A novel adult neurons screening technology to repurpose FDA-approved drugs for spinal cord injury

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About 1.3 million Americans suffer from paralysis due to spinal cord injury (SCI) costing our economy billions of dollars each year. To date, no FDA-approved therapeutic options exist for SCI, demonstrating the need for new therapeutic options. Reducing neuronal cell death and enhancing regenerative capacities of adult cortical neurons to form connections at different levels of the spinal cord via the corticospinal tract are keys to increasing recovery after SCI. Ideally, candidate therapeutic screenings should be conducted on cortical neural cells (CNCs). However, current screening technologies only utilize embryonic or early post-natal neural cells, which do not represent the SCI patient demographic, majority of whom are either in their 20s or 60s, equivalent to mice of 6 and 18 months of age, respectively. Using neural cells with characteristics that differ from the targeted cells in clinical settings, without taking age into consideration, results in low translational success. Additionally, current screens do not differentiate for sex, while neurological diseases and trauma can be sex dependent (78% of SCI patients are male). Age- and sex-appropriate drug screens have previously not been plausible resulting in false positives and negatives which can explain the failure of many drugs during the clinical phases. Developing a screen taking age and sex as variables would increase the chance of translational success. Our long-term goal is to develop novel therapeutic options that enhance recovery for patients with SCI. The main objective during this proposal is to find new compounds that improve recovery in a pre-clinical mouse model of SCI. A 3-step screening platform using adult sheep and mice CNCs that includes species, age and sex as variables was developed. This is the first screen using CNCs in a high-throughput fashion and the first capable of using brain tissue from large mammals. This technology 1) reduces processing time and animal use while providing a high number of CNCs at increased neuron purity for a cost-effective screen; 2) finds compounds beneficial to adults prematurely dismissed by other screens; and 3) determines the interspecies efficacy of the screened compounds mouse and sheep), increasing the likelihood of being effective in humans. A targeted screen of >1,200 unique compounds was conducted in 2-years-old adult sheep CNCs (identifying drugs in clinical testing for neurological disorders) and in 6 and 18-month-old male/female mice CNCs. 4 positive hits were tested in a mouse model of SCI, 3 promoted functional recovery. This validates the use of this technology to find compounds with pre-clinical efficacy and potential clinical translation. The overarching hypothesis is that screening of approved drugs in adult CNCs from various species, age and sex groups will increase the pre-clinical success rate by 1) uncovering beneficial drugs previously dismissed or untested in conventional screens, and 2) identifying drugs with demographics-independent efficacies. This proposal will screen the L1000 Approved Drug Library (>2,800 drugs) to find 4 leads (Aim 1) and determine their efficacy in promoting functional recovery in a clinically relevant mouse model of SCI (Aim 2). At the end of the studies, at least one novel drug enhancing recovery will be uncovered. Future studies will include understanding the cellular and molecular mechanisms of the drug and gathering IND-enabling data for future clinical testing in the ever-aging SCI population.