251
|
Abstract
There has been unprecedented recent interest in stem cells, mainly because of the hope they offer for cell therapy. Adult stem cells are an attractive source of cells for therapy, especially in view of the recent claims that they are remarkably plastic in their developmental potential when exposed to new environments. Some of these claims have been either difficult to reproduce or shown to be misinterpretations, leaving the phenomenon of adult stem cell plasticity under a cloud. There are, however, other examples of plasticity where differentiated cells or their precursors can be reprogrammed by extracellular cues to alter their character in ways that could have important implications for cell therapy and other forms of regenerative treatment.
Collapse
Affiliation(s)
- Martin Raff
- Medical Research Council Laboratory for Molecular Cell Biology, Cell Biology Unit, University College London, London WC1E 6BT, United Kingdom.
| |
Collapse
|
252
|
|
253
|
Alison MR, Poulsom R, Otto WR, Vig P, Brittan M, Direkze NC, Lovell M, Fang TC, Preston SL, Wright NA. Recipes for adult stem cell plasticity: fusion cuisine or readymade? J Clin Pathol 2004; 57:113-20. [PMID: 14747430 PMCID: PMC1770217 DOI: 10.1136/jcp.2003.010074] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2003] [Indexed: 01/25/2023]
Abstract
A large body of evidence supports the idea that certain adult stem cells, particularly those of bone marrow origin, can engraft at alternative locations, particularly when the recipient organ is damaged. Under strong and positive selection pressure these cells will clonally expand/differentiate, making an important contribution to tissue replacement. Similarly, bone marrow derived cells can be amplified in vitro and differentiated into many types of tissue. Despite seemingly irrefutable evidence for stem cell plasticity, a veritable chorus of detractors has emerged, some doubting its very existence, motivated perhaps by more than a little self interest. The issues that have led to this situation include the inability to reproduce certain quite startling observations, and extrapolation from the behaviour of embryonic stem cells to suggest that adult bone marrow cells simply fuse with other cells and adopt their phenotype. Although these issues need resolving and, accepting that cell fusion does appear to allow reprogramming of haemopoietic cells in special circumstances, criticising this whole new field because some areas remain unclear is not good science.
Collapse
Affiliation(s)
- M R Alison
- Histopathology Unit, Cancer Research (UK), London WC2A 3PX, UK.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
254
|
Roels F. Why study regulation of genes in inherited disorders? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2004; 544:1-8. [PMID: 14713207 DOI: 10.1007/978-1-4419-9072-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Frank Roels
- Department of Pathology, Ghent University, University Hospital, De Pintelaan 185, 9000 Gent, Belgium.
| |
Collapse
|
255
|
Kuniyasu H, Kitadai Y, Mieno H, Yasui W. Helicobactor pylori infection is closely associated with telomere reduction in gastric mucosa. Oncology 2004; 65:275-82. [PMID: 14657602 DOI: 10.1159/000074481] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To investigate differential reduction in telomere DNA in tissue components of gastric mucosa with respect to Helicobactor pylori infection. MATERIALS AND METHODS The telomere content was examined by fluorescent in situ hybridization with the (TTAGGG)(4) probe. To compare the signal intensities from the probe (telomere volume) with telomere length, five gastric carcinoma cell lines were used. Telomere volumes were examined in 9 healthy persons, 124 non-cancer patients, and 86 gastric cancer patients. RESULTS Telomere volume showed a linear correlation with telomere length measured by Southern blotting in gastric carcinoma cells. In healthy persons without H. pylori infection, the telomere volumes of gastric epithelial tissues were 70-79% that of intramucosal lymphocytes (internal control). In 124 patients without gastric cancer, telomere volume of H.-PYLORI-infected mucosa was significantly less than that of H.-pylori-negative mucosa in both metaplastic and non- metaplastic tissues (p < 0.0001). In 86 gastric cancer patients, telomere volumes in intestinal metaplasia adjacent to cancer were 75% that of intestinal metaplasia of non-cancer patients (p = 0.0001). hTERT expression was detected in 6 cancer-associated and 2 cancer-negative intestinal metaplasia specimens, in which telomere volume was markedly reduced. CONCLUSION H. pylori infection is closely associated with telomere reduction in gastric epithelium.
