https://www.pure.ed.ac.uk/ws/files/14186931/A_Perivascular_Origin_for_Mesenchymal_Stem_Cells_in_Multiple_Human_Organs.pdf

A perivascular origin for mesenchymal stem cells in multiple human organs

Endometriosis

The terms MSC and MSCs have become the preferred acronym to describe a cell and a cell population of multipotential stem/progenitor cells commonly referred to as mesenchymal stem cells, multipotential stromal cells, mesenchymal stromal cells, and mesenchymal progenitor cells. The MSCs can differentiate to important lineages under defined conditions in vitro and in limited situations after implantation in vivo. MSCs were isolated and described about 30 years ago and now there are over 55,000 publications on MSCs readily available. Here, we have focused on human MSCs whenever possible. The MSCs have broad anti-inflammatory and immune-modulatory properties. At present, these provide the greatest focus of human MSCs in clinical testing; however, the properties of cultured MSCs in vitro suggest they can have broader applications. The medical utility of MSCs continues to be investigated in over 950 clinical trials. There has been much progress in understanding MSCs over the years, and there is a strong foundation for future scientific research and clinical applications, but also some important questions remain to be answered. Developing further methods to understand and unlock MSC potential through intracellular and intercellular signaling, biomedical engineering, delivery methods and patient selection should all provide substantial advancements in the coming years and greater clinical opportunities. The expansive and growing field of MSC research is teaching us basic human cell biology as well as how to use this type of cell for cellular therapy in a variety of clinical settings, and while much promise is evident, careful new work is still needed.

/pdf/mesenchymal-stem-cell-perspective-cell-biology-to-clinical-2twe95ou3n.pdf

Mesenchymal stem cell perspective: cell biology to clinical progress

Leptin-receptor-expressing mesenchymal stromal cells represent the main source of bone formed by adult bone marrow

The concept of mesenchymal stem cells (MSCs) is becoming increasingly obscure due to the recent findings of heterogeneous populations with different levels of stemness within MSCs isolated by traditional plastic adherence. MSCs were originally identified in bone marrow and later detected in many other tissues. Currently, no cloning based on single surface marker is capable of isolating cells that satisfy the minimal criteria of MSCs from various tissue environments. Markers that associate with the stemness of MSCs await to be elucidated. A number of candidate MSC surface markers or markers possibly related to their stemness have been brought forward so far, including Stro-1, SSEA-4, CD271, and CD146, yet there is a large difference in their expression in various sources of MSCs. The exact identity of MSCs in vivo is not yet clear, although reports have suggested they may have a fibroblastic or pericytic origin. In this review, we revisit the reported expression of surface molecules in MSCs from various sources, aiming to assess their potential as MSC markers and define the critical panel for future investigation. We also discuss the relationship of MSCs to fibroblasts and pericytes in an attempt to shed light on their identity in vivo.

https://stemcellsjournals.onlinelibrary.wiley.com/doi/epdf/10.1002/stem.1681

Concise review: the surface markers and identity of human mesenchymal stem cells.

The human endometrium regenerates from the lower basalis layer, a germinal compartment that persists after menstruation to give rise to the new upper functionalis layer. Because adult stem cells are present in tissues that undergo regeneration, we hypothesized that human endometrium contains small populations of epithelial and stromal stem cells responsible for cyclical regeneration of endometrial glands and stroma and that these cells would exhibit clonogenicity, a stem-cell property. The aims of this study were to determine 1) the clonogenic activity of human endometrial epithelial and stromal cells, 2) which growth factors support this clonogenic activity, and 3) determine the cellular phenotypes of the clones. Endometrial tissue was obtained from women undergoing hysterectomy. Purified single- cell suspensions of epithelial and stromal cells were cultured at cloning density (300–500/cm2) in serum medium or in serum- free medium supplemented with one of eight growth factors. Small numbers of e...

https://bioone.org/journals/biology-of-reproduction/volume-70/issue-6/biolreprod.103.024109/Clonogenicity-of-Human-Endometrial-Epithelial-and-Stromal-Cells1/10.1095/biolreprod.103.024109.pdf

Clonogenicity of Human Endometrial Epithelial and Stromal Cells

BACKGROUND: Human endometrium has immense regenerative capacity, growing ~5 mm in 7 days every month. We have previously identified a small population of colony-forming endometrial stromal cells which we hypothesize are mesenchymal stem cells (MSC). The aim of this study was to determine if the co-expression of two perivascular cell markers, CD146 and platelet-derived growth factor-receptor b (PDGF-Rb), will prospectively isolate endometrial stromal cells which exhibit MSC properties, and determine their location in human endometrium. METHODS: Single cell suspensions of human endometrial stromal cells were fluorescence activated cell sorting (FACS) sorted into CD146 1 PDGF-Rb 1 and CD146 2 PDGF-Rb 2 populations and analysed for colony-forming ability, in vitro differentiation and expression of typical MSC markers. Full thickness human endometrial sections were co-stained for CD146 and PDGF-Rb. RESULTS: FACS stromal CD146 1 PDGF-Rb 1 stromal cells (1.5% of sorted population) were enriched for colony-forming cells compared with CD146 2 PDGF-Rb 2 cells (7.7+1.7 versus 0.7+0.2% P< 0.0001), and also underwent differentiation into adipogenic, osteogenic, myogenic and chondrogenic lineages. They expressed MSC phenotypic surface markers and were located near blood vessels. CONCLUSION: This study shows that human endometrium contains a small population of MSC-like cells that may be responsible for its cyclical growth, and may provide a readily available source of MSC for tissue engineering applications.

