Nature tells us of yet another reason to be pushing ahead with stem cell research. Scientists have demonstrated that "potentially limitless" numbers of T cells, a vital part of the immune system, can be created in the laboratory using stem cells. A quote: "In theory, the lab-made immune cells could be used for any patient, because they lack surface molecules that trigger rejection." We can now add immune system deficiencies to the long list of medical conditions open to stem cell based therapies. How much longer can European and US governments continue to block and criminalize this vital research?