Comparison of ethanol concentration as stock solution on mechanical properties of iBTA-induced collagenous tubular tissue “Biotube”

Collagenous tubular tissues “Biotubes,” formed by in-body tissue engineering, is implanted already as clinical vascular grafts in hemodialysis surgery. In almost all previous study, Biotubes were stored in 70% alcohol before implantation, but the influence of alcohol concentration on the mechanical properties of Biotubes has not been investigated in depth. In this study, the mechanical properties of Biotubes stored at room temperature in two different concentrations of ethanol (10% or 70%) were compared through fatigue and tensile tests. Biotubes with an internal diameter of 6 mm and wall thickness of ca. 2 mm was prepared by subcutaneous embedding of molds into goat for two months, and stored in 10% or 70% alcohol solution for 20 d. In the fatigue test, performed by repeatable loading of tension corresponding to arterial pressure (700,000 cycles at 10 Hz), Biotubes stored in 10% solution elongated by approximately 80%, but in 70% solution, the elongation was <20%. Storing Biotubes in high concentration ethanol solution improved practical compliance and prevented stretching. The preservation of ECM with 70% ethanol is a cost effective, safe and easy method.