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Chong HK, Ma Z, Wong KKC, Morokoff A, French C. An In Vitro Brain Tumour Model in Organotypic Slice Cultures Displaying Epileptiform Activity. Brain Sci 2023; 13:1451. [PMID: 37891819 PMCID: PMC10605659 DOI: 10.3390/brainsci13101451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 10/04/2023] [Accepted: 10/07/2023] [Indexed: 10/29/2023] Open
Abstract
Brain tumours have significant impacts on patients' quality of life, and current treatments have limited effectiveness. To improve understanding of tumour development and explore new therapies, researchers rely on experimental models. However, reproducing tumour-associated epilepsy (TAE) in these models has been challenging. Existing models vary from cell lines to in vivo studies, but in vivo models are resource-intensive and often fail to mimic crucial features like seizures. In this study, we developed a technique in which normal rat organotypic brain tissue is implanted with an aggressive brain tumour. This method produces a focal invasive lesion that preserves neural responsiveness and exhibits epileptiform hyperexcitability. It allows for real-time imaging of tumour growth and invasion for up to four weeks and microvolume fluid sampling analysis of different regions, including the tumour, brain parenchyma, and peritumoral areas. The tumour cells expand and infiltrate the organotypic slice, resembling in vivo behaviour. Spontaneous seizure-like events occur in the tumour slice preparation and can be induced with stimulation or high extracellular potassium. Furthermore, we assess extracellular fluid composition in various regions of interest. This technique enables live cell confocal microscopy to record real-time tumour invasion properties, whilst maintaining neural excitability, generating field potentials, and epileptiform discharges, and provides a versatile preparation for the study of major clinical problems of tumour-associated epilepsy.
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Affiliation(s)
- Harvey K. Chong
- Neural Dynamics Laboratory, Department of Medicine, University of Melbourne, Melbourne, VIC 3052, Australia; (H.K.C.); (K.K.C.W.); (A.M.); (C.F.)
| | - Ziang Ma
- Neural Dynamics Laboratory, Department of Medicine, University of Melbourne, Melbourne, VIC 3052, Australia; (H.K.C.); (K.K.C.W.); (A.M.); (C.F.)
| | - Kendrew Ka Chuon Wong
- Neural Dynamics Laboratory, Department of Medicine, University of Melbourne, Melbourne, VIC 3052, Australia; (H.K.C.); (K.K.C.W.); (A.M.); (C.F.)
| | - Andrew Morokoff
- Neural Dynamics Laboratory, Department of Medicine, University of Melbourne, Melbourne, VIC 3052, Australia; (H.K.C.); (K.K.C.W.); (A.M.); (C.F.)
- Department of Medicine, Royal Melbourne Hospital, Parkville, Melbourne, VIC 3000, Australia
| | - Chris French
- Neural Dynamics Laboratory, Department of Medicine, University of Melbourne, Melbourne, VIC 3052, Australia; (H.K.C.); (K.K.C.W.); (A.M.); (C.F.)
