Exploring the effects of electrospun fiber surface nanotopography on neurite outgrowth and branching in neuron cultures

Abstract

Three aligned, electrospun fiber scaffolds with unique surface features were created from poly-L-lactic acid (PLLA). Fibers without surface nanotopography (smooth fibers), fibers with surface divots (shallow pits), and fibers with surface pits (deeper pits) were fabricated, and fiber alignment, diameter, and density were characterized using scanning electron microscopy (SEM). Whole dorsal root ganglia (DRG) were isolated from rats and placed onto uncoated fibers or fibers coated with laminin. On uncoated fibers, neurite outgrowth was restricted by fibers displaying divoted or pitted nanotopography when compared to neurite outgrowth on smooth fibers. However, neurites extending from whole DRG cultured on laminin-coated fibers were not restricted by divoted or pitted surface nanotopography. Thus, neurites extending on laminin-coated fibers were able to extend long neurites even in the presence of surface divots or pits. To further explore this result, individual neurons isolated from dissociated DRG were seeded onto laminin-coated smooth, pitted, or divoted fibers. Interestingly, neurons on pitted or divoted fibers exhibited a 1.5-fold increase in total neurite length, and a 2.3 or 2.7-fold increase in neurite branching compared to neurons on smooth fibers, respectively. Based on these findings, we conclude that fiber roughness in the form of pits or divots can promote extension and branching of long neurites along aligned electrospun fibers in the presence of an extracellular matrix protein coating. Thus, aligned, electrospun fibers can be crafted to not only direct the extension of axons but to induce unique branching morphologies.

Aligned Fingolimod-Releasing Electrospun Fibers Increase Dorsal Root Ganglia Neurite Extension and Decrease Schwann Cell Expression of Promyelinating Factors

“…The following imaging parameters were used: 5.0 kV-accelerating voltage, 10 mmworking distance, 5.0 nm-spot size, 30 µm-aperture, and ×2,500-magnification. Fiber alignment, diameter, and percent coverage were characterized using FIJI Software as described previously (D'Amato et al, 2019b) to ensure consistency between each fiber group and isolate fingolimod release as the sole variable. A total of 300 fiber angles (100 fiber angles per replicate) and 300 fiber diameters (100 fiber diameters per replicate) were measured for each fiber type, and at least three fields of view were assessed for percent fiber coverage.…”

“…The following procedures were approved by the Institutional Animal Care and Use Committee (IACUC) at Rensselaer Polytechnic Institute. Whole DRG were isolated from 2day-old Sprague Dawley rats (P2) as described previously (D'Amato et al, 2019b). Before culturing the whole DRG, all fiber types were plasmatreated on high for 1 min using an expanded plasma cleaner to improve cell adhesion.…”

“…DRG from two rats were isolated as described previously (D'Amato et al, 2019b) and placed in chilled Ham's F12 nutrient mixture for dissociation. DRG were centrifuged at 300 rcf for 5 min, and the F12 media mixture was carefully pipetted off.…”

Biofunctional scaffolds with high packing density of aligned electrospun fibers support neural regeneration

“…Indeed, a higher fiber density implies more topography. Previous studies have demonstrated the effects of topography on axonal growth (Chew et al, 2007;D'Amato et al, 2019;Xie et al, 2014). In this study, we focused on the effect of the amount of space between the fibers, even though the amount of topography may have played an important role in axon guidance and regeneration.…”

A mini review on the generation of crimped ultrathin fibers via electrospinning: Materials, strategies, and applications

“…Studies have shown that maneuvering the surface morphology of electrospun fibers (eg, crimped fibers, wrinkled fibers, porous fibers, grooved fibers, cactus‐like fibers, tree‐like fibers, ribbon fibers, rough fibers, beaded fibers, and butterfly wings fibers) leads to enhancing or changing their properties …”