Ewa K. Zuba-Surma

Mobilization of bone marrow-derived Oct-4+ SSEA-4+ very small embryonic-like stem cells in patients with acute myocardial infarction.

OBJECTIVESnThis study sought to assess of the mobilization of nonhematopoietic very small embryonic-like stem cells (VSELs) in acute myocardial infarction (MI).nnnBACKGROUNDnAcute MI induces mobilization of bone marrow stem cells. Recently, a rare population of VSELs, expressing markers of embryonic pluripotent stem cells (PSCs), was identified in adult murine bone marrow and human umbilical cord blood.nnnMETHODSnThirty-one patients with acute MI and 30 healthy subjects were enrolled. Blood was sampled on admission, after 24 h, and 5 days later. Erythrocytes were lysed and lin(-)CD45(-) VSELs were isolated using a live cell sorting system (FACSAria, Beckton Dickinson, San Jose, California).nnnRESULTSnIn healthy subjects the median number of circulating VSELs was very low (median 0.8 [range 0 to 1.3]) cells/microl. In acute MI, VSELs were mobilized early (median 2.7 [range 0.2 to 3.9] cells/microl; p < 0.001) and remained elevated after 24 h and 5 days (median 4.7 [range 0.2 to 6.4] cells/microl; p < 0.003, and median 2.6 [range 0.3 to 3.6] cells/microl; p < 0.03, respectively). The mobilization of VSEL was significantly reduced in patients older than 50 years and with diabetes in comparison with younger and nondiabetic patients. Circulating VSELs were small (7 to 8 microm) and enriched in the messenger ribonucleic acid of PSC markers (Oct-4, Nanog), cardiac lineage (GATA-4, Nkx2.5/Csx, MEF2C), and endothelial (VE-cadherin) markers. The presence of PSC markers (Oct-4, SSEA-4) and the chemokine receptor CXCR4 in circulating VSELs was confirmed at the protein level by immunofluorescent staining and ImageStream system (Amnis Corporation, Seattle, Washington) analysis.nnnCONCLUSIONSnAcute MI induced mobilization of VSELs expressing pluripotent markers, early cardiac and endothelial markers, and chemokine receptor CXCR4.

Granulocyte colony-stimulating factor therapy for cardiac repair after acute myocardial infarction: a systematic review and meta-analysis of randomized controlled trials

BACKGROUNDnSmall clinical studies of granulocyte colony-stimulating factor (G-CSF) therapy for cardiac repair after acute myocardial infarction (MI) have yielded divergent results. The effect of G-CSF therapy on left ventricular (LV) function and structure in these patients remains unclear.nnnMETHODSnWe searched MEDLINE, EMBASE, Science Citation Index, CINAHL, and the Cochrane CENTRAL database of controlled clinical trials (July 2007) for randomized controlled trials of G-CSF therapy in patients with acute MI. We conducted a fixed-effects meta-analysis across 8 eligible studies (n = 385 patients).nnnRESULTSnCompared with controls, G-CSF therapy increased LV ejection fraction (EF) by 1.09%, increased LV scar size by 0.22%, decreased LV end-diastolic volume by 4.26 mL, and decreased LV end-systolic volume by 2.50 mL. None of these effects were statistically significant. The risk of death, recurrent MI, and in-stent restenosis was similar in G-CSF-treated patients and controls. Subgroup analysis revealed a modest but statistically significant increase in EF (4.73%, P < .0001) with G-CSF therapy in studies that enrolled patients with mean EF <50% at baseline. Subgroup analysis also showed a significant increase in EF (4.65%, P < .0001) when G-CSF was administered relatively early (< or =37 hours) after the acute event.nnnCONCLUSIONSnGranulocyte colony-stimulating factor therapy in unselected patients with acute MI appears safe but does not provide an overall benefit. Subgroup analyses suggest that G-CSF therapy may be salutary in acute MI patients with LV dysfunction and when started early. Larger randomized studies may be conducted to evaluate the potential benefits of early G-CSF therapy in acute MI patients with LV dysfunction.

