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Background: The extracellular matrix (ECM) is a critical determinant of neovessel integrity. Materials and Methods: Thirty-six (polyglycolic acid + polycaprolactone and poly lactic acid) tissue-engineered vascular grafts seeded with syngeneic bone marrow mononuclear cells were implanted as inferior vena cava interposition grafts in C57BL/6 mice. Specimens were characterized using immunohistochemical staining and qPCR for representative ECM components in addition to matrix metalloproteinases (MMPs). Total collagen, elastin, and glycosaminoglycan (GAG) contents were determined. MMP activity was measured using zymography. Results: Collagen production on histology demonstrated an initial increase in type III at 1 week followed by type I production at 2 weeks and type IV at 4 weeks. Gene expression of both type I and type III peaked at 2 weeks, whereas type IV continued to increase over the 4-week period. Histology demonstrated fibrillin-1 deposition at 1 week followed by elastin production at 4 weeks. Elastin gene expression significantly increased at 4 weeks, whereas fibrillin-1 decreased at 4 weeks. GAG demonstrated abundant production at each time point on histology. Gene expression of decorin significantly increased at 4 weeks, whereas versican decreased over time. Biochemical analysis showed that total collagen production was greatest at 2 weeks, and there was a significant increase in elastin and GAG production at 4 weeks. Histological characterization of MMPs showed abundant production of MMP-2 at each time point, while MMP-9 decreased over the 4-week period. Gene expression of MMP-2 significantly increased at 4 weeks, whereas MMP-9 significantly decreased at 4 weeks. Conclusions: ECM production during neovessel formation is characterized by early ECM deposition followed by extensive remodeling.

A new, simple method of producing optimal cuffs using thin paper and then setting it in resin for vascular reconstruction in canine liver transplantation is herein described. Thin Paper was cut into a paper tape strip. By fixing both ends of this paper tape, a cylinder paper core of any desired size could thus be obtained. The paper core was immersed into a two-liquid mixture-type resin, removed, and left to harden. The paper cuffs (0.2 mm or less in thickness) were then used for anastomoses of the portal vein and the infrahepatic inferior vena cava in a series of 10 consecutive canine liver transplantations. Out of 10 animals, 8 survived for more than 5 days. The vascular patency in these 8 animals at the cuff anastomotic sites was 100% at postmortem. We therefore conclude that this paper cuff appears to be useful for various types of experimental liver transplantations in large animals.