Abstract 4931: RGDS-Epitope Presenting Peptide Amphiphile Nanofibers Enhance Therapeutic Potency of Cell-based Strategies in Ischemic Tissue

Abstract

Cell-based therapies have emerged as a promising option in ischemic tissue repair. Impaired viability and retention of injected cells in the ischemic target zone and reduced biopotency of autologous cells from pts with advanced disease remain significant challenges. Advances in bionanotechnology have led to development of biomaterials that may offer solutions to overcome limitations and to enhance the efficacy of cell therapy by modulating the microenvironment. Interaction with fibronectin (FN) has been shown to effect cell survival, adhesion and motility. We developed a self-assembling peptide amphiphile (PA) nanofiber that presents the binding domain epitope of FN, Arg-Gly-Asp-Ser (RGDS). Incubation of BM-derived pro-angiogenic cells (BMPAC) with this RGDS-PA (0.2w%) reduced H 2 O 2 -induced apoptosis (0.22±0.02 TUNEL + /TUNEL − cells) compared to cells without RGDS-PA (0.60±0.07, n=5–10, P<0.01). In addition, RGDS-PA increased proliferation (MTS assay; RGDS-PA 174±30% vs. 100% control, n=7–12, P<0.01), adhesion to uncoated (185±95 vs. 59±25, P<0.05) and vitronectin (201±84 vs. 53±26, P<0.05) surfaces. Tube formation (matrigel assay) and migration (Boyden chamber), endpoints that integrate several cell functions, were enhanced and impaired respectively. Local injection of RGDS-PA combined with a sub-therapeutic dose of BMPAC (10 5 ) (R+B) vs. BMPAC alone (B) 3 days after surgical hind-limb ischemia (HLI) in 8-week-old, male FVB/N mice, improved blood flow recovery (laser Doppler, ischemic/non-ischemic limb ratio: R+B, 0.67±0.06; B, 0.55±0.04), limb salvage (score: R+B, 3.4±0.3; B 2.9±0.4; n=8 –9/group, P<0.05), and motor function of the ischemic limb (score: R+B, 3.6±0.2; B, 2.9±0.2; n=8 –9/group, P<0.05) at day 28. Viablity tracking with β -actin-luc + cells revealed higher bioluminescent signals, reflecting more viable cells at day 7 (R+B, 692±141%; B, 132±50%; n=7–9/group, p<0.01). These findings correspond with incr CD31 + capillaries in the ischemic limb muscle at day 28 (Tx: 56±2/hpf; R+B: 91±5/hpf; B: 72±2/hpf; n=5–9/group, p<0.001). Conclusion : RGDS-PA nanofibers enhance functionality of BMPAC and thereby augment potency of cell-based therapies in ischemic tissue repair. This research has received full or partial funding support from the American Heart Association, Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota & Wisconsin).