Collapse
Affiliation(s)
- Hiroki Kuniyasu
- Department of Oncological Pathology, Cancer Center, Nara Medical University, Kashihara, Japan.
| | | | | | | |
Collapse
|
256
|
Abstract
In recent years, there have been a number of well-documented examples demonstrating that one cell type can be converted to another. Two such examples are the appearance of ectopic pancreas in the liver and formation of hepatic tissue in the pancreas. The conversion of liver to pancreas raises the intriguing possibility of generating insulin-producing beta cells for therapeutic transplantation into diabetics. There is now a striking addition to the growing list of pancreatic conversions: the formation of pancreatic tissue in the developing biliary system.
Collapse
Affiliation(s)
- Zoë D Burke
- Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, UK
| | | | | |
Collapse
|
257
|
Kuwana M, Okazaki Y, Kodama H, Izumi K, Yasuoka H, Ogawa Y, Kawakami Y, Ikeda Y. Human circulating CD14+ monocytes as a source of progenitors that exhibit mesenchymal cell differentiation. J Leukoc Biol 2003; 74:833-45. [PMID: 12960274 DOI: 10.1189/jlb.0403170] [Citation(s) in RCA: 238] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Circulating CD14+ monocytes are precursors of phagocytes, such as macrophages and dendritic cells. Here we report primitive cells with a fibroblast-like morphology derived from human peripheral blood CD14+ monocytes that can differentiate into several distinct mesenchymal cell lineages. We named this cell population monocyte-derived mesenchymal progenitor (MOMP). MOMPs were obtained in vitro from human peripheral blood mononuclear cells cultured on fibronectin in the presence of fetal bovine serum alone as a source of growth factors. MOMPs had a unique molecular phenotype-CD14+CD45+CD34+type I collagen+-and showed mixed morphologic and molecular features of monocytes and endothelial and mesenchymal cells. MOMPs were found to be derived from a subset of circulating CD14+ monocytes, and their differentiation required that they bind fibronectin and be exposed to one or more soluble factors derived from peripheral blood CD14- cells. MOMPs could be expanded in culture without losing their original phenotype for up to five passages. The induction of MOMPs to differentiate along multiple limb-bud mesodermal lineages resulted in the expression of genes and proteins specific for osteoblasts, skeletal myoblasts, chondrocytes, and adipocytes. Our findings represent the first evidence that human circulating CD14+ monocytes are a source of progenitors that exhibit mesenchymal cell differentiation.
Collapse
Affiliation(s)
- Masataka Kuwana
- Instiute for Advanced Medical Research, Keio University School of Medicine, Tokyo, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
258
|
Shen CN, Seckl JR, Slack JMW, Tosh D. Glucocorticoids suppress beta-cell development and induce hepatic metaplasia in embryonic pancreas. Biochem J 2003; 375:41-50. [PMID: 14509268 PMCID: PMC1223676 DOI: 10.1042/bj20030140] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Elevated glucocorticoids are associated with low birth weight and fetal 'programming' of hypertension and glucose intolerance. In the present paper, we show that treatment of fetal rats with dexamethasone during the last week of gestation reduces the insulin content of their pancreatic beta-cells. We reproduce this effect of dexamethasone in vitro using organ cultures of mouse embryonic pancreas, and show that it is associated with an elevation of expression of the transcription factor C/EBPbeta (CCAAT/enhancer-binding protein beta) and a reduction of the transcription factor Pdx-1 (pancreatic duodenal homeobox-1). Dexamethasone also induces the appearance of hepatocyte-like cells in organ cultures of pancreas, based on the expression of liver markers, albumin, alpha1-antitrypsin and transthyretin. Evidence that C/EBPbeta is responsible for compromising the differentiation and later function of beta-cells is obtained from its effects on the beta-cell-like cell line RIN-5F. Transfection with a constitutive form of C/EBPb suppresses insulin formation, whereas introduction of a dominant-negative inhibitor of C/EBPb has no effect. We conclude that dexamethasone inhibits insulin expression in pancreatic beta-cells via a mechanism involving down-regulation of Pdx-1 and induction of C/EBPbeta. This mechanism may operate in combination with other changes during fetal programming, leading to type 2 diabetes in later life.
