Degradable synthetic vascular prosthesis: experimental aortic replacement

Objectives: Vascular tissue engineering necessitates a degradable scaffold. The purpose of this study was to evaluate biocompatibility and thrombogenicity of electrospun co-polymers of poly-dioxanone (PDS) and poly-lactic-acid (PLA) grafts.

Methods: Electrospun PDS-PLA (50 : 50) was selected because of biomechanical strength, surgeon's handling, degradation, cellular ingrowth and tissue reaction in subcutaneous and vascular implantation models. In 18 Sprague Dawley rats, 1-mm ePTFE grafts (n=9) and 1-mm PDS-PLA grafts (n=9) were interposed in the infrarenal abdominal aorta for 3, 6 and 12 weeks. Digital substraction angiography was performed for patency assessment before euthanasia and grafts were harvested for morphologic as well as scanning electron microscopic examination.

Results: Patency rates were excellent for both types of grafts (100%). No dilatation was found in the degradable PDS-PLA grafts at 3 weeks. However, saccular aneurysm formation was observed in 1/3 animals at three and twelve weeks. The neoendothelialization measured by morphometry was significantly increased in PDS-PLA compared to ePTFE grafts at 3 weeks (75±3 vs. 22±5%; p<0.001).

Fig. 1 Vascular replacement of the rat abdominal aorta with PDS/PLA

Conclusions: Patency of electrospun PDS-PLA 1-mm grafts is excellent. Aneurysm formation was seen in 33% with PDS-PLA grafts after 6 and 12 weeks. Therefore, combinations or wrapping of the grafts with slower degrading polymers may be required. In conclusion, electrospun PDS-based polymers may be promising materials for vascular tissue engineering.