Abstract 3957: RGDS-Epitope Presenting Peptide Amphiphile Nanofibers Enhance Regenerative Potency of Cell-based Strategies in Ischemic Tissue

Abstract

Cell-based therapies have emerged as a promising therapeutic option, however autologous approaches may be limited by the impaired potency of cells collected from patients with advanced vascular disease. Advances in bionanotechnology have led to the development of biomaterials that may offer solutions to overcome certain limitations and to enhance the therapeutic potency of cell-therapies. We evaluated a peptide amphiphile (PA) nanofiber that self-assembles 3-dimensionally, mimicing the extracellular matrix, and incorporates bioactive epitopes of interest. Based on the importance of fibronectin for endothelial progenitor cell (EPC) adhesion, motility and survival, the RGDS-epitope that functionally mimics the integrin-binding sequence of fibronectin was integrated for presentation (RGDS PA). For in vitro studies, EPCs were expanded from the bone marrow derived mononuclear cell fraction under endothelial culture conditions. Incubation with RGDS-PA (0.2w%) reduced H 2 O 2 induced apoptosis of EPCs significantly (0.20±0.02 TUNEL + /TUNEL − EPCs) compared to control cells without RGDS-PA (0.64±0.09, n= 5–7, P<0.01). RGDS-PA also induced proliferation of EPC in vitro (MTS assay; RGDS-PA 356±42% vs. 100% control, n= 5–9, P<0.01). Pre-incubation/Culture of EPCs with RGDS-PA led to an increase in adherent cells on uncoated (32±10 vs. 3±1, P<0.05), vitronectin (130±18 vs. 5±3, P<0.01) and fibronectin (109±12 vs. 39±2, P<0.05) coated but not on collagen coated surfaces compared to control cells. Hind-limb ischemia was surgically induced in 8 week-old, male FVB/N mice by complete ligation of the proximal femoral artery including all superficial and deep branches; postoperatively ischemia was verified by laser Doppler imaging. Suspension of subtherapeutic cell-doses in RGDS-PA solution for combined application enhanced recovery of laser Doppler-derived blood flow (ischemic vs. non-ischemic limb ratio: RGDS-PA 0.67±0.06 vs. saline 0.55±0.04) and reduced the amputation rate compared to cells alone at day 28 (amputation score: RGDS-PA 3.6±0.2 vs. saline 3.0±0.1; n=5– 8/group, P<0.05).In conclusion, the RGDS-epitope presenting PA nanofiber enhances survival, proliferation and adhesion of EPCs and augments potency for ischemic tissue repair.