A mold for the preparation of an in-body tissue architecture-induced autologous vascular graft, termed "biotube," was prepared by covering a main silicone rod (outer diameter, 3 mm; length, 30 mm) with two pieces of polyurethane sponge tubes (internal diameter, 3 mm; length, 3 mm) at both ends. The molds were embedded into the dorsal subcutaneous pouch of rabbits (weighing ca. 2 kg) for 2 months. After harvesting the rods with the formed surrounding tissues, the rods were removed to create biotubes impregnated with anastomotic reinforcement cuffs at both ends. The biotubes had homogeneous, thin connective tissue wall (thickness, 76 ± 37 μm) that was primarily composed of collagen and fibroblasts. One biotube was loaded with argatroban and autoimplanted in the carotid artery for 26 months. Neither antiplatelet nor anticoagulant agents were administered, except for an intraoperative heparin injection. Follow-up angiography showed no aneurysm formation, rupturing, or stenosis during implantation. At the end of implantation, the wall thickness of biotube (212 ± 24 μm at the anastomosis portion and 150 ± 14 μm at the midportion) was similar to that of native artery (189 ± 23 μm). The luminal surface was completely covered with endothelial cells on the formed lamina elastica interna-like layer. The regenerated vascular walls comprised multilayered smooth muscle cells and dense collagen fibers with regular circumferential orientation. A remarkable multilayered elastin fiber network was observed near the anastomosis portion. Biotubes could thus be used as small-caliber vascular prostheses that greatly facilitate the healing process and exhibit excellent biocompatibility.
Background-We developed autologous prosthetic implants by simple and safe in-body tissue architecture technology. We present the first report on the development of autologous valved conduit with the sinus of Valsalva (BIOVALVE) by using this unique technology and its subsequent implantation in the pulmonary valves in a beagle model. Methods and Results-A mold of BIOVALVE organization was assembled using 2 types of specially designed silicone rods with a small aperture in a trileaflet shape between them. The concave rods had 3 projections that resembled the protrusions of the sinus of Valsalva. The molds were placed in the dorsal subcutaneous spaces of beagle dogs for 4 weeks. The molds were covered with autologous connective tissues. BIOVALVEs with 3 leaflets in the inner side of the conduit with the sinus of Valsalva were obtained after removing the molds. These valves had adequate burst strength, similar to that of native valves. Tight valvular coaptation and sufficient open orifice area were observed in vitro. These BIOVALVEs were implanted to the main pulmonary arteries as allogenic conduit valves (nϭ3). Postoperative echocardiography demonstrated smooth movement of the leaflets with trivial regurgitation. Histological examination of specimens obtained at 84 days showed that the surface of the leaflet was covered by endothelial cells and neointima, including an elastin fiber network, and was formed at the anastomosis sides on the luminal surface of the conduit. Conclusion-We developed the first completely autologous BIOVALVE and successfully implanted these BIOVALVEs in a beagle model in a pilot study. (Circulation. 2010;122[suppl 1]:S100 -S106.)Key Words: prosthesis Ⅲ regenerative medicine Ⅲ tissue Ⅲ Valsalva Ⅲ valves T issue engineering combines the principles of engineering and biological sciences to develop viable structures that can replace diseased or deficient natural structures. Recently, autologous valve prostheses with enhanced maturation characteristics, such as anticoagulation, self-repair, tissue regeneration, and growth adaptability, have been developed using in vitro tissue engineering technology. Some investigators have successfully implanted in vitro engineered heart valves in animals and humans by using either decellularized natural tissues or biodegradable synthetic polymers as scaffolds. [1][2][3] However, these procedures require complicated cellmanagement protocols, including harvesting, seeding on appropriate scaffolds, and development of neotissues, by culturing cells in bioreactors under strictly sterile conditions; all of these procedures are time-consuming and expensive.We developed autologous prosthetic tissues using "in-body tissue architecture" technology, which is a novel and practical approach of regenerative medicine based on the tissue encapsulation phenomenon of foreign materials in living bodies. 4 This technology has the following advantages. The tissue prostheses can be fabricated in a wide range of shapes and sizes to suit the need of individual recipients and, most imp...
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