Investigating the Therapeutic Mechanism of Cannabidiol in a Human Induced Pluripotent Stem Cell (iPSC)-Based Model of Dravet Syndrome

Human In Vitro Models of Epilepsy Using Embryonic and Induced Pluripotent Stem Cells

The challenges in making animal models of complex human epilepsy phenotypes with varied aetiology highlights the need to develop alternative disease models that can address the limitations of animal models by effectively recapitulating human pathophysiology. The advances in stem cell technology provide an opportunity to use human iPSCs to make disease-in-a-dish models. The focus of this review is to report the current information and progress in the generation of epileptic patient-specific iPSCs lines, isogenic control cell lines, and neuronal models. These in vitro models can be used to study the underlying pathological mechanisms of epilepsies, anti-seizure medication resistance, and can also be used for drug testing and drug screening with their isogenic control cell lines.

A nutraceutical product, extracted from Cannabis sativa, modulates voltage-gated sodium channel function

Background

Purified cannabidiol (CBD), a non-psychoactive phytocannabinoid, has gained regulatory approval to treat intractable childhood epilepsies. Despite this, artisanal and commercial CBD-dominant hemp-based products continue to be used by epilepsy patients. Notably, the CBD doses used in these latter products are much lower than that found to be effective in reducing seizures in clinical trials with purified CBD. This might be because these CBD-dominant hemp products contain other bioactive compounds, including phytocannabinoids and terpenes, which may exert unique effects on epilepsy-relevant drug targets. Voltage-gated sodium (Na_V) channels are vital for initiation of neuronal action potential propagation and genetic mutations in these channels result in epilepsy phenotypes. Recent studies suggest that Na_V channels are inhibited by purified CBD. However, the effect of cannabis-based products on the function of Na_V channels is unknown.

Methods

Using automated-planar patch-clamp technology, we profile a hemp-derived nutraceutical product (NP) against human Na_V1.1–Na_V1.8 expressed in mammalian cells to examine effects on the biophysical properties of channel conductance, steady-state fast inactivation and recovery from fast inactivation.

Results

NP modifies peak current amplitude of the Na_V1.1–Na_V1.7 subtypes and has variable effects on the biophysical properties for all channel subtypes tested. NP potently inhibits Na_V channels revealing half-maximal inhibitory concentration (IC₅₀) values of between 1.6 and 4.2 μg NP/mL. Purified CBD inhibits Na_V1.1, Na_V1.2, Na_V1.6 and Na_V1.7 to reveal IC₅₀ values in the micromolar range. The CBD content of the product equates to IC₅₀ values (93–245 nM), which are at least an order of magnitude lower than purified CBD. Unlike NP, hemp seed oil vehicle alone did not inhibit Na_V channels, suggesting that the inhibitory effects of NP are independent of hemp seed oil.

Conclusions

This CBD-dominant NP potently inhibits Na_V channels. Future study of the individual elements of NP, including phytocannabinoids and terpenes, may reveal a potent individual component or that its components interact to modulate Na_V channels.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42238-022-00136-x.

In Vitro Studies on Therapeutic Effects of Cannabidiol in Neural Cells: Neurons, Glia, and Neural Stem Cells

(‒)-Cannabidiol (CBD) is one of the major phytocannabinoids extracted from the Cannabis genus. Its non-psychoactiveness and therapeutic potential, partly along with some anecdotal—if not scientific or clinical—evidence on the prevention and treatment of neurological diseases, have led researchers to investigate the biochemical actions of CBD on neural cells. This review summarizes the previously reported mechanistic studies of the CBD actions on primary neural cells at the in vitro cell-culture level. The neural cells are classified into neurons, microglia, astrocytes, oligodendrocytes, and neural stem cells, and the CBD effects on each cell type are described. After brief introduction on CBD and in vitro studies of CBD actions on neural cells, the neuroprotective capability of CBD on primary neurons with the suggested operating actions is discussed, followed by the reported CBD actions on glia and the CBD-induced regeneration from neural stem cells. A summary section gives a general overview of the biochemical actions of CBD on neural cells, with a future perspective. This review will provide a basic and fundamental, but crucial, insight on the mechanistic understanding of CBD actions on neural cells in the brain, at the molecular level, and the therapeutic potential of CBD in the prevention and treatment of neurological diseases, although to date, there seem to have been relatively limited research activities and reports on the cell culture-level, in vitro studies of CBD effects on primary neural cells.