Collapse
Affiliation(s)
- Chia-Ning Shen
- Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| | | | | | | |
Collapse
|
259
|
Abstract
The direct conversion of one differentiated cell type into another--a process referred to as transdifferentiation--would be beneficial for producing isogenic (patient's own) cells to replace sick or damaged cells or tissue. Adult stem cells display a broader differentiation potential than anticipated and might contribute to tissues other than those in which they reside. As such, they could be worthy therapeutic agents. Recent advances in transdifferentiation involve nuclear transplantation, manipulation of cell culture conditions, induction of ectopic gene expression and uptake of molecules from cellular extracts. These approaches open the doors to new avenues for engineering isogenic replacement cells. To avoid unpredictable tissue transformation, nuclear reprogramming requires controlled and heritable epigenetic modifications. Considerable efforts remain to unravel the molecular processes underlying nuclear reprogramming and evaluate stable of the changes in reprogrammed cells.
Collapse
Affiliation(s)
- Philippe Collas
- Institute of Medical Biochemistry, University of Oslo, PO Box 1112 Blindern, 0317 Oslo, Norway.
| | | |
Collapse
|
260
|
Rishniw M, Xin HB, Deng KY, Kotlikoff MI. Skeletal myogenesis in the mouse esophagus does not occur through transdifferentiation. Genesis 2003; 36:81-2. [PMID: 12820168 DOI: 10.1002/gene.10198] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
To determine the developmental history of murine esophageal skeletal muscle, smooth muscle cells were fate mapped by lineage-specific recombination and phenotypically marked by eGFP. Examination of embryonic and postnatal tissues revealed that esophageal skeletal muscle does not arise from transdifferentiation of committed smooth muscle cells.
Collapse
|
261
|
Abstract
The therapeutic potential of stem cells and nuclear cloning has led to renewed interest in classical models of regeneration. This longstanding problem is undergoing a renaissance spurred by the availability of new techniques that finally allow analysis on the cellular and molecular level.
Collapse
Affiliation(s)
- Elly M Tanaka
- Max-Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany.
| |
Collapse
|
262
|
Marchetti M, Caliot E, Pringault E. Chronic acid exposure leads to activation of the cdx2 intestinal homeobox gene in a long-term culture of mouse esophageal keratinocytes. J Cell Sci 2003; 116:1429-36. [PMID: 12640028 DOI: 10.1242/jcs.00338] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
To explore mechanisms whereby Malpighian keratinocytes can transdifferentiate into an intestinal-like epithelium, as observed in the early steps of Barrett's esophagus (BE) development, long-standing cultures of esophageal keratinocytes derived from normal mouse esophageal explants were developed. These cells were able to form multilayers and to differentiate on filter support by the formation of differentiated layers of basal cells (cytokeratine 14 positive) on which secondary suprabasal cell layers (cytokeratine 4 positive) spontaneously developed. Thus, these cultured cells, referred to as P3E6, reproduced, at least in part, the proliferation and stratification pattern existing in the normal esophagus. Because chronic exposure to acid pH is known to be a critical factor for BE development, culture medium at pH 3.5 was added into the apical chamber of cell cultures. This led to a decrease in the overall number of cells but it did not affect cell proliferation. Furthermore, external acid environment triggered expression of the GFP reporter gene fused downstream of the cdx2 intestinal homeogene regulatory sequences in P3E6 transfected cells. Expression of the endogenous CDX2 protein, detected by western blot and immunocytochemical analysis, correlated with promoter activation. These findings demonstrate that chronic exposure of esophageal keratinocytes to acid pH induces transcription of cdx2, an intestinal specific homeobox gene known to play a critical role in the differentiation and maintenance of intestinal epithelial functions. The results suggest that chronic acid exposure can modify the fate of P3E6 esophageal keratinocytes towards an intestinal program. This can be a key step in the development of intestinal metaplasia often observed in esophagus-cardia junction.
