Human Stem Cell-Derived GABAergic Interneurons Establish Efferent Synapses onto Host Neurons in Rat Epileptic Hippocampus and Inhibit Spontaneous Recurrent Seizures

Peimine promotes microglial polarization to the M2 phenotype to attenuate drug-resistant epilepsy through suppressing the TLR4/NF-κB/HIF-1α signaling pathway in a rat model and in BV-2 microglia

Epilepsy is a chronic neurological disorder. Drug-resistant epilepsy (DRE) accounts for about one-third of epilepsy patients worldwide. Peimine, a main active component of Fritillaria, has been reported to show anti-inflammatory effects. However, its potential therapeutic role in DRE is not yet fully understood. In this work, a DRE rat model was established by injecting 1 μg kainic acid (KA), followed by a 250 mg/kg administration of valproic acid (VPA) from day 4-31. Rats were treated with different doses of peimine (2.5 mg/kg, 5 mg/kg and 10 mg/kg) daily from day 32-62. In vitro, BV-2 microglia were exposed to different doses of peimine (7.5 μg/ml, 15 μg/ml, and 30 μg/ml) in presence of LPS. The aim of this study was to investigate the potential therapeutic effects of peimine on DRE. The results showed that peimine efficiently suppressed the KA-induced epileptic behaviors of rats in a dose-dependent manner, as recorded by electroencephalography. Furthermore, peimine ameliorated hippocampal neuron injury in DRE rats, and promoted an M1-to-M2 microglial phenotype shift in a dose-dependent manner. Mechanistically, peimine inhibited the TLR4/NF-κB/HIF-1α signaling pathway both in vivo and in vitro. Additionally, peimine suppressed the apoptosis of primary neurons induced by LPS-treated microglia. In conclusion, peimine augments the microglial polarization towards an M2 phenotype by inhibiting the TLR4/NF-κB/HIF-1α signaling pathway, thereby attenuating DRE.

Updated Toolbox for Assessing Neuronal Network Reconstruction after Cell Therapy

Cell therapy has proven to be a promising treatment for a range of neurological disorders, including Parkinson Disease, drug-resistant epilepsy, and stroke, by restoring function after brain damage. Nevertheless, evaluating the true effectiveness of these therapeutic interventions requires a deep understanding of the functional integration of grafted cells into existing neural networks. This review explores a powerful arsenal of molecular techniques revolutionizing our ability to unveil functional integration of grafted cells within the host brain. From precise manipulation of neuronal activity to pinpoint the functional contribution of transplanted cells by using opto- and chemo-genetics, to real-time monitoring of neuronal dynamics shedding light on functional connectivity within the reconstructed circuits by using genetically encoded (calcium) indicators in vivo. Finally, structural reconstruction and mapping communication pathways between grafted and host neurons can be achieved by monosynaptic tracing with viral vectors. The cutting-edge toolbox presented here holds immense promise for elucidating the impact of cell therapy on neural circuitry and guiding the development of more effective treatments for neurological disorders.

Interneuron Transplantation for Drug-Resistant Epilepsy

Current epilepsy surgical techniques, such as brain resection, laser ablation, and neurostimulation, target seizure networks macroscopically, and they may yield an unfavorable balance between seizure reduction, procedural invasiveness, and neurologic morbidity. The transplantation of GABAergic interneurons is a regenerative technique for altering neural inhibition in cortical circuits, with potential as an alternative and minimally invasive approach to epilepsy treatment. This article (1) reviews some of the preclinical evidence supporting interneuron transplantation as an epilepsy therapy, (2) describes a first-in-human study of interneuron transplantation for epilepsy, and (3) considers knowledge gaps that stand before the effective clinical application of this novel treatment.

Human pallial MGE-type GABAergic interneuron cell therapy for chronic focal epilepsy

Mesial temporal lobe epilepsy (MTLE) is the most common focal epilepsy. One-third of patients have drug-refractory seizures and are left with suboptimal therapeutic options such as brain tissue-destructive surgery. Here, we report the development and characterization of a cell therapy alternative for drug-resistant MTLE, which is derived from a human embryonic stem cell line and comprises cryopreserved, post-mitotic, medial ganglionic eminence (MGE) pallial-type GABAergic interneurons. Single-dose intrahippocampal delivery of the interneurons in a mouse model of chronic MTLE resulted in consistent mesiotemporal seizure suppression, with most animals becoming seizure-free and surviving longer. The grafted interneurons dispersed locally, functionally integrated, persisted long term, and significantly reduced dentate granule cell dispersion, a pathological hallmark of MTLE. These disease-modifying effects were dose-dependent, with a broad therapeutic range. No adverse effects were observed. These findings support an ongoing phase 1/2 clinical trial (NCT05135091) for drug-resistant MTLE.

