Abstract 731: Biophysical Properties of Nanofibrillar Scaffolds Modulate Endothelial Cell Survival in the Ischemic Hind Limb

Research Background and Objectives: Endothelial cells (ECs) are a promising cell type for the treatment of peripheral arterial disease (PAD). We previously showed that anisotropic nanofibrillar scaffolds augment the angiogenic function of ECs. Here we reported the effect of nanofibril size and crosslinking on EC survival and function to optimize the biophysical properties of scaffolds for treatment of PAD. Methods: Aligned nanofibrillar collagen scaffolds of varying fibril diameters and stiffness were prepared by altering the ionic strength (IS) of monomeric collagen and then crosslinked at varying levels of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC). Scaffolds were characterized for surface topography and nanofibril diameter by atomic force microscopy (AFM). Primary human ECs seeded onto the scaffolds were assessed for migration and survival under hypoxia. The regenerative potential of EC-seeded scaffolds was examined in a mouse hind limb ischemia (HLI) model. Results: Scaffold formulation with varying ionic strength (IS) resulted in different fibril diameter regardless of the degree of crosslinking ( Figure 1A: ~100 nm in low IS group vs. ~200 nm in high IS groups). When cultured under hypoxia, ECs seeded on high IS scaffold crosslinked by 1xEDC exhibited improved survival compared to those on low IS. Accordingly, the high IS 1xEDC scaffold was selectively tested in a mouse HLI model for cell survival and blood perfusion restoration. Bioluminescently-tagged ECs were seeded onto high IS 1xEDC scaffold or a randomly oriented fibrillar scaffold (20 mm of each). Non-invasive bioluminescence imaging for quantification of viable cells demonstrated markedly higher cell survival on aligned nanofibrillar scaffold than on randomly oriented scaffold ( Figure 1B, C ). Significance: Aligned nanofibrillar scaffolds that improve survival and angiogenesis of ECs provide a viable clinical strategy for the therapeutic neovascularization.