Blindness affects all demographics within the United States. While some cases occur at birth, other cases occur as a side effect of degenerative diseases.
One group of researchers from UC Santa Barbara believes there is a simple cure. The team has been analyzing and developing a use for embryonic stem cells in the treatment of damaged retinal cells. This new treatment could effectively help cure some forms of blindness due to degenerating retinas.
There are two main causes of the deterioration of retinal cells. One is age-related macular degeneration, and the second is due to diabetes. The first is natural, exclusively affecting the elderly, but the latter has become a bigger issue. According to the National Institutes of Health, diabetes is the leading cause of blindness in the U.S. In the past decade alone, there has been a 21-percent increase in the number of cases of type 2 diabetes. This brings us to a possible side effect of diabetes: diabetic retinopathy.
“Diabetic retinopathy is a disease prevalent in young adults due to the increase in obesity rates. It causes the deterioration of retinal cells, [and] we hope the use of stem cells can help repair this degeneration,” said Dennis Clegg, a leading researcher on the UCSB team studying stem cell development. “We have some sort of timeframe for our project, but right now we’ve just begun to explore this field. We’re reporting back to the FDA the research on stem cells with our initial studies, and hopefully we’ll be able to explore deeper.”
In a healthy person, the body is able to secrete enough insulin to help absorb glucose, the smallest biologically active sugar. A diabetic person, on the other hand, is unable to absorb glucose normally, which results in free-floating sugars in the bloodstream. This glucose builds up over the course of several years, damaging blood vessels throughout the body, leading to diabetic retinopathy and damage to the blood vessels in the eyes.
The damage inhibits blood flow to the rest of the retina, which depletes the retina of oxygen and vital nutrients. The damage can also cause blood to leak, create scar tissues or even create a detached retina. The only treatment available is to physically remove the damaged areas of the retinas using lasers, and as usual, there are risks and unwanted side effects that could permanently impair vision. This is where embryonic stem cells can help provide the key to repairing damaged retinas. By manipulating the stem cells to mimic retinal cells, doctors can inject the cells under the retina and start the repair process.
Although the UCSB research team is pursuing a relatively new form of regenerative medicine, there are already some applications of stem cells in use.
“If you inject [stem cells] into a knee that’s damaged, you can regenerate the cartilage. This is currently being done with horses at the vet school,” said said Gerhard Bauer, an assistant professor at the UC Davis Institute for Regenerative Cures. “So here at UC Davis, we treat horses with stem cells from fat or bone marrow stem cells, and inject them into the joints so they can walk again … we can do very similar things in humans, so they have many many applications.”
Applications for human use have already undergone testing. In collaboration with the UC Davis Cancer Center Hematologists and the UC Davis Stem Cell Program, Susanna Park, an ophthalmologist from the UC Davis Eye Center, performed a procedure that involves the use of adult stem cells in the repair of retinal tissue on Wednesday, a first in the U.S. Results are unclear right now, but there are high hopes of success. The process included the injection of adult cells, rather than embryonic cells, directly into the eye.
“With this method, we do not inject the cells directly into the retinas. In animal studies, adult cells, unlike embryonic cells, are able to hone into the diseased tissue … and migrate into the area,” Park said. “It takes a couple of days and migrates to the area where they need to be. The differences between adult cells and embryonic cells is [that] adult cells can get incorporated and do the repairs, and then go back into the bone marrow … [whereas] embryonic stem cells just stick around.”
If successful, the procedure could help millions of Americans using only a simple extraction of bone marrow and an injection into the eye, a much easier process than cutting damaged tissue out with lasers.
ALLEN GUAN can be reached at science@theaggie.org
