Inconsistency in Graft Outcome of Bilayered Bioresorbable Supramolecular Arterial Scaffolds in Rats

There is a continuous search for the ideal bioresorbable material to develop scaffolds forin situvascular tissue engineering. As these scaffolds are exposed to the harsh hemodynamic environment during the entire transformation process from scaffold to neotissue, it is of crucial importance to maintain mechanical integrity and stability at all times. Bilayered scaffolds made of supramolecular polycarbonate-ester-bisurea were manufactured using dual electrospinning. These scaffolds contained a porous inner layer to allow for cellular infiltration and a dense outer layer to provide strength. Scaffolds (n = 21) were implanted as an interposition graft into the abdominal aorta of male Lewis rats and explanted after 1, 3, and 5 monthsin vivoto assess mechanical functionality and neotissue formation upon scaffold resorption. Results demonstrated conflicting graft outcomes despite homogeneity in the experimental group and scaffold production. Most grafts exhibited adverse remodeling, resulting in aneurysmal dilatation and calcification. However, a few grafts did not demonstrate such features, but instead were characterized by graft extension and smooth muscle cell proliferation in the absence of endothelium, while remaining patent throughout the study. We conclude that it remains extremely difficult to anticipate graft development and performancein vivo. Next to rational mechanical design and good performancein vitro, a thorough understanding of the mechanobiological mechanisms governing scaffold-driven arterial regeneration as well as potential influences of surgical procedures is warranted to further optimize scaffold designs. Careful analysis of the differences between preclinical successes and failures, as is done in this study, may provide initial handles for scaffold optimization and standardized surgical procedures to improve graft performancein vivo. Impact statement In situvascular tissue engineering using cell-free bioresorbable scaffolds is investigated as an off-the-shelf option to grow small caliber arteries inside the body. In this study, we developed a bilayered electrospun supramolecular scaffold with a dense outer layer to provide mechanical integrity and a porous inner layer for cell recruitment and tissue formation. Despite homogenous scaffold properties and mechanical performancein vitro,in vivotesting as rat aorta interposition grafts revealed distinct graft outcomes, ranging from aneurysms to functional arteries. Careful analysis of this variability provided valuable insights into materials-drivenin situartery formation relevant for scaffold design and implantation procedures.

Automated summary

The study developed bilayered electrospun supramolecular scaffolds for in situ vascular tissue engineering, with a dense outer layer for mechanical integrity and a porous inner layer for tissue formation. Despite uniform scaffold properties and mechanical performance in vitro, in vivo testing revealed distinct graft outcomes, ranging from aneurysms to functional arteries. This variability provided valuable insights into materials-driven artery formation relevant for scaffold design and implantation procedures.