Collapse
Affiliation(s)
- Marta Marchetti
- Laboratory of Lympho-Epithelial Interactions, Department of Cell Biology and Infection, Pasteur Institute, 28, Rue du Dr Roux, 75015 Paris, France
| | | | | |
Collapse
|
263
|
Smallridge R. Time to change jobs? Nat Rev Mol Cell Biol 2003. [DOI: 10.1038/nrm1063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
264
|
Alison MR, Poulsom R, Otto WR, Vig P, Brittan M, Direkze NC, Preston SL, Wright NA. Plastic adult stem cells: will they graduate from the school of hard knocks? J Cell Sci 2003; 116:599-603. [PMID: 12538760 DOI: 10.1242/jcs.00269] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Notwithstanding the fact that adult bone marrow cell engraftment to epithelial organs seems a somewhat uncommon event, there is no doubt it does occur, and under appropriate conditions of a strong and positive selection pressure these cells will expand clonally and make a significant contribution to tissue replacement. Likewise, bone-marrow-derived cells can be amplified in vitro and differentiated into a multitude of tissues. These in essence are the goals of regenerative medicine using any source of stem cells, be it embryonic or adult. Despite such irrefutable evidence of what is possible, a veritable chorus of detractors of adult stem cell plasticity has emerged, some doubting its very existence, motivated perhaps by more than a little self-interest. The issues that have led to this state of affairs have included the inability to reproduce certain widely quoted data, one case where the apparent transdifferentiation was due to contamination of the donor tissue with haematopoietic cells and, most notoriously, extrapolating from the behaviour of embryonic stem cells to suggest that adult bone marrow cells simply fuse with other cells and adopt their phenotype. While these issues need resolving, slamming this whole new field because not everything is crystal clear is not good science. The fact that a phenomenon is quite rare in no way mitigates against its very existence: asteroid collisions with the Earth are rare, but try telling the dinosaurs they do not occur! When such events do occur (transdifferentiation or collision), they certainly can make an impact.
Collapse
|
265
|
Abstract
Making endocrine pancreas cells at will is one of the major goals of cellular based therapies for diabetes. The experimentally induced conversion of hepatocytes into pancreatic cells, using a modified version of the transcription factor Pdx-1, may provide an alternative to stem cell approaches.
Collapse
Affiliation(s)
- Valerie A McLin
- Division of Gastroenterology, Hepatology and Nutrition,Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, USA
| | | |
Collapse
|
266
|
Affiliation(s)
- J M W Slack
- Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, Bath, United Kingdom.
| |
Collapse
|
267
|
Hao HN, Zhao J, Thomas RL, Parker GC, Lyman WD. Fetal human hematopoietic stem cells can differentiate sequentially into neural stem cells and then astrocytes in vitro. JOURNAL OF HEMATOTHERAPY & STEM CELL RESEARCH 2003; 12:23-32. [PMID: 12662433 DOI: 10.1089/152581603321210109] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In some rodent models, there is evidence that hematopoietic stem cells (HSC) can differentiate into neural cells. However, it is not known whether humans share this potential, and, if so, what conditions are sufficient for this transdifferentiation to occur. We addressed this question by assessing the ability of fetal human liver CD34(+)/CD133(+)/CD3(-) hematopoietic stem cells to generate neural cells and astrocytes in culture. We cultured fetal liver-derived hematopoietic stem cells in human astrocyte culture-conditioned medium or using a method wherein growing human astrocytes were separated from cultured, nonadherent hematopoietic stem cells by a semipermeable membrane in a double-chamber co-culture system. Hematopoietic stem cell cultures were probed for neural progenitor cell marker expression (nestin and bone morphogenic protein-2 [BMP-2]) during growth in both culture conditions. RT-PCR, western blotting, and immunocytochemistry assays showed that cells cultured in either condition expressed nestin mRNA and protein and BMP-2 mRNA. HSC similarly cultured in nonconditioned medium or in the absence of astrocytes did not express either marker. Cells expressing these neural markers were transferred and cultured on poly-D-lysine-coated dishes with nonconditioned growth medium for further study. Immunocytochemistry demonstrated that these cells differentiated into astrocytes after 8 days in culture as indicated by their morphology and expression of the astrocytic markers glial fibrillary acidic protein (GFAP) and S100, as well as by their rate of proliferation, which was identical to that of freshly isolated fetal brain astrocytes. These findings demonstrate that neural precursor gene expression can be induced when human hematopoietic stem cells are exposed to a suitable microenvironment. Furthermore, the neural stem cells generated in this environment can then differentiate into astrocytes. Therefore, human hematopoietic stem cells may be an alternative resource for generation of neural stem cells for therapy of central nervous system defects resulting from disease or trauma.
