Electrospun Elastomeric Leaflet Substrates that Structurally and Mechanically Mimic Human Aortic Valve Leaflets

Abstract

Creating leaflet substrates that accurately mimic the trilayered structure, anisotropic tensile characteristics, and elastomeric features of native human heart valve leaflets is essential to the success of heart valve tissue engineering. Earlier leaflet substrates have successfully replicated the mechanical properties of animal (porcine) heart valve leaflets. However, not one of them has been able to simultaneously replicate the trilayered structure and the highly anisotropic and elastomeric mechanical properties of human aortic heart valve leaflets. In this study, we employed a combination of polymers − polycaprolactone (PCL), poly-(trimethylene carbonate-co-L-lactide) (PTMC-LA), and poly-(trimethylene carbonate-co-caprolactone) (PTMC-CL) − in an electrospinning system to create elastomeric trilayer PCL/PTMC leaflet substrates that possess mechanical, flexural, and anisotropic properties similar to those of human native heart valve leaflets. We then compared these substrates with non-elastomeric trilayer PCL leaflet substrates to determine their effect on leaflet tissue engineering. Porcine valvular interstitial cells (PVICs) were cultured on these substrates for 1 month in static conditions to develop trilayer PCL and PCL/PTMC cell-cultured constructs. The PCL/PTMC substrates exhibited lower crystallinity and hydrophobicity than the PCL substrate, resulting in better cell adhesion and infiltration. The PCL/PTMC substrates demonstrated significantly greater cell proliferation, extracellular matrix production, and preferable gene and protein expression than the PCL substrates. Furthermore, in an osteogenic environment, the PCL/PTMC substrates showed superior resistance to calcification compared to the PCL substrates. The development of trilayer PCL/PTMC substrates with mechanical and structural characteristics resembling native tissue enhances leaflet tissue engineering.

Influence of Substrate Structure and Associated Properties on Endothelial Cell Behavior in the Context of Behaviors Associated with Laminar Flow Conditions

“…The metabolic activity of cells seeded on the substrates was evaluated using an Alamar Blue assay to characterize the cell behavior on the substrates. The cell metabolic activity on a substrate correlates to the number of cells and can thus be used to determine the rate of cellular proliferation . There was no difference in the relative cell number in these substrates after 1 day of cell culture (Figure a).…”

“…The cell metabolic activity on a substrate correlates to the number of cells and can thus be used to determine the rate of cellular proliferation. 59 There was no difference in the relative cell number in these substrates after 1 day of cell culture (Figure 6a). After 3 days of cell culture, the relative cell number on the aligned substrate was significantly higher than on the random substrate.…”

Tailoring biomaterials for biomimetic organs-on-chips

“…As an alternative, synthetic biomaterials with tuneable physical and chemical properties have received extensive investigation. Among various synthetic biomaterials, aliphatic polyesters such as polylactic acid (PLA), 81 poly(ε-caprolactone) (PCL), 82 poly(lactic- co -glycolic acid) (PLGA), 64,83 and poly( l -lactic acid) (PLLA) 84 are widely utilized in tissue engineering and organs-on-chips, which are degradable when exposing their ester bond to hydrolysis. To improve the functionality, these synthetic biomaterials could be decorated with biological molecules ( e.g.…”