Merab Kokaia

Lund University | LU · Department of Clinical Sciences, Lund

The advent of optogenetic tools has had a profound impact on modern neuroscience research, revolutionizing our understanding of the brain. These tools offer a remarkable ability to precisely manipulate specific groups of neurons with an unprecedented level of temporal precision, on the order of milliseconds. This breakthrough has significantly adva...

Gene therapy with AAV vectors carrying genes for neuropeptide Y and its receptor Y2 has been shown to inhibit seizures in multiple animal models of epilepsy. It is however unknown how the AAV serotype or the sequence order of these two transgenes in the expression cassette affects the actual parenchymal gene expression levels and the seizure-suppre...

During epileptic seizures, neuronal network activity is hyper synchronized whereby GABAergic parvalbumin-interneurons may have a key role. Previous studies have mostly utilized 4-aminopyridine to induce epileptiform discharges in brain slices from healthy animals. However, it is not clear if the seizure-triggering ability of parvalbumin-interneuron...

Glial cell line-derived neurotrophic factor (GDNF) has been shown to counteract seizures when overexpressed or delivered into the brain in various animal models of epileptogenesis or chronic epilepsy. The mechanisms underlying this effect have not been investigated. We here demonstrate for the first time that GDNF enhances GABAergic inhibitory driv...

Epilepsy is a severe neurological disease manifested by spontaneous recurrent seizures due to abnormal hyper‐synchronization of neuronal activity. Epilepsy affects about 1% of the population and up to 40% of patients experience seizures that are resistant to currently available drugs, thus highlighting an urgent need for novel treatments. In this r...

Epilepsy is a severe neurological disease characterized by spontaneous recurrent seizures (SRS). A complex pathophysiological process referred to as epileptogenesis transforms a normal brain into an epileptic one. Prevention of epileptogenesis is a subject of intensive research. Currently, there are no clinically approved drugs that can act as prev...

Epilepsy is a complex disorder affecting the central nervous system and is characterised by spontaneously recurring seizures (SRSs). Epileptic patients undergo symptomatic pharmacological treatments, however, in 30% of cases, they are ineffective, mostly in patients with temporal lobe epilepsy. Therefore, there is a need for developing novel treatm...

Gamma-aminobutyric acid (GABA)-releasing interneurons modulate neuronal network activity in the brain by inhibiting other neurons. The alteration or absence of these cells disrupts the balance between excitatory and inhibitory processes, leading to neurological disorders such as epilepsy. In this regard, cell-based therapy may be an alternative the...

Epilepsy is a severe neurological disease manifested by spontaneous recurrent seizures due to abnormal hyper-synchronisation of neuronal activity. Epilepsy affects about 1% of the population and up to 40% of patients experience seizures that are resistant to currently available drugs, thus highlighting an urgent need for novel treatments. In this r...

Gene therapy to treat pharmacoresistant temporal lobe epilepsy in humans is now being developed using an AAV vector (CG01) that encodes the combination of neuropeptide Y and its antiepileptic receptor Y2. With this in mind, the present study aimed to provide important preclinical data on the effects of CG01 on the duration of transgene expression,...

In epilepsy patients, drug-resistant seizures often originate in one of the temporal lobes. In selected cases, when certain requirements are met, this area is surgically resected for therapeutic reasons. We kept the resected tissue slices alive in vitro for 48 h to create a platform for testing a novel treatment strategy based on neuropeptide Y (NP...

In Parkinson's disease, the degeneration of dopaminergic neurons in substantia nigra leads to a decrease in the physiological levels of dopamine in striatum. The existing dopaminergic therapies effectively alleviate the symptoms, albeit they do not revert the disease progression and result in significant adverse effects. Transplanting dopaminergic...

Gene therapy has been suggested as a plausible novel approach to achieve seizure control in patients with focal epilepsy that do not adequately respond to pharmacological treatment. We investigated the seizure-suppressant potential of combinatorial neuropeptide Y and Y2 receptor single vector gene therapy based on adeno-associated virus serotype 1...

Epilepsy is one of the most widespread neurological diseases characterized by spontaneous recurrent seizures. There is no cure for epilepsy, and available pharmacological treatments with anti-seizure drugs are only symptomatic. Moreover, about third of epilepsy patients are resistant to the anti-seizure drugs. Thus, it is essential to discover new...

