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Side population in human uterine myometrium displays phenotypic and functional characteristics of myometrial stem cells.

ABSTRACT: Over the course of pregnancy, the human uterus undergoes a 500- to 1,000-fold increase in volume and a 24-fold increase in weight. The uterine smooth muscle layer or myometrium is remodeled, and both cell hypertrophy and hyperplasia are evident. The origin of the new smooth muscle cells, however, is unclear. They may arise from existing smooth muscle cells, or they may be the product of stem cell differentiation. This study describes a subset of myometrial cells isolated from nonpregnant human myometrium that represents the myometrial stem cell population. This was characterized as side population of myometrial cells (myoSP) by a distinct Hoechst dye efflux pattern. In contrast to the main population of myometrial cells (myoMP), myoSP resided in quiescence, underexpressed or lacked myometrial cell markers, and could proliferate and eventually differentiate into mature myometrial cells in vitro only under low oxygen concentration. Although myoMP displayed mature myometrial phenotypes before and after in vitro cultivation, only myoSP, not myoMP, generated functional human myometrial tissues efficiently when transplanted into the uteri of severely immunodeficient mice. Finally, myoSP were multipotent and made to differentiate into osteocytes and adipocytes in vitro under the appropriate differentiation-inducing conditions. Thus, myoSP exhibited phenotypic and functional characteristics of myometrial stem cells. Study of myoSP will improve the understanding of myometrial physiology and the pathogenesis of myometrium-derived diseases such as leiomyoma. myoSP may also represent a novel source of biological material that could be used in the reconstruction of not only the human uterus but also other organs as well.

SUBMITTER: Ono M

PROVIDER: S-EPMC2141840 | biostudies-other | 2007 Nov

REPOSITORIES: biostudies-other

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Side population in human uterine myometrium displays phenotypic and functional characteristics of myometrial stem cells.

Ono Masanori M Maruyama Tetsuo T Masuda Hirotaka H Kajitani Takashi T Nagashima Takashi T Arase Toru T Ito Mamoru M Ohta Kuniaki K Uchida Hiroshi H Asada Hironori H Yoshimura Yasunori Y Okano Hideyuki H Matsuzaki Yumi Y

Proceedings of the National Academy of Sciences of the United States of America 20071114 47

Over the course of pregnancy, the human uterus undergoes a 500- to 1,000-fold increase in volume and a 24-fold increase in weight. The uterine smooth muscle layer or myometrium is remodeled, and both cell hypertrophy and hyperplasia are evident. The origin of the new smooth muscle cells, however, is unclear. They may arise from existing smooth muscle cells, or they may be the product of stem cell differentiation. This study describes a subset of myometrial cells isolated from nonpregnant human m ...[more]

