Development of in vivo tissue-engineered autologous tissue-covered stents (biocovered stents).

Biocovered stents, which are stents covered with autologous membranous tissues, were developed by applying a novel concept based on in vivo tissue engineering. Balloon-expandable stents crimped on silicone rods as a mold (diameter: 2 mm) were embedded into dorsal subcutaneous pouches in rabbits. After 1 month, the struts of the stents were fully encapsulated with membranous connective tissues formed around the silicone rods. Upon removing the silicone rod, stents covered with tubular connective tissues, in which the struts were completely impregnated, were obtained as biocovered stents. These tissues were composed mainly of collagen and fibroblasts and had a thickness of less than approximately 200 microm with an excellent high burst strength of approximately 1000 mmHg. The luminal surface of the tissues was extremely flat and smooth. The stents could be mounted on balloon catheters with a hand crimping tool and could be expanded by inflation with little damage to the tissues. It is anticipated that these novel stents may greatly enhance early normal vascular reconstruction with high reliability, thereby reducing the rate of in-stent restenosis.