March 16 (UPI) — Using new organoid technology, scientists have successfully grown miniature tear glands that actually cry.
The breakthrough — described Tuesday in the journal Cell Stem Cell — could help researchers study the tear-production process and determine why some duct cells fail to produce tears.
Scientists hope the organic models can be used to develop treatments for tear gland disorders like dry eye disease.
Eventually, tear glands grown in the lab could be used as transplants.
Tears are vital to healthy eyes. Produced by the ducts in the corner of the eye socket, tears lubricate the eyes and deliver nutrition to the cornea.
Antibacterial properties in tears also help prevent eye infections.
“Dysfunction of the tear gland, for example in Sjögren’s syndrome, can have serious consequences including dryness of the eye or even ulceration of the cornea,” study co-author Rachel Kalmann said in a press release.
“This can, in severe cases, lead to blindness,” said Kalmann, an ophthalmologist and researcher at the Hubrecht Institute at the University Medical Center Utrecht in the Netherlands.
After growing 3D gland-like cell structures in a dish — miniature versions of human and mouse tear ducts — scientists had to find a way to make them cry.
“Organoids are grown using a cocktail of growth-stimulating factors,” said lead author Marie Bannier-Hélaouët, researcher at the Hubrecht Institute. “We had to modify the usual cocktail to make the organoids capable of crying.”
After experimenting with different growth factors, researchers found a combination that kept the gland moist, just as human tear glands keep our eyes constantly wet — they exposed them to a hormone called noradrenaline.
Because the organoids cried internally, the tears collected inside what’s called the lumen and caused the models to expand like balloons.
“Further experiments revealed that different cells in the tear gland make different components of tears,” said co-author Yorick Post, also a researcher at the Hubrecht Institute. “And these cells respond differently to tear-inducing stimuli.”
Though scientists used genetic sequencing to identify and describe the different types of cells that form human tear glands, their organoids were grown using just one kind — the ductal cell.
“In the future, we would like to also grow the other tear gland cell type, so-called acinar cell, in a dish,” Post said. “That way, we can eventually grow a full tear gland in the lab.”
Scientists expect their models to be adopted by medical researchers for drug testing, in addition to their potential for modeling tear duct cancers.
“And hopefully in the future, this type of organoids may even be transplantable to patients with non-functioning tear glands,” Bannier-Hélaouët said.