Vascular lumen preservation and optimization for in vivo-like peripheral vasculature dimensions in histology for proper preclinical peripheral, non-permanent scaffold, device evaluation

Abstract

At necropsy, following harvesting, arterial segments experience pronounced radial and longitudinal recoil. We aim to establish an innovative methodology with the intent of preserving the in vivo vascular dimensions in histology. Peripheral arteries of seven Yucatan naïve swine were evaluated. Arteries were flushed and pressure fixated. While still in situ, some vessels were infused with a polymeric-based vascular intraluminar support. Vessels were evaluated by histology and histomorphometry and compared to equivalent angiographic data. Following randomization, 10 arteries were fixed with 10%NBF (unsupported intraluminal vasculature, UIV) and 18 arteries were preserved with the vascular intraluminal support (VIS). When VIS was utilized (external iliac artery [EIA] = 3.77 ± 0.61 mm; superficial femoral artery [SFA] = 3.3 ± 1.26 mm), the lumen diameters were preserved compared to angiography (EIA = 4.87 ± 0.46 mm; SFA = 3.63 ± 0.34 mm). UIV SFAs showed a significant decrease (EIA = 2.07 ± 0.56 mm; SFA = 1.94 ± 0.36 mm). Histomorphometry showed a reduction in lumen area of iliac (VIS = 11.49 ± 3.5 mm2; UIV = 3.83 ± 1.6 mm2) and SFA (VIS = 6.99 ± 1.8 mm2; UIV = 3.09 ± 1.2 mm2). Vessel area followed the same pattern (EIA [VIS = 12.94 ± 3.6 mm2; UIV = 5.92 ± 1.5 mm2]; SFA [VIS = 8.06 ± 1.9 mm2; UIV = 4.83 ± 1.1 mm2]). In the absence of VIS, both EIA and SFA showed an artificially thicker vascular wall (EIA = 249.18 ± 87.7 μm; SFA = 243.15 ± 87.7 μm) compared to VIS group (EIA = 117.46 ± 25.2 μm; SFA = 108.75 ± 20.6 μm). UIV displayed the prototypical features, such as collapse profile, ‘zig-zags’ internal elastic lamina (IEL) pattern, thick media, and is thick and corrugated external elastic lamina (EEL). In contrast, VIS showed a circular profile, stretched and curvilinear IEL and EEL, thin media layer, with concentrically layered streams of smooth muscle cells. Both groups had a continuous and confluent endothelium. We conclude that in relevant preclinical studies where luminal support is lacking, it is of paramount importance to implement this novel histology paradigm.