Embora muito se tenha avançado no desenvolvimento de novas terapias para as cardiomiopatias, ainda não existe uma opção curativa que substitua a necessidade do transplante. A medicina regenerativa vem se consolidando pelo mundo ao trazer novas alternativas para doenças cardíacas crônicas. Embora os cardiomiócitos sejam afetados de maneira importante no processo de degeneração do órgão, sendo os responsáveis pela contração cardíaca, eles não são, na verdade, as células mais abundantes no coração de mamíferos. Esse lugar é ocupado pelos fibroblastos: células alongadas presentes entre as fibras musculares e que ajudam na manutenção do equilíbrio da matriz extracelular. Durante a insuficiência cardíaca, dois processos contribuem para o desbalanço desse equilíbrio e consequente fibrose e remodelamento do coração. O primeiro processo é a diferenciação de fibroblastos em miofibroblastos; o segundo é a transição de células endoteliais em mesenquimais (EndMT). Ambos os processos levam ao aumento de células responsáveis por depositar matriz extracelular e, portanto, à fibrose e remodelamento. Assim, abordagens direcionadas a impedir o progresso desses processos podem ser uma alternativa interessante para o tratamento das cardiomiopatias. Utilizando-se de células-tronco, biomateriais e fatores de crescimento, o objetivo desta tese é a criação de uma nova abordagem terapêutica que vise diminuir ou extinguir o processo de fibrose no tecido cardíaco, a fim de manter preservada a função do órgão. Para isso em nosso primeiro estudo, Fibroblast growth factor-2, but not the adipose tissuederived stromal cells secretome, inhibits TGF-Beta1-induced differentiation of human cardiac fibroblasts into myofibroblasts (Scientific Reports, 2018) fibroblastos cardíacos humanos primários, foram cultivados e sua diferenciação foi estimulada através do uso de TGF-Beta1 in vitro. Como tentativa de prevenir sua transformação em miofibroblastos, foi realizada a coleta do secretoma de células estromais derivadas de tecido adiposo (ASC-CMed) e os fibroblastos foram tratados com tal secretoma. Neste trabalho, os resultados demonstraram que não foi possível inibir a diferenciação dos fibroblastos em miofibroblastos com o uso de ASC-CMed. Em nosso segundo estudo, Adipose tissue-derived stromal cells' conditioned medium modulates endothelial-mesenchymal transition induced by IL-1Beta/TGF-Beta2 but does not restore endothelial function (Cell Proliferation, 2019), induzimos a diferenciação de células endoteliais através de um ambiente pró-inflamatório e prófibrótico, utilizando IL-1Beta e TGF-Beta1, e buscamos impedir a diferenciação dessas utilizando ASC-CMed. Os resultados mostraram que, embora as células endoteliais não tenham retornado a um fenótipo funcional, nós conseguimos inibir o processo de EndMT. Nosso terceiro estudo, Bioactive decellularized cardiac extracellular matrix-based hydrogel as a sustained-release platform for human adipose tissue-derived stromal cell-secreted factors (submetido), teve como objetivo desenvolver uma plataforma baseada em um hidrogel derivado de matriz extracelular miocárdica para liberação do ASC-CMed, processo que foi testado utilizando em diferentes concentrações de secretoma (1x, 10x e 100x). Nossos resultados demonstraram que esse biomaterial demonstrou ser uma excelente plataforma para a liberação fatores de crescimento de maneira contínua. Finalizando a presente tese, com a utilização desse mesmo hidrogel, no quarto estudo, Intrapericardial injection of hydrogels derived from decellularized cardiac extracellular matrix loaded with mesenchymal stromal cells and their secretome: a novel therapeutic approach to treat cytostatics-induced dilated cardiomyopathy, nós levamos em consideração a resposta imune in vivo, ao realizarmos a aplicação intrapericárdica do hidrogel carreado de ASC e seu secretoma em um modelo crônico de cardiomiopatia dilatada em ratos. Neste estudo foi possível concluir que nossa terapia foi capaz de diminuir a fibrose cardíaca e reduzir o remodelamento, bem como melhorar a função cardíaca e parâmetros hemodinâmicos dos animais. Assim, o conteúdo da presente tese demonstra que a aplicação intrapericárdica de um hidrogel composto de matriz extracelular miocárdica carreada com células estromais derivadas de tecido adiposo e seus fatores de crescimento proporciona um ambiente que predispõe a regeneração cardíaca. Futuros estudos são necessários para melhor elucidar os mecanismos envolvidos nessa melhora de função, bem como o estudo em modelos animais que mais se assemelham aos humanos, objetivando, em um momento futuro, a aplicação dessa terapia em clinical trials

