Development of long in vivo tissue-engineered "Biotube" vascular grafts.

In-body tissue architecture (iBTA), a cell-free, in vivo tissue engineering technology that can produce autologous implantable tissues of the desired shape by subcutaneously embedding specially designed molds, was used to develop long tubular collagenous tissues called Biotubes. Spiral molds for long Biotubes were assembled with an outer pipe-shaped spiral shell and an inner spiral mandrel, and embedded into subcutaneous pouches of beagle dogs or goats for 1 or 2 months. Tubular collagenous tissues were formed at the space between the shell and the mandrel of the mold. Depending on the spiral turn number in the mold, Biotubes of 25 cm or 50 cm (internal diameter 4 mm or 5 mm) were prepared with nearly homogeneous mechanical and histological properties over their entire length. Biotubes stored in 70% ethanol were allogenically implanted into beagle dogs or goats to evaluate their in vivo performance. The 25-cm Biotubes functioned as arterial grafts with no need for luminal modification or mechanical support, and demonstrated vascular reconstruction within 3 months after implantation into dogs. The 50-cm Biotubes functioned as arteriovenous shunt grafts in the neck region of goats without thrombus formation and vascular deformation for 1 month. Thus, the world's longest tissue-engineered vascular grafts with small diameter could be developed using iBTA.