Collapse
Affiliation(s)
- Hsiao-Nan Hao
- Department of Pediatrics, Wayne State University School of Medicine and Children's Research Center of Michigan, Detroit, MI 48201, USA.
| | | | | | | | | |
Collapse
|
268
|
Abstract
BACKGROUND The liver and the pancreas arise from adjacent regions of endoderm in embryonic development. Pdx1 is a key transcription factor that is essential for the development of the pancreas and is not expressed in the liver. The aim of this study was to determine whether a gene overexpression protocol based on Pdx1 would be able to cause conversion of liver to pancreas. RESULTS We show that a modified form of Pdx1, carrying the VP16 transcriptional activation domain, can cause conversion of liver to pancreas, both in vivo and in vitro. Transgenic Xenopus tadpoles carrying the construct TTR-Xlhbox8-VP16:Elas-GFP were prepared. Xlhbox8 is the Xenopus homolog of Pdx1, the TTR (transthyretin) promoter directs expression to the liver, and the GFP is under the control of an elastase promoter and provides a real-time visible marker of pancreatic differentiation. In the transgenic tadpoles, part or all of the liver is converted to pancreas, containing both exocrine and endocrine cells, while liver differentiation products are lost from the regions converted to pancreas. The timing of events is such that the liver is differentiating by the time Xlhbox8-VP16 is expressed, so we consider this a transdifferentiation event rather than a reprogramming of embryonic development. Furthermore, this same construct will bring about transdifferentiation of human hepatocytes in culture, with formation of both exocrine and endocrine cells. CONCLUSIONS We consider that the conversion of liver to pancreas could be the basis of a new type of therapy for insulin-dependent diabetes. Although expression of the transgene is transient, once the ectopic pancreas is established, it persists thereafter.
Collapse
Affiliation(s)
- Marko E Horb
- Centre for Regenerative Medicine, Department of Biology and Biochemistry, University of Bath, BA2 7AY, Bath, United Kingdom.
| | | | | | | |
Collapse
|
269
|
Abstract
Normal development appears to involve a progressive restriction in developmental potential. However, recent evidence suggests that this progressive restriction is not irreversible and can be altered to reveal novel phenotypic potentials of stem, progenitor, and even differentiated cells. While some of these results can be explained by the presence of contaminating cell populations, persistence of pluripotent stem cells, cell fusion, etc., several examples exist that are difficult to explain as anything other than "true transdifferentiation" and/or dedifferentiation. These examples of transdifferentiation are best explained by understanding how the normal process of progressive cell fate restriction occurs during development. We suggest that subversion of epigenetic controls regulating cell type specific gene expression likely underlies the process of transdifferentiation and it may be possible to identify specific factors to control the transdifferentiation process. We predict, however, that transdifferentiation will not be reliable or reproducible and will probably require complex manipulations.
Collapse
Affiliation(s)
- Ying Liu
- Laboratory of Neurosciences, National Institute on Aging, 5600 Nathan Shock Drive, Baltimore, Maryland 21224, USA
| | | |
Collapse
|
270
|
Abstract
Transdifferentiation is the name used to describe the direct conversion of one differentiated cell type into another. Cells which have the potential to interconvert by transdifferentiation generally arise from adjacent regions in the developing embryo. For example, the liver and pancreas arise from the same region of the endoderm. The transdifferentiation of pancreas to liver (and vice versa) has been observed in animal experiments and in certain human pathologies. Understanding transdifferentiation is important to developmental biologists because it will help elucidate the cellular and molecular differences that distinguish neighbouring regions of the embryo. While the in vivo models for the transdifferentiation of liver to pancreas have been valuable, it is more difficult to extrapolate from these studies to individual changes at the cellular or molecular levels. The recent development of two in vitro systems (AR42J cells and embryonic pancreatic cultures) for the transdifferentiation of pancreas to liver has shown that an environmental change in the form of an exogenous glucocorticoid can cause the conversion of pancreatic exocrine cells into hepatocytes. The AR42J cell system has been used to elucidate the cell lineage and the molecular basis of transdifferentiation of pancreas to liver.
