Scottish scientists have been given the go-ahead to start trials on synthetic blood developed from stem cells. After years of denials, the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) gave researchers at the Scottish Centre for Regenerative Medicine the all-clear to manufacture blood on an "industrial scale". Scientists will use stem cell technology to create a new compound that could end blood shortages and eradicate infections passed on in blood transfusions. Wired investigates the potential challenges researchers will face when culturing cells to manufacture synthetic blood, also considering the effect it could have on the medical industry if the compound is patented.