Ovarian adult stem cells: hope or pitfall?

Abstract

For many years, ovarian biology has been based on the dogma that oocytes reserve in female mammals included a finite number, established before or at birth and it is determined by the number and quality of primordial follicles developed during the neonatal period. The restricted supply of oocytes in adult female mammals has been disputed in recent years by supporters of postnatal neo-oogenesis. Recent experimental data showed that ovarian surface epithelium and cortical tissue from both mouse and human were proved to contain very low proportion of cells able to propagate themselves, but also to generate immature oocytes in vitro or in vivo, when transplanted into immunodeficient mice ovaries. By mentioning several landmarks of ovarian stem cell reserve and addressing the exciting perspective of translation into clinical practice as treatment for infertility pathologies, the purpose of this article is to review the knowledge about adult mammalian ovarian stem cells, a topic that, since the first approach quickly attracted the attention of both the scientific media and patients.

Germ cell-specific Atg7 knockout results in primary ovarian insufficiency in female mice

“… 41 , 42 However, the terminally differentiated oocytes are unable to propagate themselves. 43 Thus only the ovary exhibits profound cell loss at birth among the organ systems. During the neonatal transition, autophagy helps the germ cell to overcome the early neonatal starvation, which can protect germ cell from over-loss in the neonatal ovaries.…”

Generation of Artificial Gamete and Embryo From Stem Cells in Reproductive Medicine

“…However, recent studies have provided evidence of mitotically active OSCs in adult murine and human ovaries ( Johnson et al, 2004 ; Zou et al, 2009 ; Parte et al, 2011 ; White et al, 2012 ). Based on the ability of stem cells, which is a function of the self-renewal and differentiation of the cells, OSCs are believed to be a potentially inexhaustible source of oocytes that can be exploited to achieve fertility in women who are infertile or have an exhausted ovarian reserve, as long as the genetic integrity of the OSCs is maintained ( Virant-Klun et al, 2008 ; Woods and Tilly, 2012 ; Dunlop et al, 2013 ; Gheorghisan-Galateanu et al, 2014 ). Unlike OSCs (expressing nuclear OCT-4B), which are large, another population of small stem cells is believed to exist in the ovary.…”

The role of mitochondria in the female germline: Implications to fertility and inheritance of mitochondrial diseases

“…Alternatively, germline stem cells derived from the ovaries of adult female mice and humans (Johnson et al, 2004;White et al, 2012) might be used as a source of autologous mitochondria (Oktay et al, 2015), with oocytelike characteristics (Meldrum et al, 2016;Woods and Tilly, 2015). However, the existence of these ovarian stem cells is yet a subject of intense debate (Gheorghisan-Galateanu et al, 2014;Bhartiya and Patel, 2017;Horan and Williams, 2017). Altogether, these reports reveal the great potential of mitochondrial supplementation in rescuing oocyte competence, making these strategies worthy of further consideration.…”