Researchers in the Netherlands have developed a new model to study snake venom, consisting of miniaturized human blood vessels grown on a chip. Until now, there was no model that could accurately replicate the effects of snake venom in real time.
“This has never been done before,” said Mátyás Bittenbinder, researcher at Vrije Universiteit Amsterdam and Naturalis Biodiversity Center, and first author of the study. “This model will hopefully lead to a decrease in the number of mice needed for toxicity studies.”
Snakebite envenoming is an often overlooked disease that claims over 100,000 lives each year and causes severe or chronic injuries in more than 400,000 victims annually, according to the World Health Organization.
Snake venoms contain toxins that can cause internal bleeding within minutes of a bite. Understanding this process is essential to developing antivenoms that can neutralize these effects. However, the methods that were available, until now, had some major limitations.
One of these methods is cell culture, where human endothelial cells — the cells that form the lining of blood vessels — are grown on a flat surface.
“Traditional cell culture models have been primarily used to research the tissue-damaging effects of snake venoms,” said Bittenbinder. However, these models cannot replicate the tube-like shape of blood vessels nor mimic important environmental factors such as blood flow or the extracellular matrix — which he described as “the ‘glue’ that keeps the cells attached to each other and their surroundings.”
The other method used traditionally relies on testing snake venoms on mice. “[In mice], it is not possible to study the venom effects in real-time, meaning that you can only study the effects after a mouse has been euthanized,” explained Bittenbinder. “Therefore, it is difficult to see what the timeframe of the observed effect is.”
Blood vessels on a chip
The new method, published in Scientific Reports, is designed to overcome the limitations of both cell culture and mice studies. The researchers worked in collaboration with Mimetas, a Dutch company that produces organ-on-a-chip models of multiple human tissues for medical research.
Organs-on-chips are tiny devices where cells can be grown, replicating the environment they’re found in inside the body. The chips used in this study consisted of three channels, one of which is a tube where the cells that form human blood vessels are grown.
“All sides of the tube are developed in such a way that it allows the endothelial cells to attach and eventually form a minuscule blood vessel. Compounds such as snake venom can be added directly to the tube to see what the effects are,” explained Bittenbinder.
The researchers tested the venoms from four different species of snake on the blood vessel organ-on-a-chip and found two main mechanisms by which the venoms may cause internal bleeding.
One mechanism had a direct effect on the cells making up blood vessels. The venom attacked the cell membrane, which resulted in the cells leaking their contents and dying. This was observed in the venom of elapids, a group of snakes that includes cobras.
The other mechanism had an indirect effect on the blood vessel cells. Here, the venom targeted the extracellular matrix and the cells remained intact. As the blood vessel loses the structural support of the extracellular matrix, the blood vessel collapses and the blood leaks out. This mechanism was observed in the venom of viper snakes.
Most existing antivenoms are made by injecting animals with snake venom and collecting the antibodies their immune system makes against the venom. These findings can prove valuable in the search for new antivenom drugs that can directly target and neutralize the different mechanisms of action of snake venoms. In future studies, the researchers are planning to study individual toxins to better understand how these venoms work.
“We want to separate the venoms into their individual components, to see whether we can figure out which toxins are responsible for the observed effect,” said Bittenbinder. “In addition, we want to initiate neutralisation studies to see whether we can neutralise the observed venom effects.”
Reference: Mátyás A. Bittenbinder et al., Using organ-on-a-chip technology to study haemorrhagic activities of snake venoms on endothelial tubules, Scientific Reports (2024). DOI: 10.1038/s41598-024-60282-5
Feature image credit: Angiola Harry on Unsplash
