Comparative morphometric characteristics of eutopic and ectopic endometrial cells in patients

with endometriomas

Paris

SEUD Congress 2015

The pathogenesis of early-onset endometriosis has recently been revisited, sparked by the discovery of endometrial stem/progenitor cells and their possible role in endometriosis, and because maternal pregnancy hormone withdrawal following delivery induces uterine bleeding in the neonate. The neonatal uterus has a large cervix to corpus ratio which is functionally blocked with mucous, supporting the concept of retrograde shedding of neonatal endometrium. Only 5% show overt bleeding. During the neonatal and prepubertal period, shed endometrial stem/progenitor cells are postulated to survive in the pelvic cavity in the absence of circulating oestrogens supported by niche cells also shed during neonatal uterine bleeding1

1. Gargett CE, Schwab KE, Brosens JJ, Puttemans P, Benagiano G, Brosens I Potential role of endometrial stem/progenitor cells in the pathogenesis of early-onset endometriosis. Mol Hum Reprod. Advance Access published March 27, 2014

Perhaps those that develop early onset endometriosis may have had larger volume bleeds, with more endometrial stem/progenitor cells finding their way into the peritoneal cavity. Or, the fundamental differences in the endometrial stem/progenitor cell populations that predispose for endometriosis, such as carrying one of the susceptibility alleles recently identified for endometriosis risk1, may favour their survival by altering their clearance in the peritoneal cavity2.

1. Nyholt DR, Low SK, Anderson CA, Painter JN, Uno S, Morris AP, MacGregor S, Gordon SD, Henders AK, Martin NG et al. Genome-wide association meta-analysis identifies new endometriosis risk loci. Nat Genet 2012;44:1355-1359 2. Gargett CE, Schwab KE, Brosens JJ, Puttemans P, Benagiano G, Brosens I. Potential role of endometrial stem/progenitor cells in the pathogenesis of early-onset endometriosis. Mol Hum Reprod. Advance Access published March 27, 2014

The identification of markers for epithelial progenitor cells (eEPC) has been technically more difficult to achieve, but several recent studies have now hypothesized that eEPC are located in the basalis1.

Stage-specific embryonic antigen-I (SSE-I), a marker of basalis epithelial cells, was also present in endometriotic lesions, confirming that cells from the basalis contribute to the pathogenesis of endometriosis2.

1. Gargett CE. Uterine stem cells: What is the evidence? Hum Reprod Update 2007;13:87- 101 2. Valentijn AJ, Palial K, Al-Lamee H, Tempest N, Drury J, Von Zglinicki T, Saretzki G, Murray P, Gargett CE, Hapangama DK. SSEA-1 isolates human endometrial basal glandular epithelial cells: phenotypic and functional characterization and implications in the pathogenesis of endometriosis. Hum Reprod 2013;28:2695-2708

Purpose of the study was to examine morphometric characteristics of eutopic and ectopic endometrial cells with endometriosis.

Samples were obtained from

51 women

Thickness of slices was 4 mm. The resulting sections were stained in the usual manner with hematoxylin-eosin and subjected to optical microscopy using immersion objective with a total optical power 10 x 100.

Data are presented as the mean ± standart deviation and were analyzed by the Pearson nonparametric correlation to indicate statistical differences.

Feature of eutopic and ectopic endometrium

Studied parameters The thickness of the gland The core area The number of nucleoli in the nucleus The thickness of the cytoplasmic membrane The thickness of the nuclear membrane The thickness of the secretory parts of the cell Average brightness The total brightness The average density of the nucleus The total density of the nucleus The diameter of the core

The thickness of the glandular cells (µm)

Р<0,05

Characteristic changes in the area of the nucleus (m2)

Eutopic Ectopic

Р<0,05

Characterization of the cytoplasmic membrane thickness (µm2)

Р<0,05

Eutopic Ectopic

The thickness of the nuclear membrane (µm)

Р<0,05

The thickness of the secretory part of the gland (µm)

The characteristics of the average brightness and the density of nuclei

Р<0,05 Р<0,05

The diameter of the core and the number of nucleoli

Р>0,05 Р<0,001

Change in the almost all researched markers indicates an increase in cell proliferation activity of ectopic epithelium.

Our findings suggest different ways of developing and pathogenetic aspects of proliferative processes in eutopic and ectopic epithelium in patients with endometriomas.

Conclusion

Mesenchymal stem cells (MSC) from peritoneal lesions and ovarian cyst represent different tissue types, migration, invasion, and proliferation ability. Ecto-MSC from an ovarian cyst showed increased proliferation, migration, and invasion with respect to Euto-MSC deriving from the same patient1,2

1. Kao AP, Wang KH, Chang CC, Lee JN, Long CY, Chen HS, Tsai CF, Hsieh TH, Tsai EM. Comparative study of human eutopic and ectopic endometrial mesenchymal stem cells and the development of an in vivo endometriotic invasion model. Fertil Steril 2011;95:1308-1315 2. Moggio A, Pittatore G, Cassoni P, Marchino GL, Revelli A, Bussolati B. Sorafenib inhibits growth, migration, and angiogenic potential of ectopic endometrial mesenchymal stem cells derived from patients with endometriosis. Fertil Steril 2012;98(6):1521-1530)

With a change in environment following retrograde menstruation potentially altering both paracrine and endocrine signalling, it is likely that a number of epigenetic changes arise in ectopic endometrium, consequently giving rise to the pathology of endometriosis1.

1. Munro SK, Farquhar CM, Mitchell MD, Ponnampalam AP. Epigenetic regulation of endometrium during the menstrual cycle Mol Hum Reprod 2010;16(5):297–310

It also defines a new theory for the etiology of endometriosis – ectopic transdifferentiation of stem cells. Bone marrow derived stem cells (BMDCs) can contribute to endometriosis, perhaps explaining the occurrence of disease outside of the peritoneal cavity1.

BMDCs migrated and differentiated into eutopic and ectopic endometrial cells, although the contribution was very modest2.

They also could be source of cells for monthly endometrial regeneration3.

However, BMDC were more likely myeloid cells rather than bone marrow-derived stem cells4.

1. Duke CMP, Taylor HS. Stem cells and the reproductive system: Historical perspective and future directions. Maturitas 2013;76:284–289 2. Du H, Taylor HS. Contribution of bone marrow-derived stem cells to endometrium and endometriosis. StemCells 2007;25:2082-2086 3. Morelli SS, Rameshwar P, Goldsmith LT. Experimental evidence for bone marrow as a source of nonhematopoietic endometrial stromal and epithelial compartment cells in a murine model. Biol Reprod 2013;89:1-7 4. Cervello I, Gil-Sanchis C, Mas A, Faus A, Sanz J, Moscardo F, Higueras G, Sanz MA, Pellicer A, Simon C. Bone marrow-derived cells from male donors do not contribute to the endometrial side population of the recipient. PLoS One 2012;7:e30260

Acknowledgements My co-authors:

Krasililnikova Lily, Gimbut Vitaly

Areshuan Knarik, Berlim Julia,

Bychkova Anna, Lemeshko Svetlana, Mazhugin Vladimir

Dmitry Lebedev and Dr. med. Jochen Ruby, Head of Business Unit Women’s Health Gynecologist & Obstetrician in Bayer HealthCare Pharmaceuticals

for there in editing the presentation