Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves [166]-172. / xi, 172 l illus., tables

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-04T21:15:20Z No. of bitstreams: 1 AngelicaFernandesGurgelDeSousa_DISSERT.pdf: 4154120 bytes, checksum: 9b7e3179ef04b1aafa2fdd770a6124d4 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-08T23:03:33Z (GMT) No. of bitstreams: 1 AngelicaFernandesGurgelDeSousa_DISSERT.pdf: 4154120 bytes, checksum: 9b7e3179ef04b1aafa2fdd770a6124d4 (MD5) / Made available in DSpace on 2017-12-08T23:03:33Z (GMT). No. of bitstreams: 1 AngelicaFernandesGurgelDeSousa_DISSERT.pdf: 4154120 bytes, checksum: 9b7e3179ef04b1aafa2fdd770a6124d4 (MD5) Previous issue date: 2017-05-26 / Os problemas relacionados com defeitos ?sseos continuam a motivar a busca de terapias mais eficazes. Assim, a combina??o de biomateriais, c?lulas-tronco e mol?culas bioativas fazem parte das ferramentas usadas pela medicina regenerativa para alcan?ar esse objetivo. Diversos estudos j? mostraram o potencial osteog?nico dos polissacar?deos sulfatados (PSs) extra?dos de macroalgas marinhas. Entre eles, o fucoidan, isolado da alga marrom Fucus vesiculosus, ? o mais estudado, sendo j? comercializado por algumas empresas. As algas verdes tamb?m s?o fonte de PSs, mas estas s?o ainda pouco exploradas para aplica??es na regenera??o ?ssea. Em geral, as aplica??es cl?nicas dos PSs extra?dos de algas ainda s?o limitadas devido ? escassez de estudos sobre os seus efeitos, como por exemplo, o potencial genot?xico ? desconhecido na maioria dos casos. Assim, neste trabalho avaliamos a atividade osteog?nica 1) do Fucoidan de F. vesiculosus (um extrato comercializado pela Sigma), 2) das amostras ricas em PSs obtidas do subfracionamento do fucoidan comercial, e 3) do extrato rico em PSs extra?dos da alga verde Caulerpa sertularioides usando como modelo c?lulas-tronco humanas isoladas da geleia de Wharton de cord?es umbilicais (CTMH-GW). Estudou-se tamb?m o potencial genot?xico dos extratos totais de F. vesiculosus e C. sertularioides e posteriormente, da subfra??o do fucoidan que apresentou maior potencial osteog?nico, utilizando do ensaio de micron?cleo com bloqueio da citocinese (CBMN) na linhagem CHO-K1. Os ensaios de redu??o do MTT evidenciaram que as amostras ricas em PSs n?o apresentaram citotoxicidade significativa ao longo de 72 h, at? 10 ?g.mL-1. Os ensaios de atividade da fosfatase alcalina (ALP) e de mineraliza??o sugerem que as amostras ricas em PSs possuem atividades osteog?nicas diferentes: a subfra??o do fucoidan FUC 0.5 (5 ?g.mL-1) foi a que apresentou melhor resultado, aumentando 124% a atividade da ALP em rela??o ao controle positivo (c?lulas mantidas em meio osteog?nico). J? o extrato total de C. sertularioides (5 ?g.mL-1) aumentou 192% a atividade da ALP. Adicionalmente, todas as amostras testadas induziram o ac?mulo de c?lcio na matriz extracelular. Quanto ? genotoxicidade, os resultados do ensaio CBMN sugerem que, nas condi??es testadas, estas amostras n?o s?o genot?xicas, indicando que podem ser uma alternativa para terapias de regenera??o ?ssea. / Problems related with bone defects continue to motivate the search for more effective therapies. Thus, the combination of biomaterials, stem cells and bioactive molecules is part of the tools used by regenerative medicine to achieve this goal. Several studies have already shown the osteogenic potential of sulfated polysaccharides (SPs) extracted from marine macroalgae. Among them, fucoidan, isolated from brown algae Fucus vesiculosus, is the most studied, and is already commercialized by some companies. Green algae are also a source of SPs, but these are even more unexploited in the scope of bone regeneration. In general, the clinical applications of SPs from algae are very limited, because studies on their effects are scarce, for example, their genotoxic effects are unknown in most cases. Thus, in this work, we evaluated the osteogenic activity of Fucoidan from F. vesiculosus (an extract commercialized by Sigma), 2) SPs-rich samples obtained from subfractionation of commercial fucoidan, and 3) SPs-enriched extract from green algae Caulerpa Sertularioides, using human mesenchymal stem cells isolated from the Wharton jelly of umbilical cords (CTMH-GW) as cell model. It was also studied the genotoxic potential of the total extracts of F. vesiculosus and C. sertularioides, using the cytokinesis block micronucleus assay (CBMN) in the line CHO-K1. The genotoxicity of fucoidan?s subfraction that presented greater osteogenic potential was also evaluated. The MTT reduction assays showed that SPs-enriched samples did not show significant cytotoxicity over 72 h, up to 10 ?g.mL-1. Alkaline phosphatase (ALP) activity and mineralization assays suggest that SPs-enriched samples have different osteogenic activities: fucoidan subfraction FUC 0.5 (5 ?g.mL-1) showed the best result, increasing 124% the ALP activity in relation to the positive control (cells maintained in osteogenic medium). The total extract of C. sertularioides (5 ?g.mL-1) increased the ALP activity by 192%. In addition, all samples tested induced calcium accumulation in the extracellular matrix. Concerning to genotoxicity, CBMN assay results suggest that, under the tested conditions, these samples are not genotoxic, indicating their potential as alternative bone regeneration therapy.