Figure 5
Histology of Fibrin only and 0.7 mg/ml collagen adventitia rings and vessels. (a) Collagen is present in H&E (pink), Masson’s Trichrome (blue/purple), and Picrosirius red (red) stains in ring cross-sections. Cell + collagen areas (black arrows) appears thicker and more dense in the 0.7 mg/ml COL rings compared to the Fibrin only rings. Additionally, collagen was present in the hydrogel on the periphery of the cellular region (Trichrome image, light blue arrow). Native human vein histological samples are shown for comparison; the adventitia layer is located on the outer edge of the native vein (white asterisk). The organization and density of the collagen in the engineered adventitia appears similar to that of the native vein. Engineered vessel scale bars = 200 µm. Native vein scale bars = 100 µm. (b) Longitudinal sections stained with H&E show the alternating organization of cells (blue arrows) and hydrogel along the ring stacked vessels in Fibrin only and 0.7 mg/ml COL vessels at 1 and 2 week culture times. Scale bars = 250 µm. (c) Masson’s Trichrome stain of a 3-ring stack of 0.7 mg/ml COL rings show the presence of (blue) collagen throughout the vessel. Scale bar = 1 cm. Collagen content quantification was performed using data from (d) Trichrome staining and (e) Picrosirius red staining. Collagen content was significantly higher in the 0.7 mg/ml COL rings compared to the Fibrin only rings (p < 0.0001). *Denotes statistical significance.
