Artificial human corneas that could circumvent the problem of limited donors or ethical concerns have been developed by scientists at Newcastle University. These are the first human corneas to have been 3D printed. [Isaacson, A. et al. Experim Eye Res. (2018); DOI: 10.1016/j.exer.2018.05.010]. The cornea is outermost, transparent layer of the eye, which covers the iris and pupil and plays a role in focusing light on to the retina.

Corneal blindness is a widespread problem often caused by infectious diseases such as trachoma and by burns, lacerations, or other diseases. However, it can be treated by corneal transplant from a donor post mortem. Unfortunately, there is an ongoing shortage of corneas available for transplant with 10 million people worldwide requiring this form of eye surgery.

Steve Swioklo, Che Connon, Abigail Isaacson, and their colleagues have demonstrated a proof of principle experiment in which they have taken human corneal stromal cells from a healthy donor cornea, mixed them with alginate and collagen and created 3D bio printer ink. Using a conventional commercially available 3D bio-printer, they were able to extrude the mixture to form increasing concentric circles allowing them to fabricate an artificial human cornea from actual cells within ten minutes.

"Our unique gel keeps the stem cells alive whilst producing a material which is stiff enough to hold its shape but soft enough to be squeezed out of the nozzle of a 3D printer," Connon explains. Swioklo adds that, "Many teams across the world have been chasing the ideal bio-ink to make this process feasible." Previously, the team sustained cells for several weeks at room temperature within a similar hydrogel. Now, they have a way to produce a ready to use bio-ink containing stem cells that allows users to start printing tissues without the concern of having to grow the cells separately. The cornea can be fabricated to match a patient's unique specifications by first scanning the eye and then programming the 3D printer to match size and shape perfectly, without the imperfections of course.

"Our 3D printed corneas will now have to undergo further testing and it will be several years before we could be in the position where we are using them for transplants," Connon adds. As such, it is vital that people are persuaded to sign up to be organ donors, after all a corneal transplant from a donor can give someone back their sight in many cases.

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".