6-MONTH AUTO-IMPLANTATION OF AUTOLOGOUS TISSUE SMALL-CALIBER VASCULAR GRAFTS, "BIOTUBE", TO CAROTID ARTERIES OF BEAGLE DOGS

Objectives: We have reported that In vivo tissue-engineered autologous tubular tissues "BIOTUBEs" could be ideal small-caliber vascular grafts in animal experiments. They are constructed in the recipient bodies safely and economically without any use of special clean facilities. In this study, BIOTUBEs were auto-implanted to the carotid arteries of the beagle dogs, and histological change of BIOTUBEs after implantation was evaluated. Methods: Biotubes were prepared by placing silicone rods (outer diameter, 5.0mm; length 80mm) used as a mold into dorsal subcutaneous pouches in the beagle dogs for 4 weeks. The obtained BIOTUBEs after nonthrombogenic drug coating were auto-implanted into the carotid arteries of the same beagle dogs by end-to-side anastomosis using 6-0 nylon continuous suture. Graft status was evaluated by digital subtraction angiography. Histological evaluation was performed 3 and 6 months after implantation. Results: After a 4-week preparation in the subcutaneous tissues, the molds were completely covered with autologous connective tissues (thickness: ca. 0.1mm) mainly consisting of fibroblasts and collagen fibers. During 6-month implantation, neither formation of aneurysms nor rupturing was observed in BIOTUBEs. On the luminal surfaces, endothelial cells were covered partially in the vicinity of the anastomotic region of the grafts at 3 months after implantation. On the other hand, endothelial lining was formed completely at 6 months. Conclusions: BIOTUBEs could be used as small-caliber vascular prostheses that greatly facilitate the healing process and exhibit excellent biocompatibility in vascular regenerative medicine.