The modulation of endothelial cell morphology, function, and survival using anisotropic nanofibrillar collagen scaffolds

Abstract

Endothelial cells (ECs) are aligned longitudinally under laminar flow, whereas they are polygonal and poorly aligned in regions of disturbed flow. The unaligned ECs in disturbed flow fields manifest altered function and reduced survival that promote lesion formation. We demonstrate that the alignment of the ECs may directly influence their biology, independent of fluid flow. We developed aligned nanofibrillar collagen scaffolds that mimic the structure of collagen bundles in blood vessels, and examined the effects of these materials on EC alignment, function, and in vivo survival. ECs cultured on 30-nm diameter aligned fibrils re-organized their F-actin along the nanofibril direction, and were 50% less adhesive for monocytes than the ECs grown on randomly oriented fibrils. After EC transplantation into both subcutaneous tissue and the ischemic hindlimb, EC viability was enhanced when ECs were cultured and implanted on aligned nanofibrillar scaffolds, in contrast to non-patterned scaffolds. ECs derived from human induced pluripotent stem cells and cultured on aligned scaffolds also persisted for over 28 days, as assessed by bioluminescence imaging, when implanted in ischemic tissue. By contrast, ECs implanted on scaffolds without nanopatterning generated no detectable bioluminescent signal by day 4 in either normal or ischemic tissues. We demonstrate that 30-nm aligned nanofibrillar collagen scaffolds guide cellular organization, modulate endothelial inflammatory response, and enhance cell survival after implantation in normal and ischemic tissues.

Microfibrous Scaffolds Enhance Endothelial Differentiation and Organization of Induced Pluripotent Stem Cells

“…24,43 The mechanism by which scaffold anisotropy modulates differentiation and cellular reorganization is not well-understood, but likely mediated by cell-ECM interactions. We previously showed that aligned nanofibrous scaffolds significantly upregulated the gene expression of integrin α1 subunit in primary human ECs, when compared to randomly oriented scaffolds Further work in this area will elucidate the signaling pathways by which anisotropic scaffolds modulate differentiation and cellular function.…”

Integrated Micro/Nanoengineered Functional Biomaterials for Cell Mechanics and Mechanobiology: A Materials Perspective

“…[65,70,71] In addition to electrospinning, microscale fibrous substrates with various levels of filament density and alignment have been successfully developed by utilizing shear flow deposition within a microfluidic channel, making it compatible with other microfluidic cell culture components and systems. [72,73] …”

Nanoscale Patterning of Extracellular Matrix Alters Endothelial Function under Shear Stress

“…1 In particular, the role of nanotopographical ECM organization on vascular endothelial cell (EC) structure and function is not well-understood, despite the presence of nano- to micro-scale fibrillar ECM networks within blood vessels. 2, 3 Although parallel-aligned (anisotropic) ECMs have been shown to direct cytoskeletal reorganization along the axis of patterning for numerous cell types, 4, 5 the physiological modulator of EC orientation is traditionally thought to be hemodynamic shear stress. 6, 7 In straight segments of vessels, the ECs that line the innermost layer morphologically are parallel-aligned along the direction of laminar blood flow.…”