The Grapevine

First 3D-Printed Human Corneas Created, Prospect Of Unlimited Supply For Transplants

Millions of patients around the world need surgery to prevent corneal blindness caused by eye disorders. Almost five million people suffer total blindness due to corneal scarring caused by burns, lacerations, abrasion or disease.

Now, scientists from Newcastle University, England, have created the first 3D-printed human corneas. The research titled "3D bioprinting of a corneal stroma equivalent" was published in Experimental Eye Research on Wednesday.

What is the function of the cornea?

The cornea is the dome-shaped transparent layer which covers the surface of the eye. The tissues of the cornea are organized into five layers which serve their own functions. The outermost layer plays a protective role by preventing dust and other foreign material from entering the eye. 

The cornea also focuses the light entering the eyes, being responsible for 65 to 75 percent of the eye’s total focusing power. The light is refracted onto the lens and refocused onto the retina, which is essential for the brain to interpret our vision.

How was the 3D-printed cornea created?

The researchers first acquired stem cells (human corneal stromal cells) from a healthy donor cornea. Then, they were able to create a "bio-ink" by mixing these cells with alginate and collagen. The bio-ink served as a solution used for 3D printing of complex tissue models.

The 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 the nozzle of a 3D printer," said lead researcher Che Connon, Professor of Tissue Engineering at the University. The research built upon the team's previous work when they kept cells alive for weeks at room temperature within a similar type of gel.

"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."

What potential does the research have for medicine?

For transplantation, corneas are harvested within 24 hours from death by trained professionals and stored in eye banks. But due to a significant shortage, there is a huge demand for donated corneas across nations

The technique demonstrated in the research could potentially be used in the future to ensure an unlimited supply of corneas.

"Many teams across the world have been chasing the ideal bio-ink to make this process feasible," Connon said, referring to the growth of stem cells achieved by the researchers.

The printed corneas were also shown to match specifications and dimensions of any patient. By scanning the person's eye, they were able to use the data to print a cornea identical in size and shape.

When will the 3D-printed corneas be ready for use?

Unfortunately, we won't see them being used any time soon in transplant procedures. Professor Connon explained that a lot of testing will need to be done to ensure the safety and efficacy of the 3D-printed corneas, a process which may take several years.

"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," he said.