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Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles

BACKGROUND: We recently published evidence to suggest that two populations of stem cells including very small embryonic-like stem cells (VSELs) and ovarian stem cells (OSCs) in ovary surface epithelium (OSE) undergo proliferation/differentiation, germ cell nests (GCN) formation, meiosis and eventual...

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Autores principales: Sharma, Diksha, Bhartiya, Deepa
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8944102/
https://www.ncbi.nlm.nih.gov/pubmed/35321734
http://dx.doi.org/10.1186/s13048-022-00968-4
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author Sharma, Diksha
Bhartiya, Deepa
author_facet Sharma, Diksha
Bhartiya, Deepa
author_sort Sharma, Diksha
collection PubMed
description BACKGROUND: We recently published evidence to suggest that two populations of stem cells including very small embryonic-like stem cells (VSELs) and ovarian stem cells (OSCs) in ovary surface epithelium (OSE) undergo proliferation/differentiation, germ cell nests (GCN) formation, meiosis and eventually differentiate into oocytes that assemble as primordial follicles on regular basis during estrus cycle. Despite presence of stem cells, follicles get exhausted with advancing age in mice and result in senescence equivalent to menopause in women. Stem cells in aged ovaries can differentiate into oocytes upon transplantation into young ovaries, however, it is still not well understood why follicles get depleted with advancing age despite the presence of stem cells. The aim of the present study was to study stem cells and GCN in aged ovaries. METHODS: OSE cells from aged mice (> 18 months equivalent to > 55 years old women) were enzymatically separated and used to study stem cells. Viable (7-AAD negative) VSELs in the size range of 2–6 µm with a surface phenotype of Lin(−)CD45(−)Sca-1(+) were enumerated by flow cytometry. Immuno-fluorescence and RT-PCR analysis were done to study stem/progenitor cells (OCT-4, MVH, SCP3) and transcripts specific for VSELs (Oct-4A, Sox-2, Nanog), primordial germ cells (Stella), germ cells (Oct-4, Mvh), early meiosis (Mlh1, Scp1) and ring canals (Tex14). RESULTS: Putative VSELs and OSCs were detected as darkly stained, spherical cells with high nucleo-cytoplasmic ratio along with germ cells nests (GCN) in Hematoxylin & Eosin stained OSE cells smears. Germ cells in GCN with distinct cytoplasmic continuity expressed OCT-4, MVH and SCP3. Transcripts specific for stem cells, early meiosis and ring canals were detected by RT-PCR studies. CONCLUSION: Rather than resulting as a consequence of accelerated loss of primordial follicle and their subsequent depletion, ovarian senescence/menopause occurs as a result of stem cells dysfunction. VSELs and OSCs exist along with increased numbers of GCNs arrested in pre-meiotic or early meiotic stage in aged ovaries and primordial follicle assembly is blocked possibly due to age-related changes in their microenvironment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13048-022-00968-4.
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spelling pubmed-89441022022-03-25 Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles Sharma, Diksha Bhartiya, Deepa J Ovarian Res Research BACKGROUND: We recently published evidence to suggest that two populations of stem cells including very small embryonic-like stem cells (VSELs) and ovarian stem cells (OSCs) in ovary surface epithelium (OSE) undergo proliferation/differentiation, germ cell nests (GCN) formation, meiosis and eventually differentiate into oocytes that assemble as primordial follicles on regular basis during estrus cycle. Despite presence of stem cells, follicles get exhausted with advancing age in mice and result in senescence equivalent to menopause in women. Stem cells in aged ovaries can differentiate into oocytes upon transplantation into young ovaries, however, it is still not well understood why follicles get depleted with advancing age despite the presence of stem cells. The aim of the present study was to study stem cells and GCN in aged ovaries. METHODS: OSE cells from aged mice (> 18 months equivalent to > 55 years old women) were enzymatically separated and used to study stem cells. Viable (7-AAD negative) VSELs in the size range of 2–6 µm with a surface phenotype of Lin(−)CD45(−)Sca-1(+) were enumerated by flow cytometry. Immuno-fluorescence and RT-PCR analysis were done to study stem/progenitor cells (OCT-4, MVH, SCP3) and transcripts specific for VSELs (Oct-4A, Sox-2, Nanog), primordial germ cells (Stella), germ cells (Oct-4, Mvh), early meiosis (Mlh1, Scp1) and ring canals (Tex14). RESULTS: Putative VSELs and OSCs were detected as darkly stained, spherical cells with high nucleo-cytoplasmic ratio along with germ cells nests (GCN) in Hematoxylin & Eosin stained OSE cells smears. Germ cells in GCN with distinct cytoplasmic continuity expressed OCT-4, MVH and SCP3. Transcripts specific for stem cells, early meiosis and ring canals were detected by RT-PCR studies. CONCLUSION: Rather than resulting as a consequence of accelerated loss of primordial follicle and their subsequent depletion, ovarian senescence/menopause occurs as a result of stem cells dysfunction. VSELs and OSCs exist along with increased numbers of GCNs arrested in pre-meiotic or early meiotic stage in aged ovaries and primordial follicle assembly is blocked possibly due to age-related changes in their microenvironment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13048-022-00968-4. BioMed Central 2022-03-23 /pmc/articles/PMC8944102/ /pubmed/35321734 http://dx.doi.org/10.1186/s13048-022-00968-4 Text en © The Author(s) 2022 https://creativecommons.org/licenses/by/4.0/Open AccessThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Sharma, Diksha
Bhartiya, Deepa
Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title_full Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title_fullStr Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title_full_unstemmed Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title_short Aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
title_sort aged mice ovaries harbor stem cells and germ cell nests but fail to form follicles
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8944102/
https://www.ncbi.nlm.nih.gov/pubmed/35321734
http://dx.doi.org/10.1186/s13048-022-00968-4
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