Niches, the Future of Regenerative Medicine
It is becoming increasingly clear that many of the very powerful future applications of regenerative medicine - such as replacing age-damaged tissue with newly repaired, youthful tissue - depend upon understanding and control of stem cell niches in addition to control of stem cells: "Niches are local tissue microenvironments that maintain and regulate stem cells. Long-predicted from mammalian studies, these structures have recently been characterized within several invertebrate tissues using methods that reliably identify individual stem cells and their functional requirements. Although similar single-cell resolution has usually not been achieved in mammalian tissues, principles likely to govern the behavior of niches in diverse organisms are emerging. Considerable progress has been made in elucidating how the microenvironment promotes stem cell maintenance. Mechanisms of stem cell maintenance are key to the regulation of homeostasis and likely contribute to aging and tumorigenesis when altered during adulthood."