Enhancing gene delivery of adeno-associated viruses by cell-permeable peptides

Yarong Liu,Young Joo Kim,Man Ji,Jinxu Fang,Natnaree Siriwon,Li I Zhang,Pin Wang

doi:10.1038/mtm.2013.12

Abstract

Adeno-associated virus type 2 (AAV2) is considered a promising gene delivery vector and has been extensively applied in several disease models; however, inefficient transduction in various cells and tissues has limited its widespread application in many areas of gene therapy. In this study, we have developed a general, but efficient, strategy to enhance viral transduction, both in vitro and in vivo, by incubating viral particles with cell-permeable peptides (CPPs). We show that CPPs increase internalization of viral particles into cells by facilitating both energy-independent and energy-dependent endocytosis. Moreover, CPPs can significantly enhance the endosomal escape process of viral particles, thus enhancing viral transduction to those cells that have exhibited very low permissiveness to AAV2 infection as a result of impaired intracellular viral processing. We also demonstrated that this approach could be applicable to other AAV serotypes. Thus, the membrane-penetrating ability of CPPs enables us to generate an efficient method for enhanced gene delivery of AAV vectors, potentially facilitating its applicability to human gene therapy.

Highlights

Adeno-associated virus type 2 (AAV2), a relatively well-characterized AAV serotype, has been evaluated in gene therapy clinical trials owing to its ability to establish long-term gene expression in both dividing and nondividing cells without known pathological consequences of infection.[1,2,3,4] the transduction of AAV2 is inefficient in a number of nonpermissive cell types,[5,6,7,8] limiting its application in many areas of gene therapy
Each of these cell-permeable peptides (CPPs) was incubated with an AAV2 vector encoding green fluorescent protein (GFP), and GFP expression was assayed after infection of HEK293T cells
Many efforts have been made to improve the efficacy of AAV2mediated gene transfer in cells, especially in nonpermissive cells, by increasing the internalization and endosomal escape process of viral particles

Summary

Introduction

Adeno-associated virus type 2 (AAV2), a relatively well-characterized AAV serotype, has been evaluated in gene therapy clinical trials owing to its ability to establish long-term gene expression in both dividing and nondividing cells without known pathological consequences of infection.[1,2,3,4] the transduction of AAV2 is inefficient in a number of nonpermissive cell types,[5,6,7,8] limiting its application in many areas of gene therapy. Low expression of receptors and/or coreceptors on the cell surface of nonpermissive cells prevents binding of the viral vector to the cell surface.[9,10,11] Second, after binding of viral vectors to the cell surfaces and successful internalization, an impairment occurs in the multistep intracellular trafficking process of AAV2.8 A novel method of enhancing AAV2 infection could overcome these obstacles, thereby expanding the utility of AAV2 vectors in gene therapy. Insertion of targeting peptides into capsid proteins of vectors enables AAV2 to bind and internalize into nonpermissive cells via alternative receptors/coreceptors.[12,13,14] this type of capsid modification could result in low production yield, reduction of vector titer, or inefficient DNA packaging.[12,15] An alternative way to increase cell-surface interactions of viral particles may be through cell-permeable peptides (CPPs). Arginine-rich and histidine-rich peptides have displayed the ability to disrupt the endosomal membrane via a buffering effect within the acidic endosomal environment.[23,24,25] CPPs could enhance AAV2-mediated transduction in various cell types for gene delivery to target cells and overcome the obstacles noted above

Methods

Results

Conclusion