Abstract 308: In Vivo Tissue-Engineered Autologous Small-Caliber Vascular Grafts “Biotubes”: Autonomical Regeneration To The Structural Vessel Wall After Implantation
Introduction: We have developed functional autologous tubular tissues “BIOTUBEs” as small-caliber vascular grafts, which were constructed by in vivo tissue-engineering. In this study, they were practically auto-implanted to the animals.
Methods: Both ends of silicone rods (diameter: 2mm, length: 20mm) were covered with short (3mm) polyurethane sponge tubes as “anastomotic reinforcement cuffs”. They were placed in dorsal subcutaneous pouches of Japanese White rabbits for 1 month. BIOTUBEs formed around the scaffolds were bilaterally auto-implanted to the carotid arteries and were morphologically investigated.
Results: The obtained BIOTUBEs had homogeneous thin (0.1mm) connective tissue walls primarily consisting of collagen and fibroblasts, high burst strength (ca. 1000mmHg), and equivalent compliance to that of native arteries. Reinforcement cuffs enabled easy end-to-end anastomosis. After 4-week implantation, all grafts were patent. Up to 3 months, neither aneurysm formation nor rupturing was observed (Fig. C⇓). Little thrombus formed on the luminal surfaces (Fig. A⇓) completely covered with endothelial cells regularly aligned longitudinally (Fig. B⇓). Regenerated BIOTUBE walls consisted of multilayered spindle smooth muscle cells and dense collagen fibers with regular circumferential orientation (Fig.D⇓), where elastin fragments began to emerge just comparable to native arteries.
Conclusions: BIOTUBEs were prepared very easily and safely without any use of clean special facilities or complex cell managements, both of which are expensive and time consuming. They can be practical vascular grafts with the diameter less than 2mm.