HEALTH
Scientists have created the first 3D model of the human conjunctiva, the clear protective outer membrane of the eye, in the lab, and it even produces its own tears. The researchers say the new model could be used to study diseases that affect millions of people, such as conjunctivitis. The replica conjunctiva is an ‘organoid’, a lab-grown mass of cells made to resemble 3D, miniature versions of full-size tissues in the body. Organoids are typically grown from stem cells and enable scientists to recreate the structure and function of human organs. Because of this, the models are emerging as promising alternatives to using animals for drug testing.
Until now, there have been no realistic lab models of the human conjunctiva, which has limited research in the field. To make the new model, the researchers collected stem cells from conjunctival tissue provided by organ donors and patients who were undergoing eye surgery. Using chemicals called growth factors, the scientists coaxed the cells into 3D structures that mimicked the human conjunctiva. These organoids contained all the cells normally found in the conjunctiva, including mucusproducing cells, such as goblet cells and keratinocytes, which enable the tissue to make mucus-rich tears that protect and lubricate the surface of the eye. However, the researchers found that the latter cells also secreted antimicrobial proteins.
“We discovered that the conjunctiva makes antimicrobial components and therefore contributes to tear production in more ways than by simply making mucus,” said Marie Bannier-Hélaouët, a postdoctoral researcher in developmental biology and stem cell research at the Hubrecht Institute in The Netherlands. The new model mimicked all the major features of the human conjunctiva, including its ability to produce mucus-rich tears. In addition to revealing these antimicrobial properties of keratinocytes, the model helped the scientists identify tuft cells, a type of cell not previously known to be in the conjunctiv
