Stem cell research is not only one of the most controversial topics in science, but also one of the most advanced forms of research available. A stem cell is a cell that can differentiate into a diverse range of cells as well as regenerate into more stem cells. In order for this research to take off, more needs to be discovered about the pathways these stem cells use. Biologists at CalTech have been investigating this topic through macrophages which stem from unspecialized blood cells.
Macrophages are a vital part of the immune system, responsible for attacking foreign organisms that enter the body. Cell proliferation and cell differentiation, or the dividing and assigning identities of cells, are already well investigated topics on their own, but the study of macrophages has led to the hypothesis that these two processes are coordinated. The key factor in this process is the protein PU1, and the level of PU1 in the cell is the deciding point of macrophage formation. Researchers discovered that the way in which these macrophages are created occurs through a positive-feedback loop that regulates the PU1 level. PU1 self regulates during the cell cycle, either speeding it up when macrophage production is needed or slowing it down when it is not. Altering the length of the cell cycle allows for more rapid division and ultimately more proteins, which is far more advanced that a transcription regulation feedback loop. Knowing and understanding this mechanism is vital for understanding stem cells as a whole, and can be the next step towards successful stem cell research. Moving forward, research can be done on other potentially useful stem cell pathways using this mechanism to advance the knowledge about this promising field.