Kenneth P. Greenberg - US grants

[unreadable] DESCRIPTION (provided by applicant): We propose to impart light sensitivity directly onto normally non-photosensitive neurons in a diseased retina. While inherited retinal degenerations have many genetic causes at their source, one common theme is the eventual apoptotic death of photoreceptor cells. In most cases, the remaining inner retinal neurons survive long after rods and cones are lost. Central to our goal is the use of novel rhodopsins that allow for precise optical control of neural activity with visible light. Channelrhodopsin-2 is a photosensitive cation channel that allows for neural excitation in response to blue light. A functional converse is Halorhodopsin, a photo- sensitive chloride pump that silences neural activity with yellow light. These rhodopsins use retinoids as their chromophore and directly modulate activity without accessory protein cascades or exogenous chemicals. We hypothesize that if initiated in the appropriate cell subtype, light-driven excitation and inhibition may re- create the ON and OFF-center visual information streams normally present in the retina. These parallel information streams are largely responsible for allowing contrast sensitivity and high acuity. Specific delivery to the desired ON or OFF-center cell population is not trivial, and we propose to approach this by a combination of transcriptional targeting along with viral gene transfer methods. Patch clamp electrophysiology combined with raster scanning stimuli will be integral to the project for both evaluating the specificity of transgene targeting and in characterizing the photocurrents generated from networks of these neurons. Finally, we hope to understand if a photosensitive inner retina can transmit functional information to higher visual centers in a disease model with simple behavioral tools. Using these combined neuroengineering and electrophysiological approaches, we aim to determine if selective photo-excitation and inhibition of ON and OFF pathway inner neurons can confer useful light sensitivity to the injured retina. PUBLIC HEALTH RELEVANCE: Gene therapy is a highly promising method for attempting to restore vision in diseases that cause photoreceptor loss, and imparting light sensitivity directly to surviving retinal neurons may be one approach. We hope to understand the potential for converting non-photosensitive neurons into photosensors and apply this knowledge toward the future development of a retinal prosthetic. [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Eos Neuroscience, Inc., in collaboration with the company's academic partners, is developing a novel technology combining gene therapeutics and optical neuromodulation techniques to enable a potential therapy for neuropathic pain. It is the hope of our company that this technology will be widely applicable and available to individuals in the United States and worldwide that suffer from debilitating chronic pain. In brief, Eos Neuroscience, Inc. is creating a technology that will restore inhibition to hyperactive neurons in the dorsal root ganglion (DRG) with fiber optic illumination. To this end, we are developing a targeted delivery mechanism using an adeno-associated virus (AAV) that is proven effective at delivering genes into DRG. We will use this mechanism to target a photosensitive inhibitory proton pump, into the nociceptive DRG neurons and study the immunohistochemical localization of our transgene and physiology of these transduced DRG. The goal of this Phase I project is to characterize the targeting efficiency and specificity with which we can deliver our transgene to nociceptive DRG neurons using ubiquitous and cell specific promoters. We will then perform electrophysiology to characterize the light driven inhibitory responses in transduced DRG neurons to determine the efficacy with which we can silence spontaneous hyperactivity. We have started this testing in rats and will continue to evaluate both vector targeting and physiological measures. Accordingly, we propose the following specific aims for our SBIR Phase I project: 1) Design and construct AAV vectors using well-characterized promoters, for specific expression of an optical silencer in nociceptive neurons of the DRG, 2) Deliver AAV vectors via intrathecal injection to rodent DRG and evaluate targeting specificity and toxicity via Immunohistochemistry, and 3) Characterize the optical silencing capability of these AAV vectors in DRG using cell attached and whole cell intracellular recording. We are very enthusiastic that results obtained from this Phase I study will enable us to submit a Phase II with the eventual goal of a clinical therapeutic product. PUBLIC HEALTH RELEVANCE: Pain is a major health problem, with 290 million people suffering worldwide and 86 million in the US. Current therapeutic approaches (e.g., pharmacological, surgical, electrical stimulation and physical rehabilitation therapy) generally fail to target pain pathways selectively, resulting in undesired side effects that can significantly impair physical and mental ability and may include central nervous system depression, cognitive dysfunction, blockade of motor neurons, and weakness. To this end, Eos Neuroscience, Inc. and academic partners will establish a gene therapy based technology that can be applied broadly using a light sensitive protein to silence pain sensation directly in sensory neurons of patients suffering from chronic pain.