Substrate stiffness affects neural network activity in an extracellular matrix proteins dependent manner

Neuronal growth, differentiation, extension, branching and neural network activity are strongly influenced by the mechanical property of extracellular matrix (ECM). However, the mechanism by which substrate stiffness regulates a neural network activity, and the importance of ECM composition in conferring substrate stiffness sensing have not been explored. To address this question, the hippocampal neurons were seeded on the polydimethylsiloxane (PDMS) substrate with different stiffness, which were coated with fibronectin and laminin respectively. Our results show that voltage-gated Ca²⁺ channel currents are greater in neurons on the stiff substrate than on the soft substrate. In addition, the neurons exhibit a greater increase of Ca²⁺ currents on laminin-coated stiff substrate than on those coated with fibronectin, indicating that the composition of ECM can modulate responses to substrate stiffness of neurons. Paired patch-clamp recordings have shown that upregulation of neural effective synaptic connectivity is greater on the laminin-coated stiff substrate than on the fibronectin-coated ones. Consistently, laminin-coated stiff substrate enhances Ca²⁺ oscillations of neurons is greater that compared with the fibronectin-coated ones. Our study demonstrates that a direct role for substrate stiffness in regulating neuronal network activity and indicate that this modulation is dependent on a specific type of ECM protein, which should be taken into account for the design of biomaterials for neuronal tissue engineering.