In vitro characterization of a compliant biodegradable scaffold with a novel bioreactor system.

The influence of scaffold compliance on blood vessel tissue engineering remains unclear and compliance mismatch issues are important to an in vivo tissue-engineering approach. We have designed and constructed a modular bioreactor system that is capable of imparting pulsatile fluid flow while simultaneously measuring vessel distension with fluid pressure changes in real time. The setup uses a pneumatic PID control system to generate variable fluid pressure profiles via LabVIEW and an LED micrometer to monitor vessel distension to an accuracy of +/-2 microm. The bioreactor was used to measure the compliance of elastomeric poly(1,8-octanediol citrate) (POC) scaffolds over physiologically relevant pressure ranges. The compliance of POC scaffolds could be adjusted by changing polymerization conditions resulting in scaffolds with compliance values that ranged from 3.8 +/- 0.2 to 15.6 +/- 4.6%/mmHg x 10(-2), depending on the distension pressures applied. Furthermore, scaffolds that were incubated in phosphate-buffered saline for 4 weeks exhibited a linear increase in compliance (2.6 +/- 0.9 to 7.7 +/- 1.2%/mmHg x 10(-2)) and were able to withstand normal physiological blood pressure without bursting. The ability to tailor scaffold compliance and easily measure vessel compliance in real time in vitro will improve our understanding of the role of scaffold compliance on vascular cell processes.