A Novel View of the Adult Stem Cell Compartment From the Perspective of a Quiescent Population of Very Small Embryonic-Like Stem Cells

Ratajczak, Mariusz Z.,Ratajczak, Janina,Suszynska, Malwina,Miller, Donald M.,Kucia, Magda,Shin, Dong-Myung Grune & Stratton 2017 Circulation research Vol.120 No.1

<P>Evidence has accumulated that adult hematopoietic tissues and other organs contain a population of dormant stem cells (SCs) that are more primitive than other, already restricted, monopotent tissue-committed SCs (TCSCs). These observations raise several questions, such as the developmental origin of these cells, their true pluripotent or multipotent nature, which surface markers they express, how they can be efficiently isolated from adult tissues, and what role they play in the adult organism. The phenotype of these cells and expression of some genes characteristic of embryonic SCs, epiblast SCs, and primordial germ cells suggests their early-embryonic deposition in developing tissues as precursors of adult SCs. In this review, we will critically discuss all these questions and the concept that small dormant SCs related to migratory primordial germ cells, described as very small embryonic-like SCs, are deposited during embryogenesis in bone marrow and other organs as a backup population for adult tissue-committed SCs and are involved in several processes related to tissue or organ rejuvenation, aging, and cancerogenesis. The most recent results on successful ex vivo expansion of human very small embryonic-like SC in chemically defined media free from feeder-layer cells open up new and exciting possibilities for their application in regenerative medicine.</P>

Molecular Characterization of Isolated from Murine Adult Tissues Very Small Embryonic/Epiblast like Stem Cells (VSELs)

Shin, Dong-Myung,Liu, Rui,Klich, Izabela,Ratajczak, Janina,Kucia, Magda,Ratajczak, Mariusz Z. Korean Society for Molecular and Cellular Biology 2010 Molecules and cells Vol.29 No.6

Pluripotent very small embryonic/epiblast derived stem cells (VSELs) as we hypothesize are deposited at begin of gastrulation in developing tissues and play an important role as backup population of pluripotent stem cells (PSCs) for tissue committed stem cells (TCSCs). We envision that during steady state conditions these cells may be involved in tissue rejuvenation and in processes of regeneration/repair after organ injuries. Molecular analysis of adult bone marrow (BM)-derived purified VSELs revealed that they i) express pluripotent stem cells markers e.g., Oct4, Nanog, Klf-4, SSEA-1 ii) share several markers characteristic for epiblast as well as migratory primordial germ cells (PGCs), and iii) possess a unique pattern of genomic imprinting (e.g., erasure of differently methylated regions at Igf2-H19 and Rasgrf1 loci and hypermethylation at KCNQ1 and Igf2R loci). This supports that VSELs are related to epiblast-derived migrating PGC-like cells and, despite their pluripotent stem cell character, changes in the epigenetic signature of imprinted genes keep these cells quiescent in adult tissues and prevent them from teratoma formation. In contrast epigenetic changes/mutations that lead to activation of imprinted genes could potentially lead to tumor formation by these cells. Mounting evidence accumulates that perturbation of expression of imprinted genes is a common phenomenon observed in developing tumors.

Very small embryonic-like stem-cell optimization of isolation protocols: an update of molecular signatures and a review of current <i>in vivo</i> applications

Shin, Dong-Myung,Suszynska, Malwina,Mierzejewska, Kasia,Ratajczak, Janina,Ratajczak, Mariusz Z Nature Publishing Group 2013 Experimental and molecular medicine Vol.45 No.11

<P>As the theory of stem cell plasticity was first proposed, we have explored an alternative hypothesis for this phenomenon: namely that adult bone marrow (BM) and umbilical cord blood (UCB) contain more developmentally primitive cells than hematopoietic stem cells (HSCs). In support of this notion, using multiparameter sorting we were able to isolate small Sca1<SUP>+</SUP>Lin<SUP>−</SUP>CD45<SUP>−</SUP> cells and CD133<SUP>+</SUP>Lin<SUP>−</SUP>CD45<SUP>−</SUP> cells from murine BM and human UCB, respectively, which were further enriched for the detection of various early developmental markers such as the SSEA antigen on the surface and the Oct4 and Nanog transcription factors in the nucleus. Similar populations of cells have been found in various organs by our team and others, including the heart, brain and gonads. Owing to their primitive cellular features, such as the high nuclear/cytoplasm ratio and the presence of euchromatin, they are called very small embryonic-like stem cells (VSELs). In the appropriate <I>in vivo</I> models, VSELs differentiate into long-term repopulating HSCs, mesenchymal stem cells (MSCs), lung epithelial cells, cardiomyocytes and gametes. In this review, we discuss the most recent data from our laboratory and other groups regarding the optimal isolation procedures and describe the updated molecular characteristics of VSELs.</P>

