Quiescent Response of Cerebral Cortical Astrocytes to Nanoscale Scaffold Properties

Abstract

Astrocytes cultured on electrospun polyamide nanofibers whose nanophysical properties may reproduce key aspects of native extracellular matrices have demonstrated promising results in both in-vitro and in-vivo situations. In vitro, astrocytes cultured on nanofibrillar scaffolds assumed morphologies that appeared to recapitulate those observed in native tissues and also demonstrated increased neurite outgrowth by co-cultured neurons. In vivo, the same scaffolds introduced into spinal cord wound sites promoted accelerated hindlimb recovery measured by standardized observational scoring with aligned and fasciculated axon development and revascularization throughout wound sites. The in-vitro and in-vivo results suggest that nanofibrillar scaffolds could induce preferential astrocyte differentiation leading to minimized glial scar formation, which has positive implications for improved treatment options for central nervous system injury repairs.The present investigation [1] examined the hypothesis that external physical cues of the nanofibrillar scaffolds can trigger specific signaling cascades with morphological consequences. The nanophysical cues of macro- and nano- scale surface roughness and surface polarity were investigated in this study. The morphological response of cerebral cortical astrocytes to nanophysical properties of the nanofibrillar scaffolds was investigated at high-resolution using AFM. The three-dimensional capability of AFM was also used to characterize cell spreading. An initial study of the corresponding activation of GTPase upstream regulators was performed using immunocytochemistry, focusing on investigation of the main GTPase regulators for the observed morphological responses: filopodia, lamellipodia, stress fiber formation, and stellation. The results support the hypothesis that the nanophysical extracellular environment can trigger preferential activation of members of the Rho GTPase family with demonstrable morphological consequences for cerebral cortical astrocytes.[1] Tiryaki VM, Ayres VM, Khan AA, Ahmed I, Shreiber DI, and Meiners S “Nanofibrillar scaffolds induce preferential activation of Rho GTPases in cerebral cortical astrocytes”, Int. J. Nanomedicine, 07:3891-3905 (2012).