Despite tremendous advances in fundamental neuroscience research, the success rate of neuroscience drug discovery has been disappointingly low. Among potential factors contributing to this unfortunate situation is the reality that fairly simplistic conditions of in vitro assays do not reflect the exquisite complexity of the brain. For example, the brain constantly receives signals from the world surrounding us, and controls the functions of many organs after processing of these signals. Yet, typical in vitro assays often do not incorporate any external signals dynamically activating neurons during drug screening, and instead novel drug candidates for neurological disorders are being routinely evaluated based on their effects on either spontaneous neuronal activity or in end-point assays. Advanced in vitro assays have started incorporating cell stimulation capabilities to address this critical shortcoming. However, existing cell stimulation technologies have some inherent shortcomings that might affect the drug screening results in an unpredictable way. For example, optogenetics requires to genetically change neurons by expressing exogenous light-sensitive ion channels to make neurons fit to be optically stimulated. In addition to being time- and expense- consuming, genetic modifications purely for the sake of the cell stimulation capability are especially not desirable in hIPSC- based neurological disease models, because they might change the model itself. We have recently developed a pioneering optical stimulation platform that do not require genetic modifications of neurons, and, thus, can provide enormous advantages when hIPSC-based disease models are used in drug screening assays. Our platform is based on our breakthrough graphene-mediated optical stimulation (GraMOS) technology that takes advantage of unique optoelectronic properties of graphene materials and provides non-invasive modulation of the cell activity via an external light-controlled electrical field near the graphene-neuron biointerface. Here we are proposing to integrate our GraMOS technology into drug screening assays for neuroscience drug discovery. We will use 2-D and 3-D hiPSC-based models generated from patients carrying mutations, known to alter the neuronal activity such as the lack of MECP2 gene. For classical 2-D models, we will fabricate graphene-based substrates to enable optical activation of neurons via the bottoms of specialized cell culture plates. We will proceed with the development of all-optical assays that combine GraMOS-enable optical stimulation with recordings of the neuronal activity using fluorescent indicators. To evaluate the synaptic connectivity of neuronal networks, we will develop patterned graphene substrates to be able to selective stimulate only a subset of neurons interfacing with G-substrates. In 3-D models, such as neuronal spheroids and brain cortical organoids, we will evaluate the functional neuronal activity by either using all-optical GraMOS-enabled assays or combining GraMOS with MEA-based recording of extracellular electric activity. GraMOS- enabled assays will be validated using benchmark compounds affecting synaptic transmission and neuronal excitability. The proposed non-genetic optical stimulation technology is expected to dramatically enhance translational neuroscience studies and support the discovery of neurological drugs with novel mechanism of actions.
The quest for enhanced understanding the brain function and predictive drug discovery for neurological disorders requires advanced technological tools that can probe and modulate the activity of neural networks without interfering with their genetic identity. To address this need and make neuroscience drug discovery process more predictive, we are proposing to develop a novel nanotechnology-based platform for optical stimulation of genetically intact neurons and incorporate it into the next generation drug screening assays. The proposed study will result in tremendous technological benefits to fundamental and translational studies that are probing the synaptic connectivity of neuronal networks in health and disease and striving to discover new drugs for a wide range of neurological disorders.
