Two separate teams of scientists developed novel approaches to creating blood stem cells. One team, based at Boston Children’s Hospital, was led by George Daley. This group started with human skin cells and “reprogrammed” them to become iPS (induced pluripotent stem) cells. An iPS cell is an artificially made, universal stem cell.
Daley’s team then injected the iPS cells with transcription factors, which are genes designed to control other genes. Afterward, the modified iPS cells were implanted in mice to develop. (If you’re keeping track, that makes those mice interspecies chimeras.)
After 12 weeks, these researchers had created something that was merely a precursor to blood stem cells. But the second team fared even better.
In Weill Cornell Medical College, Shahin Rafii and his team skipped iPS creation. Instead, they took cells from blood vessels in adult mice and injected them with four transcription factors. Then they moved the cells into petri dishes that were outfitted to recreate the environment within a human blood vessel.
These cells transformed into blood stem cells. The stem cells from this experiment were so powerful that they completely healed a group of mice that were suffering from a low blood cell count due to radiation treatments.