Histological assessment demonstrated active vessel remodeling and neo-vessel formation at 12 months after Implantation.

<p>Histologic analysis of TEVG was performed by Hematoxylin and Eosin staining at 5x (top) and 20x (bottom). At 4 months, there is a thin endothelium and some cellular infiltration at the periphery of the TEVG. By 8 months, tissue ingrowth at the periphery has increased. By 12 months, tissue ingrowth has increased at the luminal and peripheral surfaces, with increasing cellularity within the graft. (n = 5 in each group.)</p

Expression of endothelial markers indicate functional endothelium in TEVG.

<p><b>A.</b> Whole mount staining of native aorta and TEVG. VE-cadherin is a marker of cellular borders of endothelial cells (green). Endothelial nitric oxide synthase (eNOS) is a marker of a functional endothelium (red). DAPI is a nuclear stain (blue). <b>B.</b> Real-time PCR analysis of ephrinB2 and eNOS. Ephrin-B2, a marker of arterial vessels. (n = 5–10 in each group)</p

Endothelialization and smooth muscle cell (SMC) differentiation in TEVG neotissue at 6 months.

TEVG ECs and SMCs were mature and well-organized, which reflected the native carotid artery (CA) in area, distribution, and density. Representative photomicrographs are shown for vWF (A, E), α- smooth muscle actin (SMA) (B, F), calponin (C, G), and myosin heavy chain (MHC) (D, H) for native CA (A-D) and nanofiber PCL/CS TEVGs (E-H). The scale bar represents a length of 20μm for A and E, and 100μm otherwise.</p

Expression of vascular cell markers in TEVG was similar to that of native aorta.

<p>A. Immuno-labeling of vascular cell markers on cross-sections of TEVG and native aorta. Left panel: von Willebrand factor (vWF, green), an endothelial cell marker and CD68 (red), a macrophage marker. Middle panel: CD31 (red), an endothelial cell marker; alpha-smooth muscle actin (α-SMA, green), a marker of smooth muscle cell and myofibroblasts. Right panel: CD31 (red) and collagen type I (Col-1, green). DAPI is for nucleus staining (blue). <b>B.</b> Immune-labeling of intracellular adhesion molecule (ICAM) as a marker of endothelial cells.</p

Preliminary study results.

<p>Representative Doppler ultrasound images of TEVGs at various time points showing graft patency <i>in vivo</i> (A). TEVG lumen diameter and wall thickness as measured by Doppler ultrasound (n = 3). Data in graphs are expressed as mean ± SD. *<i>P</i> <0.05. There was a statistically significant difference in both luminal diameter and wall thickness between TEVG and IAA at each time point. However, no statistically significant difference (NS) was found between all time points for either TEVG or native IAA (B).</p

Histological assessment of vascular neotissue formation at 6 months.

<p>The vascular neotissue including collagen and elastin deposition is similar to native carotid artery (CA) without ectopic calcification. Representative pictures are shown for H&E staining (A, E), Masson’s trichrome staining (B, F), Hart’s staining (C, G), and von Kossa staining (D, H). Native CA (A-D) is compared to nanofiber PCL/CS TEVGs (E-H). The scale bar represents a length of 1,000μm for A and E, and 100μm otherwise.</p

Lumen diameter and wall thickness analysis.

Histomorphometric comparison of the inner diameter (A) and wall thickness (B) between the nanofiber PCL/CS TEVGs and the native CA revealed no significant difference in the inner diameter and a significant difference in the wall thickness.</p

Mechanical properties.

<p>The burst pressure (A) and compliance (B) of the native CA, TEVG, and pre-operation/implantation were indicated respectively. There was no significant difference in burst pressure between the native CA and TEVG at 6 months. However, the TEVG at 6 months was significantly less compliant when compared to the native CA.</p

Luminal patency and laminar flow were similar between TEVG and native aorta over the course of the 12 month experiment.

<p><b>A</b>. Doppler ultrasound examinations were performed on tissue engineered vascular grafts from 2 weeks to 12 months after implantation. Doppler signals proximal to the graft, distal, and within the graft showed propagation of systemic arterial impulse through the graft. <b>B.</b><i>In vivo</i> microCTs were performed at 4, 8, and 12 months. Using image analysis software, luminal volume measurements were recorded and then standardized to a 3mm segment. <b>C. & D.</b> When compared to native Aorta in mice having undergone sham operation, there was no significant difference in luminal diameter between both groups and in ratio of TEVG to native aorta at any of the time points.</p

Characterization of Scaffolds.

Representative scanning electron microscopy of PCL/CS TEVGs prior to implantation at low powered (A) and high powered fields (B). Perioperative image of freshly implanted scaffold (C). In vitro degradation of PCL/CS measured by change in mass (D), change in strain at failure (E) and change in UTS (F) (n = 5).</p