Article Source: IET

Researchers based at the University of Newcastle have demonstrated that it is possible to print custom human corneas using a bio-ink composed of alginate, collagen and stem cells.

The cornea – the outer film of the eye – plays an important role in focusing vision.  There are an estimated 10 million people who require surgery to prevent corneal blindness resulting from disease, while a further five million people are entirely blind due to corneal scarring caused by disease or injury.

Corneas can be transferred from a (normally deceased) donor to a patient, although there are not enough registered eye donors in the UK to fulfil the demand for healthy corneas. Many organ donors decline to donate their corneas; it has been suggested that this could be due to squeamish associations and a change in the appearance of the corpse.

In the future, an effectively unlimited supply of corneas and other organs could be created in the lab by tissue engineers using tools such as bio-printers.

Researchers from the University of Newcastle have recently 3D printed human corneas, in a world first. In order to achieve this, they created a “bio-ink” using stem cells – human corneal stromal cells from a healthy donor – mixed with collagen and alginate. The corneas were printed using a conventional, low-cost 3D bio-printer.

“Many teams across the world have been chasing the ideal bio-ink to make this process feasible,” said Professor Che Connon, a tissue engineer at Newcastle University. “Our unique gel – a combination of alginate and collagen – keeps the stem cells alive whilst producing a material which is stiff enough to hold its shape but soft enough to be squeezed out the nozzle of a 3D printer.”

“This builds upon our previous work in which we kept cells alive for weeks at room temperature within a similar hydrogel. Now we have a ready to use bio-ink containing stem cells allowing users to start printing tissues without having to worry about growing the cells separately.”

The bio-ink was extruded in concentric circles to form the shape of a human cornea; the entire printing process took less than 10 minutes. After printing, the stem cells began to grow as the researchers hoped.

The researchers also found that there were able to create custom corneas to suit individual patients; by scanning the eye of a patient, they were able to print a cornea which perfectly matched the size and shape of their eyes.

“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,” said Connon. “However, what we have shown is that it is feasible to print corneas using coordinates taken from a patient eye, and that this approach has potential to combat the worldwide shortage.”

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