Although considerable progress has been made in the development of new therapies for cardiomyopathies, there is still no curative alternative to replace the need for transplantation. Regenerative medicine has been consolidated around the world by bringing new alternatives to chronic heart disease. Although cardiomyocytes are significantly affected in the cardiac degeneration process, being responsible for the muscle contraction, they are not, in fact, the most abundant cells in the heart of mammals. This place is occupied by fibroblasts: elongated cells present between the muscle fibers and which help to maintain the extracellular matrix balance. During heart failure, two processes contribute to the disruption of this balance and the consequent fibrosis and heart remodeling. The first process is the transdifferentiation of cardiac fibroblasts into myofibroblasts; the second is the endothelial-mesenchymal transition (EndMT). Both processes lead to an increase in the number of cells responsible for depositing extracellular matrix and, therefore, fibrosis and remodeling. Thus, approaches aimed at preventing the progress of these processes can be an interesting alternative for the treatment of cardiomyopathies. Using stem cells, biomaterials and growth factors, the objective of this thesis was to create a new therapeutic approach to decrease or extinguish the process of fibrosis in the cardiac tissue, in order to maintain the organ's function preserved. For that, in our first study, Fibroblast growth factor-2, but not the adipose tissue-derived stromal cells secretome, inhibits TGF-Beta1-induced differentiation of human cardiac fibroblasts into myofibroblasts (Scientific Reports, 2018), primary human cardiac fibroblasts stimulated TGF-Beta1 in vitro and their transdifferentiation was assessed. In an attempt to prevent its transformation into myofibroblasts, the secretome of adipose tissuederived stromal cells (ASC-CMed) was collected and the fibroblasts were treated with it. In this work, the results demonstrated that it was not possible to inhibit the transdifferentiation of fibroblasts into myofibroblasts with the use of ASC-CMed. In our second study, Adipose tissue-derived stromal cells' conditioned medium modulates endothelial-mesenchymal transition induced by IL-1Beta / TGF-Beta2 but does not restore endothelial function (Cell Proliferation, 2019), we induced the differentiation of endothelial cells through a pro-inflammatory and pro-fibrotic environment, using IL-1Beta and TGF-Beta1, and we sought to prevent their differentiation using ASC-CMed. The results showed that, although the endothelial cells did not return to a functional phenotype, we were able to inhibit the EndMT process. Our third study, Bioactive decellularized cardiac extracellular matrix-based hydrogel as a sustained-release platform for human adipose tissue-derived stromal cellsecreted factors (submitted), aimed to develop a platform based on a hydrogel derived from myocardial extracellular matrix for the release of ASC-CMed, a process that was tested using different concentrations of secretome (1X, 10X and 100X). Our results demonstrated that this biomaterial proved to be an excellent platform for releasing growth factors in a sustained manner. Concluding the present thesis, using this same hydrogel, in the fourth study, Intrapericardial injection of hydrogels derived from decellularized cardiac extracellular matrix loaded with mesenchymal stromal cells and their secretome: a novel therapeutic approach to treat cytostatics-induced dilated cardiomyopathy, we took into account the immune response in vivo, when carrying out the intrapericardial application of the dECM hydrogel loaded with ASC and their secretome in a rat model of dilated cardiomyopathy. In this study it was possible to conclude that our therapy was able to decrease cardiac fibrosis and reduce remodeling, as well as improving cardiac function and hemodynamic parameters of the treated animals. Thus, the content of the present thesis demonstrates that the intrapericardial application of a myocardial extracellular matrix-derived hydrogel loaded with ASC and their growth factors constitutes a potential approach for cardiac regeneration. Further studies are necessary to better elucidate the mechanisms involved in the process, as well as to investigate the approach in large animal models that better resemble humans, aiming, in the future, the application of this therapy in clinical trials