Organoids developed in the laboratory produced real snake venom

In some countries or regions of the world, poisonous snakes pose a constant threat. Each year, these animals permanently kill or injure more than half a million people. Yet researchers still know surprisingly little about the biology of venom, which complicates efforts to develop treatments. But a new breakthrough made by researchers at the Hubrecht Institute in the Netherlands is very promising in this area: they have succeeded in developing miniature organs from snake stem cells in the laboratory. Cultured organoids work just like the snake's venom glands, and produce real venom.

"It's a breakthrough," says José María Gutiérrez, toxicologist specializing in snake venom at the University of Costa Rica (San José), who did not participate in the study. "This work offers the possibility of studying the cell biology of cells secreting venom at a very fine level, which has not been possible in the past".

The breakthrough could also help researchers study the venom of rare snakes, which are difficult to keep in captivity, paving the way for new treatments for a variety of venoms.

Researchers have been creating mini-organs (or organoids) for years from adult human and mouse stem cells. These so-called pluripotent cells are able to divide and develop into new types of tissue throughout the body. Recently, scientists have used them to produce tiny livers and even rudimentary brains . But until now, scientists have never tried the technique with reptile cells.

"No one knew anything about snake stem cells ," said Hans Clevers, molecular biologist at the Hubrecht Institute and one of the most renowned organoid researchers in the world." In fact, we had no idea if it was possible."

Mini-organs created from pluripotent stem cells

To find out, Clevers and his colleagues took venom gland stem cells from nine snake species, including the Cape Coral Snake ( Aspidelaps lubricus ) and the Western Diamondback Rattlesnake ( Crotalus atrox ). placed in a mixture containing in particular hormones and proteins, called growth factors.

To the surprise of the team, snake stem cells responded to the same growth factors as human and mouse cells. This suggests that certain properties of these stem cells appeared hundreds of millions of years ago, from a common ancestor of mammals and reptiles.

Miniature snake (organoid) venom glands, cultivated in the laboratory. Credits: Ravian van Ineveld / Princess Maxima Center

After a week immersed in the cocktail, the snake cells had become small clumps of tissue half a millimeter in diameter, visible to the naked eye. When scientists removed the growth factors, the growth factors began to develop into venom-producing epithelial cells in the glands of snakes. The mini-organs expressed genes similar to those of the actual venom glands, the team reports in the document.

Diagram summarizing the process of creation of organoids producing venom. Credits: Hans Clevers et al./Institut Hubrecht

Artificial venom-producing mini glands

Organoids have even produced venom. Chemical and genetic analysis of the secretions revealed that they correspond to the venom produced by real snakes. Tests have shown that laboratory-made venom is also dangerous: it disrupts the function of mouse muscle cells and rat neurons in the same way as real venom.

Until now, scientists have not known whether the many toxins found in snake venom are produced by a general type of cell or by specialized toxin-specific cells. By sequencing RNA from individual cells and examining gene expression, the Clevers team has determined that actual venom glands and organoids contain different types of cells that specialize in the production of certain toxins.

Organoids grown using stem cells from separate regions of the venom gland also produce toxins in different proportions, indicating that the location in the organ counts.

The proportions and types of toxins in the venom differ from one species to another, even within the same species. "This can be problematic for the production of antivenom," says study author Yorick Post, molecular biologist at the Hubrecht Institute. Most antivenoms are developed using a single type of venom, so they only work against the bite of a single type of snake.

Now that Clevers and his colleagues have developed a way to study the complexity of venom and venom glands without manipulating live and dangerous snakes, they plan to compile a "biobank" of frozen organoids from venomous reptiles around the world. , which could help researchers find broader treatments.

"It would make it easier to create antibodies," says Clevers. The biobank could also be a "rich resource for identifying new drugs," he adds. Scientists believe that snake venom may hold the key to the development of new treatments for pain, high blood pressure and cancer, for example.

Organoids created by the Clevers team will provide an unprecedented new opportunity to supplement genomic information on poisonous snakes.


ARTICLE| VOLUME 180, ISSUE 2, P233-247.E21, JANUARY 23, 2020

Snake Venom Gland Organoids

Yorick Post, Jens Puschhof, Joep Beumer, Michael K. Richardson, Nicholas R. Casewell, Hans Clevers


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