Resected hippocampal tissue from patients with drug-resistant epilepsy presents a unique possibility to test novel treatment strategies directly in target tissue. The post-resection time for testing and analysis however is normally limited. Acute tissue slices allow for electrophysiological recordings typically up to 12 hours. To enable longer time to test novel treatment strategies such as, e.g., gene-therapy, we developed a method for keeping acute human brain slices viable over a longer period. Our protocol keeps neurons viable well up to 48 hours. Using a dual-flow chamber, which allows for microscopic visualisation of individual neurons with a submerged objective for whole-cell patch-clamp recordings, we report stable electrophysiological properties, such as action potential amplitude and threshold during this time. We also demonstrate that epileptiform activity, monitored by individual dentate granule whole-cell recordings, can be consistently induced in these slices, underlying the usefulness of this methodology for testing and/or validating novel treatment strategies for epilepsy.