the potential to support recellularization with adipose-derived cells and their subsequent differentiation into different lineages. Thus, in order to provide information on the ability of the mesenchymal stem cell (MSC) - placental scaffold complex to be used in tissue engineering approaches, the objectives of this thesis were: to study the potential of bovine placental scaffolds to support adipose-derived cell recellularization and their differentiation into osteogenic and chondrogenic lineages. The first article of this thesis is a literature review that discusses the nature of mesenchymal stem cells, their applications in regenerative medicine, the importance of stem cell technologies to the livestock industry and the use of bovine species for translational medicine. The second article consists of an evaluation of scaffold recellularization and the differentiation of cells on the scaffolds. The bovine placentae were decellularized by umbilical vessel sodium dodecyl sulfate (SDS) perfusion and cell lines were established after the enzymatic digestion of adipose tissue from six cows and cell selection by rapid adherence to the culture plate. Then, cells were seeded onto the scaffolds and cultured in a 2D rocker system for 21 days in either differentiation or maintenance medium. The isolated cells, when cultured in the plastic dish, exhibited fibroblast-like morphology, CD90, CD73 and CD105 expression, and lacked CD34 and CD45 expression. Moreover, the cells were able to undergo differentiation into chondrogenic and osteogenic lineages, providing evidence of their mesenchymal nature. 8 Subsequently, the cells adhered to the scaffolds by cell projections, established cell-scaffold communication, and proliferated while maintaining cell-cell communication, which was evidenced by histological and scanning electron microscopy (SEM) assays. Throughout a 21- day culture period in the osteogenic medium, the cells exhibited proliferation and differentiation in a time-dependent manner, which can be observed by the greater abundance of cells in later periods, evidenced by cell nuclei staining (4′,6-diamidino-2- phenylindole - DAPI) and increased intensity of staining for COLLAGEN 1 (COL1) in the immunohistochemical assay, and by its expression as measured by real time polymerase chain reaction (qRT-PCR). This same pattern was observed by histological analysis. Widespread calcium accumulations were also more abundant on the scaffolds as time progressed, as evidenced by Von Kossa staining. The SEM analysis revealed that cells secreted globular/round structures when seeded under osteogenic induction conditions, in accordance with histological findings. Regarding chondrogenic differentiation, Safranin O and Fast Green staining revealed successful differentiation through staining of proteoglycans, chondrocyte-like cells and type II collagen on the scaffold. The SEM analysis showed that the cells changed morphology from fibroblast-like to globular when cultured with chondrogenic induction medium for 21 days. Additionally, cell-scaffold complexes expressed a cartilage marker, COLLAGEN 2 (COL2), which is conducive to the histological and SEM observations. Considering the results as a whole, this study demonstrated that placental scaffolds seeded with adipose-derived cells have the potential to be used in bone and cartilage tissue- engineering applications