Subcellular Optogenetic Stimulation for Activity-Dependent Myelination of Axons in a Novel Microfluidic Compartmentalized Platform

Abstract

Myelination is governed by neuron-glia communication, which in turn is modulated by neural activity. The exact mechanisms remain elusive. We developed a novel in vitro optogenetic stimulation platform that facilitates subcellular activity induction in hundreds of neurons simultaneously. The light isolation was achieved by creating a biocompatible, light-absorbent, black microfluidic device integrated with a programmable, high-power LED array. The system was applied to a compartmentalized culture of primary neurons whose distal axons were interacting with oligodendrocyte precursor cells. Neural activity was induced along whole neurons or was constrained to cell bodies with proximal axons or distal axons only. All three modes of stimulation promoted oligodendrocyte differentiation and the myelination of axons as evidenced by a decrease in the number of oligodendrocyte precursor cells followed by increases in the number of mature oligodendrocytes and myelin sheath fragments. These results demonstrated the potential of our novel optogenetic stimulation system for the global and focal induction of neural activity in vitro for studying axon myelination.

Drug discovery for remyelination and treatment of MS

“…This data suggests that the neuron-glia communication events that mediate activity-dependent myelination as reported in vivo may also be conserved in vitro and could allow for the careful dissection of neuronal versus oligodendrocyte components of this process (Gibson et al, 2014;Hines, Ravanelli, Schwindt, Scott, & Appel, 2015;Koudelka et al, 2016;Mensch et al, 2015;Yang et al, 2012). This finding was further exemplified in a recent study whereby optical stimulation of neurons expressing light-sensitive ion channels within microfluidic chambers resulted in increased numbers of myelin sheath structures (Lee et al, 2016). While vesicular-mediated signaling between neurons and oligodendrocytes has been reported (Fr€ uhbeis et al, 2013;Hines et al, 2015;Koudelka et al, 2016;Mensch et al, 2015;Wake et al, 2015;Wake, Lee, & Fields, 2011), the exact signaling events underlying activity-dependent regulation of myelination are still unknown.…”

Mechanical plasticity during oligodendrocyte differentiation and myelination

“…The lack of robust in vitro CNS myelination models has led to the development and optimization of microfluidic‐based compartmentalized culture systems to achieve segregation of neuron and OL cell bodies while simultaneously allowing the formation of myelin sheaths (Kerman et al, ; Park, Koito, Li, & Han, 2009a, 2009b, 2012). Interestingly, some microfluidic systems have included electrical stimulation to achieve increased levels of myelination (Lee et al, ; Yang et al, ). Altogether, microfluidic cell culture systems have become an important platform for studying development, function and de(re)generation of the nervous system at the molecular and cellular level.…”

Myelin development, plasticity, and pathology in the auditory system

“…How might auditory experience influence myelin in the auditory system? Neuronal activity has been shown to promote both oligodendrocyte progenitors cell proliferation and myelin formational along axons (Barres and Raff, 1993;Demerens et al, 1996;Wake et al, 2011;Gibson et al, 2014;Mensch et al, 2015;Lee et al, 2016). Activity may regulate myelin formation by inducing the release of various neuronally derived factors that act on oligodendrocytes to promote myelin development.…”