Seven large European Union (EU)–funded epilepsy‐related research projects joined forces in May 2018 in Brussels, Belgium, in a unique community building event—the epiXchange conference. During this conference, 170 investigators from the projects DESIRE, EpimiRNA, EPISTOP, EpiTarget, EpiXchange, and EpiPGX as well as the European Reference Network E...

Temporal lobe epilepsy (TLE) is the most common type of epilepsy in adults. This neurological disorder is characterized by focal seizures originating in the temporal lobe, often with secondary generalization. A variety of pharmacological treatments exist for patients suffering from focal seizures, but systemically administered drugs offer only symp...

Epilepsy is one of the most devastating neurological diseases and despite significant efforts there is no cure available. Occurrence of spontaneous seizures in epilepsy is preceded by numerous functional and structural pathophysiological reorganizations in the brain—a process called epileptogenesis. Treatment strategies targeting this process may b...

Neurotrophic factors are candidates for treating epilepsy, but their development has been hampered by difficulties in achieving stable and targeted delivery of efficacious concentrations within the desired brain region. We have developed an encapsulated cell technology that overcomes these obstacles by providing a targeted, continuous, de novo synt...

The detailed mechanisms of progressive intensification of seizures often occurring in epilepsy are not well understood. Animal models of kindling, with progressive intensification of stimulation-induced seizures, have been previously used to investigate alterations in neuronal networks, but has been obscured by limited recording capabilities during...

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...

Parvalbumin- (PV-) containing basket cells constitute perisomatic GABAergic inhibitory interneurons innervating principal cells at perisomatic area, a strategic location that allows them to efficiently control the output and synchronize oscillatory activity at gamma frequency (30–90 Hz) oscillations. This oscillatory activity can convert into highe...

Chloride ions play an important role in controlling excitability of principal neurons in the central nervous system. When neurotransmitter GABA is released from inhibitory interneurons, activated GABA type A (GABAA) receptors on principal neurons become permeable to chloride. Typically, chloride flows through activated GABAA receptors into the neur...

Direct conversion of human somatic cells to induced neurons (iNs), using lineage-specific transcription factors has opened new opportunities for cell therapy in a number of neurological diseases, including epilepsy. In most severe cases of epilepsy, seizures often originate in the hippocampus, where populations of inhibitory interneurons degenerate...

Over the past decade, 'optogenetics' has been consolidated as a game-changing tool in the neuroscience field, by allowing optical control of neuronal activity with high cell-type specificity. The ability to activate or inhibit targeted neurons at millisecond resolution not only offers an investigative tool, but potentially also provides a therapeut...

Discovered little more than a decade ago, optogenetics - a revolutionary technique combining genetic and optical methods to observe and control the function of neurons - is now a widely used research tool. Optogenetics-driven research has led to insights into Parkinson's disease and other neurological and psychiatric disorders. With contributions f...

Lack of translation of data obtained in preclinical trials to clinic has kindled researchers to develop new methodologies to increase the power and reproducibility of preclinical studies. One approach relates to harmonization of data collection and analysis, and has been used for a long time in clinical studies testing anti-seizure drugs. EPITARGET...

Epilepsy is a neurological disorder with a prevalence of ≈1% of general population. Available antiepileptic drugs (AEDs) have multiple side effects and are ineffective in 30% of patients. Therefore, development of effective treatment strategies is highly needed, requiring drug-screening models that are relevant and reliable. We investigated novel c...

Over 50 million people worldwide have epilepsy. In nearly 30% of these cases, epilepsy remains unsatisfactorily controlled despite the availability of over 20 antiepileptic drugs. Moreover, no treatments exist to prevent the development of epilepsy in those at risk, despite an increasing understanding of the underlying molecular and cellular pathwa...

Cell replacement therapy in Parkinson's disease still lacks a study addressing the acquisition of electrophysiological properties of human grafted neural stem cells and their relation with the emergence of behavioral recovery after transplantation in the short-term. Here we study the electrophysiological and biochemical profiles of two ventral mese...

