Suppression of hypersynchronous network activity in cultured cortical neurons using an ultrasoft silicone scaffold

Abstract

The spontaneous activity pattern of cortical neurons in dissociated culture is characterized by burst firing that is highly synchronized among a wide population of cells. The degree of synchrony, however, is excessively higher than that in cortical tissues. Here, we employed polydimethylsiloxane (PDMS) elastomers to establish a novel system for culturing neurons on a scaffold with an elastic modulus resembling brain tissue, and investigated the effect of the scaffold's elasticity on network activity patterns in cultured rat cortical neurons. Using whole-cell patch clamp to assess the scaffold effect on the development of synaptic connections, we found that the amplitude of excitatory postsynaptic current, as well as the frequency of spontaneous transmissions, was reduced in neuronal networks grown on an ultrasoft PDMS with an elastic modulus of 0.5 kPa. Furthermore, the ultrasoft scaffold was found to suppress neural correlations in the spontaneous activity of the cultured neuronal network. The dose of GsMTx-4, an antagonist of stretch-activated cation channels (SACs), required to reduce the generation of the events below 1.0 event/min on PDMS substrates was lower than that for neurons on a glass substrate. This suggests that the difference in the baseline level of SAC activation is a molecular mechanism underlying the alteration in neuronal network activity depending on scaffold stiffness. Our results demonstrate the potential application of PDMS with biomimetic elasticity as cell-culture scaffold for bridging the in vivo-in vitro gap in neuronal systems.

Axonal plasticity in response to active forces generated through magnetic nano-pulling

“…Because the plasma membrane is involved in mechanosensing via mechanosensitive ion channels (MSCs), mouse hippocampal neurons were treated with GsMTx-4, a spider venom peptide that inhibits cationic MSCs. 50 , 51 , 52 , 53 We treated hippocampal neurons with 500 nM GsMTx-4, a dose that was found to block cationic MSCs in cortical neurons. 52 , 53 We did not find statistically significant differences in axon length in control neurons ( Figure 2 E; control [Ctrl]: GsMTx-4 − versus GsMTx-4 + , p > 0.05), excluding an influence on axon length by the treatment per se .…”

Substrate stiffness effect on molecular crosstalk of epithelial-mesenchymal transition mediators of human glioblastoma cells

“…Therefore we used Sylgard 184 (E = 12.6 MPa, Figure 1B ) topped with a thin layer of PDMS (50:1) referred herein as Stiff substrates ( 4 ). PDMS substrates with stiffness similar to that of normal brain tissue and glioma tumors were obtained using Sylgard 527 ( 33 , 34 ) (5:4, E ~ 1.5 kPa, Figure 1B ), referred as our Soft substrates. This is in fact consistent with the rigidity of the environment in which GBMs infiltrate, which ranges from 0.1 to 10 kPa ( 35 ).…”

The dual action of glioma-derived exosomes on neuronal activity: synchronization and disruption of synchrony

“…Synchronization depends on the culture density as well as on the physical and biochemical environment, such as substrate stiffness [ 44 ], and less critically on the nature of cultured neurons [ 45 ]. The number and efficiency of synaptic connections, the degree of coupling, the relative weight of inputs from other neurons, and the intrinsic firing of each neuron are all critical parameters.…”