Cells collected from the intestines of patients with the disease cystic fibrosis can be grown in the laboratory dish to produce balls of cells that scientists are calling mini guts. These can be used to test a series of new cystic fibrosis drugs that are now entering the clinic. But because these agents don't work on everyone, finding out who will benefit can mean a laborious trial for the patient. Mini guts on the other hand take just a few weeks to grow and give results in just days or hours. Jeffrey Beekman, from the Wilhelmina Children's Hospital, Utrecht, invented the technique...