From The Editors Science

Scientists Create 3D-Printed Corneas Using Human Stem Cells

Professor of Tissue Engineering Che Connon and his team of scientists at Newcastle University in the U.K. have developed the first human corneas using an ordinary 3D bioprinter.

What was challenging for the researchers was finding the right combination of ingredients in order to produce a bio-ink that was not only thin in consistency – so that it could easily pass through a 3D printer’s nozzle – but also stiff enough to maintain its 3D shape.

Connon and his team used a technique that involved combining human corneal stromal cells from a healthy donor cornea with alginate and collagen to create an ideal printable solution, or “bio-ink,” which was then used with a low-cost 3D bio-printer to reproduce the shape of a human cornea in a matter of minutes.

“Many teams across the world have been chasing the ideal bio-ink to make this process feasible,” Connon said in a statement.

“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,” he said.

“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,” Connon added.

This groundbreaking technique, capable of producing exact replicas of the human cornea, still requires a great deal of trials and tests before it can become a mainstream remedy for cornea-related visual impairment that nearly five million people around the world suffer from.

“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 said.

“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 further said.

The 3D bio-printing technique explained in the journal ‘Experimental Eye Research,’ does not, in any way, suggest that the need for cornea donations will be totally eliminated; don’t forget that stem cells from a healthy donor cornea is one of the key ingredients for developing the 3D printable “bio-ink.”

What the technique can do, however, is reduce the need for donor corneas to an absolute minimum because one single donor cornea can provide enough stem cells to print 50 clones.

“We are delighted at the success of researchers at Newcastle University in developing 3D printing of corneas using human tissue,’ said Dr. Neil Ebenezer, who’s the “Fight for Sight” director of research, policy and innovation.

“This research highlights the significant progress that has been made in this area and this study is important in bringing us one step closer to reducing the need for donor corneas, which would positively impact some patients living with sight loss,’ he said.

Dr. Ebenezer, who is also, obviously, concerned about the current shortage of donor corneas within the UK, has stressed upon the importance of continuing to donate corneal tissue for transplant purposes because the bio-ink solution is still some years away from becoming a workable reality.

“It is important to note that this is still years away from potentially being available to patients and it is still vitally important that people continue to donate corneal tissue for transplant as there is a shortage within the UK. A corneal transplant can give someone back the gift of sight,” said Dr. Ebenezer

Shortage of donor cornea is not limited to the UK, though, as a 2016 global survey of corneal transplants suggests.

The study revealed that the demand to supply ratio, globally, was a dismal 70:1, concluding that bioengineering was probably the “essential” solution to the corneal supply dilemma.

What is Cornea?

The cornea is a clear, transparent layer in the front part of the eye that covers the iris, pupil, and the anterior chamber.

It is devoid of any blood vessels and allows light to refract through it before forming an image on the retina; and, while the anterior chamber and lens are also responsible for bending the light on to the retina, the cornea does the bulk of the refraction – nearly two-thirds of it.

The cornea is practically the first line of defense for the eye, shielding it from dirt and infection but, ironically, because it forms the outermost layer of the eye, it is itself susceptible to injuries and infections.

Statistics show that some 10 million people worldwide are at risk of corneal blindness caused by corneal disorders like trachoma, for example, which is a contagious bacterial infection of the eye, causing inflamed granulation on the inner surface of the lids.

Keratoconus is another corneal disease that not only makes the cornea thin but changes its curvature, too, resulting in mild to severe astigmatism (distortion) as well as myopia, or nearsightedness.

Keratitis is also a common cornea condition and can be of two types, infectious and non-non-infectious; the former caused by bacteria, parasites, fungi, or viruses and the latter is generally the result of minor injuries to the cornea, which regular use of contact lenses can also cause.

To put it as simply as possible, the cornea is a clear, outer layer of the eye, which along with the sclera, or the white of your eyes, protects the eye against dirt; microorganisms like bacteria and viruses; and other cornea-damaging agents.

However, when infection and injuries scar the cornea itself, impaired vision or blindness is the result.

With donor corneas being in such short supply, transplant is not an option for everyone, and as mentioned earlier, only one in seventy hopefuls are likely to get the desired cornea.

Che Connon and his research team have created a ray of hope, as distant as it may seem, for all those millions out there with damaged or diseased corneas, by creating the bio-ink 3D reproduction of the human cornea.

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