BOSTON (Boston Globe) - The triumph when high-tech medicine saves a tiny premature baby can be bittersweet: Some "preemies" are prone to poor vision or even blindness as a complication of coming into the world too early.

Thousands of U.S. infants lose their vision each year to retinopathy of prematurity, or ROP, the major blinding disease of infants in the developed world. The smallest babies are at highest risk of the disease, in which twisted, leaky blood vessels grow across the light-sensitive retina, and current treatments are only partly successful.

Now, researchers at Children's Hospital and Harvard Medical School in Boston, along with collaborators in Sweden, have found a way to prevent ROP in mice using an existing biotech drug, and they are moving rapidly to try it in human infants.

"We're already setting up ... a multicenter trial to look at prevention in infants," said Dr. Lois E.H. Smith, an ophthalmologist at Children's and Harvard Medical School. She led the mouse study published in the current Proceedings of the National Academy of Sciences.

"There's no doubt that pharmacologic treatment will be important in this disease," given that available treatments, while successful in many cases, still have a "horrendously high failure rate," said Dr. Michael Tracy, scientific director for the Association for Retinopathy of Prematurity and Related Diseases, who had not seen the new study.

Tracy estimated that 30,000 infants in the United States are at risk of the disease each year, and thousands are blinded. But the problem is growing fastest in other countries where improved medical care is saving more preemies - and raising the risk of ROP.

But there may be a problem in going ahead with drug trials: Pharmaceutical companies are leery of testing potential new treatments in these fragile babies out of fear they'll be hurt and the company will be sued.

"They're just terrified of the liability," Tracy said. Because the drug would only have to be given a short period of time to see if it worked on ROP, he added, "it would be the very best disease to test it in" while possibly having application to other blinding diseases.

The drug used in the newly reported experiments is a natural substance known as IGF-1 (insulin-like growth factor 1) that's needed by the infant to kick-start normal development of blood vessels in the eye. Lacking IGF-1, the eye doesn't get normal nourishment from the blood. In this case, at around 34 weeks' gestation, blood vessel growth turns on in a sudden, abnormal fashion and, if it continues, the retina may be damaged.

Smith and her team showed that in mice bioengineered to lack IGF-1, adding the growth factor early on triggered normal blood vessel development and protected the retina from later harm.

Retinopathy of prematurity often is mild and goes away without further treatment, and not all preemies get ROP. To see if the amount of IGF-1 in babies' blood would predict whether they got the disease, the researchers measured IGF-1 levels in 31 babies born at 26 to 30 weeks' gestation. Normal birth is at around 38 weeks

"The ones who got the disease had very low levels of IGF-1," said Smith in an interview. The new research bolsters the hope that giving IGF-1 to premature infants may trigger normal vessel development and prevent ROP.

In mice, IGF-1 didn't cause discernible side effects, she said, but caution is needed in trying it in human infants. Smith said the drug probably would need to be given during the period the infant was in the neonatal intensive care unit, and could be stopped when the baby started to make its own.

Smith also emphasized that the drug works only as a preventive; once the disease has developed, it does not appear to help.

The Children's researcher said she hoped a human trial of IGF-1 could begin in the next year or two. Drug companies had made IGF-1 when researchers were testing it in diabetes, but currently the drug is out of production. Smith said getting a company to re-enter the market is a next step.

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