Mechanically Flexible Polymeric Nanoneedle Arrays for Promoting Differentiation and Functional Activity of Neural Progenitor Cells

Abstract

Various environmental factors, including mechanical stimuli such as material stiffness, topography, and cell-cell interactions shape cellular responses to biomaterial surfaces. In particular, high aspect ratio structures have shown promise for drug delivery, biosensing, and cell differentiation applications. In this study, we present poly(urethane acrylate) (PUA)-based polymeric nanoneedles (NNs) fabricated using UV-assisted nanoimprint lithography (UV-NIL) and explore their potential as cell culture platforms for neural differentiation and connectivity. PUA NNs, high aspect ratio and mechanical flexibility, provide a softer substrate than traditional silicon (Si)-based NNs, demonstrating high biocompatibility with mouse fibroblasts (NIH 3T3), rat neural-like cells (PC12), and human neural progenitor cells (ReN), all of which exhibit high cell viability and sustained proliferation. Live-cell imaging revealed extensive interaction of ReN cells with the nanostructures, fostering an elongated cell morphology and increased neurite outgrowth. As confirmed by immunofluorescence staining and quantitative gene expression analyses, PUA NNs significantly enhanced neuronal differentiation in both PC12 and ReN cells. Furthermore, PUA NNs improved synchronized calcium signaling in ReN cells, suggesting enhanced neural connectivity. These findings highlight the ability of PUA NNs to modulate cellular behavior through mechano-transduction, thus providing a promising platform for neural repair and regenerative medicine.