Stem Cells Unleashed

Mar 29, 2012

Stem cells, under the right conditions, can turn into almost any kind of cell, including those that make up the retina, giving them the potential to help treat many retinal diseases.

Historically, reservations surrounding the “stem cell debate” overwhelmed the science, as the majority of early research revolved around using human embryonic-derived tissues as a source for stem cell acquisition. In fact, embryos created for in vitro fertilization – but never used – can be donated for this purpose.

Since President Obama signed an executive order in 2009 allowing more scientific research involving human stem cells, work has moved forward at a faster pace. Today, we can acquire and use stem cells derived from blood, bone marrow and adipose tissue (human fat). Current research in the field of ophthalmology involves cells that have been taken from embryonic tissue, as well as adult cells.

Research is being done to try and get these cells to develop into different kinds of retinal cells, both retinal epithelial cells and retinal photoreceptors. If these could be developed and successfully implanted, this could significantly help a large number of participants with retinal-related vision loss, including those patients with diabetes, macular degeneration and other rarer, inherited visual diseases.

For the past five years, we at Retina Institute of Hawaii have been working to bring this science here. To date, our partners have started various FDA-approved trials. Using and expanding on this research, RIH is taking its first steps and enrolling Hawaii’s first stem cell participants, exploring this process for various blinding conditions.

During the past year, a number of scientists have been able to grow stem cells into retinal cells. Embryonic mouse stem cells cultured in a dish with a specific set of nutrients grew into retinal cells. Surprisingly, these cells went through the normal developmental stages of growth and went on to resemble the optic cup of the mouse eye, even without any nervous system to tell the cells what to do. The next task will be to connect them to the nervous system.

Our colleagues working with advanced cell technology are currently running two trials simultaneously, using human embryonic stem cells that have been differentiated into retinal epithelial cells. Eventually, two small groups of participants (12 each) who are legally blind will receive the retinal epithelial cells. One group has Stargardt’s macular dystrophy, which causes a loss of vision beginning at about 20 years of age. The other group of participants has the more common dry age-related macular degeneration.

The first two procedures have already been done, implanting the cells in one participant with each disease in 2011. Participants enrolled in a related trial in the United Kingdom have also been transplanted.

This is an FDA-approved study designed to evaluate the safety of this treatment. After four months, there has been absolutely no evidence of abnormality in either eye, neither damage nor signs of rejection.

Both participants have had some improvement in their vision. While the investigators in this trial did not agree on the significance of the improvement, they suggested that using the procedure in participants with less advanced disease might lead to better and more obviously improved vision.

The U.K. participants are also believed to have shown some visual improvement. There are multiple other areas of research related to the use of stem cells for eye problems. For example, one group of researchers found that retinal stem cells are still present in the adult eye. If they can be collected and grown, they can be used to make new cells with photoreceptors. These cells, like those in the mouse studies, need to be able to link up with nerve cells in order for vision to be restored.

The full promise of stem cells has yet to be realized, but there are clear early successes. RIH hopes to add to these successes with the early phase of its clinical trials and will be enrolling select candidates as early as summer 2012.

References:

1. Scientists Make Eye’s Retina from Stem Cells. http://www.bbc.co.uk/news/health-12963297
2. Real Retinas Grown in Lab Hold Eye Transplant Promise http://www.livescience.com/13587-stem-cell-retinas-eyeballs-110407.html
3. Scicurious Guest Post: An Optic Cup in a Dish. http://scientopia.org/blogs/scicurious/2011/04/20/2267/
4. Stem Cell-Derived Retinal Cells Safe for Transplant (updated January 24, 2012). http://www.doctorslounge.com/index.php/news/pb/26199
5. Schwartz, S.D., Hubschman, J. P., Heilwell, G, et al. Embryonic stem cell trials for macular degeneration: a preliminary report. www.thelancet.com. Published online January 23, 2012
6. The Foundation Fighting Blindness. Grant to Derek van der Kooy, University of Toronto. Specification and Transplantation of Adult Retinal Stem Cell Progeny. http://www.ffb.ca/research/current.html

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