The overall goal of this proposal is to improve the chronic performance of intracortical recording microelectrodes using a targeted drug-delivery approach. Microelectrode-based devices have the potential to resolve many challenges in rehabilitation for Veterans with paralysis and/or amputation. Notably, brain-computer interface (BCI) endeavors within the VA have provided patients the ability to control electromechanical or neuromuscular prostheses using ?thoughts? or signals from their motor cortex. BCIs are further being extended by researchers at the VA to restore the sensation of touch by integrating sensors and stimulators into mechanical prosthetic limbs.3-5 While the promises of intracortical microelectrode interfaces are significant, the devices suffer from a key challenge: long term stability and functionality. The failure modes are multifaceted, but a substantial component is attributed to vascular trauma from implantation that initiates bleeding and a prolonged biological response, including inflammation which leads to significant reduction in healthy neurons near recording contacts. Several FDA-approved drugs have demonstrated the ability to reduce the biological inflammatory response and augment microelectrode recording performance in rodents. However, due to limitations of pharmacokinetics and pharmacodynamics, most of the agents reach the implant site in relatively low concentrations, limiting the magnitude of effect and/or requiring frequent dosages to attain meaningful results. Additionally, in the case of steroids and antibiotics, long-term systemic administration is contraindicated due to side effects on peripheral systems. Leveraging a platelet-inspired drug delivery platform currently undergoing commercialization, we have engineered a method for targeting drugs specifically to the microelectrode implantation site. Localizing the drug to the microelectrode site will reduce the systemically administered dose, while minimizing the payload delivered to peripheral organs, e.g., liver and kidneys. During this study, we will focus on delivering the drug, dexamethasone (Dex), which is a potent glucocorticoid steroidal anti-inflammatory drug. While we have demonstrated the ability to target the microelectrode with drug-loaded nanoparticles, further optimization of dosing with Dex and characterization of chronic recordings are needed. Our objective is to establish a safe and effective drug-delivery platform for localized therapy to improve chronic BCI performance. We hypothesize that administration of targeted dexamethasone-loaded nanoparticles (Dex-NPs) will prevent chronic scarring and neurodegeneration associated with improved chronic recording quality of intracortical microelectrodes and associated motor-behavioral function. If proven effective, the platform may be further developed and characterized to release other pharmaceutical payloads that have unique or complementary effects on the system. Additionally since the delivery platform is being commercialized, there is increased potential for scaling the technology to human application.
Implanted medical devices in the central nervous system (CNS) are used for a number of current and future applications including control of tremor (Parkinson?s disease, ~60,000 Veterans?), pain block/relief (chronic pain, >30 million US?), shunting cerebrospinal fluid (hydrocephalous, ~24,000 Veterans?), and brain-controlled prostheses (spinal cord injury paralysis, ~50,000 Veterans?), among others (?: prevalence). Chronic inflammation may reduce the longevity and performance of CNS-implanted devices. The proposed research plan focuses on advancing one such technology, intracortical microelectrodes for brain-computer interface (BCI) controlled prostheses, which are particularly sensitive to inflammation. The project seeks to mitigate the inflammatory response to enable long-term use of BCI microelectrodes to restore functional limb movement and improve quality of life for paralyzed Veterans.
