Shape memory of in-body tissue-engineered Biotube® vascular grafts and the preliminary evaluation in animal implantation experiments.

BACKGROUND

Tissues formed by in-body tissue architecture (iBTA) are soft and flexible. However, strongly bending iBTA-induced vascular grafts, called biotubes, may cause lumen collapse by kinking, subsequently leading to occlusion after implantation. In this study, we developed a method for biotube shape memory and verified its performance in preliminary animal implantation experiments.

METHODS

Straight biotubes were prepared by subcutaneous embedding of straight molds into beagle dogs for two months. Upon overnight immersion of the obtained straight biotubes in a 70% ethanol solution under U-shape framing, the biotubes maintained their U shape even after washing with saline solution. Additionally, spiral-shaped biotubes formed from goats using spiral molds could be stretched straight via the same alcohol treatment.

RESULTS

Within limited acute-phase animal implantation experiments, U-shaped biotubes functioned as AV shunt grafts in the femoral region of the beagle without deformation of vascular shape (N.=11). In addition, the long straight biotubes derived from spiral molds could be interposed between goat carotid arteries while maintaining their straight shape (N.=2). All implants maintained perfect patency at the 1-month follow-up period without any evidence of vascular deformation.

CONCLUSIONS

By retaining iBTA-induced tissues in an alcohol solution in the target shape, the shape of the tissues was imprinted and maintained even after implantation within a limited acute period. Therefore, in order to obtain tissues of various shapes, it is unnecessary to use a mold design to maintain the individual shape.