Human arteries have been grown from scratch in the lab. The technique could produce spare blood vessels for bypass surgery, researchers at Duke University School of Medicine hope.

The researchers first encourage ordinary human muscle cells to multiply. Then they add a gene called hTERT to make them live longer. Next they seed the cells on a hose-shaped scaffold of biodegradable polymer. After two months, the support dissolves leaving a tubular structure. Lining cells are then dropped inside to complete the artificial artery.