Screening Platforms for Genetic Epilepsies-Zebrafish, iPSC-Derived Neurons, and Organoids

Recent advances in molecular and cellular engineering, such as human cell reprogramming, genome editing, and patient-specific organoids, have provided unprecedented opportunities for investigating human disorders in both animals and human-based models at an improved pace and precision. This progress will inevitably lead to the development of innovative drug-screening platforms and new patient-specific therapeutics. In this review, we discuss recent advances that have been made using zebrafish and human-induced pluripotent stem cell (iPSC)-derived neurons and organoids for modeling genetic epilepsies. We also provide our prospective on how these models can potentially be combined to build new screening platforms for antiseizure and antiepileptogenic drug discovery that harness the robustness and tractability of zebrafish models as well as the patient-specific genetics and biology of iPSC-derived neurons and organoids.

A Review of Hemp as Food and Nutritional Supplement

The term "hemp" refers to Cannabis sativa cultivars grown for industrial purposes that are characterized by lower levels of tetrahydrocannabinol (THC), the active principle responsible for Cannabis psychotropic effects. Hemp is an extraordinary crop, with enormous social and economic value, since it can be used to produce food, textiles, clothing, biodegradable plastics, paper, paint, biofuel, and animal feed, as well as lighting oil. Various parts of the hemp plant represent a valuable source of food and ingredients for nutritional supplements. While hemp inflorescence is rich in nonpsychoactive, yet biologically active cannabinoids, such as cannabidiol (CBD), which exerts potent anxiolytic, spasmolytic, as well as anticonvulsant effects, hempseed has a pleasant nutty taste and represents a valuable source of essential amino acids and fatty acids, minerals, vitamins, and fibers. In addition, hempseed oil is a source of healthy polyunsaturated fatty acids, and hemp sprouts are rich in antioxidants. This review article aims to provide a comprehensive outlook from a multidisciplinary perspective on the scientific evidence supporting hemp beneficial properties when consumed as food or supplement. Marketing of hemp-derived products is subjected to diversified and complex regulations worldwide for several reasons, including the fact that CBD is also the active principal of pharmaceutical agents and that regulatory bodies in some cases ban Cannabis inflorescence regardless of its THC content. Some key regulatory aspects of such a complex scenario are also analyzed and discussed in this review article.

Personalized Medicine Using Cutting Edge Technologies for Genetic Epilepsies

Epilepsy is the most common chronic neurologic disorder in the world, affecting 1-2% of the population. Besides, 30% of epilepsy patients are drug-resistant. Genomic mutations seem to play a key role in its etiology and knowledge of strong effect mutations in protein structures might improve prediction and the development of efficacious drugs to treat epilepsy. Several genetic association studies have been undertaken to examine the effect of a range of candidate genes for resistance. Although, few studies have explored the effect of the mutations into protein structure and biophysics in the epilepsy field. Much work remains to be done, but the plans made for exciting developments will hold therapeutic potential for patients with drug-resistance. In summary, we provide a critical review of the perspectives for the development of individualized medicine for epilepsy based on genetic polymorphisms/mutations in light of core elements such as transcriptomics, structural biology, disease model, pharmacogenomics and pharmacokinetics in a manner to improve the success of trial designs of antiepileptic drugs.

Great Expectations: Induced pluripotent stem cell technologies in neurodevelopmental impairments

