Scientists are using 3D printing and patient stem cells to help millions with eye problems

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

A team of researchers at the National Eye Institute (NEI), part of the National Institutes of Health, has printed a combination of cells that make up the outer blood-retinal barrier – the 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-retinal barrier,’ said Dr. sc. Kapil Bharti, who heads the NEI Division of Eye and Translational Stem Cell Research.

“However, the 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 statement.

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

In people with AMD, deposits of lipoproteins 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 is the leading cause of vision loss in Americans age 60 and older; it is also the leading cause of irreversible blindness and vision loss worldwide.

“Our joint efforts have resulted in highly relevant retinal tissue models of degenerative eye diseases,” said co-author Marc Ferrer, director of the 3D Tissue Bioprinting Laboratory at NIH’s National Center for Advanced Translational Sciences.

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

Bharti and colleagues combined three types of immature choroidal cells in a hydrogel: pericytes and endothelial cells, which are key components of capillaries; and fibroblasts, which give tissues structure.

They then printed the gel onto a biodegradable scaffold and within days the cells began to mature into a dense capillary network.

By the ninth day, the scientists had seeded retinal pigment epithelial cells on the other side of the scaffold. A little more than a month later, the tissue reached full maturity.

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

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

“By printing cells, we facilitate the exchange of cellular signals that are essential for the normal anatomy of the outer blood-retinal barrier,” explained Bharti.

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

Today, the scientists published the results of their work in Methods of nature.

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