Biotechnologies that allow targeting of very specific cell types are a powerful and versatile tool, as demonstrated in this application via Reuters: "Although human embryonic stem cells are a very powerful source to make differentiated cells, like heart cells, the problem is that you can have residual cells and there is a safety concern because they can form [a] mass of tumour cells ... So if you give a product that is 95 percent heart cells, but 5 percent embryonic stem cells, it may be a problem later on ... The researchers managed to generate antibodies in mice after injecting human embryonic stem cells into the animals. The antibodies were then harvested and added to cultured embryonic stem cells that had been newly differentiated on laboratory dishes. ... [the antibody] specifically eliminated undifferentiated cells within 30 minutes but left differentiated cells untouched." So here, tools developed in cancer research are turned to making a foundation for regenerative medicine more practical.