Biomimetic Multilayered Aortic Grafts: Combining 3D-Printing and Electrospinning to Improve Prosthesis Performance

Background: The mechanical properties of the aorta are very unique. Although open surgical repair of the ascending aorta has for many years successfully been performed using long-term stable polyethylene terephthalate (PET) and expanded polytetrafluoroethylene (ePTFE) prostheses, it has not been possible to manufacture grafts that reproduce aortic compliance. The aim of this work was to develop a long-term stable synthetic graft showing the physiological compliance of the ascending aorta.

Method: Polyurethane (PU) was selected to create multilayered aortic grafts (n = 10) using electrospinning. A 3D-printed rotating mandrel was used as the collector. A mesh tube was incorporated and a hydrogel coating was added. Compliance measurements were performed in a static as well as a pulsatile environment. Extended near physiological perfusion was employed to determine whether the grafts dilated over time. Uniaxial tensile stress tests were performed and suture retention strength was analyzed with different types of sutures. Burst pressure tests were performed and graft permeability was assessed. PET and ePTFE prostheses of the same diameter and length were tested for comparison. All grafts were evaluated by scanning electron microscopy (SEM) regarding defects and fiber alignment.

Results: The electrospun grafts showed good adhesion between layers. PU outperformed PET and ePTFE prostheses in terms of elasticity. However, a significant increase in graft diameter was observed with time. Therefore, a mesh tube was incorporated into the graft. The high elasticity and anisotropy of PU was confirmed by uniaxial tensile testing. Equivalent suture retention strength compared with commercial grafts was achieved. Sufficient maximum burst pressure was obtained. After hydrogel coating, burst pressure increased and graft permeability was reduced. The SEM samples demonstrated fibers with uniform diameter, no defects and desired arrangement. Individualized 3D-printed collectors were created using patient-specific CT datasets. Subsequently, electrospinning was performed and customized prostheses were successfully created.

Conclusion: Combining 3D-printing and electrospinning is a promising alternative to build composite grafts for the replacement of the ascending aorta. With PU as a highly elastic component and the addition of another, stiffer material, to limit diameter distension over time, it may be possible to fabricate grafts with physiological aortic compliance and prevent fatigue dilatation over time.

Publication History

Article published online:
28 January 2023