Collapse
Affiliation(s)
- Chia Ning Shen
- Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, BA2 7AY Bath, UK
| | | | | | | |
Collapse
|
271
|
Dupont S, Dennefeld C, Krust A, Chambon P, Mark M. Expression of Sox9 in granulosa cells lacking the estrogen receptors, ERalpha and ERbeta. Dev Dyn 2003; 226:103-6. [PMID: 12508230 DOI: 10.1002/dvdy.10202] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Ovaries from adult mice lacking both estrogen receptors ERalpha and ERbeta (ERalphabetaKO mice) contain abnormal cells sharing morphologic features with Sertoli cells, which are located mainly in the interstitial compartment. We show here that these cells express the Sertoli cell markers TIF1beta, TIF2, and Sox9. In ERalphabetaKO ovaries, Sox9 is expressed by granulosa cells before the morphologic appearance of Sertoli cells, but neither by granulosa cell precursors nor by non-Sertolian interstitial cells. These findings suggest that functional Sertoli cells can transdifferentiate from mature granulosa cells devoid of estrogen receptors as a result of Sox9 expression.
Collapse
Affiliation(s)
- Sonia Dupont
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, Collège de France, Illkirch Cedex, France
| | | | | | | | | |
Collapse
|
272
|
Abstract
Pancreatic ductal adenocarcinoma is an aggressive and devastating disease, which is characterized by invasiveness, rapid progression and profound resistance to treatment. Advances in pathological classification and cancer genetics have improved our descriptive understanding of this disease; however, important aspects of pancreatic cancer biology remain poorly understood. What is the pathogenic role of specific gene mutations? What is the cell of origin? And how does the stroma contribute to tumorigenesis? A better understanding of pancreatic cancer biology should lead the way to more effective treatments.
Collapse
Affiliation(s)
- Nabeel Bardeesy
- Department of Adult Oncology, Dana-Farber Cancer Institute and Departments of Medicine and Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA
| | | |
Collapse
|
273
|
Abstract
Despite some recent setbacks, it remains clear that adult stem cells under appropriate experimental conditions can at some frequency exhibit a wider range of differentiation potentials than previously appreciated. This is underscored by the recent demonstration of the extensive differentiation potential of mesenchymal stem cells. In terms of mechanism, it remains unclear in many cases to what extent plasticity reflects in vitro adaptation, transdifferentiation/cell-type switching or the persistence in adult tissues of stem cells with extensive endogenous or bona fide developmental potentials. These issues will need to be resolved before the full therapeutic potential of adult-derived stem cells can be realised.
Collapse
Affiliation(s)
- Chirag V Joshi
- Section of Gene Function and Regulation, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, SW3 6JB, London, UK.
| | | |
Collapse
|
274
|
Silani V, Fogh I, Ratti A, Sassone J, Ciammola A, Cova L. Stem cells in the treatment of amyotrophic lateral sclerosis (ALS). AMYOTROPHIC LATERAL SCLEROSIS AND OTHER MOTOR NEURON DISORDERS : OFFICIAL PUBLICATION OF THE WORLD FEDERATION OF NEUROLOGY, RESEARCH GROUP ON MOTOR NEURON DISEASES 2002; 3:173-81. [PMID: 12710505 DOI: 10.1080/146608202760839001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Until fairly recently, interest in stem cells was restricted to neurobiology studies on the principles of embryonic development. This situation has changed rapidly in the last few years when neuronal stems and precursors were isolated in vitro, thus allowing expansion and controlled differentiation of selective populations of neuronal cells. This theoretically unlimited reserve would then supply specific cells for transplantation in diseases characterized by widespread degeneration of selective cell populations as motor neurons in Amyotrophic Lateral Sclerosis (ALS). The recent evidence of cell transdifferentiation has further amplified the potential therapeutic use of stem cells. Stem cell technology is at an early stage but the desperate need for a therapy in ALS patients may legitimize clinical trials in absence of conclusive scientific evidence. This paper discusses the premises for stem cell therapy in ALS.
