Stem cells can be obtained from unwanted embryos created during in vitro fertilization.

nobeastsofierce Science / Alamy

A type of stem cell transplant that has long been seen as one of the most promising new types of medical treatment. Cancer As we thought earlier. A study found that a fifth of stem cells grown in laboratories for regenerative medicine research contain cancer-causing mutations.

The test cells have not been injected into people, but are being used in research to explore their clinical uses. The results show…