Group creates model that mimics malformation associated with severe epilepsy – 03/15/2022

Focal cortical dysplasia is a brain malformation responsible for one of the most serious types of epilepsy. Treatment for these cases is still difficult, either due to lack of effective drugs or difficult access to surgery.

Now, a new human model created by researchers from Unicamp (Universidade Estadual de Campinas) using cells from patients opens up opportunities to test more specific therapies and drugs.

In partnership with a group from the University of California, San Diego, the scientists created the first models of cortical organoids (3D cell culture that contain specific cell types of the organ to be studied) that mimic focal cortical dysplasia, characterized by a cortex malformation.

They identified mechanisms that may be involved in the emergence of the anomaly during brain formation. They were also able to obtain electrical recordings that approximate the neuronal discharge associated with epileptic seizures in humans.

The results were published in the journal brain, from Oxford Academic, one of the most relevant in clinical neurology and neurosciences. They may contribute to future work aimed at testing drugs against severe epilepsy, the one that affects individuals who, even after two years of using adequate medication and/or surgery, continue to have frequent seizures.

The organoids (organs developed in vitro that simulate the morphology and functioning of part of the brain) were cultured from skin cells from four patients with severe epilepsy treated at Hospital de Clínicas, Unicamp. These cells were reprogrammed to become pluripotent stem cells, then differentiating into neural cells.

By carrying out morphological, molecular and functional analyzes of the organoids, the group identified characteristics of this cortical malformation, including changes in cell proliferation, hyperexcitability of the neuronal network, presence of dysmorphic neurons and “balloon” cells, so called because of their shape ( appear hybrid, having the nucleus like that of a neuron and the cytoplasm like that of an astrocyte).

“We found a molecular alteration compatible with what is expected in cellular pathways related to the development and maturation of neurons. We also demonstrated that it is possible to generate cortical organoids with electrical activity that approximates what is understood as neuronal discharge associated with epilepsy. Therefore, we obtained a model similar to what we see in patients, which could, in the future, be used to screen existing medications”, summarizes Iscia Lopes-Cendes, professor at the Faculty of Medical Sciences at Unicamp and co-author of the article.

The research was carried out during Simoni Avansini’s postdoctoral period, within the scope of the Brazilian Institute of Neuroscience and Neurotechnology (BRAINN) – a CEPID (Center for Research, Innovation and Dissemination) of Fapesp. The work also received funding through three other projects.

Until then, there was a limitation for studies of this type of epilepsy in animal models, including rodents, because the cerebral cortex is very different from the human cortex and does not present this type of malformation.

“In the area of ​​epilepsy, this is a very important study. Over the years there have been several attempts, with successes and errors. The result crowns Simoni’s search, which kept something important in a researcher: perseverance”, says Lopes-Cendes , who is a principal investigator at BRAINN.

A neurological disease with no cure, epilepsy affects about 50 million people worldwide, according to data from the WHO (World Health Organization). It is estimated that in Brazil there are 2 million records.

Patients with severe cases have between 40 and 50 seizures a day, with loss of sense and fall. Treatment is with a combination of drugs, which does not always work.

Most drugs decrease the activity of neurons in a generalized way, controlling the seizures, but causing many side effects, such as drowsiness and memory alteration. Another alternative is surgery, in which the part of the brain affected by the malformation is removed.

Uncontrolled seizures, in addition to having an impact on the patient’s routine, are a serious risk of sudden and premature death (up to three times greater than among the general population). In addition, approximately half of adult people with epilepsy have other types of disorders, such as depression and anxiety.

“We were able to mimic the development of the neocortex and some basic features of focal cortical dysplasia. The advantage is that we obtained a human model, maintaining the patient’s genetic background. With the organoid it is possible to study each stage of the malformation, which begins in the development of the cortex, with repercussions on the proliferation and differentiation of cells”, says Avansini to Agência Fapesp.

In the literature, it is still unclear how abnormal cortical development may contribute to the generation of epileptic seizures in dysplastic cortical tissue.

In 2018, another article published by the group, the result of Avansini’s doctorate, had suggested that dysregulation in the expression of a gene called NEUROG2, important for the process of differentiation of neurons and glial cells (astrocytes, oligodendrocytes and microglia), would have a key role in the development of the disease.

Sample

The researchers used skin cells from four patients who had not responded to drug treatment or surgery. One of them underwent three surgical procedures that resulted in a reduction in the number of crises, but still without achieving the expected result. The other three subjects had two surgeries, among them a child who started with seizures at 14 months of age and had part of his speech affected.

“Our data point to a molecular rupture at the junction of neuroepithelial cells that would affect some neurons that form the cortical plate, leading to changes in the neural network. These, in turn, would make these patients susceptible to epilepsy”, says Professor Alysson Muotri, from the University of California and one of the corresponding authors of the article, in a video publicizing the work.

To capture the electrical records, the scientists used two techniques, one of which was innovative in the area: they placed the organoid on a plate with electrodes and introduced the electrode inside the organoid. These electrodes were developed specifically for research.

The group was also able to work with three- and five-month-old organoids, which is difficult to obtain because they tend to die in a short time because they lack a vascular system.

“We are driven by challenges. I had a family member with epilepsy who died as a result of one of the crises. When we experience this, we know exactly what is in the hearts of families. This is what moves me. need to do more, the search continues”, says Avansini.

According to the researcher, the next step is to seek to understand more about the formation of epilepsy and focus on the proliferative region to understand how cells and the circuit are formed. And, if there is a change in this step, how is it possible to interfere with the system to lead to new treatments.

Now, Avansini is a researcher at the Bioimaging Laboratory, within the National Biosciences Laboratory (LNBio), a research institution especially focused on the use of synchrotron light. LNBio integrates the CNPEM (National Center for Research in Energy and Materials) with three other laboratories: the National Synchrotron Light (LNLS/Sirius), the National Biorenewables (LNBr) and the National Nanotechnology (LNNano).

“Our CEPID accomplished the task of producing good science and training independent researchers who will continue doing good science”, completes Lopes-Cendes.

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She's our PC girl, so anything is up to her. She is also responsible for the videos of Play Crazy Game, as well as giving a leg in the news.

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