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Abstract
The past decade has seen an explosion of research directed toward better understanding of the mechanisms of mesenchymal stem/stromal cell (MSC) function during rescue and repair of injured organs and tissues. In addition to delineating cell–cell signaling and molecular controls for MSC differentiation, the field has made particular progress in defining several other mechanisms through which administered MSCs can promote tissue rescue/repair. These include: 1) paracrine activity that involves secretion of proteins/peptides and hormones; 2) transfer of mitochondria by way of tunneling nanotubes or microvesicles; and 3) transfer of exosomes or microvesicles containing RNA and other molecules. Improved understanding of MSC function holds great promise for the application of cell therapy and also for the development of powerful cell-derived therapeutics for regenerative medicine. Focusing on these three mechanisms, we discuss MSC-mediated effects on immune cell responses, cell survival, and fibrosis and review recent progress with MSC-based or MSC-derived therapeutics.
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Affiliation(s)
- Jeffrey L Spees
- University of Vermont, Burlington, VT, USA. .,Department of Medicine, Stem Cell Core, University of Vermont, 208 South Park Drive, Ste 2, Colchester, VT, 05446, USA.
| | - Ryang Hwa Lee
- Institute for Regenerative Medicine, Texas A & M University College of Medicine, 206 Olsen Blvd., Room 228, MS1114, College Station, TX, 77845, USA
| | - Carl A Gregory
- Institute for Regenerative Medicine, Texas A & M University College of Medicine, 206 Olsen Blvd., Room 228, MS1114, College Station, TX, 77845, USA.
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2
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Rapp YG, Ransbotyn V, Grafi G. Senescence Meets Dedifferentiation. PLANTS 2015; 4:356-68. [PMID: 27135333 PMCID: PMC4844402 DOI: 10.3390/plants4030356] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Revised: 06/16/2015] [Accepted: 06/23/2015] [Indexed: 01/07/2023]
Abstract
Senescence represents the final stage of leaf development but is often induced prematurely following exposure to biotic and abiotic stresses. Leaf senescence is manifested by color change from green to yellow (due to chlorophyll degradation) or to red (due to de novo synthesis of anthocyanins coupled with chlorophyll degradation) and frequently culminates in programmed death of leaves. However, the breakdown of chlorophyll and macromolecules such as proteins and RNAs that occurs during leaf senescence does not necessarily represent a one-way road to death but rather a reversible process whereby senescing leaves can, under certain conditions, re-green and regain their photosynthetic capacity. This phenomenon essentially distinguishes senescence from programmed cell death, leading researchers to hypothesize that changes occurring during senescence might represent a process of trans-differentiation, that is the conversion of one cell type to another. In this review, we highlight attributes common to senescence and dedifferentiation including chromatin structure and activation of transposable elements and provide further support to the notion that senescence is not merely a deterioration process leading to death but rather a unique developmental state resembling dedifferentiation.
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Affiliation(s)
- Yemima Givaty Rapp
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 84990 Israel.
| | - Vanessa Ransbotyn
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 84990 Israel.
| | - Gideon Grafi
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, 84990 Israel.
