Fuente: WIPO "tomato" The inventors discovered that ectodermal mesenchymal stem cells circulating in peripheral blood that are induced by necrotic tissue damage contribute to the regeneration of damaged tissue. On the basis of this discovery, provided are ectodermal mesenchymal stem cells, a method for producing the same, and a screening method for a substance having pluripotent stem cell inductive activity, the screening method using cells induced by necrotic tissue damage in peripheral blood as an index.