Clinical NeuroscienceAn organotypic brain slice preparation from adult patients with temporal lobe epilepsy

- An organotypic culture preparation of brain tissue from epileptic patients.
- A novel defined culture medium.
- Spontaneous and induced epileptiform activity maintained for 2-4 weeks.

BackgroundA long-term in vitro preparation of diseased brain tissue would facilitate work on human pathologies. Organotypic tissue cultures retain an appropriate neuronal form, spatial arrangement, connectivity and electrical activity over several weeks. However, they are typically prepared with tissue from immature animals. In work using tissue from adult animals or humans, survival times longer than a few days have not been reported and it is not clear that pathological neuronal activities are retained.New methodWe modified tissue preparation procedures and used a defined culture medium to make organotypic cultures of temporal lobe tissue obtained after operations on adult patients with pharmaco-resistant mesial temporal lobe epilepsies.ResultsOrganototypic culture preparation and maintenance techniques were judged on criteria of morphology and the generation of epileptiform activities. Short-duration (30-100 ms) interictal-like population activities were initiated spontaneously in either the subiculum, dentate gyrus or the CA2/CA3 region, but not the cortex, for up to 3-4 weeks in culture. Ictal-like discharges, of duration greater than 10 s, were induced by convulsants. Epileptiform activities were modulated by both glutamatergic and GABAergic receptor antagonists.Comparison with existing methodsOur methods now permit the maintenance in organotypic culture of epileptic adult human tissue, generating appropriate epileptiform activity over 3-4 weeks.ConclusionsWe have shown that characteristic morphology and pathological activities are maintained in organotypic cultures of adult human tissue. These cultures should permit studies on the effects of prolonged drug treatments and long-term procedures such as viral transduction.

Tissue of the hippocampal formation and temporal cortex (A), resected from patients with epilepsies of the temporal lobe was dissected (B) and sliced at 300 μm (C). Slices were cultured on a transwell semi-porous membrane (D) for up to 4 weeks using a new defined culture medium. Morphological (E) and electrophysiological (F) data were used to assess the success of organotypic culture procedures.