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Mauda-Havakuk M, Litichever N, Chernichovski E, Nakar O, Winkler E, Mazkereth R, Orenstein A, Bar-Meir E, Ravassard P, Meivar-Levy I, Ferber S. Ectopic PDX-1 expression directly reprograms human keratinocytes along pancreatic insulin-producing cells fate. PLoS One 2011; 6:e26298. [PMID: 22028850 PMCID: PMC3196540 DOI: 10.1371/journal.pone.0026298] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 09/23/2011] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Cellular differentiation and lineage commitment have previously been considered irreversible processes. However, recent studies have indicated that differentiated adult cells can be reprogrammed to pluripotency and, in some cases, directly into alternate committed lineages. However, although pluripotent cells can be induced in numerous somatic cell sources, it was thought that inducing alternate committed lineages is primarily only possible in cells of developmentally related tissues. Here, we challenge this view and analyze whether direct adult cell reprogramming to alternate committed lineages can cross the boundaries of distinct developmental germ layers. METHODOLOGY/PRINCIPAL FINDINGS We ectopically expressed non-integrating pancreatic differentiation factors in ectoderm-derived human keratinocytes to determine whether these factors could directly induce endoderm-derived pancreatic lineage and β-cell-like function. We found that PDX-1 and to a lesser extent other pancreatic transcription factors, could rapidly and specifically activate pancreatic lineage and β-cell-like functional characteristics in ectoderm-derived human keratinocytes. Human keratinocytes transdifferentiated along the β cell lineage produced processed and secreted insulin in response to elevated glucose concentrations. Using irreversible lineage tracing for KRT-5 promoter activity, we present supporting evidence that insulin-positive cells induced by ectopic PDX-1 expression are generated in ectoderm derived keratinocytes. CONCLUSIONS/SIGNIFICANCE These findings constitute the first demonstration of human ectoderm cells to endoderm derived pancreatic cells transdifferentiation. The study represents a proof of concept which suggests that transcription factors induced reprogramming is wider and more general developmental process than initially considered. These results expanded the arsenal of adult cells that can be used as a cell source for generating functional endocrine pancreatic cells. Directly reprogramming somatic cells into alternate desired tissues has important implications in developing patient-specific, regenerative medicine approaches.
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Affiliation(s)
- Michal Mauda-Havakuk
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Naomi Litichever
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Ellad Chernichovski
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Odelia Nakar
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Eyal Winkler
- Department of Plastic and Reconstructive Surgery, Sheba Medical Center, Tel-Hashomer, Israel
| | - Ram Mazkereth
- Albert Katz Department of Neonatology, Sheba Medical Center, Tel-Hashomer, Israel
| | - Arie Orenstein
- Department of Plastic and Reconstructive Surgery, Sheba Medical Center, Tel-Hashomer, Israel
| | - Eran Bar-Meir
- Department of Plastic and Reconstructive Surgery, Sheba Medical Center, Tel-Hashomer, Israel
| | - Philippe Ravassard
- Biotechnology and Biotherapy group Centre de Recherche Institut du Cerveau et de la Moelle CNRS UMR7225, INSERM UMRS795, Université Pierre et Marie Curie, Paris, France
| | - Irit Meivar-Levy
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
| | - Sarah Ferber
- Sheba Regenerative Medicine, Stem Cells and Tissue Engineering Center, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- * E-mail:
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4
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Abstract
The capacity of hepatocytes and cholangiocytes to contribute to their own maintenance has long been recognized. More recently, studies have indicated the presence of both intra-hepatic and extra-hepatic stem/progenitor cell populations. The intraorgan compartment probably derives primarily from the biliary tree, most particularly the most proximal branches, i.e. the canals of Hering and smallest ductules. The extra-organ compartment is at least in part derived from diverse populations of cells from the bone marrow. These three tiers of liver cell regeneration serve to maintain the normal organ and to regenerate damaged parenchyma in response to a variety of insults. The nature and extent of the insult determines the balance between these stem/progenitor compartments.
