Germline stem cells (GSCs) are one type of stem cells which can only produce gametes for reproduction. Both male and female of invertebrates and low vertebrates animals have long-term self-renewing GSCs. People have not reached an agreement whether postnatal mammalian females have GSCs. But mammalian males have GSCs in the testis to support spermatogenesis.
In most organisms, GSCs usually exist in a defined anatomical niche and the self-renewal and differentiation of GSCs are regulated by factors within the niche. GSCs deliver genetic information from generation to generation by asymmetric division to form daughter cells. The molecular mechanisms to regulate GSCs by proteins or factors are also important to study stem cell regulation and tumorigenesis. As a primary manufacturer, Creative Biomart provides recombinant proteins of several sources, grades and formulations for germline stem cell research applications.
Stem cell niche
Stem cells purified from their surrounding tissues often lose their ability to self-renew, suggesting that intrinsic factors are not sufficient. It has long been thought that the local cellular microenvironment, or niche, provides the factors that instruct and maintain stem cells, and that differentiation occurs outside of the niche. Niches can be composed of support cells, extracellular matrix, or a combination of both, but difficulties locating stem cells have made characterizing mammalian niche architecture difficult. However, the gross anatomical locations of many types of stem cells are known. For example, hair follicle stem cells reside in the bulge region of the hair follicle; muscle stem cells reside near the basement membrane of the muscle fiber; hematopoietic stem cells reside either near the endosteum and /or sinusoids within the bone marrow; intestinal stem cells reside in the crypt of the gut; neural stem cells reside in the subventricular zone in the brain, and spermatogonial stem cells reside near the vasculature in the testis.
Most stem cells require one or a combination of the major developmental pathways such as Wnt, Hedgehog, Notch, and BMP for their maintenance. One potential method for identifying niche cells is to identify the cells within the tissue that express ligands for these pathways. Interestingly, single stem cells in culture have been shown to form organoids, suggesting that the stem cell itself may be able to produce its own niche in vivo. While the current notion of the niche is that of a static structure of cells or extra-cellular material, future studies may find that niches, like stem cells, are dynamic and can remodel to change position, structure, or even signaling properties. Studying and manipulating the stem cell niche is key to understanding stem cell biology and developing treatments for degenerative diseases.