Substrate stiffness effects on SH-SY5Y: The dichotomy of morphology and neuronal behavior

Like many other cell types, neuroblastoma cells are also known to respond to mechanical cues in their microenvironment in vitro. They were shown to have mechanotransduction pathways, which result in enhanced neuronal morphology on stiff substrates. However, in previous studies, the differentiation process was monitored only by morphological parameters. Motivated by the lack of comprehensive studies that investigate the effects of mechanical cues on neuroblastoma differentiation, we used SH-SY5Y cells differentiated on polyacrylamide (PA) gels as a model. Cells differentiated on the surface of PA hydrogels with three different elastic moduli (0.1, 1, and 50 kPa) were morphologically evaluated and their electrophysiological responsiveness was probed using calcium imaging. Immunodetection of neural marker TUJ1 and p-FAK was used for biochemical characterization. Groups with defined stiffness that are matching and nonmatching to neural tissue extracellular matrix were used to distinguish biomimetic results from other effects. Results show that while cells display morphologies that do not resemble neurons on soft substrates, they are in fact electrophysiologically more responsive and abundant in neuronal marker TUJ1. Our findings suggest that while neuronal differentiation occurs more efficiently in microenvironments mechanically mimicking neural tissue, the SH-SY5Y model demonstrates morphologies that conflict with neuronal behavior under these conditions. These results are expected to contribute considerable input to researchers that use SH-SY5Y as a neuron model.