Optogenetics is one of the most powerful tools in neuroscience, allowing for selective control of specific neuronal populations in the brain of experimental animals, including mammals. We report, for the first time, the application of optogenetic tools to human brain tissue providing a proof-of-concept for the use of optogenetics in neuromodulation...

Development of novel disease-modifying treatment strategies for neurological disorders, which at present have no cure, represents a major challenge for today's neurology. Translation of findings from animal models to humans represents an unresolved gap in most of the preclinical studies. Gene therapy is an evolving innovative approach that may prov...

The present invention relates to the use of one or more expression vectors comprising certain nucleic acid sequences encoding a combination of NPY and/or one or more of its receptors (Y1, Y2, Y4, Y5, y6), and/or galanin and/or one or more of its receptors (GALR1, GALR2, GALR3), and/or somatostatin and/or one or more of its receptors (SST1, SST2, SS...

Down scaling of microfluidic cell culture and detection devices for electrochemical monitoring is mostly focused on the miniaturization of the microfluidic chips which are often designed for specific applications and therefore they lack functional flexibility. We present a compact microfluidic cell culture and electrochemical analysis platform with...

Optogenetics is a novel technology that combines optics and genetics by optical control of microbial opsins, targeted to living cell membranes. The versatility and the electrophysiologic characteristics of the light-sensitive ion-channels channelrhodopsin-2 (ChR2), halorhodopsin (NpHR), and the light-sensitive proton pump archaerhodopsin-3 (Arch) m...

Reprogramming of somatic cells into pluripotency stem cell state have opened new opportunities in cell replacement therapy and disease modeling in a number of neurological disorders. It still remains unknown, however, to what degree the grafted human induced pluripotent stem cells (hiPSCs) differentiate into a functional neuronal phenotype and if t...

Recent technological advances open exciting avenues for improving the understanding of mechanisms in a broad range of epilepsies. This chapter focuses on the development of optogenetics and on-demand technologies for the study of epilepsy and the control of seizures. Optogenetics is a technique which, through cell-type selective expression of light...

Optogenetic techniques provide powerful tools for bidirectional control of neuronal activity and investigating alterations occurring in excitability disorders, such as epilepsy. In particular, the possibility to specifically activate by light-determined interneuron populations expressing channelrhodopsin-2 provides an unprecedented opportunity of e...

Synchronized activity is common during various physiological operations but can culminate in seizures and consequently in epilepsy in pathological hyperexcitable conditions in the brain. Many types of seizures are not possible to control and impose significant disability for patients with epilepsy. Such intractable epilepsy cases are often associat...

Purpose: Encapsulated cell biodelivery (ECB) is a relatively safe approach, since the devices can be removed in the event of adverse effects. The main objectives of the present study were to evaluate whether ECB could be a viable alternative of cell therapy for epilepsy. We therefore developed a human cell line producing galanin, a neuropeptide th...

There is a pressing need to address the current major gaps in epilepsy treatment, in particular drug-resistant epilepsy, antiepileptogenic therapies, and comorbidities. A major concern in the development of new therapies is that current preclinical testing is not sufficiently predictive for clinical efficacy. Methodologic limitations of current pre...

The search for new treatments for seizures, epilepsies, and their comorbidities faces considerable challenges. This is due in part to gaps in our understanding of the etiology and pathophysiology of most forms of epilepsy. An additional challenge is the difficulty in predicting the efficacy, tolerability, and impact of potential new treatments on e...

Affecting over 1.5 million people across the world, Parkinson's disease is a progressive neurological condition characterized, in part, by the loss of dopaminergic neurons in the substantia nigra pars compacta. It affects 1.5% of the global population over 65 years of age. As life expectancy is increasing, over the next few years the number of pati...

The functional synaptic integration of grafted stem cell-derived neurons is one of the key aspects of neural cell replacement therapies for neurological disorders such as Parkinson's disease. However, little is currently known about the synaptic connectivity between graft and host cells after transplantation, not only in the settings of clinical tr...

The aim of epilepsy treatment is to achieve complete seizure freedom. Nonetheless, numerous side effects and seizure resistance to antiepileptic drugs (AEDs) affecting about 30-40% of all patients are main unmet needs in today's epileptology. For this reason, novel approaches to treat epilepsy are highly needed. Herein, we highlight recent progress...

