Made available in DSpace on 2014-12-17T14:05:18Z (GMT). No. of bitstreams: 1 LourenaMF_TESE_Capa_ate_pag79.pdf: 4572586 bytes, checksum: 2630047160ff526cc964f166fb86ab33 (MD5) Previous issue date: 2011-03-14 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Gene therapy is one of the major challenges of the post-genomic research and it is based on the transfer of genetic material into a cell, tissue or organ in order to cure or improve the patient s clinical status. In general, gene therapy consists in the insertion of functional genes aiming substitute, complement or inhibit defective genes. The achievement of a foreigner DNA expression into a population of cells requires its transfer to the target. Therefore, a key issue is to create systems, vectors, able to transfer and protect the DNA until it reaches the target. The disadvantages related to the use of viral vectors have encouraged efforts to develop emulsions as non-viral vectors. In fact, they are easy to produce, present suitable stability and enable transfection. The aim of this work was to evaluate two different non-viral vectors, cationic liposomes and nanoemulsions, and the possibility of their use in gene therapy. For the two systems, cationic lipids and helper lipids were used. Nanoemulsions were prepared using sonication method and were composed of Captex? 355; Tween? 80; Spam? 80; cationic lipid, Stearylamine (SA) or 1,2-dioleoyl-3-trimethylammoniumpropane (DOTAP) and water (Milli-Q?). These systems were characterized by average droplet size, Polidispersion Index (PI) and Zeta Potential. The stability of the systems; as well as the DNA compaction capacity; their cytotoxicity and the cytotoxicity of the isolated components; and their transfection capacity; were also evaluated. Liposomes were made by hydration film method and were composed of DOTAP; 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), containing or not Rhodaminephosphatidylethanolamine (PE- Rhodamine) and the conjugate Hyaluronic Acid DOPE (HA-DOPE). These systems were also characterized as nanoemulsions. Stability of the systems and the influence of time, size of plasmid and presence or absence of endotoxin in the formation of lipoplexes were also analyzed. Besides, the ophthalmic biodistribution of PE-Rhodamine containing liposomes was studied after intravitreal injection. The obtained results show that these systems are promising non-viral vector for further utilization in gene therapy and that this field seems to be very important in the clinical practice in this century. However, from the possibility to the practice, there is still a long way / A terapia g?nica ? um dos maiores desafios propostos pela pesquisa p?s-gen?mica e se baseia na transfer?ncia de material gen?tico a uma c?lula, tecido ou ?rg?o com o intuito de curar ou melhorar o estado cl?nico do paciente. Em sua forma mais simples, a terapia g?nica consiste na inser??o de genes funcionais em c?lulas com genes defeituosos objetivando substituir, complementar ou inibir esses genes causadores de doen?as. Para que o DNA ex?geno seja expresso em uma popula??o celular faz-se necess?ria a sua transfer?ncia at? o local de a??o. Assim, ? necess?rio criar ve?culos, que transportem e protejam o DNA at? que este chegue a uma popula??o celular alvo. Os obst?culos encontrados com a utiliza??o de vetores virais t?m proporcionado o interesse no desenvolvimento de vetores n?o-virais, por serem f?ceis de produzir, apresentarem estabilidade control?vel e facilitarem a transfec??o g?nica. O objetivo deste trabalho foi avaliar dois diferentes vetores n?o virais, lipossomas e nanoemuls?es cati?nicos, e sua poss?vel utiliza??o na terapia g?nica. Para isso, foram utilizados lip?deos cati?nicos e co-tensoativos na produ??o dos dois sistemas. As nanoemuls?es foram produzidas pelo m?todo de sonica??o e compostas por Captex? 355; Tween? 80; Spam? 80; lip?deo cati?nico, Estearilamina (EA) ou N-[1-(2,3-Dioleoiloxi)propil]-N,N,Ntrimetilamonio metilsulfato (DOTAP); e ?gua ultra-pura (Milli-Q?). Estes sistemas foram caracterizados quanto ao tamanho m?dio de got?cula, ?ndice de polidispers?o (PI) e potencial zeta. Avaliou-se ainda a estabilidade dos sistemas e suas capacidades de compacta??o do material gen?tico. Os lipossomas foram preparados a partir do m?todo de hidrata??o do filme e compostos por DOTAP, Dioleilfosfatidiletanolamina (DOPE), na presen?a ou aus?ncia de Rodaminafosfatidiletanolamina (PE-Rodamina) e do conjugado ?cido Hialur?nico DOPE (HA-DOPE). Estes sistemas foram caracterizados da mesma forma que as nanoemuls?es e tamb?m foram avaliados estabilidade, influ?ncia do tempo, tamanho de material gen?tico e presen?a ou aus?ncia de endotoxinas na forma??o dos lipoplexos. Os resultados obtidos permitem afirmar que os sistemas s?o promissores para posterior utiliza??o na terapia g?nica e que esta ?rea promete ser uma ?rea f?rtil de pesquisa cient?fica e cl?nica por muitos anos, e provavelmente se tornar? uma pr?tica cl?nica importante neste s?culo. No entanto, da possibilidade ? pr?tica existe um longo caminho a percorrer