A stem cell researcher who doesn't really have time for your ethics hang-ups because he is rushing to save his children pauses to offer this intriguing question: If he could inject human stem cells into a monkey embryo and create a chimera, what part of its brain would have to be human before it could talk to you? Sitting in doug melton's harvard university office on a spring day, I look at the faces of his children in photographs on the desk. Sam is 14 years old now, with short hair and a slightly awkward smile; Emma has long, dark hair and serious eyes. A college freshman, Emma once wrote in an essay that she wants to become an embryolo-gist like her father. "I am also interested in becoming a member of Congress and petitioning for a cure that way," she wrote. Her father says, "I just hope she gets the chance." Inside Sam and Emma is an immune system that has destroyed cells called islets that are responsible for producing insulin in the pancreas. Insulin is an enzyme that helps transport sugars from the blood into cells for use as fuel. Without it, sugars gum up in the blood vessels as sugar does in a gas tank, causing an untreated diabetic to go into shock and die. Most diabetics today are saved by frequent shots of synthetic insulin, but the balance between blood sugar and injected insulin is a crude calculation. Diabetics receive either too much or too little insulin each day, which causes damage to organs and muscles. For Melton's children, this imbalance is most likely an early death sentence, unless, of course, their father can discover a stem cell fix for pancreatic cells in diabetics that are inexplicably attacked by the body's immune system.
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