Selective targeting of gene transfer to vascular endothelial cells by use of peptides isolated by phage display

Background-Gene transfer to vascular cells is a highly inefficient and nons elective process, defined by the lack of specific cell-surface receptors fo r both nonviral and viral gene delivery vectors. Methods and Results-We used filamentous phage display to isolate a panel of peptides that have the ability to bind selectively and efficiently to quie scent human umbilical vein endothelial cells (HUVECs) with reduced or negli gible binding to nonendothelial cells, including vascular smooth muscle cel ls and hepatocytes. By direct biopanning on HUVECs and a second approach in volving preclearing steps before panning on HUVECs, we isolated and sequenc ed 140 individual phages and identified 59 peptides, We selected 7 candidat es for further investigation by secondary screening of homogeneous phages o n a panel of cell types. Using adenovirus-mediated gene transfer as a model gene delivery system, we cloned the peptide SIGYPLP and the positive contr ol peptide KKKKKKK upstream of the S11e single-chain Fv (" adenobody") dire cted against the knob domain of the adenovirus to create fusion proteins. A denovirus-mediated gene transfer via fiber-dependent infection was blocked with S11e, whereas inclusion of the KKKKKKK peptide retargeted gene transfe r. The peptide SIGYPLP, however, retargeted gene delivery specifically to e ndothelial cells with a significantly enhanced efficiency over nontargeted adenovirus and without transduction of nontarget cells. Conclusions-Our study demonstrates the feasibility of using small, novel pe ptides isolated via phage display to target gene delivery specifically and efficiently to HUVECs and highlights their use for retargeting both viral a nd nonviral gene transfer to vascular endothelial cells for future clinical applications.