Hormone and growth factor signaling in endometrial renewal: Role of stem/progenitor cells

Commonalities in the endocrinology of stem cell biology and organ regeneration

“…M a n u s c r i p t 6 Structurally, the hair follicle stem cell with its crypt-like configuration is reminiscent of the intestinal epithelium. A similar arrangement is apparent in the uterus and reviewed by Gargett and colleagues (Gargett et al, 2008). During reproductive life, if ovulation goes unfertilized the luminal epithelium regenerates on a monthly basis from basal crypt-like glands, highly congruent with an underlying stem cell population.…”

“…Such an occurrence is not necessarily restricted to tumour (stem) cells. A similar theory could explain endometriosis, where epithelial stem or progenitor cells escape the normal uterine environment and set up monthly regenerative cycles in ectopic locations, such as the peritoneum of the abdominal cavity (Gargett et al, 2008).…”

“…IGFBPs have been noted in the hair follicle and seem likely to be relevant (Paus et al, 2008), questioning whether this autoregulation is also true of the gut epithelium (Rowland and Brubaker, 2008) and haematopoietic niches (Garrett and Emerson, 2008). On the basis of colony formation in culture and distinct gene expression profiles, the stem or progenitor cells for the uterine epithelium are thought to be different from those for its underlying stroma (Gargett et al, 2008). …”

“…The result is ten articles (Berry et al, 2008;Gargett et al, 2008;Garrett and Emerson, 2008;Gray, 2008;Hanley et al, 2008;Hoffman, 2008;Ishizuya-Oka and Shi, 2008;Kristensen et al, 2008;Paus et al, 2008;Rowland and Brubaker, 2008) that should be considered alongside a previous review in Molecular & Cellular Endocrinology on the regeneration of the adrenal cortex from resident stem cells (Kim and Hammer, 2007). To complement these in vivo paradigms, three examples are included here of current in vitro stem cell work aiming to generate terminally differentiated cell-types for clinical therapy (Best et al, 2008;Moore et al, 2008;Tare et al, 2008): an endocrine twist on cell therapy meets regenerative biology.…”

Attributes of adult stem cells

“…The acidic vaginal environment results in squamous metaplasia of the transformation zone, preceded by the appearance of subcolumnar 'reserve cells' that undergo hyperplasia before forming metaplastic squamous epithelium indistinguishable from the squamous epithelia of the ectocervix. In mouse endometrium, rare stromal LRCs that are oestrogen receptor α-positive, have been proposed as niche cells [124], and LRCs (stem cells?) are also found in surface epithelial cells that are not menstruated in the mouse [125].…”