Transplantation of Bone Marrow-Derived Very Small Embryonic-Like Stem Cells Attenuates Left Ventricular Dysfunction and Remodeling After Myocardial Infarction

Adult bone marrow (BM) contains Sca‐1+/Lin−/CD45− very small embryonic‐like stem cells (VSELs) that express markers of several lineages, including cardiac markers, and differentiate into cardiomyocytes in vitro. We examined whether BM‐derived VSELs promote myocardial repair after a reperfused myocardial infarction (MI). Mice underwent a 30‐minute coronary occlusion followed by reperfusion and received intramyocardial injection of vehicle (n= 11), 1 × 105 Sca‐1+/Lin−/CD45+ enhanced green fluorescent protein (EGFP)‐labeled hematopoietic stem cells (n= 13 [cell control group]), or 1 × 104 Sca‐1+/Lin−/CD45− EGFP‐labeled cells (n= 14 [VSEL‐treated group]) at 48 hours after MI. At 35 days after MI, VSEL‐treated mice exhibited improved global and regional left ventricular (LV) systolic function (echocardiography) and attenuated myocyte hypertrophy in surviving tissue (histology and echocardiography) compared with vehicle‐treated controls. In contrast, transplantation of Sca‐1+/Lin−/CD45+ cells failed to confer any functional or structural benefits. Scattered EGFP+ myocytes and capillaries were present in the infarct region in VSEL‐treated mice, but their numbers were very small. These results indicate that transplantation of a relatively small number of CD45− VSELs is sufficient to improve LV function and alleviate myocyte hypertrophy after MI, supporting the potential therapeutic utility of these cells for cardiac repair.

Evidence That Very Small Embryonic‐Like Stem Cells Are Mobilized into Peripheral Blood

Recently, we identified in murine adult tissues, including bone marrow, a population of very small embryonic‐like (VSEL) stem cells. Here, we provide further evidence that under steady‐state conditions these cells circulate at very low levels in peripheral blood (PB) (∼100–200 cells/ml) and could be additionally mobilized during pharmacological granulocyte‐colony‐stimulating factor‐induced or stress‐related mobilization, as demonstrated in a model of toxic liver or skeletal muscle damage induced by injection of carbon tetrachloride or cardiotoxin, respectively. The number of circulating VSEL stem cells under steady‐state conditions in PB of 2‐month‐old animals was five times higher than that in 1‐year‐old mice. In conclusion, this study supports a hypothesis that VSEL stem cells are a mobile pool of primitive stem cells that could be released from the stem cell niches into PB. Further studies are needed, however, to see whether the level of these cells circulating in PB could become a prognostic indicator to assess the regenerative potential of an adult organism and/or clinical outcome from an injury.

Very small embryonic-like stem cells are present in adult murine organs: ImageStream-based morphological analysis and distribution studies†

Recently, we purified a population of CXCR4+/Oct‐4+/SSEA‐1+/Sca‐1+/Lin−/CD45− very small embryonic‐like stem cells (VSELs) from adult murine bone marrow (BM). After using flow cytometry, ImageStream analysis, confocal microscopy, and real time RT‐PCR, we report that similar cells could be also identified and isolated from several organs in adult mice. The highest total numbers of Oct‐4+ VSELs were found in the brain, kidneys, muscles, pancreas, and BM. These observations support our hypothesis that a population of very primitive cells expressing germ line/epiblast markers (Oct‐4, SSEA‐1) is deposited early during embryogenesis in various organs and survives into adulthood. Further studies are needed to determine whether these cells, after being isolated from various adult human organs similarly to their murine BM‐derived counterparts, are endowed with pluripotent stem cell properties.

Very Small Embryonic-Like (VSEL) Stem Cells: Purification from Adult Organs, Characterization, and Biological Significance

In this review, we discuss current views of the bone marrow (BM) stem cell (SC) compartment and present data showing that BM contains heterogeneous populations of hematopoietic (H)SCs and non-HSCs. These cells are variously described in the literature as: endothelial progenitor cells (EPCs); mesenchymal (M)SCs; multipotent adult progenitor cells (MAPCs); marrow-isolated adult multilineage inducible (MIAMI) cells; and multipotent adult (MA)SCs. In some cases, it is likely that similar or overlapping populations of primitive SCs in the BM detected using various experimental strategies were assigned different names. Recently, we purified rare CXC chemokine receptor 4 expressing (CXCR4+) small SCs from the murine BM that express markers characteristic for embryonic (E)SCs, epiblast (EP)SCs, and primordial germ cells (PGCs). We named these primitive cells very small embryonic-like (VSEL) SCs. Our data indicate that VSELs may differentiate into cells from all three germ layers.

“Small stem cells” in adult tissues: Very small embryonic‐like stem cells stand up!

