Abstracts

Rationale: The latent period between brain injury and subsequent epilepsy provides an ideal window for deployment of antiepileptogenic therapy. Unfortunately, the gradual time course of epileptogenesis that provides such a compelling therapeutic window also makes screening antiepileptogenic compounds exceptionally challenging. We developed an organotypic hippocampal slice culture model of post-traumatic epileptogenesis. This model captures key features of epileptogenesis on a compressed time scale of 4 weeks, and enables moderate-throughput screens of candidate antiepileptic compounds.Methods: Organotypic cultures were maintained in six-well plates on a rocking platform in a 37 C, 5% CO2 incubator for four weeks. We developed methods to rapidly assay the levels of epileptiform activity and cell death in organotypic cultures. We found that lactate and lactate dehydrogenase (LDH) levels in culture supernatant are good indicators of seizure activity and neuronal death, respectively. We verified accuracy of lactate and LDH assays with chronic electrical recordings, imaging of dead cells, and morphological analysis of Nissl-stained cultures.Results: We used lactate and LDH assays carry out a medium-throughput screen of drugs for anti-epileptic or neuroprotective effects. We were able to screen more than 50 compounds from a library of FDA-approved drugs in less than four months. Drugs were chosen from anticonvulsant, immunosuppressant, anti-inflammatory, anti-depressant, anti-psychotic, anti-mitotic and diuretic categories. Our findings revealed four candidate drugs from immunosuppressant, anti-inflammatory, and diuretic categories that significantly reduced epileptiform activity or cell death in this in vitro model of post-traumatic epileptogenesis.Conclusions: The rate of 50 compounds screened for anti-epileptogenic properties in four months is at least an order of magnitude improvement over existing methods and models. The organotypic hippocampal culture model of post-traumatic epilepsy, coupled with rapid analyses of biomarkers for epileptiform activity and cell death, comprises a novel, scalable platform for moderate-throughput screens of candidate antiepileptic drugs.