Trilayer anisotropic structure versus randomly oriented structure in heart valve leaflet tissue engineering

It has been hypothesized that leaflet substrates with a trilayer structure and anisotropic mechanical properties could be useful for the production of functional and long-lasting tissue-engineered leaflets. To investigate the influence of the anisotropic structural and mechanical characteristics of a substrate on cells, in this study, we electrospun trilayer anisotropic fibrous substrates and randomly oriented isotropic fibrous substrates (used as controls) from polycaprolactone polymers. Consequently, the random substrates had higher radial and lower circumferential tensile properties than the trilayer substrates; however, they had similar flexural properties. Porcine valvular interstitial cells cultured on both substrates produced random and trilayer cell-cultured constructs, respectively. The trilayer cell-cultured constructs had more anisotropic mechanical properties, 17% higher cellular proliferation, 14% more extracellular matrix (i.e., collagen and glycosaminoglycan) production, and superior gene and protein expression, suggesting that more cells were in a growth state in the trilayer constructs than in the random constructs. Furthermore, the random and radial layers of the trilayer constructs had more vimentin, collagen, transforming growth factor-beta 1 (TGF-ss1), transforming growth factor-beta 3 (TGF-ss3) gene expression than in the circumferential layer of the constructs. This study verifies that the differences in structural, tensile, and anisotropic properties of the trilayer and random substrates influence the characteristics of the cells and ECM in the constructs.

Automated summary

This study investigated the influence of anisotropic structural and mechanical characteristics on cell behavior. Trilayer anisotropic fibrous substrates and randomly oriented isotropic fibrous substrates were created, and cells cultured on the trilayer substrates had higher proliferation, increased extracellular matrix production, and superior gene and protein expression compared to cells on random substrates. The different layers of the trilayer constructs also showed variations in gene expression. Overall, this study demonstrates the importance of substrate properties in tissue engineering.