(Nature) – Meanwhile, in Japan, a more worrisome approach is unfolding. Last month, researchers at Sapporo Medical University leapfrogged all other spinal-cord injury treatments that use stem cells — including the one being investigated by Asterias — and received market approval for injections of a type of cell called a mesenchymal stem cell. There are reasons to be sceptical, or at least to delay the sale of this procedure to patients.