The Molecular Nature of Very Small Embryonic-Like Stem Cells in Adult Tissues

Kim, YongHwan,Jeong, Jaeho,Kang, Hyunsook,Lim, Jisun,Heo, Jinbeom,Ratajczak, Janina,Ratajczak, Mariusz Z.,Shin, Dong-Myung Korean Society for Stem Cell Research 2014 International journal of stem cells Vol.7 No.2

<P>Pluripotent stem cells (PSCs) have been considered as the most important cells in regenerative medicine as they are able to differentiate into all types of cells in the human body. PSCs have been established from several sources of embryo tissue or by reprogramming of terminally differentiated adult tissue by transduction of so-called Yamanaka factors (<I>Oct4</I>, <I>Sox2</I>, <I>Klf4</I>, and <I>cMyc</I>). Interestingly, accumulating evidence has demonstrated the residence of PSCs in adult tissue and with the ability to differentiate into multiple types of tissue-committed stem cells (TCSCs). We also recently demonstrated that a population of pluripotent Oct4<SUP>+</SUP> SSEA-1<SUP>+</SUP>Sca-1<SUP>+</SUP>Lin<SUP>−</SUP>CD45<SUP>−</SUP> very small embryonic-like stem cells (VSELs) resides in the adult murine bone marrow (BM) and in other murine tissue. These very small (∼3–6 <I>μ</I>m) cells express pluripotent markers such as Oct4, Nanog, and SSEA-1. VSELs could be specified into several tissue-residing TCSCs in response to tissue/organ injury, and thus suggesting that these cells have a physiological role in the rejuvenation of a pool of TCSCs under steady-state conditions. In this review article, we discuss the molecular nature of the rare population of VSELs which have a crucial role in regulating the pluripotency, proliferation, differentiation, and aging of these cells.</P>

Very small embryonic-like stem-cell optimization of isolation protocols: an update of molecular signatures and a review of current in vivo applications

Dong-Myung Shin, Ph.D.,Malwina Suszynska,Kasia Mierzejewska,Janina Ratajczak,Mariusz Z. Ratajczak 생화학분자생물학회 2013 Experimental and molecular medicine Vol.45 No.s

As the theory of stem cell plasticity was first proposed, we have explored an alternative hypothesis for this phenomenon: namely that adult bone marrow (BM) and umbilical cord blood (UCB) contain more developmentally primitive cells than hematopoietic stem cells (HSCs). In support of this notion, using multiparameter sorting we were able to isolate small Sca1þLinCD45cells and CD133þLinCD45 cells from murine BM and human UCB, respectively, which were further enriched for the detection of various early developmental markers such as the SSEA antigen on the surface and the Oct4 and Nanog transcription factors in the nucleus. Similar populations of cells have been found in various organs by our team and others,including the heart, brain and gonads. Owing to their primitive cellular features, such as the high nuclear/cytoplasm ratio and the presence of euchromatin, they are called very small embryonic-like stem cells (VSELs). In the appropriate in vivo models,VSELs differentiate into long-term repopulating HSCs, mesenchymal stem cells (MSCs), lung epithelial cells, cardiomyocytes and gametes. In this review, we discuss the most recent data from our laboratory and other groups regarding the optimal isolation procedures and describe the updated molecular characteristics of VSELs.

Molecular Characterization of Isolated from Murine Adult Tissues Very Small Embryonic/Epiblast like Stem Cells (VSELs)

Dong-Myung Shin,Rui Liu,Izabela Klich,Janina Ratajczak,Magda Kucia,Mariusz Z. Ratajczak 한국분자세포생물학회 2010 Molecules and cells Vol.29 No.6