Somatic cells such as skin fibroblasts, umbilical cord blood, peripheral blood, urinary epithelial cells, etc., are transformed into induced pluripotent stem cells (iPSCs) by reprogramming technology, a milestone in the stem-cell research field. IPSCs are similar to embryonic stem cells (ESCs), exhibiting the potential to differentiate into various somatic cells. Still, the former avoid problems of immune rejection and medical ethics in the study of ESCs and clinical trials. Neurodevelopmental disorders are chronic developmental brain dysfunctions that affect cognition, exercise, social adaptability, behavior, etc. Due to various inherited or acquired causes, they seriously affect the physical and psychological health of infants and children. These include generalized stunting / mental disability (GDD/ID), Epilepsy, autism spectrum disease (ASD), and attention deficit hyperactivity disorder (ADHD). Most neurodevelopmental disorders are challenging to cure. Establishing a neurodevelopmental disorder system model is essential for researching and treating neurodevelopmental disorders. At this stage, the scarcity of samples is a bigger problem for studying neurological diseases based on the donor, ethics, etc. Some iPSCs are reprogrammed from somatic cells that carry disease-causing mutations. They differentiate into nerve cells by induction, which has the original characteristics of diseases. Disease-specific iPSCs are used to study the mechanism and pathogenesis of neurodevelopmental disorders. The process provided samples and the impetus for developing drugs and developing treatment plans for neurodevelopmental disorders. Here, this article mainly introduced the development of iPSCs, the currently established iPSCs disease models, and artificial organoids related to neurodevelopmental impairments. This technology will promote our understanding of neurodevelopmental impairments and bring great expectations to children with neurological disorders.

Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies

The pathological alterations that manifest during the early embryonic development due to inherited and acquired factors trigger various neurodevelopmental disorders (NDDs). Besides major NDDs, there are several rare NDDs, exhibiting specific characteristics and varying levels of severity triggered due to genetic and epigenetic anomalies. The rarity of subjects, paucity of neural tissues for detailed analysis, and the unavailability of disease-specific animal models have hampered detailed comprehension of rare NDDs, imposing heightened challenge to the medical and scientific community until a decade ago. The generation of functional neurons and glia through directed differentiation protocols for patient-derived iPSCs, CRISPR/Cas9 technology, and 3D brain organoid models have provided an excellent opportunity and vibrant resource for decoding the etiology of brain development for rare NDDs caused due to monogenic as well as polygenic disorders. The present review identifies cellular and molecular phenotypes demonstrated from patient-derived iPSCs and possible therapeutic opportunities identified for these disorders. New insights to reinforce the existing knowledge of the pathophysiology of these disorders and prospective therapeutic applications are discussed.

Role of marijuana components on the regenerative ability of stem cells

Stem cell therapy promotes tissue regeneration and wound healing. Efforts have been made to prime stem cells to enhance their regenerative abilities. Certain marijuana components, namely the non-psychoactive cannabidiol (CBD) and psychoactive tetrahydrocannabinol (THC), are defined as immunomodulators.⁹ We test whether two sources of stem cells, primed with CBD or THC, would demonstrate improved regenerative abilities. Human adipose-derived stem cells (ASCs) and bone marrow-derived stem cells (BMDSCs), not obtained from the same individual, were treated with low (300 nM) or high (3 μM) concentration CBD. Porcine ASCs and BMDSCs were isolated from a single pig, and treated with either low or high concentrations of CBD or THC. Transwell migration and MTT proliferation assays were performed on the human ASCs and BMDSCs. Also, transwell migration assay was performed on the porcine ASCs and BMDSCs. Finally, a wound healing scratch assay in porcine primary fibroblasts (PFs) was performed, co-cultured with the cannabinoid-treated ASCs. CBD priming at low concentration induces migration by 180% (P < .01) in porcine ASCs, and by only 93% (P < .02) in porcine BMDSCs. In porcine stem cells, THC priming at low concentration induces migration by 91.6% (P < .01) in ASCs but by only 44.3% (P < .03) in BMDSCs. Compared to PFs co-cultured with untreated ASCs, PFs co-cultured with low CBD-primed ASCs had 75% faster wound closure at 18 hours (P < .01). CBD and THC priming of ASCs and BMDSCs, particularly at lower doses, enhances a number of regenerative parameters, suggesting that these major marijuana components may improve stem cell-based therapies. SIGNIFICANCE OF THE STUDY: Our study demonstrates that cannabinoids can enhance the regenerative capacity of two major sources of stem cells, adipose- and bone marrow-derived, from human and porcine donors. Stem cell isolation and expansion is invasive, costly and time consuming. Stem cells with improved regenerative properties may be effective in the treatment of acute or chronic wounds. This is the first study to compare the priming potential of two sources of stem cells from the same animal, with the same genetic and epigenetic profile, as well as the first to prime with THC.

