Effective uptake of N-acetylglucosamine-conjugated liposomes by cardiomyocytes in vitro

A drug delivery system (DDS) that targets the injured myocardium would serve as a novel therapeutic tool for cardiac diseases. To develop such a DDS, we investigated the interaction of 2 types of glycoside-conjugated liposomes containing a fluorescence substrate with cardiomyocytes. Flow cytometry revealed that cardiomyocytes adequately interact with N-acetylglucosamine-conjugated liposomes (GlcNAc-Ls). Furthermore, to confirm whether the agents encapsulated in GlcNAc-Ls affect the intracellular environment of cardiomyocytes, we prepared GlcNAc-Ls-containing pravastatin and examined the effect of pravastatin on cardiomyocytes. Pravastatin is a 3-hydroxy-3-methylglutaryl-CoA reductase inhibitor (statin) and is hydrophilic. It is reported that lipophilic statins enhance nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) expression by interieukin-1 beta (IL-1 beta)-stimulated cardiomyocytes. The hydrophilic nature of pravastatin prevents its entry into cardiomyocytes; therefore, it cannot enhance both these processes. Treatment with GlcNAc-Ls-containing pravastatin specifically enhanced NO production and iNOS expression by IL-1 beta-stimulated cardiomyocytes. Based on these results, we found that cardiomyocytes exhibit a high degree of interaction with GlcNAc-Ls, and GlcNAc-Ls-encapsulated agents can be effectively taken up by cardiomyocytes. We suggest that GlcNAc-Ls can be utilized therapeutically as a DDS for the injured myocardium. (C) 2007 Elsevier B.V. All rights reserved.