BBC Science Focus

Off with my head!

The ‘organoids’ teared up as part of a study looking to stop dry eye diseases

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Sea slugs lose their heads… but live on to grow new bodies

Researcher­s in the Netherland­s have grown tear glands in a lab – and then made them cry. Don’t worry, this isn’t the result of evil scientists with too much time on their hands; the cluster of cells was created to help the researcher­s understand eye diseases.

Using stem cells and a cocktail of growth factors, experts at University Medical Centre Utrecht were able to build tear ‘organoids’ – a three-dimensiona­l collection of cells designed to resemble miniature tear glands (also known as lacrimal glands). In order to mimic the wetness of the human eye, these organoids were suspended in liquid.

In humans, tear production is controlled by nerves which release neurotrans­mitters that trigger the secretion of tears. The scientists soon discovered that the glands reacted to the same neurotrans­mitters, but as the organoids lacked ducts to secrete the tears, they swelled up like balloons and some ruptured. Once transplant­ed into mice, however, the organoids eventually developed duct-like structures.

“Further experiment­s revealed that different cells in the tear gland make different components of tears. And these cells respond differentl­y to tear-inducing stimuli,” said Dr Yorick Post, who took part in the project.

Tear glands aren’t only useful to convey emotions in humans, but they also lubricate the eye, providing a protective layer of liquid over the cornea. Unhealthy glands can therefore lead to serious medical problems.

“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,” said Dr Rachel Kalmann, ophthalmol­ogist and researcher on the project.

It’s hoped the developmen­t of the tear organoids can help when it comes to testing new drugs and will enable scientists to understand how cancers in the gland form.

“Hopefully in the future, this type of organoid may even be transplant­able to patients with non-functionin­g tear glands,” added PhD student Marie Bannier-Hélaouët, who worked on the project.

This isn’t the first time that sections of the eye have been sculpted using stem cells. In 2018, a team from Johns Hopkins University in the US grew human retinas to investigat­e how colour vision in humans developed.

“Hopefully in the future, this type of organoid may even be transplant­able”

 ??  ?? The red areas are tear components that the organoid ‘cried’
The red areas are tear components that the organoid ‘cried’

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