2002 Fiscal Year Final Research Report Summary
Intracellular control of transferrin-modified liposomes with Cholesteryl GALA for optimum drug delivery system
| Project/Area Number |
12470521
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
応用薬理学・医療系薬学
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
HIDEYOSHI Harashima Graduate School of Pharmaceutical Sciences, Professor, 大学院・薬学研究科, 教授 (00183567)
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| Co-Investigator(Kenkyū-buntansha) |
SABURO Sone UNIVERSITY OF TOKUSHIMA Dpartment of Medicine, Professor, 医学部, 教授 (40145024)
KAZUO Maruyama TEIKYO UNIVERSITY Dpartment of Pharmaceutical Sciences, Professor, 薬学部, 助教授 (30130040)
YASUYUKI Igarashi Graduate School of Pharmaceutical Sciences, Professor, 大学院・薬学研究科, 教授 (70091965)
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| Project Period (FY) |
2000 – 2002
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| Keywords | intracellular trafficking / transferrin liposomes / endocytosis / recycling / GALA |
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| Research Abstract |
Liposomes can be applied for selective cellular targeting system with introducing specific ligands. In most cases, liposomes follow intracellular pathways of receptor-ligand system and controlled intracelluar trafficking is required for optimized drug delivery system. In this study, we have succeeded to alter the intracellular fate of transferrin-modified liposomes by introducing pH-sensitive fusogenic peptide, GALA, and also analyzed endosomal release mechanism of liposomally encapsulated rhodamines. Transferrins were chemistry attached to liposomal surface (Tf-L), which were internalized via receptor-mediated endocytosis, although the rate of internalization was slow compared to free transferrins. Liposomally encapsulated rhodamines as well as liposomal surface attached transferris were shown to be kept in vesicular compartments by confocal laser microscopy. When cholesteryl-GALA(Chol-GALA) was introduced into liposomal membranes, rhodamines were released and diffused into cytosol, while free GALA in liposomes could not release it. These results clearly indicate that GALA should be fixed on the surface of liposomes to exert its function. To get further insight on endosomal escape mechanism, energy transfer was measured to evaluate the membrane fusion activity of Tf-L with Chol-GALA in the in vitro experiments. Remarkable pH-dependent energy transfer and large vesicle formation were observed, which supported the fusion hypothesis as an underlying endosomal release mechanism of Tf-L with Chol-GALA. In conclusion, Chol-GALA was shown to be a useful sorting device for controlling intracellular trafficking of liposomes after receptor-mediated endocytosis.
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