Co-expression of two perivascular cell markers isolates mesenchymal stem-like cells from human endometrium

Human endometrium is a highly regenerative tissue undergoing more than 400 cycles of growth, differentiation, and shedding during a woman’s reproductive years. Endometrial regeneration is likely mediated by adult stem/progenitor cells. This study investigated key stem cell properties of individual clonogenic epithelial and stromal cells obtained from human endometrium. Single-cell suspensions of endometrial epithelial or stromal cells were obtained from hysterectomy tissues from 15 women experiencing normal menstrual cycles, and were cultured at clonal density (10 cells/cm 2 ) or limiting dilution. The adult stem cell properties—self-renewal, high proliferative potential, and differentiation of single epithelial and stromal cells—were assessed by harvesting individual colonies and undertaking serial clonal culture, serial passaging, and culture in differentiation-induction media, respectively. Lineage differentiation markers were examined by RT-PCR, immunocytochemistry, and flow cytometry. Rare single human endometrial

/pdf/isolation-and-culture-of-epithelial-progenitors-and-32v12fdhye.pdf

Isolation and Culture of Epithelial Progenitors and Mesenchymal Stem Cells from Human Endometrium

BACKGROUND The existence of stem/progenitor cells in the endometrium was postulated many years ago, but the first functional evidence was only published in 2004. The identification of rare epithelial and stromal populations of clonogenic cells in human endometrium has opened an active area of research on endometrial stem/progenitor cells in the subsequent 10 years.
 METHODS
 The published literature was searched using the PubMed database with the search terms ‘endometrial stem cells and menstrual blood stem cells' until December 2014.
 RESULTS
 Endometrial epithelial stem/progenitor cells have been identified as clonogenic cells in human and as label-retaining or CD44+ cells in mouse endometrium, but their characterization has been modest. In contrast, endometrial mesenchymal stem/stromal cells (MSCs) have been well characterized and show similar properties to bone marrow MSCs. Specific markers for their enrichment have been identified, CD146+PDGFRβ+ (platelet-derived growth factor receptor beta) and SUSD2+ (sushi domain containing-2), which detected their perivascular location and likely pericyte identity in endometrial basalis and functionalis vessels. Transcriptomics and secretomics of SUSD2+ cells confirm their perivascular phenotype. Stromal fibroblasts cultured from endometrial tissue or menstrual blood also have some MSC characteristics and demonstrate broad multilineage differentiation potential for mesodermal, endodermal and ectodermal lineages, indicating their plasticity. Side population (SP) cells are a mixed population, although predominantly vascular cells, which exhibit adult stem cell properties, including tissue reconstitution. There is some evidence that bone marrow cells contribute a small population of endometrial epithelial and stromal cells. The discovery of specific markers for endometrial stem/progenitor cells has enabled the examination of their role in endometrial proliferative disorders, including endometriosis, adenomyosis and Asherman's syndrome. Endometrial MSCs (eMSCs) and menstrual blood stromal fibroblasts are an attractive source of MSCs for regenerative medicine because of their relative ease of acquisition with minimal morbidity. Their homologous and non-homologous use as autologous and allogeneic cells for therapeutic purposes is currently being assessed in preclinical animal models of pelvic organ prolapse and phase I/II clinical trials for cardiac failure. eMSCs and stromal fibroblasts also exhibit non-stem cell-associated immunomodulatory and anti-inflammatory properties, further emphasizing their desirable properties for cell-based therapies.
 CONCLUSIONS
 Much has been learnt about endometrial stem/progenitor cells in the 10 years since their discovery, although several unresolved issues remain. These include rationalizing the terminology and diagnostic characteristics used for distinguishing perivascular stem/progenitor cells from stromal fibroblasts, which also have considerable differentiation potential. The hierarchical relationship between clonogenic epithelial progenitor cells, endometrial and decidual SP cells, CD146+PDGFR-β+ and SUSD2+ cells and menstrual blood stromal fibroblasts still needs to be resolved. Developing more genetic animal models for investigating the role of endometrial stem/progenitor cells in endometrial disorders is required, as well as elucidating which bone marrow cells contribute to endometrial tissue. Deep sequencing and epigenetic profiling of enriched populations of endometrial stem/progenitor cells and their differentiated progeny at the population and single-cell level will shed new light on the regulation and function of endometrial stem/progenitor cells.

/pdf/endometrial-stem-progenitor-cells-the-first-10-years-25kadt0o0y.pdf

Kjiana Elkje Schwab

Papers

Clonogenicity of Human Endometrial Epithelial and Stromal Cells

Co-expression of two perivascular cell markers isolates mesenchymal stem-like cells from human endometrium

Isolation and Culture of Epithelial Progenitors and Mesenchymal Stem Cells from Human Endometrium

Endometrial stem/progenitor cells: the first 10 years

Putative stem cell activity of human endometrial epithelial and stromal cells during the menstrual cycle