Understanding the molecular programs of the generation of human dopaminergic neurons (DAn) from their ventral mesencephalic (VM) precursors is of key importance for basic studies, progress in cell therapy, drug screening and pharmacology in the context of Parkinson's disease. The nature of human DAn precursors in vitro is poorly understood, their p...

Vascular endothelial growth factor (VEGF) was first described as an angiogenic agent, but has recently also been shown to exert various neurotrophic and neuroprotective effects in the nervous system. These effects of VEGF are mainly mediated by its receptor, VEGFR-2, which is also referred to as the fetal liver kinase receptor 1 (Flk-1). VEGF is up...

Optogenetic tools comprise a variety of different light-sensitive proteins from single-cell organisms that can be expressed in mammalian neurons and effectively control their excitability. Two main classes of optogenetic tools allow to either depolarize or hyperpolarize, and respectively generate or inhibit action potentials in selective population...

Cholecystokinin (CCK-) positive basket cells form a distinct class of inhibitory GABAergic interneurons, proposed to act as fine-tuning devices of hippocampal gamma-frequency (30-90 Hz) oscillations, which can convert into higher frequency seizure activity. Therefore, CCK-basket cells may play an important role in regulation of hyper-excitability a...

Neuropeptide Y (NPY) exerts anxiolytic- and antidepressant-like effects in rodents that appear to be mediated via Y1 receptors. Gene therapy using recombinant viral vectors to induce overexpression of NPY in the hippocampus or amygdala has previously been shown to confer anxiolytic-like effect in rodents. The present study explored an alternative a...

Optogenetics allow for timely precise and cell-population specific activation or inhibition of neuronal activity. Hallorhodopsin NpHR is an inward cholride pump, which when activated by orange light, hyperpolarises neuronal membrane and inhibitis action potential generation. We were first to show that transduction of principal neurons with NpHR in...

We recently demonstrated that recombinant adeno-associated viral vector-induced hippocampal overexpression of neuropeptide Y receptor, Y2, exerts a seizure-suppressant effect in kindling and kainate-induced models of epilepsy in rats. Interestingly, additional overexpression of neuropeptide Y in the hippocampus strengthened the seizure-suppressant...

Increased Wnt5a expression 1 day after plasmid transfection. Q-PCR results, comparing Wnt5a expression to that of control pCAIP-transfected cells. Wnt5a transfection increased the expression to 35.9±8.3 when normalized to empty plasmid control transfections at 1.0±0.14 (both n = 4). (TIF)

Organotypic cultures after 7 months of culturing. (A) Organotypic hemisphere cultures were densely populated by cells as assessed by Hoechst staining, though there seemed to be fewer NeuN expressing cells as compared to 3–5 weeks time point. (B, C) VMN-Wnt5a-derived GFP expressing neurons, morphologically identical to those at 3–5 weeks of culturin...

Grafted VMN-Wnt5a-derived dopaminergic neurons in vivo. (A) VMN-Wnt5a neuron expressing TH-GFP 10 weeks after grafting in vivo into the DA-depleted mouse striatum. (B) magnified square in (A). Note that GFP-expressing cells were predominantly observed in, or immediately around, the injection tract (A, B). Biocytin-filled cells revealed processes fr...

Supporting Results. (DOC)

Intrinsic electrophysiological properties. Intrinsic membrane properties of VMN and VMN-Wnt5a cells grafted into striatal slice cultures, and of VMN-Wnt5a cells grafted into striatum of 6-OHDA lesioned mice. Note no differences in parameters between VMN and VMN-Wnt5a cells in striatal slice cultures after 3–5 weeks in vitro. Last column represents...

Intrastriatal grafts of stem cell-derived dopamine (DA) neurons induce behavioral recovery in animal models of Parkinson's disease (PD), but how they functionally integrate in host neural circuitries is poorly understood. Here, Wnt5a-overexpressing neural stem cells derived from embryonic ventral mesencephalon of tyrosine hydroxylase-GFP transgenic...

It is well established that seizures increase adult neurogenesis in the subventricular and subgranular zones, the most neurogenic regions of the adult rodent and apparently human brain. However, the role of increased neurogenesis in these areas in seizure generation (ictogenesis) and epileptogenesis remains elusive. It is of utmost importance to ex...