Stem cell niche

As a stem cell niche is an environment in biology called within a multicellular organism receives the stem cells. The anatomical structure, cellular and non-cellular components are important components of the stem cell niche.

A special role in the formation of the niche can play adjacent supportive cells presenting the stem cells of certain surface molecules emit (eg, cadherins, catenins and integrins ), or the signaling molecules in the environment. Signals from the recess to regulate self-renewal, the survival and allow the maintenance of stem cells. The adhesion between stem cells and supportive stromal cells or the extracellular matrix anchoring the stem cells in the stem cell niche and thus close to the stem cell -maintaining signals. The specific spatial relationships of stem cells with the supporting cells may lead to a polarization of stem cell and thus an asymmetric cell division. In addition to a permanent stem cell results in a precursor cell that divides more often and their daughter cells differentiate further. Proliferation and / or differentiation of the stem cells can also be controlled by systemic factors.

Niches for different types of stem cells differ substantially. A deregulation of the stem cell niche can be a cause of tissue degeneration, aging, and tumorigenesis.

The existence of a stem cell niche was first proposed in 1978 by R. Schofield. Meanwhile she has been demonstrated in vertebrates and animal model organisms such as the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans.

Examples

The niche for hematopoietic stem cells, which show the blood- cell formation, the blood cells, located in adult mammals in the marrow of many bones, specifically in the substantia spongiosa of the bone ( " spongy " bone ). The stem cells are here closely associated with osteoblasts and endothelial cells of blood vessels. Neural stem cells occur in two different regions of the brain. In the subventricular zone of the hippocampus and in the olfactory bulb. In both niches are the stem cells in close proximity to endothelial cells. Epithelial stem cells sit in a specialized region of the outer root sheath of the hair follicle.