Collapse
Affiliation(s)
- Vincenzo Silani
- Department of Neurology, Laboratory of Neuroscience, Dino Ferrari Center, University of Milan Medical School, IRCCS Istituto Auxologico Italiano, Via Spagnoletto 3, 1-20149 Milano, Italy.
| | | | | | | | | | | |
Collapse
|
275
|
Avots A, Harder F, Schmittwolf C, Petrovic S, Müller AM. Plasticity of hematopoietic stem cells and cellular memory. Immunol Rev 2002; 187:9-21. [PMID: 12366679 DOI: 10.1034/j.1600-065x.2002.18702.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Stem cell systems represent an effective and powerful approach for tissue development and regeneration of diverse tissue types. Common and defining features of these exceptional cells are the capacity for self-renewal and the potential for differentiation into multiple mature cell types. Recently, surprising new observations have indicated that stem cells isolated from one adult tissue can also give rise to mature cells of other cell lineages, irrespective of classical germ layer designations. This discovery has resulted in quantum leaps in both scientific knowledge and the potential applications of stem cells. The new findings contradict central dogmas of commitment and differentiation of stem and progenitor cells. However, the true potential of somatic stem cells is just emerging and the new findings have to be defined more fully and integrated into a unifying model of stem cell potential and behavior. Here we analyze the developmental potential of hematopoietic stem cells of mouse and man following their injection into the murine preimplantation blastocyst, an environment that allows the development of all cell lineages. In addition, we discuss the emerging lines of evidence of the developmental plasticity of hematopoietic and other somatic stem cells and consider how cellular memory of transcriptional states is established and may be potentially involved in this phenomenon.
Collapse
Affiliation(s)
- Andris Avots
- Institut für Medizinische Strahlenkunde und Zellforschung, Universität Würzburg, 97078 Würzburg, Germany
| | | | | | | | | |
Collapse
|
276
|
Abstract
Transdifferentiation of pancreas to liver is a well-recognized phenomenon and has been described in animal experiments and human pathology. We recently produced an in vitro model for the transdifferentiation (or conversion) of the pancreatic cell line AR42J-B13 to hepatocytes based on culture with dexamethasone (Dex). To determine whether the hepatocytes express markers of hepatic intermediary metabolism and detoxification, we investigated the patterns of expression of glucokinase, cytochrome P450s CYP3A1 and CYP2B1/2, testosterone/4-nitrophenol uridine diphosphate glucuronosyltransferase (UDPGT), and aryl sulfotransferase. All were expressed. We also determined the expression of 2 enzymes involved in ammonia detoxification: carbamoylphosphate synthetase I (CPS I) and glutamine synthetase (GS). These enzymes are normally strictly compartmentalized in liver in a wide periportal pattern and the last downstream perivenous hepatocytes, respectively. Following culture with Dex, CPS I and GS are expressed in 2 different cell populations, suggesting that both periportal and perivenous hepatocytes are induced. We also produced a reporter assay based on the activation of green fluorescent protein (GFP) by the transthyretin (TTR) promoter or glucose-6-phosphatase (G6Pase) promoter. After culture with Dex, transfected cells begin to express GFP, showing that hepatic promoters are activated in concert with the induction of the hepatocyte phenotype. Lastly, we examined the stability of the hepatic phenotype and found that some cells still express liver markers (transferrin or albumin) up to 14 days after removal of Dex. In conclusion, these results suggest that pancreatic hepatocytes produced by this method may offer an alternative model to primary cultures of hepatocytes for the study of liver function.
Collapse
Affiliation(s)
- David Tosh
- Developmental Biology Programme, Department of Biology and Biochemistry, University of Bath, Bath, England.
| | | | | |
Collapse
|
277
|
Brockes JP, Kumar A. Plasticity and reprogramming of differentiated cells in amphibian regeneration. Nat Rev Mol Cell Biol 2002; 3:566-74. [PMID: 12154368 DOI: 10.1038/nrm881] [Citation(s) in RCA: 313] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Adult urodele amphibians, such as the newt, can regenerate their limbs and various other structures. This is the result of the plasticity and reprogramming of residual differentiated cells, rather than the existence of a 'reserve-cell' mechanism. The recent demonstrations of plasticity in mouse myotubes should facilitate comparative studies of the pathways that underlie the regenerative response, as well as proposing new approaches to promote mammalian regeneration.
Collapse
Affiliation(s)
- Jeremy P Brockes
- Department of Biochemistry & Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
| | | |
Collapse
|