scholarly journals How do tissue-specific stem cells produce specialized cells? What is the stem-cell niche?

2007 ◽  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Niche ◽  
Tissue Specific ◽  
Cell Niche ◽  
Tissue Specific Stem Cells

scholarly journals The Germline Stem Cell Niche Unit in Mammalian Testes

2012 ◽  
Vol 92 (2) ◽  
pp. 577-595 ◽  
Author(s):  
Jon M. Oatley ◽  
Ralph L. Brinster
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Regenerative Medicine ◽  
Stem Cell Niche ◽  
Germline Stem Cell ◽  
Tissue Specific ◽  
Support Cell ◽  
Age Related ◽  
Cell Niche ◽  
Germline Stem Cell Niche

This review addresses current understanding of the germline stem cell niche unit in mammalian testes. Spermatogenesis is a classic model of tissue-specific stem cell function relying on self-renewal and differentiation of spermatogonial stem cells (SSCs). These fate decisions are influenced by a niche microenvironment composed of a growth factor milieu that is provided by several testis somatic support cell populations. Investigations over the last two decades have identified key determinants of the SSC niche including cytokines that regulate SSC functions and support cells providing these factors, adhesion molecules that influence SSC homing, and developmental heterogeneity of the niche during postnatal aging. Emerging evidence suggests that Sertoli cells are a key support cell population influencing the formation and function of niches by secreting soluble factors and possibly orchestrating contributions of other support cells. Investigations with mice have shown that niche influence on SSC proliferation differs during early postnatal development and adulthood. Moreover, there is mounting evidence of an age-related decline in niche function, which is likely influenced by systemic factors. Defining the attributes of stem cell niches is key to developing methods to utilize these cells for regenerative medicine. The SSC population and associated niche comprise a valuable model system for study that provides fundamental knowledge about the biology of tissue-specific stem cells and their capacity to sustain homeostasis of regenerating tissue lineages. While the stem cell is essential for maintenance of all self-renewing tissues and has received considerable attention, the role of niche cells is at least as important and may prove to be more receptive to modification in regenerative medicine.

Tissue Stem Cells and Stem Cell Niche of the Human Vocal Fold

2020 ◽  
Vol 71 (2) ◽  
pp. 211-213
Author(s):  
K. Sato ◽  
S. Chitose ◽  
K. Sato ◽  
F. Sato ◽  
T. Kurita ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Niche ◽  
Vocal Fold ◽  
Cell Niche

scholarly journals Immunostaining of Lgr5, an Intestinal Stem Cell Marker, in Normal and Premalignant Human Gastrointestinal Tissue

2008 ◽  
Vol 8 ◽  
pp. 1168-1176 ◽  
Author(s):  
Laren Becker ◽  
Qin Huang ◽  
Hiroshi Mashimo
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Niche ◽  
Intestinal Stem Cells ◽  
Stem Cell Marker ◽  
Tumor Initiating Cells ◽  
Colonic Adenomas ◽  
Potential Marker ◽  
Cell Niche ◽  
Crypt Base

Lgr5 has recently been identified as a murine marker of intestinal stem cells. Its expression has not been well characterized in human gastrointestinal tissues, but has been reported in certain cancers. With the increasing appreciation for the role of cancer stem cells or tumor-initiating cells in certain tumors, we sought to explore the expression of Lgr5 in normal and premalignant human gastrointestinal tissues. Using standard immunostaining, we compared expression of Lgr5 in normal colon and small intestine vs. small intestinal and colonic adenomas and Barrett's esophagus. In the normal tissue, Lgr5 was expressed in the expected stem cell niche, at the base of crypts, as seen in mice. However, in premalignant lesions, Lgr5+cells were not restricted to the crypt base. Additionally, their overall numbers were increased. In colonic adenomas, Lgr5+cells were commonly found clustered at the luminal surface and rarely at the crypt base. Finally, we compared immunostaining of Lgr5 with that of CD133, a previously characterized marker for tumor-initiating cells in colon cancer, and found that they identified distinct subpopulations of cells that were in close proximity, but did not costain. Our findings suggest that (1) Lgr5 is a potential marker of intestinal stem cells in humans and (2) loss of restriction to the stem cell niche is an early event in the premalignant transformation of stem cells and may play a role in carcinogenesis.

scholarly journals Understanding the Influence of Substrate When Growing Tumorspheres

2020 ◽  
Author(s):  
Lucía Benítez ◽  
Lucas Barberis ◽  
Luciano Vellón ◽  
Carlos Alberto Condat
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Growth Factors ◽  
Cell Growth ◽  
Cancer Stem Cells ◽  
Cancer Stem Cell ◽  
Stem Cell Niche ◽  
Cell Number ◽  
Hard Substrate ◽  
Cell Niche

Abstract Background: Cancer stem cells are important for the development of many solid tumors. These cells receive promoting and inhibitory signals that depend on the nature of their environment (their niche) and determine cell dynamics. Mechanical stresses are crucial to the initiation and interpretation of these signals. Methods: A two-population mathematical model of tumorsphere growth is used to interpret the results of a series of experiments recently carried out in Tianjin, China, and extract information about the intraspecific and interspecific interactions between cancer stem cell and differentiated cancer cell populations. Results: The model allows us to reconstruct the time evolution of the cancer stem cell fraction, which was not directly measured. We find that, in the presence of stem cell growth factors, the interspecific cooperation between cancer stem cells and differentiated cancer cells induces a positive feedback loop that determines growth, independently of substrate hardness. In a frustrated attempt to reconstitute the stem cell niche, the number of cancer stem cells increases continuously with a reproduction rate that is enhanced by a hard substrate. For growth on soft agar, intraspecific interactions are always inhibitory, but on hard agar the interactions between stem cells are collaborative while those between differentiated cells are strongly inhibitory. Evidence also suggests that a hard substrate brings about a large fraction of asymmetric stem cell divisions. In the absence of stem cell growth factors, the barrier to differentiation is broken and overall growth is faster, even if the stem cell number is conserved. Conclusions: Our interpretation of the experimental results validates the centrality of the concept of stem cell niche when tumor growth is fueled by cancer stem cells. Niche memory is found to be responsible for the characteristic population dynamics observed in tumorspheres. A specific condition for the growth of the cancer stem cell number is also obtained.

scholarly journals Maintenance of Adult Stem Cells: Role of the Stem Cell Niche

2011 ◽  
pp. 35-55 ◽  
Author(s):  
Yoshiko Matsumoto ◽  
Hiroko Iwasaki ◽  
Toshio Suda
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Stem Cell Niche ◽  
Adult Stem Cells ◽  
Cell Niche
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