Molecular and Cellular Mechanisms of Epilepsy

Despite the availability of a large number of antiepileptic drugs, about 30% of patients with epilepsy, especially temporal lobe epilepsy (TLE), continue to experience seizures [...].

Stem Cells: Recent Developments Redefining Epilepsy Therapy

The field of stem cell therapy is growing rapidly and hopes to offer an alternative solution to diseases that are historically treated medically or surgically. One such focus of research is the treatment of medically refractory epilepsy, which is traditionally approached from a surgical or interventional standpoint. Research shows that stem cell transplantation has potential to offer significant benefits to the epilepsy patient by reducing seizure frequency, intensity, and neurological deficits that often result from the condition. This review explores the basic science progress made on the topic of stem cells and epilepsy by focusing on experiments using animal models and highlighting the most recent developments from the last 4 years.

Hippocampal orexin-1 and endocannabinoid-1 receptors underlie the kainate-induced occlusion in theta-burst long- term potentiation

INTRODUCTION

Seizures may result from the hyperexcitable neuronal activity of the brain. Multiple neurotransmitter receptors, including orexin (OX) and endocannabinoids interfere with forming the synaptic responses linked to the seizures. Therefore, this study investigates the involvement of OX-1 (OX1R) and endocannbinoid-1 (CB1R) receptors in the kainate- induced excitability in the synaptic field responses.

MATERIAL AND METHODS

Theta pattern used to stimulate Schaffer collaterals and then metal microelectrodes to record the CA1 field excitatory postsynaptic potentials (fEPSPs). Input/ output stimulation and responses and paired- pulse (PP) stimuli employed to measure the state of synaptic activity in normal and kainate- induced seizure-like hyperexcitable activities and the slope of fEPSPs used as a measure of the change in the synaptic activity. Furthermore, agonists and antagonists of OX and endocannabinoids infused to investigate the involvement of their receptors.

RESULT

The results showed that kainate application increased the fEPSP slope either in input stimuli with different intensities/output synaptic responses (I/O), or test pulse stimulated baseline synaptic responses (BSR) and, hence, increased the excitability of field responses in the CA1 region. However, neither kainate nor theta burst stimulation (TBS) could alter the PP stimuli -induced synaptic responses. TBS increased the fEPSP slope of the kainate-applied I/O and BSR, however, the increase was not high enough in BSR to be classified as long-term potentiation (LTP). The single-antagonist OX1R and CB1R administration prevented TBS- induced potentiation and partially recovered the effect by adding eCB or OX agonists in kainate-injected animals. In contrast, OX or combined eCB-OX antagonist application group demonstrated nearly full recovery of LTP induction.

CONCLUSION

Our study concludes that blockade of OX1 or CB1 prevents the induction of LTP, and OX infusion or both receptor blockade recovers the LTP.

Stem Cell Therapy in Treating Epilepsy

Epilepsy is a common disabling chronic neurological disorder characterized by an enduring propensity for the generation of seizures that result from abnormal hypersynchronous firing of neurons in the brain. Over 20–30% of epilepsy patients fail to achieve seizure control or soon become resistant to currently available therapies. Prolonged seizures or uncontrolled chronic seizures would give rise to neuronal damage or death, astrocyte activation, reactive oxygen species production, and mitochondrial dysfunction. Stem cell therapy is potentially a promising novel therapeutic strategy for epilepsy. The regenerative properties of stem cell-based treatment provide an attractive approach for long-term seizure control, particularly in drug-resistant epilepsy. Embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), neural stem cells (NSCs), induced pluripotent stem cells (iPSCs), and adipose-derived regenerative cells (ADRCs) are capable of differentiating into specialized cell types has been applied for epilepsy treatment in preclinical animal research and clinical trials. In this review, we focused on the advances in stem cell therapy for epilepsies. The goals of stem cell transplantation, its mechanisms underlying graft effects, the types of grafts, and their therapeutic effects were discussed. The cell and animal models used for investigating stem cell technology in epilepsy treatment were summarized.

Regulation of Inhibitory Signaling at the Receptor and Cellular Level; Advances in Our Understanding of GABAergic Neurotransmission and the Mechanisms by Which It Is Disrupted in Epilepsy

Inhibitory signaling in the brain organizes the neural circuits that orchestrate how living creatures interact with the world around them and how they build representations of objects and ideas. Without tight control at multiple points of cellular engagement, the brain’s inhibitory systems would run down and the ability to extract meaningful information from excitatory events would be lost leaving behind a system vulnerable to seizures and to cognitive decline. In this review, we will cover many of the salient features that have emerged regarding the dynamic regulation of inhibitory signaling seen through the lens of cell biology with an emphasis on the major building blocks, the ligand-gated ion channel receptors that are the first transduction point when the neurotransmitter GABA is released into the synapse. Epilepsy association will be used to indicate importance of key proteins and their pathways to brain function and to introduce novel areas for therapeutic intervention.