Screening for Anti-Epileptic Compounds with an in vitro Epilepsy Model based on the human iPSC-Derived microBrain® 3D Platform
With over 50 million sufferers worldwide, epilepsy is one of the most prevalent neurological disorders. All anti-epileptic dugs (AEDs) developed to date only treat symptoms, with little to no effect on the underlying disease mechanisms or co-morbidities, and carry significant risk for adverse effects. Moreover, up to one-third of all epileptic patients are refractory to AEDs. As such, there is an urgent demand and significant unmet medical need for more effective and safer AEDs. Towards that end, we set out to develop an in vitro epilepsy model based on the StemoniX human induced pluripotent stem cell (iPSC)-derived microBrain® 3D Platform. The microBrain 3D 384-well screening plates contain neural spheroids comprised of a physiologically relevant mixture of astrocytes and cortical neurons from a single human donor source of iPSCs. The homogeneous spheroids show large, consistent, spontaneous and synchronous calcium oscillations, and are responsive to a variety of pharmacological neuromodulators. For epilepsy drug screening, the microBrain 3D spheroids were first characterized with known neuromodulators and AEDs alone. Next, a collection of 120 targeted Pairnomix proprietary compounds was used. These compounds were selected based on their demonstrated ability to modulate the in vitro activity of ion channels implicated in epilepsy. The library comprises compounds with different mechanism of actions: sodium channel inhibitors, potassium channel activators, GABAA channel activators, and glutamate channel inhibitors. This 120 drug panel was screened against the microBrain 3D platform, at 3 different concentrations (0.1, 1, 10 µM). Synchronous, large calcium oscillations were inhibited over 40% by 72 of the 120 compounds, consistent with their known ion channel activity and potential as novel AEDs. The assay also showed a large dynamic range, with 36 compounds reaching over 99% inhibition in a concentration-dependent fashion. None of the test compounds demonstrated toxicity as neuronal activity recovered upon washout and there was no change in the fine structure of the spheroids. Finally, the microBrain 3D platform generated remarkably consistent and reproducible results, displaying minimal variability across wells and plate replicates. These results suggest that the microBrain 3D platform is a useful and robust cell-based platform for high-throughput drug screening.