ARVO: Insulin Implants May Help Treat Diabetic Retinopathy
Animal study shows that subconjunctival implants reduce retinal degeneration and inflammation
MONDAY, May 14 (HealthDay News) -- In diabetic rats, subconjunctival insulin implants help prevent degenerative and inflammatory responses in the retina, suggesting that such implants could be used to treat people with diabetic retinopathy, according to research presented at the annual meeting of the Association for Research in Vision and Ophthalmology in Fort Lauderdale, Fla.
Ravi S.J. Singh, M.D., of the Pennsylvania State College of Medicine in Hershey, Penn., and colleagues previously reported insulin receptor signaling defects in the retina of diabetic rats and mice. So they treated control and diabetic male Sprague Dawley rats with subconjunctival implants containing regular human insulin in dosages starting at 0.01 U. They also studied the in vitro pharmacokinetic and pharmacodynamic effects of the insulin-loaded hydrogels on cultured cells.
The researchers found that the optimal dose of subconjunctivally administered insulin was 0.0325 U/100g. They found that this dose stimulated the pro survival insulin signaling pathway in the retina without affecting the contralateral uninjected eye or systemic blood glucose levels.
"This low-dose of subconjunctival insulin reaches the retina where it normalizes synaptic protein and c-Jun N-terminal Kinase expression," the authors write. "Insulin-loaded hydrogels release low amounts of biologically active insulin for over a month and are non-toxic to cells in culture and are well tolerated by rat eyes after subconjunctival implantation, and do not induce inflammatory response."