Researchers Move Closer to Developing Transplantable Retinal Tissue from Stem Cells

March 20, 2012

A Foundation-funded University of Wisconsin research team led by Dr. David Gamm has achieved a significant milestone in developing stem cell treatments for saving and restoring vision in people with retinal degenerations. For the first time, the scientists used stem cells derived from blood to produce multiple layers of cells that resemble retinal tissue. Most important, these cellular structures have some of the characteristics considered necessary for vision.

“In the past, we and others have been able to generate relatively disorganized collections of different retinal cell types,” explains Dr. Gamm. “But to provide vision in individuals with more severe retinal damage, we may need to build a layered, interconnected structure of multiple cell types that are capable of communicating with one another and processing visual information. While there is certainly more work to do, this represents a step toward that goal.”

The outermost layer of the structure Dr. Gamm’s team developed was comprised of photoreceptors, the cells that convert light into electronic signals. The innermost layers of cells contained neurons and ganglion cells, which process signals from the photoreceptors and send them through the optic nerve to the brain, where they are perceived as vision.

Dr. Gamm and his colleagues are perfecting the development of these structures so they can be transplanted into animal models of retinal degeneration and, ultimately, into affected people.

To develop the retinal tissue, the researchers, in collaboration with the stem cell development company Cellular Dynamics International, Inc., genetically tweaked the mature cells in blood to revert them back to an embryonic-like state. The cells were then coaxed forward to become retinal cells. In previous studies, they used stem cells derived from human skin.

The technique, which enables researchers to derive stem cells from any cell type in the body, is attractive, because it doesn’t use embryos. In addition, the patient serves as the cell donor, minimizing the chance that the cells will be rejected by the immune system. In two prior FFB-funded studies, the laboratories of Dr. Gamm and his colleague Dr. James Thomson were also able to correct the disease-causing genetic defect in the cells and restore normal function, making them more suitable as a treatment for humans.

“Dr. Gamm and the Wisconsin team are on the forefront of stem cell research for retinal diseases,” says Dr. Stephen Rose, chief research officer, Foundation Fighting Blindness. “It is difficult work, because the retina is such a fragile and complex piece of tissue. And developing transplantable tissue is a particularly daunting challenge. But just a few years ago, these techniques for deriving stem cell treatments from blood or skin weren’t even on our radar screen. So we are delighted by their progress.”

The results of the study were published in the March 12, 2012, online issue of Investigative Ophthalmology & Visual Science.