Scientists create 3D printed transparent artificial corneas
Schematic illustration of the alignment of collagen fibers within the nozzle during bioink extrusion. Credit: POSTECH
When a person has a severely damaged cornea, a corneal transplant is required. However, there are 2,000 patients waiting for cornea donations in the country as of 2018 and they wait for 6 or more years on average for the donation. For this reason, many scientists have put their efforts into developing an artificial cornea. The existing artificial cornea uses recombinant collagen or chemical substances such as a synthetic polymer. Therefore, it does not incorporate well with the eye and is not transparent.
Professor Dong-Woo Cho of Mechanical Engineering, Professor Jinah Jang of Creative IT Convergence Engineering, and Ms. Hyeonji Kim at POSTECH, collaborated with Professor Hong Kyun Kim of Ophthalmology at Kyungpook National University School of Medicine, to create 3D printed artificial corneas using the bioink, which is made of decellularized corneal stroma and stem cells. Because this cornea is made of corneal tissue-derived bioink, it is biocompatible, and 3D cell printing technology recapitulates the corneal microenvironment, therefore, its transparency is similar to the human cornea. This research was recently published in Biofabrication.
The cornea is a thin outermost layer that covers the pupil and it protects the eye from the external environment. It is the first layer that admits light and therefore it needs to be transparent and flexible in order to be able to move as the pupil moves. However, it has been difficult to develop an artificial cornea using synthetic biocompatible materials because of different cornea-related properties. In addition, although many researchers have tried to replicate the transparency of the corneal microenvironment, the materials used in existing studies have limiting microstructures that do not allow optimal light penetration.
The human cornea is organized in a lattice pattern of collagen fibrils which play a significant role in transparency. The research team used shear stress generated in the 3D printing to manufacture the corneal lattice pattern and demonstrated that the corneal stroma-derived decellularized extracellular matrix bioink was biocompatible.
In the 3D printing process, when ink in the printer passes through the nozzle, frictional force produces shear stress. The research team successfully produced transparent artificial cornea with the lattice pattern of human cornea by regulating the shear stress to control the pattern of collagen fibrils.
The research team also observed that the collagen fibrils remodeled along with the printing path create a lattice pattern similar to the structure of native human cornea after 4 weeks in vivo.
Professor Jinah Jang said with excitement, “the suggested strategy can achieve the criteria for both transparency and safety of engineered cornea stroma. We believe it will give hope to many patients who suffer from cornea related diseases.”
Materials provided by Pohang University of Science & Technology (POSTECH). Content may be edited for clarity, style, and length.