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Affiliation(s)
- Neil D Theise
- Department of Pathology, New York University School of Medicine, New York, NY, U.S.A. (E-mail,
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5
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Stem cell plasticity: recapping the decade, mapping the future. Exp Hematol 2010; 38:529-39. [PMID: 20438800 DOI: 10.1016/j.exphem.2010.04.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 04/08/2010] [Accepted: 04/13/2010] [Indexed: 12/20/2022]
Abstract
In slightly more than a decade of stem cell plasticity research, 24 peer-reviewed articles have demonstrated plasticity across organ and/or embryonic lineage boundaries at the single-cell level, with only 1 article showing negative results. These data, taken together with data about reversibility of gene restrictions that have also accumulated during the same period, indicate that postnatal cells, even "terminally differentiated" ones, have a degree of plasticity not appreciated previously. This review looks back at the four known pathways of cell plasticity and at previously described "plasticity principles" of Genomic Completeness, Cellular Uncertainty, Stochasticity of Cell Origin and Fate, relating these to issues of experimental design and discourse that are key to understanding and evaluating plasticity data. Although the physiologic roles played by such plasticity may still be debated, the manipulations of these phenomena for therapeutic or industrial purposes should finally be considered ripe for exploration. For the future, plasticity, indeed all stem cell biology, must be considered as part of a larger web of cell-to-cell and cell-to-matrix interactions that function fully only at the tissue level; thus, the success of stem cell biology necessarily must involve assembling data from cell and molecular biology research into systems of interactions that might be reasonably called "tissue biology." Interdisciplinary collaborations with complexity and chaos theorists, using mathematical/computer modeling of cell behaviors, will be vital to fully exploring stem cell behaviors in the coming decades.
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7
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Abstract
Communication in the stem cell field requires a common understanding of terminology and that "plasticity" phenomena are model- and, perhaps, species-dependent. Plasticity has generally been applied to unexpected differentiative events; will the term cease being useful when these unexpected pathways become recognized as normative? Four pathways of cell plasticity have now been recognized: (1) facultative, intraorgan self-renewing stem cells; (2) reversion of differentiated cells to blastema-like appearances, common in amphibians, perhaps restricted to neoplasia in mammals; (3) cells of one lineage directly changing to differentiation of another lineage cued by microenvironemental signals; (4) cell-cell fusion leading to changes in differentiation of the "incoming" cell in response to cytoplasmic and perhaps nuclear cues. In all of these, "differentiation" must be understood as a reflection of gene expression that is a highly intricate system of parallel, i.e., nonlinear molecular interactions. Present controversies regarding the plasticity of adult stem cells may be explained both by differences in experimental variables and techniques as well as by differing nonscientific, political, and/or polemical needs of investigators and commentators. Some of the variables in transplantation experiments, which are likely to be important in experimental outcome, but rarely addressed in interpretation of data, are the age of the cell donor and of the strain of mice or species used, the isolation technique used to obtain the putative stem cells, and the inherent effects of transgenic markers used to identify the donor or host cells. Also of great importance, but rarely controlled for in experimental design and interpretation, are the reproducibility and sensitivity of methods used to detect the markers of donor origin, the capacity of differentiated tissue to silence transgenes or alter marker expression, and--finally and most importantly--the different signals that influence plasticity phenomena in very different types of injury and regeneration. In different models of injury there are likely to be significant differences in promoting cell localization, proliferation, and predominance of "plasticity pathway," if any are involved, in determining outcome.
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Affiliation(s)
- Neil D Theise
- Department of Pathology and Medicine, Beth Israel Medical Center and Albert Einstein College of Medicine, New York, NY 10003, USA.
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Abstract
Recent insights regarding stem cells, repression and de-repression of gene expression, and the application of Complexity Theory to cell and molecular biology require a re-evaluation of many long-held dogmas regarding the nature of the human body in health and disease. Greater than expected cell plasticity, trafficking of cells between organs, 'cellular uncertainty', stochasticity of cell origins and fates, and a reconsideration of Cell Doctrine itself all logically follow from these observations and conceptual approaches. In this paper, these themes will be considered and some implications for the investigative pathologist will be explored.
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Affiliation(s)
- Neil D Theise
- Department of Pathology, Albert Einstein College of Medicine, Beth Israel Medical Center, New York, NY 10003, USA.
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Theise ND. Cell Doctrine in a Complex and Uncertain World: Time for Reappraisal? CLONING AND STEM CELLS 2005; 7:209-13. [PMID: 16390256 DOI: 10.1089/clo.2005.7.209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Neil D Theise
- Department of Pathology, Division of Digestive Diseases, Beth Israel Medical Center/Albert Einstein College of Medicine, New York, New York 10003, USA.
