Scientists have figured out a way to create eye tissue using stem cells and 3D printing – in new research that could lead to breakthroughs in treating a range of degenerative eye diseases. 

A team of researchers 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. 

Their technique provides a theoretically unlimited supply of patient-derived tissue to study degenerative retinal diseases such as age-related macular degeneration (AMD) – and use them to better understand how to treat or cure these diseases. 

‘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,’ he explained in a statement.

The eye’s outer blood-retina barrier consists of the retinal pigment epithelium (RPE), which is separated by Bruch’s membrane from the choriocapillaris. The membrane regulates how nutrients and waste are moved between the RPE and the choriocapillaris. 

In people with AMD, lipoprotein deposits called drusen form outside Bruch’s membrane, preventing it from functioning properly. 

Nearly 20 million Americans suffer from some form of age-related macular degeneration. It’s the leading cause of vision loss in Americans age 60 and older; it’s also the leading cause of irreversible blindness and vision loss worldwide. 

‘Our collaborative efforts have resulted in very relevant retina tissue models of degenerative eye diseases,’ co-author Marc Ferrer, director of the 3D Tissue Bioprinting Laboratory at NIH’s National Center for Advancing Translational Sciences, said. 

‘Such tissue models have many potential uses in translational applications, including therapeutics development.’ 

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. 

Next, they printed the gel on a biodegradable scaffold, and within a few days, the cells started to mature into a dense capillary network. 

By day nine, the scientists seeded retinal pigment epithelial cells on the other side of the scaffold. Just over a month after that, the tissue reached full maturity. 

The outer blood-retina barrier is the interface of the retina and the choroid, including Bruch’s membrane and the choriocapillaris

The printed tissue looked and behaved similarly to native outer blood-retina barrier, according to the researchers’ analysis and testing. 

Under induced stress, the printed tissue exhibited patterns of early AMD such as drusen deposits underneath the RPE and progression to late dry stage AMD. 

‘By printing cells, we’re facilitating the exchange of cellular cues that are necessary for normal outer blood-retina barrier anatomy,’ explained Bharti. 

‘For example, presence of RPE cells induces gene expression changes in fibroblasts that contribute to the formation of Bruch’s membrane – something that was suggested many years ago but wasn’t proven until our model.’

The scientists published the results of their work today in Nature Methods. 

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