PMID: 18003928

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Project description:During reproductive life, the human endometrium undergoes around 480 cycles of growth, breakdown and regeneration should pregnancy not be achieved. This outstanding regenerative capacity is the basis for women’s cycling and its dysfunction may be involved in the etiology of pathological disorders. Therefore, the human endometrial tissue must rely on a remarkable endometrial somatic stem cells (SSC) population. Here we explore the hypothesis that human endometrial side population (SP) cells correspond to somatic stem cells. We isolated, identified and characterized the SP corresponding to the stromal and epithelial compartments using endometrial SP genes signature, immunophenotyping and characteristic telomerase pattern. We analyzed the clonogenic activity of SP cells under hypoxic conditions and the differentiation capacity in vitro to adipogenic and osteogenic lineages. Finally, we demonstrated the functional capability of endometrial SP to develop human endometrium after subcutaneous injection in NOD-SCID mice. Briefly, SP cells of human endometrium from epithelial and stromal compartments display genotypic, phenotypic and functional features of SSC. Human tissue collection: Human endometrial biopsies were taken using a Pipelle catheter under sterile conditions (from 18 to 48 years) throughout the menstrual cycle. Epithelial and stromal separation: Epithelial and stromal fractions were isolated using an established protocol with modifications. Briefly, samples were carefully dissected and minced into 1-2mm fragments, and enzymatically digested in DMEM containing 10 mg/ml collagenase type IA. Stromal cells (single cells or small aggregates) and epithelial glands were separated on a size basis using gravity sedimentation and membrane filtration. Cell suspensions were treated with erythrocyte lysis solution and evaluation of cell viability was performed with Propidium Iodide (PI; 5 μg/ml). Hoechst 33342 labeling: Cells isolated from the endometrial epithelial and stromal fractions were resuspended in DMEM prewarmed at 37ºC and supplemented with 2% FBS and 10mM HEPES. The cell suspension was labeled in the same media with 5 μg/ml of Hoechst 33342 dye (Ho-33342), either alone or in combination with 100 μM verapamil (Vp), in a water bath at 37ºC for 90-120 minutes. Then, cells were centrifuged for 6 minutes at 4ºC, and were resuspended in cold HBSS supplemented with 2%FBS and 10mM HEPES. PI permits to exclude dead cells prior to the flow cytometric analysis and sorting. Isolation of human endometrial SP cells: Cells were analyzed and sorted by a MoFlo® jet-in-air high speed sorter. Excitation was performed with a water cooled Enterprise II ion laser which operated at the 351 nm and 488 nm wavelengths, and worked at 30 mW. Hoechst 33342 blue and red fluorescences were detected through 405/30 and 670/20 nm band-pass filters respectively, by measuring the signals on a linear scale. PI fluorescence was detected through a band-pass filter of 613/20 on a logarithmic scale. The gates for cell sorting were defined to collect live cells with a low Hoechst 33342 fluorescence (SP fraction), as well as live cells with a high Hoechst 33342 fluorescence (NSP fraction). Microarrays experiments: Endometrial tissue consisted in a total of 8 endometrial biopsies (epithelial (n=8) and stromal (n=8) endometrial cell suspensions, epithelial SP fraction (n=8) and stromal SP fractions (n=8) separately) which were pooled in pairs at the RNA levels. Four microarrays were analyzed per group.

Project description:Pituitary adenomas cause significant endocrine and mass-related morbidity. Not much is known about mechanisms underlying pituitary tumor pathogenesis.We searched for a side population (SP) in pituitary tumor, representing cells with high efflux capacity and potentially enriching for cancer/tumor stem cells (CSC/TSC). Human pituitary adenomas contain a SP irrespective of hormonal phenotype. This adenoma SP, as well as the further purified SP (pSP) depleted from endothelial and immune cells, enriches for cells that express ‘tumor stemness’ markers and signaling pathways, including epithelial-mesenchymal transition (EMT)-linked factors. The adenomas were found to contain self-renewing sphere-forming cells, considered a property of TSC. The sphere-initiating cells were retrieved in the pSP.Because benign pituitary adenomas do not grow in vitro and failed to expand in immunodeficient mice, the pituitary tumor cell line AtT20 was further used. We identified a SP in this cell line and found it more tumorigenic than the main population (MP). Of the two EMT-regulatory pathways tested, inhibition of Cxcr4 signaling reduced EMT-linked cell motility in vitro as well as xenograft tumor growth, whereas activation of TGFβ had no effect.The tumor pSP showed upregulated expression of the pituitary stem cell marker SOX2. Pituitaries from dopamine receptor D2 knockout (Drd2-/-) mice bearing prolactinomas, contain more pSP, Sox2+ and colony-forming cells than wildtype glands.In conclusion, we detected a SP in pituitary tumors and identified TSC-associated characteristics. Our study may contribute to a better understanding of pituitary tumor pathogenesis and lead to new therapeutic targets. We determined gene expression profiles for 9 human pituitary adenoma samples (5 x NF-A; 4 x GH-A). The samples were obtained immediately after transsphenoidal resection (by the neurosurgeon Dr. van Loon, Division Neurosurgery, University Hospitals Leuven). Informed consent was received from the patients. Hormonal phenotype was determined by the Department of Imaging and Pathology (University Hospitals Leuven). For each sample, total SP and MP cells were sorted by FACS. Separate assays were run subsequently for the two fractions. As such we present data from 18 microarrays.

Dataset Information

Side population in human uterine myometrium displays phenotypic and functional characteristics of myometrial stem cells.

Publications

Side population in human uterine myometrium displays phenotypic and functional characteristics of myometrial stem cells.

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