Longevity medicine's do-or-die moment

The world's first human trial of whether a drug can essentially make a person's cells younger sets up a reality check for one of the longevity field's most promising theories.Why it matters: The early-stage clinical trial will signal whether "cellular reprogramming" can be performed safely in humans, a prerequisite for any future claim that a treatment can slow or even reverse biological aging.The big picture: Attempts to prolong the human lifespan can refer to anything from better diet and exer...