Stem cells are the building blocks of the body. All the tissues of
the body—the heart, lung, brain and even the eye—can be made from the
same stem cell. Because stem cells have the potential to create any cell
type, they can be used to cure any inherited disease. In the case of
most retinal diseases such as macular degeneration and retinitis
pigmentosa, the main cells damaged are the photoreceptors—the cells that
convert light to an electrical signal that is sent to the brain, where
the image we see is created. The latest research and how we are
beginning to treat blinding diseases with stem cell therapy are is
exciting and encouraging.
Stem cells are undifferentiated cells that have the potential to
become any cell in the body. When they are placed in the tissue they
need to repair, the surrounding cells release signals that direct the
stem cells to develop into the correct cell type. In the case of the
retina, placing a stem cell in the deep layers of the retina leads to
the creation of photoreceptors, as the surrounding cells release the
right factors to produce this cell type.
An impediment to stem cell research has been the need for fetal
tissue, where stem cells are normally found. There remain significant
social and political barriers to the use of fetal tissue. Fortunately,
recent discoveries show that adults also carry stem cells. A bone marrow
biopsy is a common means for collecting stem cells. More recent studies
have shown that stem cells are also found in circulating blood, and
blood donation alone is adequate for collecting stem cells in some
cases! In addition, stem cells collected in adults from the “limbus”—the
tissue next to the cornea at the front of the eye—have now been used to
grow cells for corneal transplantation as well as to grow photoreceptor
cells for retinal transplantation!
A number of blinding diseases have now been treated with stem cell
research. Neuronal ceroid lipofuscinoses (NCLs) are a common cause of
brain damage and blindness in children. A mouse model of the disorder,
mouse neuronal degeneration (MND), was treated with transplantation of
stem cells into the retina by simply injecting the cells into the
eyeball. The cells migrated into the retina and made connections that
allowed the retina to function when it was normally destroyed. Traumatic
retinal injury has also been treated in a rat model of retinal damage
by using a similar approach. Closer to humans, a mouse model of
retinitis pigmentosa and macular degeneration has been successfully
treated with stem cells derived from human bone marrow. Recently, stem
cells have been used to treat an adult patient with retinitis pigmentosa
for the first time, and we are awaiting the follow-up results of this
study.
Blinding eye diseases have now been treated in animal models, and new
treatment strategies have been developed for human conditions including
retinitis pigmentosa, macular degeneration, diabetic retinopathy,
corneal disorders and glaucoma. Clinical trials are in development. Your
eye doctor may refer you for appropriate evaluation in a clinical study
and help you or your family member affected by these disorders get the
best possible care now and in the future.
For more information, please contact Dr. Ron P. Gallemore, M.D.,
Ph.D., Director and Founder, Retina Macula Institute, 4201 Torrance
Blvd., Ste. 220, Torrance, CA 90503, (310) 944-9393.
About Dr. Gallemore
Ron P. Gallemore, M.D., Ph.D., practices as an ophthalmologist at
Retina Macula Institute in Torrance, California. He graduated from the
University of California, San Francisco, with a certification from the
American Board of Ophthalmology and earned a Vitreoretinal Surgery
Fellowship from Duke University Medical Center. Dr. Gallemore maintains
affiliations with numerous hospitals throughout the greater Los Angeles
metropolitan area.