Scientists printed in 3D the thin protective film over the eye, called the cornea, using human cells, and it is the most advanced version of an artificial cornea. If technology improves, it could help millions of people to see again.
It was difficult to find the right recipe for an ink thin enough to run through the nozzle of a 3D printer, says Che Connon, a tissue engineer at the University of Newcastle who was one of the creators of the cornea artificial. This bio-ink not only had to be thin, it also had to be stiff enough to maintain its shape as a 3D structure. To obtain the proper consistency, the researchers added a substance similar to gelatin called alginate and stem cells extracted from donor corneas, along with some ropy proteins called collagen.
The cornea is the first lens that pbades through the light before hitting the retina at the back of the eye. Damage to the cornea, from injury or infection, can distort vision or even cause blindness. At this time, damaged corneas are replaced with healthy ones from deceased donors, but there are not enough donated corneas for everyone. Almost 5 million people around the world are blind because the infection marked their corneas, according to the World Health Organization.
The new technique, described today in the journal Experimental Eye Research does not completely eliminate the need for corneal donations, which are the key to making the stem cell part of the recipe. But, using this technique, the donation goes much further, says Connon. Instead of replacing a damaged cornea with a healthy one, you can grow enough cells from a donated cornea to print 50 artificial ones.
To discover what exactly to print, the team also had to discover the shape of a human cornea. Then, the researcher used a special camera to photograph a volunteer's eyeball and create a three-dimensional model of his cornea. Then, the team fed that template to a 3D printer, which injected the bio-ink into a Jello support bed to create the cornea. The result looks like a soft contact lens in a water bath.
But there's still a long way to go before these artificial corneas get close to the human eyeball: Connon wants to fine-tune the printing process first, he says, and the artificial cornea will also have to undergo animal safety studies. But this study is proof that you can print something in 3D that looks as a cornea, and contains mostly the same ingredients. It is also the first time that researchers have recreated the curvilinear and distinctive shape of the cornea. Connon says that's the key to making the artificial cornea work: "Without the shape, you do not have a cornea, you have something else"