Pluripotent very small embryonic/epiblast derived stem cells (VSELs) as we hypothesize are deposited at begin of gastrulation in developing tissues and play an important role as backup population of pluripotent stem cells (PSCs) for tissue committed stem cells (TCSCs). We envision that during steady state conditions these cells may be involved in tissue rejuvenation and in processes of regenera-tion/repair after organ injuries. Molecular analysis of adult bone marrow (BM)-derived purified VSELs revealed that they i) express pluripotent stem cells markers e.g., Oct4, Nanog, Klf-4, SSEA-1 ii) share several markers characteris-tic for epiblast as well as migratory primordial germ cells (PGCs), and iii) possess a unique pattern of genomic im-printing (e.g., erasure of differently methylated regions at Igf2-H19 and Rasgrf1 loci and hypermethylation at KCNQ1 and Igf2R loci). This supports that VSELs are related to epiblast-derived migrating PGC-like cells and, despite their pluripotent stem cell character, changes in the epigenetic signature of imprinted genes keep these cells quiescent in adult tissues and prevent them from teratoma formation. In contrast epigenetic changes/mutations that lead to activa-tion of imprinted genes could potentially lead to tumor formation by these cells. Mounting evidence accumulates that perturbation of expression of imprinted genes is a common phenomenon observed in developing tumors.

Atomically smooth interfaces of type-II InAs/GaSb superlattice on metamorphic GaSb buffer grown in 2D mode on GaAs substrate using MBE

A. Jasik,I. Sankowska,J. Ratajczak,A. Wawro,D. Smoczyński,K. Czuba,M. Wzorek 한국물리학회 2019 Current Applied Physics Vol.19 No.2

In the paper, the comparative analysis of type-II InAs/GaSb SLs deposited on three types of GaSb buffers: homoepitaxial, metamorphic and one grown using the interfacial misfit (IMF) array technique has been presented. The buffer layers as well as superlattices were grown under nominally identical technological conditions. HRXRD investigations proved better crystal quality of the metamorphic material than the IMF-GaSb. FWHMRC were equal to 156 arcsec and 196 arcsec, respectively. The surface roughness of about 1 ML and 4 MLs was obtained using the atomic force microscope for 4.0 μm–metamorphic GaSb and 1.5 μm-IMF-GaSb layers, respectively. The etch pits density for both buffers was similar, 1–2 × 107 cm−2. Superlattice with 500 periods deposited on the homoepitaxial buffer was used as a reference of the best crystal quality. HRTEM images revealed straight InAs/GaSb interfaces with 1 ML thicknesses in this sample. The interfaces in SL deposited on IMFGaSb buffer were undulated and smeared over 3 MLs. The use of the metamorphic buffer resulted in 1–2 ML straight InAs/GaSb interfaces. The main reason for this is the roughness of IMF-GaSb buffer with mounds on the surface. Based on the obtained results we have demonstrated the advantage of metamorphic approach over IMF growth mode in GaSb/GaAs material system. A two times thicker buffer could be the price worth paying for high quality structures, even when working in the production mode.

GaSb layers with low defect density deposited on (001) GaAs substrate in two-dimensional growth mode using molecular beam epitaxy

Agata Jasik,Iwona Sankowska,Andrzej Wawro,Jacek Ratajczak,Dariusz Smoczyński,Krzysztof Czuba 한국물리학회 2019 Current Applied Physics Vol.19 No.4

We report on the growth of fully relaxed and smooth GaSb layers with reduced density of threading dislocations, deposited on GaAs substrate. We prove that three parameters have to be controlled in order to obtain applicable GaSb buffers with atomically smooth surface: interfacial misfit (IMF), the etch pit density (EPD) and the growth mode. The GaSb/GaAs interfacial misfit array and reduced EPD ≤1.0×107 cm−2 were easily obtained using Asflux reduction for 3 min and Sb-soaking surface for 10 s before the GaSb growth initiation. The successive growth of GaSb layer proceeded under the technological conditions described by the wide range of the following parameters: rG ∈ (1.5 ÷ 1.9) Å/s, TG ∈ (400 ÷ 520)°C, V/III ∈ (2.3 ÷ 3.5). Unfortunately, a spiral or 3D growth modes were observed for this material resulting in the surface roughness of 1.1 ÷ 3.0 nm. Two-dimensional growth mode (layer by layer) can only be achieved under the strictly defined conditions. In our case, the best quality 1-μm-thick GaSb buffer layer with atomically smooth surface was obtained for the following set of parameters: rG=1.5 Å/s, TG=530 °C, V/III=2.9. The layer was characterized by the strain relaxation over 99.6%, 90° dislocations array with the average distance of 5.56 nm, EPD ∼8.0×106 cm−2 and 2D undulated terraces on the surface with roughness of about 1 ML. No mounds were observed. We belive that only thin and smooth GaSb layer with reduced EPD may be applied as the buffer layer in complex device heterostructures. Otherwise, it may cause the device parameters deterioration.