What are the roles of quiescent cells?

The continuity of quiescence and re-entry of a cell into the cell cycle are vital for the functions of quiescent cells in tissue repair, reproduction, and immunity. For example, muscle stem cells remain in a quiescent state until a cellular injury arises and stimulates their renewed proliferation to regenerate damaged muscle tissue. Quiescent cells assist in maintaining tissue homeostasis by providing a “reservoir” of undifferentiated cells that may later be activated and differentiate into specialized cell types when necessary. Thus, these cells act as a source for tissue repair and regeneration. Additionally, this same mechanism occurs in response to infection or hormonal cues. Quiescent cells also function to withstand cellular stressors such as oxidative stress, nutrient deprivation, and DNA damage. Quinessence helps cells to survive adverse conditions by reducing vulnerability and therefore increasing their chances to remain viable. Lastly, quiescent cells assist in immune response regulation. Lymphocytes are quiescent immune cells and may be activated in response to specific antigens or immune signals. This stimulates rapid response of the immune system to pathogens and helps to regulate immune cells.