Development of a Long Autologous Small-Caliber Biotube Vascular Graft

Abstract

Introduction - Small-caliber synthetic vascular grafts (<6 mm) with acceptable patency for coronary bypass or peripheral vascular repair below the knee are very rare. We have developed an autologous small-caliber vascular graft, Biotube, using the simple, safe, and economical in-body tissue architecture technology, which is a novel concept in regenerative medicine. Biotubes have shown good performance as aortic grafts for almost 10 years in a canine model. Recently, first-in-human study of Biotube was successfully performed for hemodialysis access. This study presents the preparation of long Biotube over 20 cm. Its in vivo performance was evaluated in an animal implantation model. Methods - For the preparation of the long Biotube spiral plastic mold was designed. The mold had spiral center rod (diameter 4 mm, length 25 mm) covered with a slitted tubular cage (clearance: 1 mm). Upon 2-month embedding into subcutaneous pouches of beagles autologous connective tissue was ingrown inside the cage through the slits and completely fulfill the clearance between the rod and the cage to form tubular connective tissue. Results - Completely autologous tissue Biotubes with diameter of 4 mm, length of over 20 cm and wall thickness of 1 mm were autonomically formed in the subcutaneous space and obtained by removing all parts after harvesting of the molds. Since their wall tissues were very flexible and robust, original spiral shape was easily regulated in desire. The Biotubes were implanted to canine carotid arteries by end-to-end anastomoses in loop shape with high performance. Conclusion - The Biotube showed excellent vascular performance, and can be considered useful in several vascular conditions with high long-term reliability.