Bone marrow (BM) contains a population of self-renewing hematopoietic stem cells (HSC) that give rise to cells from all hemato-lymphopoietic lineages. The concept that HSC could also be plastic and be able to transdifferentiate into stem/progenitor cells for different non-hematopoietic tissues became one of the most controversial issues of modern stem cell biology. Accumulating experimental evidence suggests that contribution of BM-derived stem cells to organ/tissue regeneration could be explained not by plasticity (transdifferentiation) of HSC but rather by the presence of non-hematopoietic stem cells in BM. In this review new evidence will be presented, that adult BM contains a small population of pluripotent very small embryonic-like (VSEL) stem cells. These cells are deposited in BM early during ontogenesis and could be mobilized from BM and circulate in peripheral blood during tissue/organ injury in an attempt to regenerate damaged organs. However, if these cells are mobilized at the wrong time and migrate to the wrong place they may contribute to the development of several pathologies, including tumor formation.
"At the beginning it was supposed that pluripotent human embryonic stem cells (hESCs) can be isolated only from the human embryo, but later it was found that embyronic-like stem cells are also present in adult human tissues and organs. The group of Ratajczak first found a novel population of CXCR4+, SSEA-1+, Oct-4+ and CD45- cells in adult bone marrow
[1,2] and CXCR4+, SSEA-4+, and Oct-4+ cells in umbilical blood
. Because these cells were small and round, with diameters of up to ~5–6 μm, they termed them very small embryonic-like stem cells (VSELs). "
[Show abstract][Hide abstract] ABSTRACT: Background
It has already been found that very small embyronic-like stem cells (VSELs) are present in adult human tissues and organs. The aim of this study was to find if there exists any similar population of cells in cell cultures of reproductive tissues and embryonic stem cells, and if these cells have any relation to pluripotency and germinal lineage.
Methods and results
Here we report that a population of small SSEA-4-positive cells with diameters of up to 4 μm was isolated by fluorescence-activated cell sorting (FACS) from the human ovarian cell cultures after enzymatic degradation of adult cortex tissues. These small cells – putative ovarian stem cells – were also observed during cell culturing of up to 6 months and more. In general, small putative ovarian stem cells, isolated by FACS, showed a relatively low gene expression profile when compared to human embryonic stem cells (hESCs) and human adult fibroblasts; this may reflect the quiescent state of these cells. In spite of that, small putative ovarian stem cells expressed several genes related to primordial germ cells (PGCs), pluripotency and germinal lineage, including VASA. The PGC-related gene PRDM1 was strongly expressed in small putative ovarian stem cells; in both hESCs and fibroblasts it was significantly down-regulated. In addition, putative ovarian stem cells expressed other PGC-related genes, such as PRDM14 and DPPA3. Most of the pluripotency and germinal lineage-related genes were up-regulated in hESCs (except VASA). When compared to fibroblasts, there were several pluripotency-related genes, which were up-regulated in small putative ovarian stem cells. Similar populations of small cells were also isolated by FACS from human testicular and hESC cultures.
Our results confirm the potential embryonic-like character of small putative stem cells isolated from human adult ovaries and their possible relation to germinal lineage.
Journal of Ovarian Research 04/2013; 6(1):24. DOI:10.1186/1757-2215-6-24 · 2.43 Impact Factor
"As a similar population has also been S692 Review. Characteristics of stem cells H. Abdulrazzak et al. found in adult bone marrow, where they also express the same primitive markers, it has been hypothesized that VSEL cells are related to a population of early PGCs that are retained during development (Kucia et al. 2006). 2.2.2. "
[Show abstract][Hide abstract] ABSTRACT: Foetal stem cells (FSCs) can be isolated during gestation from many different tissues such as blood, liver and bone marrow as well as from a variety of extraembryonic tissues such as amniotic fluid and placenta. Strong evidence suggests that these cells differ on many biological aspects such as growth kinetics, morphology, immunophenotype, differentiation potential and engraftment capacity in vivo. Despite these differences, FSCs appear to be more primitive and have greater multi-potentiality than their adult counterparts. For example, foetal blood haemopoietic stem cells proliferate more rapidly than those found in cord blood or adult bone marrow. These features have led to FSCs being investigated for pre- and post-natal cell therapy and regenerative medicine applications. The cells have been used in pre-clinical studies to treat a wide range of diseases such as skeletal dysplasia, diaphragmatic hernia and respiratory failure, white matter damage, renal pathologies as well as cancers. Their intermediate state between adult and embryonic stem cells also makes them an ideal candidate for reprogramming to the pluripotent status.
Journal of The Royal Society Interface 12/2010; 7 Suppl 6(Suppl 6):S689-706. DOI:10.1098/rsif.2010.0347.focus · 3.92 Impact Factor
"It was confirmed, that these cells express markers characteristic of embryonic PSC, like SSEA- 1, Oct-4, Nanog and Rex-1, as well as they differentiate in vitro into cells from all three germ layers . This discovery gave a new impulse to the researches in adult stem cells and their potential application in regenerative medicine . "
[Show abstract][Hide abstract] ABSTRACT: The identification in murine bone marrow (BM) of very small embryonic-like (VSEL) stem cells, possessing several features of pluripotent stem cells, encouraged us to investigate if similar population of cells could be also isolated from the human umbilical cord blood (UCB). Here our approach to purify VSEL from human UCB is described by employing a two step isolation strategy based on i) hypotonic lysis of erythrocytes followed ii) by multi-parameter FACS sorting. Accordingly, first, erythrocytes are removed from the UCB samples by hypotonic ammonium chloride solution and next, the UCB mononuclear cells (UCB MNC) are stained with monoclonal antibodies against all hematopoietic lineages including the common leukocyte antigen CD45. The cells carrying these markers (lin+CD45+) are eliminated from the sort by electronic gating. At the same time the antibodies against CXCR4, CD34 and CD133 are employed as positive markers to enrich the UCB MNC for VSEL. This combined two step approach enables to purify VSEL stem cells, which are small and express mRNA for pluripotent stem cells (PSC) (Oct-4 and Nanog) and tissue-committed stem cells (TCSC) (Nkx2.5/Csx, VE-cadherin and GFAP) similarly to those isolated from the adult BM (3-5 microm cells with large nuclei).
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