COMPARTMENTALIZED CELL-TO-CELL COMMUNICATION
The function and response of neural tissues rely upon cell to cell communication achieved via synaptic and cytoplasmic connectivity. The complex network of axonal extensions and positioning in the NS produces compartmentalized signaling, where communicating cells are not proximal to one another. Micro and nanofluidic tools provide newfound abilities to interrogate these mechanisms of communication to enrich neuro-repair.
Nanoscale interactions between cells and extracellular signaling molecules are essential elements of numerous biological processes. Neuronal interactions with their neighbors are limited to diffusive or convective solute transport within a micro/nanofluidic space and direct communication via ion channels and gap junctions. The Vaz Lab has developed a Macro-micro-nanofluidic system, called the MuN, to examine nanoscale interactions within controlled cellular environments1. Our work has used the system to measure the release and diffusion of purinergic signals from motor neurons, over time, in response to controlled extrinsic stimuli. We have further verified gap junctional communication between cells seeded in opposite compartments of the MuN device over several days. This contribution was noteworthy because we developed the first nanofluidic system that facilitates real-time observation of cell to cell communication between groups in distinct, but fluidically coupled regions. In addition, our device’s the range of geometric scales enables insight into downstream cell behaviors governed by compartmentalized cell communication.
We have applied the MuN system towards the study of bone innervation by first examining bystander signaling from osteocyte cells. Our work showed that heat shock stimulus increased ATP release from osteocytes, but not from motor neurons. Most significantly, our results illustrated that repair was impacted by osteocyte apoptosis‐dependent release of ATP signals through Panx1 channels and activation of purinergic receptors2. This work was an invited presentation at the American Society for Bone Mineral Research and was awarded internal university funding in partnership with the state-funded Nanofabrication Facility in New York, NY.
Figure 4: Cell to cell communication modeled via compartmentalized signaling. (A) Image of the Macro-micro-nanofluidic system (or MuN) comprised of macrosized chemical reservoirs connecting two microfluidic cell compartments that interface via nanofluidic channels. (B) Cell to cell communication between compartments of the MuN enables study and measurement of cell cytoplasmic connections and ion exchange in response to external stimuli (F-actin highlighted). (C) Our current work uses explanted mouse retina to guide modelling of (D) retinal Müller and ganglion cell connectivity within the MuN.(E) Retinal cytoplasmic exchange shown via calcein (Scale:100um).
(i) Visual NS: We have begun to use the MuN system to examine nanocellular communication between retinal neurons and glia in healthy and diseased eye. Our work has shown that Müller glia extend and retract their processes towards retinal ganglion cells in the presence of elevated VEGF3, indicative of damage to the blood retinal barrier. This work is performed in collaboration with Rutgers BME (Dr J. Zahn, Dr. L. Cai).
(ii) Central NS: Our lab is using the MuN system to examine ion channel communication between motor neurons in concert with computational simulations of neuronal response to stress. This work is performed in collaboration with Rutgers BME (Dr. T. Shinbrot) and was a successful Capstone Design project4 currently in preparation for a joint manuscript.
Selected References (Click for Pubmed Access):
McCutcheon S.; Majeska R.; Schaffler M.B.; Vazquez M., 'A multiscale fluidic device for the study of dendrite-mediated cell to cell communication.' Biomed Microdevices 2017, Aug 8;19(3):71.
McCutcheon S.; Majeska, R.; Spray, D.; Schaffler, M.B.; Vazquez, M., 'Apoptotic osteocytes induce RANKL production in bystanders via purinergic signaling and activation of pannexin channels,' J Bone Miner Res. 2020 May;35(5):966-977.
Pena, J.S.; Vazquez, M., VEGF upregulates EGFR expression to stimulate chemotactic behaviors in Müller glia, Brain Sci 2020, 10(6), 330.
Cliver, R.; Vazquez, M.; Shinbrot, T.; ‘Neuronal networks in silico and in vitro’, AXON: Advancing Cross-Disciplinary Outreach in Neuroscience, Rutgers University 5/2020. *Student Conference Winner*