This review summarizes information regarding the rare population of very small embryonic‐like stem cells (VSELs) that has been identified in adult tissues, emphasizing both their unique morphological features and potential biological significance. We focus on their pluripotent nature and expression of markers characteristic for embryonic stem cells (ESCs), epiblast (EP)SCs, and primordial germ cells (PGCs). Furthermore, we will discuss their rank in the developmental hierarchy of the SC compartment as well as their relationship to other bone marrow‐derived, primitive, nonhematopoietic SCs including: (i) endothelial progenitor cells (EPCs); (ii) mesenchymal (M)SCs; (iii) multipotent adult progenitor cells (MAPCs); (iv) marrow‐isolated adult multilineage inducible (MIAMIs) cells; (v) multipotent adult (MA)SCs; and (vi) OmniCytes. We will also present different populations of very “small SCs” that have been recently described in the literature (e.g., spore‐like cells and Lin−/ALDHhigh long‐term repopulating hematopoietic SCs).

Very small embryonic-like (VSEL) stem cells in adult organs and their potential role in rejuvenation of tissues and longevity.

Recently, we purified rare CXC chemokine receptor 4 expressing (CXCR4(+)) small stem cells (SCs) from the murine bone marrow (BM) that express markers characteristic for embryonic (E)SCs, epiblast (EP)SCs, and primordial germ cells (PGCs). We named these primitive cells very small embryonic-like (VSEL) SCs (VSELs). Our data indicate that VSELs are also present in many other organs in mice and that they may differentiate into cells from all three germ layers. Similar SCs were also isolated from human cord blood (CB) and mobilized peripheral blood (mPB). We hypothesize that VSELs are deposited during gastrulation and organogenesis in developing organs/tissues of mammals as a population of pluripotent stem cells (PSCs) that give rise to tissue committed monopotent SCs and that their number decreases with age. Therefore VSELs could play a pivotal role in normal rejuvenation of adult tissues as well as involvement in regeneration of damaged organs. Thus, these cells are potential SCs candidates for regenerative medicine and we envision that the regenerative potential of these cells could be harnessed to decelerate the aging processes.

Adult murine bone marrow-derived very small embryonic-like stem cells differentiate into the hematopoietic lineage after coculture over OP9 stromal cells

OBJECTIVEnWe recently identified a population of small Sca-1(+)/Lin(-)/CD45(-) cells in adult murine bone marrow that express several epiblast/germ line and pluripotent stem cell markers (e.g., Oct-4 and SSEA-4) that we named very small embryonic-like stem cells (VSELs). In this report, we test the hypothesis that VSELs can differentiate along the hemato/lymphopoietic lineage.nnnMATERIALS AND METHODSnPurified from bone marrow, VSELs were primed/cocultured over OP9 stroma cell line and subsequently tested in vitro and in vivo assays for their hematopoietic potential. In parallel, cells derived from VSELs were evaluated for expression of hematopoietic genes and surface markers.nnnRESULTSnAlthough we observed that freshly isolated VSELs do not exhibit in vitro and in vivo hematopoietic potential, they may, after coculture over OP9 stromal cells, differentiate along the hematopoietic lineage in a similar way as embryonic stem cells or inducible pluripotent stem cells. OP9-primed, VSEL-derived cells acquired expression of several hemato/lymphopoiesis-specific genes and markers, gave rise to hematopoietic colonies in vitro, and protected lethally irradiated mice in both primary and secondary transplant models on transplantation. We also observed that, compared to hematopoietic stem/progenitor cells, VSELs are highly resistant to total body irradiation.nnnCONCLUSIONSnBased on these observations, we postulate that VSELs are the most primitive murine bone marrow-residing population of stem cells that have the potential to become specified into the hematopoietic lineage and may share some of the characteristics of long-term repopulating HSCs.

Hunt for Pluripotent Stem Cell – Regenerative Medicine Search for Almighty Cell

Regenerative medicine and tissue engineering are searching for a novel stem cell based therapeutic strategy that will allow for efficient treatment or even potential replacement of damaged organs. The pluripotent stem cell (PSC), which gives rise to cells from all three germ lineages, seems to be the most ideal candidate for such therapies. PSC could be extracted from developing embryos. However, since this source of stem cells for potential therapeutic purposes remains controversial, stem cell researchers look for PSC that could be isolated from the adult tissues or generated from already differentiated cells. True PSC should possess both potential for multilineage differentiation in vitro and, more importantly, also be able to complement in vivo blastocyst development. This review will summarize current approaches and limitations to isolate PSC from adult tissues or, alternatively, to generate it by nuclear reprogramming from already differentiated somatic cells.