Monday, 23 May 2005 - 10:45 AM

This presentation is part of: Nanoparticles, Microparticles and Vesicles

Degradable Polymersomes Foster Endosomal Release and Delivery of Cytotoxic Drugs to Cancer Cells

fariyal Ahmed, Goundla Srinivas, Michael L. Klein, and Dennis Discher. Univ. Pennsylvania, Philadelphia, PA

Carrier-mediated entry of cytotoxic drugs into a cell's cytoplasm is often limited by release from the carrier as well as endosomal release after internalization. Here we demonstrate by molecular simulation and experiment that degradable, non-ionic polymersomes of PEG-(polyester) foster endosome rupture and release of cytotoxic drugs doxorubicin (DOX) and paclitaxel (TAX). These drugs are typical soluble and insoluble anticancer agents. We characterize the stability, delivery and intracellular toxicity of DOX- and TAX-loaded nano-polymersomes with breast and lung cancer cell lines that take up the vesicles. While degradable polymersome formulations retain their load for over a month at 4C, they exhibit facilitated release at 37C and low pH. Copolymer degradation fosters endosomal escape through copolymer-induced disruption of the lipid membrane, enhancing intracellular drug release and cytotoxicity up to 40-fold relative to free drug. More generally, the results show that macro-surfactants, which are increasingly being applied, will interact with cell membranes.

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