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3-D printed corneas an ‘exciting’ breakthrough
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Researchers at Newcastle University in the United Kingdom have created human corneas using a 3-D printer and stem cells, according to a university press release.
A paper published in Experimental Eye Research discusses the proof-of-concept research, which includes mixing stem cells from a healthy human donor with alginate and collagen to create a “bio-ink” that can be extruded through a 3-D printer in the shape of a human cornea. The stem cells then cultivate in the printed cornea.
“Many teams across the world have been chasing the ideal bio-ink to make this process feasible,” Che Connon, PhD, a professor of tissue engineering at Newcastle University who led the research, said in the release. “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.”
Four experts — Francis W. Price Jr., MD, David R. Hardten, MD, FACS, Kenneth A. Beckman, MD, FACS, and Thomas “TJ” John, MD — shared their opinions with Healio.com/OSN regarding the new development.
Francis W. Price Jr., MD
The news about the first “successful” 3-D printed cornea is quite exciting and opens up the mind to nearly unlimited applications in cornea and refractive surgery. However, I place quotation marks around the word successful. Many groups have claimed the ability to manufacture synthetic corneas for human transplantation, but actually surgically applying these artificial corneas to real eyes has proven elusive at best. Currently we do not even fully understand the structural makeup of the cornea as witnessed by the multiple methods to try and predict why and when ectasia will occur after refractive surgery.
Providing an artificial cornea in the correct shape is nice, but will it structurally be able to allow a suture to pass through it while not “cheese wiring” out of it? Will it allow fluids and nutrients to pass through it while allowing the cells within it to maintain IOP? Will it maintain optical clarity and not distort image quality? Will it allow normal or functional IOP measurements? Will it stand the test of time in a human without degrading, melting or extruding from the surrounding tissue?
The human cornea, like the rest of the body, is an engineering masterpiece, and our understanding of how it works and functions is still primitive. This is a great step in our development of a replacement to the cornea, but we may need one that is built with much more sophistication than this.
David R. Hardten, MD, FACS
Corneal stromal transplants (ie, anterior lamellar transplants) are an important procedure for anterior corneal scars and thinning disorders such as keratoconus. The ability to custom print this type of tissue in an immunologically neutral manner is an exciting development. If this tissue can be created that can be customized to the shape and size and corneal power that is needed, in tissues that are biologically compatible, this would revolutionize this field. Even though the anterior lamellar transplants are a small percentage of the corneal tissue needs, any step forward is exciting.
Kenneth A. Beckman, MD, FACS
The concept of creating a cornea rather than using a human donor cornea is exciting for many reasons. First, there is limited access to donor corneas around the world. Although we don’t have tremendous difficulty obtaining corneas here in the United States, there are many places in the world that do, so being able to produce something that could give people more access is amazing.
Secondly, this would not be a donor like we traditionally think of. Therefore, we may have some benefits if we can make a cornea that is going to be dependable and reliable — maybe less likely to be rejected and maybe better able to last a lifetime.
At this point we don’t know what this cornea is going to be, but if it has those components, that certainly would be amazing because you’ll have increased access and you may have a better product. Right now we just don’t know enough about this product, and time will tell. The science and technology behind it are still in their infancy. Then, once this device is created to the point where it feels like it does work, there will still be steps to get it approved, which is not an easy task. Look how long it took cross-linking to get approved in the U.S. when it was the standard of care internationally for many years. The bar is set so high to get these products approved that it’s not going to be easy.
The other thing is cost. Corneal transplants are not cheap. I don’t know if this will be less expensive. I’m sure initially it won’t be, but that could be another barrier.
I’m optimistic that they will have something there, even if it’s not in the form that we see it now.
Thomas “TJ” John, MD
3-D printing of biological tissue such as the cornea is a true milestone. It is the beginning of an exciting era for continued corneal research and future surgical possibilities at a time when the global demand for corneal transplantation far outweighs the supply chain of available donor corneas for such transplantation. The combination of healthy donor human stem cells with collagen and alginate has led to the production of a “bio-ink” that is compatible and functional with a 3-D bioprinter. This bio-ink was laid in concentric circles to print-produce a model of a human cornea. The gel made of alginate and collagen was able to support the survival of the stem cells. This step forward where the stem cells are contained in the bio-ink allows for such 3-D biological printing process. While it is still many years away to take this technology from the laboratory to the operating room, it is a remarkable scientific achievement that forms the basis for continued research and refinements to make this a workable reality in the domain of corneal transplantation.
References:
First 3D printed human corneas. www.ncl.ac.uk/press/articles/latest/2018/05/first3dprintingofcorneas/.
Isaacson A, et al. Exp Eye Res. 2018;doi:10.1016/j.exer.2018.05.010.
For more information:
Kenneth A. Beckman, MD, FACS, can be reached at Comprehensive Eye Care of Central Ohio, 450 Alkyre Run Drive, No. 100, Westerville, OH 43209; email: kenbeckman22@aol.com.
David R. Hardten, MD, FACS, can be reached at Minnesota Eye Consultants, 10709 Wayzata Blvd., Minnetonka, MN 55305; email: drhardten@mneye.com.
Thomas “TJ” John, MD, can be reached at Thomas John Vision Institute, 120 Oak Brook Center, Oak Brook, IL 60523; email: tjcornea@gmail.com.
Francis W. Price Jr., MD, can be reached at Price Vision Group, 9002 N. Meridian St., Suite 100, Indianapolis, IN; email: fprice@pricevisiongroup.net.
Disclosures: Beckman, Hardten, John and Price report no relevant financial disclosures.