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Roeder I, Kamminga LM, Braesel K, Dontje B, de Haan G, Loeffler M. Competitive clonal hematopoiesis in mouse chimeras explained by a stochastic model of stem cell organization. Blood 2005; 105:609-16. [PMID: 15374890 DOI: 10.1182/blood-2004-01-0282] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
AbstractMany current experimental results show the necessity of new conceptual approaches to understand hematopoietic stem cell organization. Recently, we proposed a novel theoretical concept and a corresponding quantitative model based on microenvironment-dependent stem cell plasticity. The objective of our present work is to subject this model to an experimental test for the situation of chimeric hematopoiesis. Investigating clonal competition processes in DBA/2-C57BL/6 mouse chimeras, we observed biphasic chimerism development with initially increasing but long-term declining DBA/2 contribution. These experimental results were used to select the parameters of the mathematical model. To validate the model beyond this specific situation, we fixed the obtained parameter configuration to simulate further experimental settings comprising variations of transplanted DBA/2-C57BL/6 proportions, secondary transplantations, and perturbation of stabilized chimeras by cytokine and cytotoxic treatment. We show that the proposed model is able to consistently describe the situation of chimeric hematopoiesis. Our results strongly support the view that the relative growth advantage of strain-specific stem cells is not a fixed cellular property but is sensitively dependent on the actual state of the entire system. We conclude that hematopoietic stem cell organization should be understood as a flexible, self-organized rather than a fixed, preprogrammed process.
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Affiliation(s)
- Ingo Roeder
- Institute for Medical Informatics, Statistics and Epidemiology, University of Leipzig, Leipzig, Germany
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Agent-Based Modelling of Stem Cell Self-organisation in a Niche. ENGINEERING SELF-ORGANISING SYSTEMS 2005. [DOI: 10.1007/11494676_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Abstract
Hematopoietic stem cell (HSC) plasticity and its clinical application have been studied profoundly in the past few years. Recent investigations indicate that HSC and other bone marrow stem cells can develop into other tissues. Because of the high morbidity and mortality of myocardial infarction and other heart disorders, myocardial regeneration is a good example of the clinical application of HSC plasticity in regenerative medicine. Preclinical studies in animals suggest that the use of this kind of treatment can reconstruct heart blood vessels, muscle, and function. Some clinical study results have been reported in the past 2 years. In 2003, reports of myocardial regeneration treatment increased significantly. Other studies include observations on the cell surface markers of transplanted cells and treatment efficacy. Some investigations, such as HSC testing, have focused on clinical applications using HSC plasticity and bone marrow transplantation to treat different types of disorders. In this review, we focus on the clinical application of bone marrow cells for myocardial regeneration.
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Affiliation(s)
- Fu-Sheng Wang
- R&D Department, Sysmex America, Mundelein, Illinois 60060, USA.
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Abstract
It may be argued that adult stem cell processes or, more precisely, the cell lineages that arise from them, represent complex reactive or adaptive systems. Approaching hematopoietic and other stem cell lineages from this perspective has direct bearing on current debates regarding the plasticity of these lineage systems as well as on interpretation and modeling of clinical data regarding many diseases.
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Affiliation(s)
- Neil D Theise
- Beth Israel Medical Center, New York, NY 10003, USA.
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Abstract
The degree to which these elephants are disruptive to the steady advancement of the adult stem cell field will become clear with time. In some ways they enliven the discourse, but in many ways they interfere with efficient progress. Naming these elephants is a first step toward dealing with them. If we remain aware of these issues when evaluating new research, we are less likely to make careless mistakes, and we are more likely to be able to hold scientists, politicians, journalists, and entrepreneurs accountable for their practices. Although all adult stem cell researchers will spend time profitably riding some of these elephants, we will all inevitably spend more time cleaning up after them. Perhaps open, careful, and unbiased discussions of these elephants will help the cleanup work be less odious and completed sooner, rather than later.
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Affiliation(s)
- Neil D Theise
- Department of Pathology, Division of Digestive Diseases, Beth Israel Medical Center, New York, NY 10003, USA.
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