Multitargeting Peptide-Functionalized Star-Shaped Copolymers with Comblike Structure and a POSS-Core To Effectively Transfect Endothelial Cells

Gene therapy meets one serious bottleneck in clinical application, namely, lack of safe and efficient gene delivery systems. In order to solve this problem, we designed a lowly cytotoxic and highly efficient gene delivery system for the transfection of endothelial cells. Octa(3-ammoniumpropyl)octasilsesquioxane octachloride reacted with 2-bromoisobutyryl bromide under alkaline condition, and sequentially initiated 2-(dimethylamino)ethyl methacrylate (DMAEMA) and poly(ethylene glycol) monomethacrylate (PEGMA) via atom transfer radical polymerization (ATRP) to prepare the eight-arm copolymer with a biocompatible polyhedral oligomericsilsesquioxane (POSS). The side chain ends of the comblike PPEGMA were double-bonded to facilitate the attachment of CAGW or CAG-TAT-NLS functional peptide, thereby enabling the star-shaped copolymers with multifunction. The peptide-functionalized star-shaped copolymers were self-assembled into nanoparticles (NPs) and used to condense pEGFP-ZNF580 (pDNA) to prepare the NPs/pDNA complexes. These complexes had low toxicity as confirmed by MTT. The results of fluorescence microscopy and flow cytometry showed that these multitargeting functionalized gene complexes could effectively transfect endothelial cells. Their transfection efficiency is higher than the positive control PEI 25 kDa group. Moreover, the Western blot test, wound healing assay, and in vitro tube formation assay also demonstrated that the transfected cells showed high migration and enhanced angiogenesis. The pDNA was effective delivered and expressed in endothelial cells by these multitargeting functionalized gene complexes, and promoted cell migration and tube formation. These star-shaped copolymers with comblike structure and a POSS core are a potential gene carrier for gene therapy.