- Department of Medicine, Royal Melbourne Hospital, Parkville, Melbourne, VIC 3000, Australia
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Hongo Y, Takasu K, Ikegaya Y, Hasegawa M, Sakaguchi G, Ogawa K. Heterogeneous effects of antiepileptic drugs in an in vitro epilepsy model--a functional multineuron calcium imaging study. Eur J Neurosci 2015; 42:1818-29. [PMID: 25967117 DOI: 10.1111/ejn.12945] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/28/2015] [Accepted: 05/06/2015] [Indexed: 01/17/2023]
Abstract
Epilepsy is a chronic brain disease characterised by recurrent seizures. Many studies of this disease have focused on local neuronal activity, such as local field potentials in the brain. In addition, several recent studies have elucidated the collective behavior of individual neurons in a neuronal network that emits epileptic activity. However, little is known about the effects of antiepileptic drugs on neuronal networks during seizure-like events (SLEs) at single-cell resolution. Using functional multineuron Ca(2+) imaging (fMCI), we monitored the activities of multiple neurons in the rat hippocampal CA1 region on treatment with the proconvulsant bicuculline under Mg(2+) -free conditions. Bicuculline induced recurrent synchronous Ca(2+) influx, and the events were correlated with SLEs. Other proconvulsants, such as 4-aminopyridine, pentetrazol, and pilocarpine, also induced synchronous Ca(2+) influx. We found that the antiepileptic drugs phenytoin, flupirtine, and ethosuximide, which have different mechanisms of action, exerted heterogeneous effects on bicuculline-induced synchronous Ca(2+) influx. Phenytoin and flupirtine significantly decreased the peak, the amount of Ca(2+) influx and the duration of synchronous events in parallel with the duration of SLEs, whereas they did not abolish the synchronous events themselves. Ethosuximide increased the duration of synchronous Ca(2+) influx and SLEs. Furthermore, the magnitude of the inhibitory effect of phenytoin on the peak synchronous Ca(2+) influx level differed according to the peak amplitude of the synchronous event in each individual cell. Evaluation of the collective behavior of individual neurons by fMCI seems to be a powerful tool for elucidating the profiles of antiepileptic drugs.
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Affiliation(s)
- Yoshie Hongo
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Keiko Takasu
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan.,Center for Information and Neural Networks, Suita City, Osaka, Japan
| | - Minoru Hasegawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Gaku Sakaguchi
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
| | - Koichi Ogawa
- Pain & Neuroscience, Discovery Research Laboratory for Core Therapeutic Areas, Shionogi Co. Ltd., 1-1 Futaba-cho 3-chome, Toyonaka, Osaka, 561-0825, Japan
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What Is the Clinical Relevance of In Vitro Epileptiform Activity? ISSUES IN CLINICAL EPILEPTOLOGY: A VIEW FROM THE BENCH 2014; 813:25-41. [DOI: 10.1007/978-94-017-8914-1_2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Optogenetically induced seizure and the longitudinal hippocampal network dynamics. PLoS One 2013; 8:e60928. [PMID: 23593349 PMCID: PMC3622611 DOI: 10.1371/journal.pone.0060928] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 03/04/2013] [Indexed: 11/19/2022] Open
Abstract
Epileptic seizure is a paroxysmal and self-limited phenomenon characterized by abnormal hypersynchrony of a large population of neurons. However, our current understanding of seizure dynamics is still limited. Here we propose a novel in vivo model of seizure-like afterdischarges using optogenetics, and report on investigation of directional network dynamics during seizure along the septo-temporal (ST) axis of hippocampus. Repetitive pulse photostimulation was applied to the rodent hippocampus, in which channelrhodopsin-2 (ChR2) was expressed, under simultaneous recording of local field potentials (LFPs). Seizure-like afterdischarges were successfully induced after the stimulation in both W-TChR2V4 transgenic (ChR2V-TG) rats and in wild type rats transfected with adeno-associated virus (AAV) vectors carrying ChR2. Pulse frequency at 10 and 20 Hz, and a 0.05 duty ratio were optimal for afterdischarge induction. Immunohistochemical c-Fos staining after a single induced afterdischarge confirmed neuronal activation of the entire hippocampus. LFPs were recorded during seizure-like afterdischarges with a multi-contact array electrode inserted along the ST axis of hippocampus. Granger causality analysis of the LFPs showed a bidirectional but asymmetric increase in signal flow along the ST direction. State space presentation of the causality and coherence revealed three discrete states of the seizure-like afterdischarge phenomenon: 1) resting state; 2) afterdischarge initiation with moderate coherence and dominant septal-to-temporal causality; and 3) afterdischarge termination with increased coherence and dominant temporal-to-septal causality. A novel in vivo model of seizure-like afterdischarge was developed using optogenetics, which was advantageous in its reproducibility and artifact-free electrophysiological observations. Our results provide additional evidence for the potential role of hippocampal septo-temporal interactions in seizure dynamics in vivo. Bidirectional networks work hierarchically along the ST hippocampus in the genesis and termination of epileptic seizures.
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