Impact of Leaflet Thickness on Polymeric Valve Scaffold Function and Remodeling: Assessment in a 1- and 3-Month Ovine...

Approaches to the structural design of tissue engineered heart valves (TEHVs) have varied broadly, ranging from material choice to microstructural and macro-scale functional characteristics. Not only will each variable on this extensive list impact functional and restorative potential after implantation, but most of these variables also have dynamic, cross-talking effects. While there has been a great deal of discussion in the field on this topic, there has only been a limited amount of evidence generated that systematically isolated specific design features and validated them in vivo. In order to reduce this knowledge gap, two groups of stented polymer tissue engineered pulmonary valve (TEPV) scaffolds were fabricated with similar structural characteristics, differing only in their initial thickness values, and implanted in an ovine pulmonary valve replacement model for 30 or 90 days. In vivo functional performance was measured by echocardiography, and histological analysis was performed on each scaffold explant. No differences were evident in valve regurgitation or neotissue formation between valve scaffolds of either thickness group or study duration. This may be due in part to broad variability between animals of the same group and even leaflets of the same valve. These results suggest that, with the condition of limited cell infiltration, modulation of leaflet thickness alone may be insufficient to address early remodeling in TEPVs, and reemphasize the complexity of designing TEHVs according to the myriad of interrelated structural variables that have direct and indirect impacts on tissue engineering viability, coupled with further variability associated with in vivo experiments.