Biodegradable small calibre polydioxanone-based vascular prostheses: Potential as coronary bypass grafts

Aims: Shelf-ready synthetic small calibre prostheses are needed for coronary artery bypass grafting. Biodegradable scaffolds resistant to degradation-induced aneurysm formation in the systemic arterial circulation have been developed for in vivo vascular tissue engineering. We evaluated patency, biocompatibility and mechanical properties (remodelling) of 3 electrospun biodegradable random nano-fibre polymer prostheses: polydioxanone (PDO) alone; blended with: poly(lactic-acid) (PDO-PLA); with polycaprolactone (PDO-PCL). Methods: In 30 anaesthetised Sprague Dawley rats, 2mm ePTFE grafts controls(n=9), PDO(n=3), PDO-PLA(n=9), PDO-PCL(n=9), were interposed in the infrarenal abdominal aorta and followed for 3, 6 and 12 weeks. Digital substraction angiography was made for patency, stenosis and aneurysmal dilatation before euthanasia. Grafts were harvested for SEM, histology and computed morphometry for assessment of neo-endothelialisation and intimal hyperplasia. Results: Patency rates were excellent for all grafts (100%) and no relevant stenoses were found. Angiography follow-up showed aneurysmal formation for all PDO-alone grafts at 3 weeks (therefore no further implantations were made) and 1/3 for PDO-PLA at 6 and 12 weeks. No aneurysms were found for PDO-PCL grafts. All PDO-based grafts show slow degradation, a significantly better neoendothelialisation and insignificant neointimal formation compared to ePTFE. Conclusion(s): Patency of electrospun biodegradable PDO-based prostheses is excellent. Using slow, biodegrading polymer blends, e.g. PDO-PCL can avoid aneurysm formation and the neoendothelialisation (blood compatibility) of such prostheses is significantly better compared to ePTFE. Therefore, biodegradable, electrospun PDO-based vascular prostheses may be a promising alternative as shelf-ready cardiopulmonary bypass grafts.