APPLICATION OF STEREOLITHOGRAPHY FOR SCAFFOLD FABRICATION FOR TISSUE ENGINEERING OF HEART VALVES

Abstract

Background: A crucial factor in tissue engineering of heart valves is the functional and physiological scaffold design. In our current experimental report we describe a new fabrication technique for heart valve scaffolds, derived from x-ray computed tomography data linked to the rapid prototype technique of stercolithography. Methods: In order to recreate the complex anatomical structure of a pulmonary and aortic homograft. we have used stereolithographic models derived from x-ray computed tomography and specific software (CP. Aachen, Germany). These stereolithogrphic models were used to generate biocompatible heart valve scaffolds by a thermal processing technique. The scaffold-forming polymer was a biodegradable and thermoplastic elastomer, a poly-4-hydroxybutyrate (P4HB) and polyhydroxyoctanoate (PHOH) (Tepha Inc. Cambridge. MA) Analysis of the heart valve scaffolds included biomechanical testing (MTS Systems Corporation Eden Prairie. MN), functional testing in a pulsatile biorcactor and direct measurements. Results: Using stereolithography, we were able to fabricate plastic models with the accurate anatomy of a human valvular homograft Moreover, we fabricated heart valve scaffolds with a physiological valve design, which included the smus of valsalva, and resembled our reconstructed homografts. One advantage of P4HB and PHO was the ability to mold a complete aortic root scaffold from a stereolithographic model without the need for suturing Biomechanical testing of the scaffold materials revealed physical properties appropriate for use in cardiovascular surgery. The heart valve scaffolds were tested in a bioreactor and it was noted that the leaflets opened and closed synchronously under sub- and supraphysiological flow conditions. Direct measurements of the homograft, the plastic models and the final heart valve scaffolds revealed only minor differences. Conclusion: Our preliminary results suggest that the reproduction of complex anatomical structures by stereolithography might be a useful technique to fabricate custom-made polymeric scaffolds for the tissue engineering of heart valves.