Scientists have grown miniature human tear glands capable of crying.
Researchers say the organoids serve as a model to study how certain cells in the human tear gland produce tears or fail to do so.
They hope it may become possible to transplant the lab-grown glands into patients with non-functioning tear glands.
The tear gland is in the upper part of the eye socket, and secretes tear fluid which is essential for lubrication and nutrition of the cornea and has antibacterial components.
Ophthalmologist and researcher on the project, Rachel Kalmann, from UMC Utrecht in the Netherlands, said: “Dysfunction of the tear gland, for example in Sjogren’s syndrome, can have serious consequences including dryness of the eye or even ulceration of the cornea.
“This can, in severe cases, lead to blindness.”
The exact biology behind the functioning of the tear gland was unknown until this study.
Researchers say the development of the miniature tear glands holds promise for patients with tear gland disorders.
Marie Bannier-Helaouet, researcher on the project, said: “Hopefully in the future, this type of organoids may even be transplantable to patients with non-functioning tear glands.”
Dutch researchers from the group of Hans Clevers (Hubrecht Institute) presented the first human model to study how the cells in the tear gland cry and what can go wrong.
They used organoid technology to grow miniature versions of mouse and human tear glands in a dish.
These so-called organoids are 3D-structures that mimic the function of actual organs.
After the tear glands were cultivated, the challenge was to get them to cry.
Ms Bannier-Helaouet said: “Organoids are grown using a cocktail of growth-stimulating factors.
“We had to modify the usual cocktail to make the organoids capable of crying.”
Once the researchers found the right mixture of growth factors, they could induce the organoids to cry.
“Our eyes are always wet, as are the tear glands in a dish,” Ms Bannier-Helaouet said.
According to the study published in Cell Stem Cell, the organoids cry in response to chemical stimuli, similar to the way people cry in response to something like pain.
The cells of the organoids shed their tears on the inside of the organoid, which is called the lumen. As a result, it will swell up like a balloon.
Therefore their size can be used as an indicator of tear production and secretion.
Yorick Post, another researcher on the project, said: “Further experiments revealed that different cells in the tear gland make different components of tears.
“And these cells respond differently to tear-inducing stimuli.”