Conversion of nanoscale topographical information of cluster-assembled zirconia surfaces into mechanotransductive events promotes neuronal differentiation

Abstract

BackgroundThanks to mechanotransductive components cells are competent to perceive nanoscale topographical features of their environment and to convert the immanent information into corresponding physiological responses. Due to its complex configuration, unraveling the role of the extracellular matrix is particularly challenging. Cell substrates with simplified topographical cues, fabricated by top-down micro- and nanofabrication approaches, have been useful in order to identify basic principles. However, the underlying molecular mechanisms of this conversion remain only partially understood.ResultsHere we present the results of a broad, systematic and quantitative approach aimed at understanding how the surface nanoscale information is converted into cell response providing a profound causal link between mechanotransductive events, proceeding from the cell/nanostructure interface to the nucleus. We produced nanostructured ZrO2 substrates with disordered yet controlled topographic features by the bottom-up technique supersonic cluster beam deposition, i.e. the assembling of zirconia nanoparticles from the gas phase on a flat substrate through a supersonic expansion. We used PC12 cells, a well-established model in the context of neuronal differentiation. We found that the cell/nanotopography interaction enforces a nanoscopic architecture of the adhesion regions that affects the focal adhesion dynamics and the cytoskeletal organization, which thereby modulates the general biomechanical properties by decreasing the rigidity of the cell. The mechanotransduction impacts furthermore on transcription factors relevant for neuronal differentiation (e.g. CREB), and eventually the protein expression profile. Detailed proteomic data validated the observed differentiation. In particular, the abundance of proteins that are involved in adhesome and/or cytoskeletal organization is striking, and their up- or downregulation is in line with their demonstrated functions in neuronal differentiation processes.ConclusionOur work provides a deep insight into the molecular mechanotransductive mechanisms that realize the conversion of the nanoscale topographical information of SCBD-fabricated surfaces into cellular responses, in this case neuronal differentiation. The results lay a profound cell biological foundation indicating the strong potential of these surfaces in promoting neuronal differentiation events which could be exploited for the development of prospective research and/or biomedical applications. These applications could be e.g. tools to study mechanotransductive processes, improved neural interfaces and circuits, or cell culture devices supporting neurogenic processes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0171-3) contains supplementary material, which is available to authorized users.

Space-resolved quantitative mechanical measurements of soft and supersoft materials by atomic force microscopy

“…This is mainly due to the high homogeneity of the solvent system for the PNIPAM chain, in which the polymer network presents a coiled conformation. 17,18 The gel synthesized in the presence of the 1:3 water-methanol mixture (v v − 1 ) (hydrogel-2) is slightly porous as very few pores are visible (Figure 2b). This is because the gel synthesized outside of the cononsolvency region and solvent remained homogeneous for the PNIPAM chain segment throughout the synthesis.…”

“…Consequently, a highly porous gel was formed. 17,18 It is clear that only a variation in the compositions of the synthesis solvent results in significant changes to the gel morphology and mechanical properties.…”

“…A real-time graphic user interface analysis was developed by simplifying the accepted custom-built routine for nanomechanical properties of living cells. 8,17,18 Finite thickness correction is unnecessary because of the thickness of macroscopic samples. 13 Raw AFM data were preprocessed to obtain FCs (F (nN)) vs indentation (δ (nm)).…”

Scale Invariant Disordered Nanotopography Promotes Hippocampal Neuron Development and Maturation with Involvement of Mechanotransductive Pathways

“…Indeed, it has been demonstrated that the polarization of neurite/axon outgrowth can be controlled by topographical cues (Hoffman-Kim et al, 2010; Ferrari et al, 2011). Several studies suggest furthermore a positive contribution of biomaterials with appropriate nanotopographical substrate features to neuronal differentiation in diverse neuronal or stem cell types (Foley et al, 2005; Cellot et al, 2009; Christopherson et al, 2009; Malarkey et al, 2009; Lee et al, 2010; Wu et al, 2010; Fabbro et al, 2012; Tamplenizza et al, 2013; Kulangara et al, 2014; Yang et al, 2014, 2016; Schulte et al, 2016) and recent data propose a prominent involvement of IAC (Yang et al, 2014, 2016; Schulte et al, 2016). However, a more detailed molecular insight into the underlying mechanotransductive processes and the determination of the key players regulating nanotopography-mediated impact on neurogenic events is needed.…”

Biological responses to nanomaterials: understanding nano-bio effects on cell behaviors

“…with most studies only concerned with their fates after incubation with cells (Moore et al, 1997;Wilhelm et al, 2003). Then more and more findings provide strong evidence that nanostructures not only passively interact with cells but also actively engage and mediate the molecular processes that are essential for regulating cell functions (Huang et al, 2010;Cai et al, 2011;Etoc et al, 2013;Amschler et al, 2014;Koo et al, 2014;Barthes et al, 2015;Kumar et al, 2015;Li et al, 2015a;Park et al, 2016;Schulte et al, 2016;Zhao et al, 2016).…”