Linheng Li, PhD, studies stem cells, a special class of cells that occur naturally in the body but have amazing qualities that set them apart from other cells. They can develop into cells with specific functions, such as brain, blood or muscle cells, but they also continue to divide and renew themselves, making them potentially useful to treat a variety of human diseases. His research focuses primarily on two adult stem cell systems – intestinal stem cells and hematopoietic, or blood-forming, stem cells. Li’s group has explored these systems by studying the cells’ microenvironments or “niches” in model systems, and the molecules and mechanisms involved in niche maintenance. They have discovered that there are two sub-populations of blood-forming cells, one active and one backup. This finding has implications for cancer treatment, as there's evidence that tumors also contain active stem cells and a reservoir of quiescent backup cells, and effective treatments are needed to attack both.