New Flow System for Compliance Testing of Collagen Fibers Reinforced Bio-Composites for Small-Diameter Tissue Engineered Blood Vessels

Background: One of the treatments for coronary artery disease is bypass surgery that includes bypassing the blocked coronary artery using a graft taken from other organs of the patient. To date, there is no available substitute for the "gold standard" autograft, since synthetic small-diameter grafts were failed to restore the physiological function, due to compliance mismatch between the native and synthetic graft.

Methods: This study introduces a new flow system that allows to test the mechanical properties of collagen fibers reinforced bio-composites for small-diameter blood vessel grafts. These new bio-composites were proven to be biocompatible and their tensile behavior was found to be similar to the native tissue properties. Herein, we have developed a new method to test their compliance properties under dynamic flow conditions (e.g. pulse wave velocity).

Results: Optical methods (using light reflection amplifier) and differential pressure gauges were used to measure the delay between the tube`s entrance and exit flow pressures to calculate the wave propagation rate. Our feasibility results of the flow system demonstrate its ability to measure the dynamical compliance in soft composite vessels.

Conclusions: Synthetic grafts for replacement of coronary arteries are not yet available due to compliance mismatch. We have introduced a new methodology that is complimentary to the fabrication of biomimetics soft collagen composites and their structural tensile mechanical characterization, by designing new flow system and testing the compliance in our soft biocomposite vessels. This methodology presents a great potential for mimicking the native vessels function towards future replacements of small-diameter blood vessels.