PhD student Ropafadzo Mzezewa is modelling human epileptic seizures without the need to study human brains

PhD student Ropafadzo Mzezewa and co-workers recently published an article on studying epileptic seizures using human neurons cultured in a dish in laboratory conditions.

Written: Miina Björninen
Photo: Jonne Renvall

In the work published in Stem Cell Research, seizures were induced by adding kainic acid, a known pro-convulsant, to the neurons. The study focused on evaluating the role of an inflammatory cytokine called interleukin-6 (IL-6) during provoked seizures. Levels of IL-6 levels are increased in patients suffering from recurrent epileptic seizures, but its role is not well-known.

In this work, the researchers were able to develop a useful human model for studying epileptic seizures. The seizure-like activity of the neurons was measured using microelectrode arrays (MEA) that are embedded to the culture vessels the cells are cultured on. IL-6 did not induce seizures alone or worsen the induced seizures. However, with the model, the search for the causing factors of seizures and epilepsy progress can be studied more efficiently in laboratory conditions.

How does this model differ from the previous epileptic models?
This study is one of the few that uses human induced pluripotent stem cells derived neurons on MEAs to study epilepsy, whereas most still use rodent neurons or brain slides for these kind of studies. As we all know, the rodent brain does not resemble the human brain which is why it is important to develop laboratory models based on human cells.

You used 2D microelectrode arrays for measuring the seizures. What’s the next step in developing the environment for the neurons?
As we were investigating the role of a key inflammatory cytokine, it will be crucial to incorporate the essential inflammatory cells into the experiments, such as astrocytes and microglia. Therefore, cultures containing all these three cell types will be the next step to mimicking the neuroinflammatory environment in relation to epileptic seizures. In addition, as this current study focused on the ‘first’ event of seizures in healthy neuronal networks, a more chronic model will be adapted in the future using the neurons together with the glial cells.

What was the most challenging task?
Functional activity development varies from different batches of the same cell line. Hence, optimization was required to ensure good functional activity from the neurons.

Can you give us an estimate, of how much work was required to the point where you were able to get a reliable model for the epileptic seizures?
As human cell cultures typically need time to mature, the prolonged culturing time of over 4 weeks was needed to be able to see functional activity from the neurons, prior to inducing seizure-like activity using kainic acid.

What’s up next in your work?
In line with modelling epileptic seizures, I am now working with cell lines of patients that suffer from Dravet syndrome, a genetic type of epilepsy. Using these patient lines in my research work will give further insight into the functional behaviours of these patient neurons using MEAs. Furthermore, by incorporating these neurons onto our previously published MEMO chip, we will be able to see how the functional pathology spreads to other neuronal networks in neighbouring compartments.