Using patient stem cells, scientists at the National Eye Institute (NEI) in the United States have discovered a method for 3D bioprinting eye tissues.
The researchers believe that their method, which involves printing three kinds of immature choroidal cells onto a biodegradable scaffold, might one day allow for the production of an infinite supply of patient-derived tissues. These, in turn, may aid clinicians in their quest to comprehend the processes behind age-related macular degeneration and other prevalent degenerative retinal illnesses.
Factors such as age, heredity, blood pressure, and nutrition may all contribute to the development of age-related macular degeneration, a condition that essentially causes blurred central vision in individuals. Drusen are lipoprotein deposits outside Bruch’s membrane, an extracellular matrix (ECM) between the retina and the choroidal capillaries of the eye, and their formation is thought to be triggered by these factors.
Besides preventing the membrane from doing its normal job of managing nutrients and waste surrounding the eye, this condition also breaks down the retinal pigment epithelium (RPE) in the outer blood-retina barrier, which ultimately results in vision loss. Although the causes of AMD are well-known, the disease’s progression is not. Bruch’s membrane and the choriocapillaris make up the outer blood-retina barrier, which separates the retina from the choroid.
Bharti and his group have developed a method of 3D bioprinting tissues from patient stem cells in order to speed up research into the development of AMD. To create a unique hydrogel, this method combines pericytes and endothelial cells, two essential components of capillaries, with fibroblasts, the cells responsible for providing tissue architecture. In order to promote cell development, this gel is printed onto a scaffold.
Scientists observed that cells put onto prototype biodegradable scaffolds began to grow into a dense capillary network within only a few days. Retinal pigment epithelial cells were seeded on the other side of the scaffold on day nine, and by day 42, the tissues had attained “complete maturity,” according the researchers.
After further tissue analysis, genetic testing, and functional evaluation, it was shown that the generated tissues resembled and functioned like a normal outer blood-retina barrier. They also showed drusen deposition patterns beneath the RPE and advanced to late dry-stage AMD when subjected to stress induction, but these symptoms resolved after treatment with anti-VEGF medications, which inhibited vessel enlargement and restored tissue shape.
Now that Bharti and colleagues have shown the viability of their method, they are employing bioprinted models of the blood-retina barrier to continue their research into AMD. To create more realistic tissues for future research, the team plans to include more cell types such as immune cells into its procedure.
Possible uses for 3D-printed eye implants
Traditional 3D printing has been used in the manufacture of a number of different optical medical procedures, even if the 3D bioprinting of eye tissues is still in the research and development phase. Surgeons at the Israeli Galilee Medical Center (GMC) used 3D printing and AR glasses to treat eye socket fractures in 2021.
In the same year, researchers from the University of Basel introduced 3D-printed implants made of porous material to repair broken eye sockets. The group’s PEEK filament-printed porous grafts were stated to be able to overcome the material’s bioinertness and help in cellular healing.
When a London man’s eye was beyond saving, physicians at Moorfields Eye Hospital used 3D printing technology to create a prosthetic eye. The technique allowed the researchers to design and produce an artificial eye that looked and felt more natural than previous acrylic prosthetics and could be made in a fraction of the time.
