Micrometer-Scale Biofabricated Scaffolds by Melt Electrowriting for Pediatric Cardiac Surgery

Background: Congenital heart diseases are the most common and lethal form of congenital malformations. Among them, congenital aortic stenosis is a progressive condition that can require early surgery. Among the best treatments in this setting is Ross procedure. Its excellent hemodynamic performance, potential for growth and no need for anticoagulation make it superior to the other available treatments when valve substitution is necessary. However, its long-term durability is compromised by progressive dilation of the pulmonary autograft under systemic pressure, often requiring reintervention. A promising solution to this problem is reinforced Ross surgery, involving the wrapping of the autograft. Currently, this procedure is performed using non resorbable materials like Gore-Tex and Dacron, limiting its use in the pediatric population. Aim: The aim of this study is to design, manufacture and evaluate the biocompatibility of a biodegradable polycaprolactone patch suitable for pulmonary autograft reinforcement in a murine model. Materials and Methods: Four scaffold designs were initially developed to meet the mechanical requirements of reinforced Ross surgery: providing external support while maintaining flexibility and compliance. Among these, a sinusoidal pattern named "Wavy 0.8" was selected. Patches were fabricated using polycaprolactone (PCL), a biodegradable and biocompatible polymer, with the aid of Melt Electrowriting. The mechanical performance of the printed scaffolds was evaluated through uniaxial tensile tests and compared with that of native aortic and pulmonary artery walls. The meshes were then implanted both subcutaneously and around the aorta in a murine model. The tissue response was assessed at 1 week and 2 months timepoints through macroscopic images and histologic analysis after animals’ euthanasia. In particular, the inflammatory response, cellular infiltration and calcification were evaluated. Results: Mechanical studies revealed that the behavior of the Wavy 0.8 design was similar to the one of the native aortic wall. This suggested its potentially suitable employment in reinforced Ross procedure. Based on current data, no definitive statement can be made regarding the overall biocompatibility of the mesh. Conclusions: This study is the first to design and characterize bioresorbable PCL scaffolds produced via Melt Electrowriting for future applications in reinforced Ross procedure. The engineered patches exhibited mechanical properties similar to the ones of the native murine aorta, supporting their potential for autograft stabilization. While biocompatibility and degradation remain to be fully assessed, these results provide a strong foundation for further research and future clinical translation.