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The disembodied human tear glands that cry sound like something out of a science fiction movie. But in the Netherlands, functional tear glands that don’t stick to anyone’s eyes (or emotions) star in their own real-life drama.
Researchers from the Hubrecht Institute and UMC Utrecht have used stem cells to grow tiny tear glands in a Petri dish, mimicking reality. They hope these so-called organoids can serve as models to study how cells in the human lacrimal glands produce tears. The ultimate goal: to better understand and treat conditions such as dry eye disease or Sjögren’s syndrome autoimmune disorder, as well as cancers of the lacrimal gland.
“Hopefully, in the future, this type of organoid may even be transplantable to patients with non-functioning lacrimal glands,” says Marie Bannier-Hélaouët, a doctoral candidate at the Hubrecht Institute for Stem Cell Research and Developmental Biology. She is the co-author of a study published Tuesday in the journal Cell Stem Cell detailing the project.
Organoids are built in vitro, in 3D suspension, from a small number of stem cells that eventually multiply to form something resembling a real organ, such as a mini-brain, bladder, or, in this case, the glands located within. of the upper eyelid. .
The lacrimal or lacrimal glands continuously supply fluid that passes over the surface of the eye each time we blink and then drains into tiny holes at the corners of our upper and lower eyelids before traveling through the tear ducts to the nose. In addition to showing excitement, the fluid is essential for eye health, lubricates the cornea, and helps ward off bacteria. Lacrimal gland dysfunction can be bothersome, causing scratching, stinging or burning sensations and sensitivity to light. But it can also be serious, causing abrasions or ulcerations of the cornea or even blindness in the most severe cases.
The lacrimal glands are made up of several types of cells. Laboratory-grown glands in the Netherlands are made up of only one type, ductal, and they cry in response to chemical stimuli such as norepinephrine, a neurotransmitter that sends a message from our neurons to our tear glands.
The cells shed tears inside the organoid, causing it to swell.
Marie Bannier-Hélaouët / Hubrecht Institute
“Our eyes are always wet, just like the lacrimal glands on a plate,” says Bannier-Hélaouët about artificial glands. Bannier-Hélaouët works in the laboratory of molecular biologist Hans Clevers, who focuses on creating organoids for disease modeling and has previously recreated snake venom glands and mouse tear glands.
It’s not like you walk into Clevers’ lab and see large teardrop droplets floating in flasks. The cells shed tears inside the organoid, called the lumen. This causes the organoid to swell like a balloon, and the size indicates how much tear production and secretion is occurring.
This is not the first time that scientists have created components of the human eye from stem cells. In 2018, a team at John Hopkins University created parts of the eyeball in hopes of better understanding how and why we developed “trichromatic vision” – the ability to see in red, blue, and green.
Dutch researchers acknowledge the limitations of your lacrimal gland, as it is made up of only one of the main types of cells found in the gland. They say they would eventually like to develop a complete lacrimal gland from the broader range of cells that make it up, gaining an even stronger understanding of how we form tears.