The debilitating memory loss of Alzheimer's disease seems linked to a deficiency of a brain hormone called nerve growth factor (NGF), according to recent research at the University of California at Los Angeles. But the obvious solution--deliver more NGF to needy brain cells--isn't easy. The digestive system would destroy the hormone if taken orally, and it can't be injected because the brain has an effective sieve that blocks foreign agents in the blood.
To get around these defenses, scientists at Cytotherapeutics Inc. in Providence have developed a miniature biotech factory that's inserted directly into the brain. No bigger than a grain of rice, it's a capsule filled with thousands of cells that produce NGF. The capsule is made from a special plastic membrane that has been engineered to shield its cells from attack by the body's immune system, yet permit NGF to escape. Researchers headed by Cytotherapeutics' founding scientist, Dr. Patrick Aebischer, have tested the concept in rats and recently began experiments with primates.