Erythropoietin, the hormone, which is known to boost red blood cells, also keeps blood vessels alive and growing in the eye.
A study conducted on mice by an ophthalmologist at Children's Hospital, Boston suggested that administering erythropoietin may worsen the condition of anaemia patients. The outcome of the study has raised the doubt for administering it to retinopathy and cancer patients.
For the study, Smith and his colleague Jing Chen, PhD, worked in mice with retinopathy, an eye disease that begins after the death of healthy blood vessels nourishing the retina. Numerous vessels then grow in, but they are deformed. Ultimately, the deformed vessels may pull the retina off the back of the eye, causing blindness.
After measuring erythropoietin produced in the retina as the disease progressed, the researchers found that the production was 3 to 10 times below normal during early-stage retinopathy, when healthy blood vessels died, and 12 to 33 times above normal during late-stage retinopathy, when deformed blood vessels grew into the retina.
The next step was to examine whether the administration of erythropoietin could treat retinopathy. For this, erythropoietin was injected into the bloodstream either early, as the mice lost healthy blood vessels, or later, when deformed blood vessels began to
invade--then compared them with untreated mice.
Early bolstering of erythropoietin slowed the disease, while raising erythropoietin later, when deformed blood vessels were present, seemed to accelerate the disease;
Smith suggested that if similar effects are found in humans, and its use is properly timed, then giving erythropoietin early could slow loss of healthy blood vessels in retinopathy.
She added that in other diseases, like cancer, in which doctors need to slow blood vessel growth, the hormone could be blocked, although clinical trials would need to confirm this idea.
Administering the hormone at the wrong time might help anaemia, but worsen the eye disease.
Cancer patients, who often take erythropoietin for anaemia,face the risk of growing tumors.
This was the study made and published in the recent issue of the Journal of Clinical Investigation.