title: Very small embryonic-like stem cells (VSELs) represent a real challenge in stem cell biology: recent pros and cons in the midst of a lively debate.
abstract: The concept that adult tissue, including bone marrow (BM), contains early-development cells with broader differentiation potential has again been recently challenged. In response, we would like to review the accumulated evidence from several independent laboratories that adult tissues, including BM, harbor a population of very rare stem cells that may cross germ layers in their differentiation potential. Thus, the BM stem cell compartment hierarchy needs to be revisited. These dormant, early-development cells that our group described as very small embryonic-like stem cells (VSELs) most likely overlap with similar populations of stem cells that have been identified in adult tissues by other investigators as the result of various experimental strategies and have been given various names. As reported, murine VSELs have some pluripotent stem cell characteristics. Moreover, they display several epiblast/germline markers that suggest their embryonic origin and developmental deposition in adult BM. Moreover, at the molecular level, changes in expression of parentally imprinted genes (for example, Igf2-H19) and resistance to insulin/insulin-like growth factor signaling (IIS) regulates their quiescent state in adult tissues. In several emergency situations related to organ damage, VSELs can be activated and mobilized into peripheral blood, and in appropriate animal models they contribute to tissue organ/regeneration. Interestingly, their number correlates with lifespan in mice, and they may also be involved in some malignancies. VSELs have been successfully isolated in several laboratories; however, some investigators experience problems with their isolation.
authors.affiliation: Stem Cell Institute at the James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA.
authors.forename: M Z
authors.initials: MZ
authors.lastname: Ratajczak
authors.affiliation: Department of Cell Biology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
authors.forename: E
authors.initials: E
authors.lastname: Zuba-Surma
authors.affiliation: Third Department of Cardiology, Silesian Medical University, Katowice, Poland.
authors.forename: W
authors.initials: W
authors.lastname: Wojakowski
authors.affiliation: Stem Cell Institute at the James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA.
authors.forename: M
authors.initials: M
authors.lastname: Suszynska
authors.affiliation: Department of Physiology, Pomeranian Medical University, Szczecin, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Mierzejewska
authors.affiliation: Stem Cell Institute at the James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA.
authors.forename: R
authors.initials: R
authors.lastname: Liu
authors.affiliation: 1] Stem Cell Institute at the James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA [2] Department of Physiology, Pomeranian Medical University, Szczecin, Poland.
authors.forename: J
authors.initials: J
authors.lastname: Ratajczak
authors.affiliation: Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: D M
authors.initials: DM
authors.lastname: Shin
authors.affiliation: 1] Stem Cell Institute at the James Graham Brown Cancer Center, University of Louisville, Louisville, KY, USA [2] Department of Physiology, Pomeranian Medical University, Szczecin, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kucia
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D053595:Embryonic Stem Cells / Q000166:cytology*; D044127:Epigenesis, Genetic; D018392:Genomic Imprinting; D051379:Mice
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