Electrospun Scaffolds are not Necessarily Always Made of Nanofibers as Demonstrated by Polymeric Heart Valves for Tissue Engineering.

In the last 30 years, there have been nearly 60, 000 publications about electrospun nanofibers, but it is still unclear whether nanoscale fibers are really necessary for electrospun tissue engineering scaffolds. The present report puts forward this argument and reveals that compared with electrospun nanofibers, microfibers with diameter of about 3 μm (named as "oligo-micro fiber" by us) is more appropriate for tissue engineering scaffolds owing to its better cell infiltration ability caused by larger pores with available nuclear deformation. To further increase pore sizes, electrospun poly(ε-caprolactone) scaffolds were fabricated using latticed collectors with meshes. Fiber orientation led to sufficient mechanical strength albeit increased porosity. The latticed scaffolds exhibited good biocompatibility and improved cell infiltration. Under aortic conditions in vitro, the performances of latticed scaffolds were satisfactory in terms of the acute systolic hemodynamic functionality, except for the higher regurgitation fraction caused by the enlarged pores. This hierarchical electrospun scaffold with sparse fibers in macropores and oligo-micro fibers in filaments provides new insight into the design of tissue engineering scaffolds, and tissue engineering may provide living heart valves with regenerative capabilities for patients with severe valve disease in the future. This article is protected by copyright. All rights reserved.