Branched oligomerization of cell-permeable peptides markedly enhances the transduction efficiency of adenovirus into mesenchymal stem cells

Cell-permeable peptides (CPPs) promote the transduction of nonpermissive cells by recombinant adenovirus (rAd) to improve the therapeutic efficacy of rAd. In this study, branched oligomerization of CPPs significantly enhanced the transduction of human mesenchymal stem cells (MSCs) by rAd in a CPP type-independent manner. In particular, tetrameric CPPs increased transduction efficiency at 3000-5000-fold lower concentrations than did monomeric CPPs. Although branched oligomerization of CPPs also increases cytotoxicity, optimal concentrations of tetrameric CPPs required for maximum transduction are at least 300-1000-fold lower than those causing 50% cytotoxicity. Furthermore, although only similar to 60% of MSCs were maximally transduced at 500 mM of monomeric CPPs, >95% of MSCs were transduced with 0.1 mM of tetrameric CPPs. Tetrameric CPPs also significantly increased the formation and net surface charge of CPP/rAd complexes, as well as the binding of rAd to cell membranes at a greater degree than did monomeric CPPs, followed by rapid internalization into MSCs. In a critical-size calvarial defect model, the inclusion of tetrameric CPPs in ex vivo transduction of rAd expressing bone morphogenetic protein 2 into MSCs promoted highly mineralized bone formation. In addition, MSCs that were transduced with rAd expressing brain-derived neurotrophic factor in the presence of tetrameric CPPs improved functional recovery in a spinal cord injury model. These results demonstrated the potential for tetrameric CPPs to provide an innovative tool for MSC-based gene therapy and for in vitro gene delivery to MSCs. Gene Therapy (2010) 17, 1052-1061; doi: 10.1038/gt.2010.58; published online 20 May 2010We thank Mun-Young Lee in the Catholic University of Korea for advising histological analysis, Yoon-Sun Yang in Medipost Co. for the human UCB-MSC, Sang-Chun Lee and Kwan Seok Lee in POSTECH for devoted animal care, as well as Hong-Hwa Jun in Genexine Co. for the technical assistance. This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST). (No. M10534050001-08N3405-00110) and by a grant from National R&D Program for Cancer Control, Ministry of Health and Welfare, Republic of Korea (0820040) and by a grant from Biod, Korea