Key idea: The new technique provides model for studying genesis of age-related macular degeneration and other eye diseases.
Original author and publication date: NIH, National Eye Institute (NEI) – December 20, 2022
Futurizonte Editor’s Note: Yet another step to create a fully synthetic human being. (I know: I need to stop reading science fiction. But it is not the first time science fiction becomes real).
From the article:
Scientists used patient stem cells and 3D bioprinting to produce eye tissue that will advance understanding of the mechanisms of blinding diseases. The research team from the National Eye Institute (NEI), part of the National Institutes of Health, printed a combination of cells that form the outer blood-retina barrier—eye tissue that supports the retina’s light-sensing photoreceptors. The technique provides a theoretically unlimited supply of patient-derived tissue to study degenerative retinal diseases such as age-related macular degeneration (AMD).
“We know that AMD starts in the outer blood-retina barrier,” said Kapil Bharti, Ph.D., who heads the NEI Section on Ocular and Stem Cell Translational Research. “However, mechanisms of AMD initiation and progression to advanced dry and wet stages remain poorly understood due to the lack of physiologically relevant human models.”
The outer blood-retina barrier consists of the retinal pigment epithelium (RPE), separated by Bruch’s membrane from the blood-vessel rich choriocapillaris. Bruch’s membrane regulates the exchange of nutrients and waste between the choriocapillaris and the RPE. In AMD, lipoprotein deposits called drusen form outside Bruch’s membrane, impeding its function. Over time, the RPE break down leading to photoreceptor degeneration and vision loss.
The eye’s outer blood-retina barrier comprises retinal pigment epithelium, Bruch’s membrane and the choriocapillaris. Image credit: National Eye Institute. Bharti and colleagues combined three immature choroidal cell types in a hydrogel: pericytes and endothelial cells, which are key components of capillaries; and fibroblasts, which give tissues structure. The scientists then printed the gel on a biodegradable scaffold. Within days, the cells began to mature into a dense capillary network.
On day nine, the scientists seeded retinal pigment epithelial cells on the flip side of the scaffold.
The printed tissue reached full maturity on day 42. Tissue analyses and genetic and functional testing showed that the printed tissue looked and behaved similarly to native outer blood-retina barrier.
Under induced stress, printed tissue exhibited patterns of early AMD such as drusen deposits underneath the RPE and progression to late dry stage AMD, where tissue degradation was observed. Low oxygen induced wet AMD-like appearance, with hyperproliferation of choroidal vessels that migrated into the sub-RPE zone. Anti-VEGF drugs, used to treat AMD suppressed this vessel overgrowth and migration and restored tissue morphology.