Scientists use 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 advances 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, imprinted a combination of cells that form the outer blood-retina barrier – the ocular tissue that supports the retina’s light-sensitive photoreceptors.

His technique provides a theoretically unlimited supply of patient-derived tissue to study retinal degenerative 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 at the outer blood-retinal barrier,” said Kapil Bharti, Ph.D., who heads the NEI Section of Translational Stem Cell and Ocular Research.

Scientists have discovered a way to grow eye tissue – in new research that could lead to advances in the treatment of a range of degenerative eye diseases

“However, the mechanisms of AMD initiation and progression to dry and wet stages remain poorly understood due to the lack of physiologically relevant human models,” he explained in a statement.

The outer blood-retinal barrier of the eye 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, deposits of lipoproteins called drusen form outside Bruch’s membrane, preventing it from working 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 collaborative efforts have resulted in very relevant retinal tissue models of degenerative eye diseases,” said co-author Marc Ferrer, director of the 3D Tissue Bioprinting Laboratory at the NIH’s National Center for Advanced Translational Sciences.

‘These tissue models have many potential uses in translational applications, including therapeutic 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 structure to tissues.

Then they printed the gel onto a biodegradable scaffold, and within days, the cells began to mature into a dense capillary network.

On the ninth day, the scientists seeded retinal pigmented epithelial cells on the other side of the scaffold. A little over a month later, the tissue reached full maturity.

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

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

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

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

“By printing the cells, we are facilitating the exchange of cellular signals that are necessary for the normal anatomy of the retina’s outer blood barrier,” explained Bharti.

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

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

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