To create these cells in the lab, independent teams led by Baldwin and by Clifford Woolf, a neuroscientist at Boston Children’s Hospital in Massachusetts, identified combinations of proteins that — when expressed in fibroblasts — transformed them into sensory neurons after several days. Baldwin's team identified neurons that make receptors that detect sensations including pain, itch, and temperature, whereas Woolf’s team looked only at pain-detecting cells. Both teams generated cells that resembled neurons in shape and fired in response to capsaicin, which gives chilli peppers their kick, and mustard oil.

Both teams say that pain cells ‘in a dish’ could speed the search for new painkillers, as they could be used in screening drugs for their ability to block or alter the activity of these cells. “The number of people who take analgesics is very large, and there’s a pretty big medical need among people who have untreatable pain during chemotherapy,” says Baldwin. The anti-malarial drug chloroquine causes some people to itch — especially people of African ancestry — and studying itch cells made from their fibroblasts could help to explain why, she adds.

It will be important to make sure that the cells respond to stimuli similarly to bona fide sensory cells, says John Wood, a neuroscientist at University College London, and to determine how they communicate with immune cells and the rest of the nervous system, which both have roles in pain. “This is important work,” he says.  “Nociceptive [pain-sensing] neurons play a key role in almost all acute and chronic pain conditions, and a better understanding of their biology should produce new analgesic drug targets.”