[HTML][HTML] Stem cell niches in the mouse airway

JF Engelhardt - American journal of respiratory cell and molecular …, 2001 - atsjournals.org
American journal of respiratory cell and molecular biology, 2001atsjournals.org
Stem cell research has progressed to new levels of understanding over the last decade.
Many adult tissues undergo continuous self-renewal and hence require resident stem cells
with the capacity for multipotent differentiation in that organ (1). Such adult stem cells are
permanently established in an organ following embryogenesis. Stem cells are most often
slow-cycling and give rise to transient amplifying cells (TAC), which impart the majority of
tissue renewal in the setting of injury. Unlike stem cells, which by definition have unlimited …
Stem cell research has progressed to new levels of understanding over the last decade. Many adult tissues undergo continuous self-renewal and hence require resident stem cells with the capacity for multipotent differentiation in that organ (1). Such adult stem cells are permanently established in an organ following embryogenesis. Stem cells are most often slow-cycling and give rise to transient amplifying cells (TAC), which impart the majority of tissue renewal in the setting of injury. Unlike stem cells, which by definition have unlimited proliferative capacity, TAC are restricted in their capacity to divide and cannot proliferate indefinitely. Although stem cells and TAC are both selfrenewing populations, TAC are primarily thought to be the major progenitor population which gives rise to terminally differentiated cell types of an adult organ. While the concept of lineage restricted stem cells in adult organs has a long history, recent research isolating stem cells from different organs with multipotent capacity for “trans-differentiation” into various tissue lineages has begun to redefine “stem cell” characteristics (2). For example, neural stem cells have been found to have the capacity to cross tissue-specific lineages in the production of blood derived hematopoietic cell types (3). Similarly, bone marrow-derived myogenic progenitors have also been demonstrated to have the capacity to regenerate muscle (4, 5). These findings have reorganized thinking in the field beyond the traditional viewpoint that stem cells of adult tissues are limited to cell lineages present only in the organ from which they are derived. The concept of whether all organs retain stem cells with multipotent capacity for trans-differentiation across tissue lineages remains to be determined. However, these findings suggest that stem cells can respond to the unique biochemical cues of a niche in which they reside.
ATS Journals