Scientific dogma has long held that a single stem cell is responsible for all of the components of the blood system. Now in a paper published in the journal Cell Stem Cell, a group at Baylor College of Medicine is challenging that dogma. The group found that there were different, distinct adult stem cell subtypes that contribute to different components of the blood system. They verified the "stem cell nature" of these different subtypes by transplanting single stem cells into individual mice, and were able to confirm that these subtypes exist, can maintain a stable population of the stem cells over time, and behave as expected. Senior author Dr. Margaret Goodell said:

"From a scientific point of view, it's making us re-evaluate the view of the stem cells that come from adults. It challenges the dogma that there is one type of stem cell."

The study has significance for stem cell patient treatments as well. According to Goodell:

"People have been looking for purer and purer stem cell types. In doing that, they may not be getting all the stem cell types they need. Maybe in the clinic, it is better to have less pure types."