Synthetic biology is seeing rapid advances, but the medical applications have thus far remained largely elusive. But now researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University and Harvard Medical School (HMS) have developed a tool that can track specific populations of bacteria in the gut of living organisms and document population changes over time.

David Southwell, a seasoned pharma exec and CEO of newly funded Tscan Therapeutics Inc., called from a small, unadorned conference room on the Harvard campus to talk about his new company. He's used to being on the clinical development side, where the accommodations are a bit more posh, but nonetheless he's pleased to be investigating T-cell therapy for cancer patients.