Development of cannabidiol as a treatment for severe childhood epilepsies

In recent years, there has been a growing appreciation by regulatory authorities that cannabis-based medicines can play a useful role in disease therapy. Although often conflagrated by proponents of recreational use, the legislative rescheduling of cannabis-derived compounds, such as cannabidiol (CBD), has been associated with the steady increase in the pursuit of use of medicinal cannabis. One key driver in this interest has been the scientific demonstration of efficacy and safety of CBD in randomised, placebo-controlled clinical trials in children and young adults with difficult-to-treat epilepsies, which has encouraged increasing numbers of human trials of CBD for other indications and in other populations. The introduction of CBD as the medicine Epidiolex in the United States (in 2018) and as Epidyolex in the European Union (in 2019) as the first cannabis-derived therapeutic for the treatment of seizures was underpinned by preclinical research performed at the University of Reading. This work was awarded the British Pharmacological Society Sir James Black Award for Contributions to Drug Discovery 2019 and is discussed in the following review article.

Emerging Use of Epidiolex (Cannabidiol) in Epilepsy

The first plant-derived, purified pharmaceutical-grade cannabidiol (CBD) medication, Epidiolex, was approved in the United States by the FDA on June 25, 2018. Its approval for patients ≥ 2 years of age with Dravet syndrome (DS) or Lennox-Gastaut syndrome (LGS) markedly altered the treatment of medically refractory seizures in these disorders. This state-of-the-art review will discuss the history of CBD, its current pharmacology and toxicology, evidence supporting its use in a variety of epileptic syndromes, common side effects and adverse effects, and pharmacokinetically based drug-drug interactions. Owing to the importance in considering side effects, adverse effects, and drug-drug interactions in patients with medically refractory epilepsy syndromes, this review will take a deeper look into the nuances of the above within a clinical context, as compared to the other antiepileptic medications. Furthermore, despite the limited data regarding clinically significant drug-drug interactions, potential pharmacokinetic drug-drug interactions with CBD and other antiepileptics are theorized on the basis of their metabolic pathways. The article will further elucidate future research in terms of long-term efficacy, safety, and drug interactions that is critical to addressing unanswered questions relevant to clinical practice.

Ion Channels Involvement in Neurodevelopmental Disorders

Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.

Progress of Induced Pluripotent Stem Cell Technologies to Understand Genetic Epilepsy

The study of the pathomechanisms by which gene mutations lead to neurological diseases has benefit from several cellular and animal models. Recently, induced Pluripotent Stem Cell (iPSC) technologies have made possible the access to human neurons to study nervous system disease-related mechanisms, and are at the forefront of the research into neurological diseases. In this review, we will focalize upon genetic epilepsy, and summarize the most recent studies in which iPSC-based technologies were used to gain insight on the molecular bases of epilepsies. Moreover, we discuss the latest advancements in epilepsy cell modeling. At the two dimensional (2D) level, single-cell models of iPSC-derived neurons lead to a mature neuronal phenotype, and now allow a reliable investigation of synaptic transmission and plasticity. In addition, functional characterization of cerebral organoids enlightens neuronal network dynamics in a three-dimensional (3D) structure. Finally, we discuss the use of iPSCs as the cutting-edge technology for cell therapy in epilepsy.

Summary: Order and Disorder in Brains and Behavior

The 83rd Cold Spring Harbor Symposium on Quantitative Biology on Brains and Behavior: Order and Disorder in the Nervous System explored the tremendous recent progress in neuroscience and how these advances may be used to improve brain health and address psychiatric and neurological disorders. The Symposium explored a vast array of topics from cell types to cognition. My summary focuses on a few emerging themes. Innovative techniques were ever-present, opening up new experimental possibilities. The commoditization of many state-of-the-art technologies is pushing neuroscience beyond its artisanal ways. Another important theme was "circuits in the middle": Numerous presentations dissected cell type-specific circuits that connect different levels of analysis from molecules to behavior. These new technologies have enabled curiosity-driven investigations in animals to connect more directly with preclinical and clinical studies of human brain disorders. Numerous emerging approaches were presented in human neuroscience, bolstering the hope that circuit-specific manipulations will soon provide improved treatments for brain disorders.