Gradients with Depth in Electrospun Fibrous Scaffolds for Directed Cell Behavior

摘要

A major obstacle in creating viable tissue engineered constructs using electrospinning is the lack of complete cellularization and vascularization due to the limited porosity in these densely packed fibrous scaffolds. One potential approach to circumvent this issue is the use of various gradients of chemical and biophysical cues to drive the infiltration of cells into these structures. Towards this goal, this study focused on creating durotactic (mechanical) and haptotactic (adhesive) gradients through the thickness of electrospun hyaluronic acid (HA) scaffolds using a unique, yet simple, modification of common electrospinning protocols. Specifically, both mechanical (via crosslinking: ranging from 27%–100% modified methacrylated HA, MeHA) and adhesive (via inclusion of the adhesive peptide RGD: 0–3mM RGD) gradients were each fabricated by mixing two solutions (one ramping up, one ramping down) prior to electrospinning and fiber collection. Gradient formation was verified by fluorescent microscopy, FTIR, atomic force microscopy, and cellular morphology assessment of scaffolds at different points of collection (i.e., with scaffold thickness). To further test the functionality of gradient scaffolds, chick aortic arch explants were cultured on adhesive gradient scaffolds for 7 days and low RGD-high RGD gradient scaffolds showed significantly greater cell infiltration compared to high RGD-low RGD gradients and uniform high RGD or uniform low RGD control scaffolds. In addition to enhanced infiltration, this approach could be used to fabricate graded tissue structures, such as those that occur at interfaces.