RESUMO
Factors affecting multilamellar vesicles transport to the blood compartment after oral administration to rats were evaluated first in vitro. A high entrapment of protein A was obtained when the vesicles were prepared by shearing a lyotropic lamellar phase composed of soybean phosphatidylcholine, cholesterol and polyoxyethylene alcohol (C12H25(OCH2CH2)4OH) as neutral detergent. In vitro tests showed that these vesicles (spherulites) were stabled in 50% of fetal calf serum, in acidic (pH 3) or basic (pH 10) buffers, in pancreatin but are partially lysed in 20mM bile salts. Oral administration of spherulites entrapping 111In-NTA in fasting rats showed a increase of radioacticivity in blood. This could be explained by passage of some spherulites in the enterocytes.
Assuntos
Lipossomos/metabolismo , Proteína Estafilocócica A/administração & dosagem , Administração Oral , Animais , Ácidos e Sais Biliares/farmacologia , Colesterol/química , Colesterol/metabolismo , Sistema Digestório/metabolismo , Portadores de Fármacos , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Radioisótopos de Índio/administração & dosagem , Radioisótopos de Índio/metabolismo , Absorção Intestinal , Lipossomos/química , Masculino , Pancreatina/farmacologia , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Polietilenoglicóis/química , Polietilenoglicóis/metabolismo , Ratos , Proteína Estafilocócica A/metabolismo , Estresse MecânicoRESUMO
Concentric multilamellar microvesicles, named spherulites(TM), were evaluated as an oligonucleotide carrier. Up to 80% oligonucleotide was encapsulated in these vesicles. The study was carried out on two different spherulite(TM) formulations. The spherulite(TM) size and stability characteristics are presented. Delivery of encapsulated oligonucleotide was performed on a rat hepatocarcinoma and on a lymphoblastoid T cell line, both expressing the luciferase gene. We showed that spherulites(TM) were able to transfect both adherent and suspension cell lines and deliver the oligonucleotide to the nucleus. Moreover, 48-62% luciferase inhibition was obtained in the rat hepatocarcinoma cell line when the antisense oligonucleotide targeted to the luciferase coding region was encapsulated at 500 nM concentration in spherulites(TM) of different compositions.
Assuntos
Portadores de Fármacos , Oligodesoxirribonucleotídeos Antissenso/administração & dosagem , Transfecção/métodos , Animais , Sequência de Bases , Linhagem Celular , Genes Reporter , Proteínas de Fluorescência Verde , Neoplasias Hepáticas Experimentais , Proteínas Luminescentes/análise , Proteínas Luminescentes/genética , Oligodesoxirribonucleotídeos , Oligodesoxirribonucleotídeos Antissenso/farmacologia , Oligorribonucleotídeos , Ratos , Proteínas Recombinantes/análise , Linfócitos T , Células Tumorais CultivadasRESUMO
Encapsulation of DNA in a new non-cationic multilamellar vector (Spherulites), composed of phosphatidylcholine, cholesterol and polyoxyethylene alcohol, is described here for the first time. Spherulites entrapping DNA were prepared by shearing a phospholipid lyotropic lamellar phase, using a recently discovered method. The average diameter of these vesicles ranges around 300 nm, and can be adjusted depending on the conditions of the process. The formulation did not result in cytotoxicity for the human cells and could be used as a DNA delivery system. More emphasis is brought to the role of condensing agents like histones on the encapsulation yield, which has been studied using radiolabelled DNA. It is shown that use of histones (histone to DNA ratio of 0.4) can increase significantly the encapsulation of DNA, thus improving the transfection efficiency. Transfection experiments were done with success using the beta-galactoside reporter gene on human primary cells (human skin fibroblasts and human bone marrow stromal cells). The results suggest that the spherulites have to be considered as a new and promising tool for gene transfection.
