Samumed is finding it easy to raise huge amounts of cash because it believes it has invented medicines that can reverse aging. Its first drugs are targeted at specific organ systems. One aims to regrow hair in bald men. The same drug may also turn gray hair back to its original color, and a cosmetic version could erase wrinkles. A second drug seeks to regenerate cartilage in arthritic knees. Additional medicines in early human studies aim to repair degenerated discs in the spine, remove scarring in the lungs and treat cancer. After that Samumed will attempt to cure a leading cause of blindness and go after Alzheimer’s. The firm’s focus, disease by disease, symptom by symptom, is to make the cells of aging people regenerate as powerfully as those of a developing fetus. ... Hood, 49, had invented a cancer drug that got his previous company, Targegen, bought by Sanofi for $635 million. He has a distinct take on drug development: He thinks everybody takes too many shortcuts and insists on doing work himself that other companies outsource, including formulating drug chemistry, testing drugs in laboratory animals and running clinical trials. ... The target Hood and Kibar went after was obvious: a gene called Wnt, which stands for “wingless integration site,” because when you knock it out in fruit flies, they never grow wings. It’s a linchpin in a group of genes that control the growth of a developing fetus–whether you’re a fly or a person. Together these genes are known as the Wnt pathway. Trigger the right ones and you might revive old flesh. Some cancers do their dirty work by hijacking Wnt, and blocking it might stop tumors.