Intestinal stem cells and the colorectal cancer microenvironment

Figure 1 Origin and development of normal intestinal stem cells. Lgr5⁺ CBCs and +4 LRCs coexist in the crypt. Each stem cell is fully multipotent. Lgr5⁺ cells likely maintain intestinal homeostasis under normal conditions. Following intestinal injury, the reserve population comprised of +4 LRCs and Dll1⁺ secretory progenitors restore both the epithelium and Lgr5⁺ CBCs. Tuft cells are Bmi1⁺ cells that may be synonymous with or descendants of +4 LRCs. CRC: Colorectal cancer; CBCs: Crypt base columnar cells; LRCs: Label-retaining intestinal stem cells.