Scientists grow tear glands and make them cry

The development may shed light on conditions that cause dry eyes, like Sjögren’s syndrome.

Emma Jones 4 minute read March 19, 2021
Close-up on female green eye, tears streaming, shallow depth of field

The developed tear glands is the latest in a long list of organoids researchers have been able to develop in the lab. leonovo / GETTY

Many researchers will admit that their work has made them cry at some point, but it’s not often that the reverse is true. Scientists from the Hubrecht Institute at the Royal Netherlands Academy of Arts and Sciences have successfully grown tear glands – also called lacrimal glands – that are capable of producing tears.

This development has the potential to help understand conditions that contribute to dysfunctional tear production and chronic dry eyes, such as Sjögren’s syndrome, which is thought to affect 2 to 5 individuals per 1,000 people in Canada.

“The biggest promise is the fact that we are now in a position to start thinking about treatment of dry eyes with cells,” Hans Clevers, one of the lead authors on the study, toldInverse.

Dr Rachel Kalmann, ophthalmologist and another researcher on this study, also weighed in on the importance of understanding how the tear glands work.

“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. This can, in severe cases, lead to blindness.”

Making petri dishes cry

The glands were formed when the researchers put human stem cells in a very specific solution of growth factors (proteins that signal cells to develop certain characteristics or stimulate growth). When the cells were exposed to the right cocktail of these factors in the right sequence, they began to form miniature version of the tear glands, called tear organoids.

This isn’t the first time this lab has developed miniature models of human organs. Over the past decade these researchers, and others around the world, have grown a litany of organoids, including livers, sections of the gut, cervical cancers and snake venom glands.

But tear glands aren’t useful unless they develop tears – a surprisingly complex substance that lubricates and protects the eye, as well as contributes antibacterial properties.

By exposing these glands to a variety of different signalling chemicals found in the body, the researchers found that norepinephrine was effective in making these glands develop tears. More research has shown that different cells within the glands are responsible for developing different aspects of human tears.

“Further experiments revealed that different cells in the tear gland make different components of tears. And these cells respond differently to tear-inducing stimuli,” explains Yorick Post, a researcher on the study.

In the petri dishes, the organoids had not developed tear ducts so there was nowhere for the developing liquid to go. Instead, the spheres swelled up, some literally bursting with the tears.

When the cells were implanted into mouse models, however, the organoids did develop tear ducts – a promising development for possible dry-eye treatments down the line.

Why do we need tears?

Tears are important not just to help us cope with the latest drama on the Bachelor, but also to keep our eyes from drying out. Tears have three distinct layers, according to the American Academy of Ophthalmology: an outer layer with properties similar to oil, which prevents the inner layers from evaporating; a middle layer which works to keep the eye hydrated and protect it from bacteria; and an inner mucous layer, which keeps the entire substance on the eye itself.

Tears are developed in the lacrimal glands (tear glands) and secreted onto the eye through the tear duct.

There are three different kinds of tears – each with their own slightly different chemical makeup.

  • Maintenance tears – also known as basal tears. These tears are constantly present and what keeps our eyes moist and functioning.
  • Emotional Tears – What happens when you really get going.  There’s not a lot of consensus on to why we cry, although it is believed that it may be more of a social signal – a way to let others know when we feel overwhelmed.
  • Reflex Tears – made up of mostly water, these tears are useful for washing irritants out of your eyes, like dust and allergens.


Developing organoids like these tear glands will be helpful to individuals who currently rely on artificial tears to keep they eyes functioning. The Clever lab is reportedly already planning to run clinical trials for patients who have chronic dry mouth for their previously developed salivary gland organoids.

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