O transplante de ilhotas é um procedimento em desenvolvimento, como alternativa para o tratamento do diabetes tipo 1 que está na fronteira entre o experimental e o clínico. É uma terapia celular na qual as células são implantadas em território diferente do fisiológico em que apenas determinado número incerto conseguirá se adaptar. Aperfeiçoar este processo para obter os mesmos resultados que no transplante de pâncreas, representa um desafio para o qual convergem contribuições da biologia celular, da imunologia e das técnicas de laboratório que se entrelaçam de maneira extremamente complexa. Este trabalho revisa a literatura expondo a evolução do procedimento, a sua metodologia atual e os resultados clínicos obtidos. As perspectivas futuras do transplante diante dos recentes avanços também são discutidas.

Islet transplant is an innovative treatment for type 1 diabetic patients, which still lies between experimental and approved transplant therapy. Islet cells are seeded in a non-physiological territory where an uncertain fraction will be able to adapt and survive. Thus, the challenge lies in improving the whole procedure, employing the tools of cell biology, immunology and laboratory techniques, in order to reach the results obtained with whole organ transplant. This review describes the procedure, its progress to the present methodology and clinical results obtained. Future perspectives of islet transplantation in the light of recent biotechnological advances are also focused.

Development of polymeric materials has been increasingly emphasized in Biomedicine. Here, we evaluate the use of microcapsules made of Biodritin®, a biocompatible polymer compound which contains sodium alginic acid, a natural polymer extracted from algae, and Cis-Chondroitin sulfate, a glycosaminoglycan from the extracellular matrix. Gelation of this polymer into microcapsules is achieved by dropping the compound into BaCl2 or CaCl2 gelling solutions. A functional microcapsule is dependent on its permeability, mechanical stability, immunoisolation capacity and biocompatibility. The mechanical stability of Biodritin-barium and Biodritin-calcium microcapsules was investigated after rotational stress upon in vitro culture and in vivo implantation. Viability studies of encapsulated cells were also performed to assess other functional parameters of the microcapsules. When subject to rotational stress, Biodritin-barium microcapsules exhibited breaks, whereas the Biodritin-calcium microcapsules did not. Both kinds of Biodritin® microcapsules proved to be mechanically resistant in in vitro and in vivo studies. However, the Biodritin-calcium material was found to be more elastic while the Biodritin-barium microcapsules displayed a more plastic behavior. These properties seem to be determinant for viability of the encapsulated cell’s, since the Biodritin-calcium microcapsules presented more viable cells than the Biodritin-barium microcapsules.

O tratamento do osso bovino com peróxidos e agentes caotrópicos visa à obtenção de uma matriz óssea acelular, com manutenção do complexo colágeno-apatita e maior resistência mecânica, denominada osso bovino misto (OBM). O objetivo desse estudo foi avaliar a citocompatitiblidade do osso bovino misto e a interação célula-OBM. Células Balb-c 3T3 foram tratadas com diferentes concentrações do extrato hidrossolúvel do OBM (0,1g por mililitro de meio de cultura sem soro). Foram avaliadas a morfologia e número de células, a capacidade de redução do metil tetrazol e a incorporação de vermelho neutro, de acordo com o padrão ISO 10993-5. A interação células-OBM foi estudada por microscopia eletrônica de varredura. Os extratos hidrosolúveis do OBM levaram à morte celular, possivelmente devido à redução da função mitocondrial e aumento da permeabilidade de membrana. Células plaqueadas diretamente sobre o OBM não sobreviveram. Entretanto, após diálise e condicionamento com DMEM +10% de soro fetal bovino, as células aderiram e proliferaram sobre o material. Com base nos resultados obtidos, concluiu-se que o OBM é citotóxico. A citotoxicidade foi revertida por diálise resultando em um material adequado para terapia celular no campo da bioengenharia.

Treatment of bovine bone with peroxides and chaotropic agents aims to obtain an acellular bone matrix that is able to maintain the collagen-apatite complex and a higher mechanical resistance, a mixed biomaterial hereby named mixed bovine bone (MBB). The purpose of this study was to evaluate the cytocompatibility of MBB and cell-MBB interaction. Cell morphology, number of viable cells, ability to reduce methyltetrazolium and to incorporate neutral red upon exposure to different concentrations of the hydrosoluble extract of MBB were assessed in Balb-c 3T3 cells according to ISO 10993-5 standard. The interaction between cells and MBB surface was evaluated by scanning electron microscopy. The water-soluble MBB extracts were cytotoxic and led to cell death possibly due to its effect on mitochondrial function and membrane permeability. Cells plated directly onto the MBB did not survive, although after dialysis and material conditioning in DMEM + 10% FCS, the cells adhered and proliferated onto the material. It may be concluded that, in vitro, water-soluble MBB extracts were cytotoxic. Nevertheless, MBB cytotoxic effect was reverted by dialysis resulting in a material that is suitable for cell based-therapy in the bioengineering field.