You are here

Comment

Discuss

Direct Orthotopic Transplantation of Fresh Surgical Specimen Preserves CD133+ Tumor Cells in Clinica

Direct Orthotopic Transplantation of Fresh Surgical Specimen Preserves CD133+ Tumor Cells in Clinically Relevant Mouse Models of Medulloblastoma and Glioma

Qin Shua,b, Kwong Kwok Wongb,e, Jack M. Sub, Adekunle M. Adesinac, Li Tian Yua,b, Yvonne T. M. Tsangb,e, Barbara C. Antalffyc, Patricia Baxterb, Laszlo Perlakyb, Jianhua Yangb, Robert C. Dauserd, Murali Chintagumpalab, Susan M. Blaneyb, Ching C. Laub, Xiao-Nan Lia,b

Abstract

Recent identification of cancer stem cells in medulloblastoma (MB) and high-grade glioma has stimulated an urgent need for animal models that will not only replicate the biology of these tumors, but also preserve their cancer stem cell pool. We hypothesize that direct injection of fresh surgical specimen of MB and high-grade glioma tissues into anatomically equivalent locations in immune-deficient mouse brains will facilitate the formation of clinically accurate xenograft tumors by allowing brain tumor stem cells, together with their non-stem tumor and stromal cells, to grow in a microenvironment that is the closest to human brains. Eight of the 14 MBs (57.1%) and two of the three high-grade gliomas (66.7%) in this study developed transplantable (up to 12 passages) xenografts in mouse cerebellum and cerebrum, respectively. These xenografts are patient specific, replicating the histopathologic, immunophenotypic, invasive/metastatic, and major genetic (analyzed with 10K single nucleotide polymorphism array) abnormalities of the original tumors. The xenograft tumor cells have also been successfully cryopreserved for long-term preservation of tumorigenicity, ensuring a sustained supply of the animal models. More importantly, the CD133+ tumor cells, ranging from 0.2%–10.4%, were preserved in all the xenograft models following repeated orthotopic subtransplantations in vivo. The isolated CD133+ tumor cells formed neurospheres and displayed multi-lineage differentiation capabilities in vitro. In summary, our study demonstrates that direct orthotopic transplantation of fresh primary tumor cells is a powerful approach in developing novel clinical relevant animal models that can reliably preserve CD133+ tumor cell pools even during serial in vivo subtransplantations.

 

AbstractReferences |  Full Text: HTML, PDF (2946K)

Problems getting Full Text?

 

Tumor Necrosis Factor-alpha Inhibition of Skeletal Muscle Regeneration Is Mediated by a Caspase

Tumor Necrosis Factor-alpha Inhibition of Skeletal Muscle Regeneration Is Mediated by a Caspase-Dependent Stem Cell Response

Viviana Moresia,b, Alessandro Pristeràa,b, Bianca M. Scicchitanoa,b, Mario Molinaroa,b, Laura Teodoric, David Sassoond, Sergio Adamoa,b, Dario Colettia,b

Abstract

Skeletal muscle is susceptible to injury following trauma, neurological dysfunction, and genetic diseases. Skeletal muscle homeostasis is maintained by a pronounced regenerative capacity, which includes the recruitment of stem cells. Chronic exposure to tumor necrosis factor-alpha (TNF) triggers a muscle wasting reminiscent of cachexia. To better understand the effects of TNF upon muscle homeostasis and stem cells, we exposed injured muscle to TNF at specific time points during regeneration. TNF exposure delayed the appearance of regenerating fibers, without exacerbating fiber death following the initial trauma. We observed modest cellular caspase activation during regeneration, which was markedly increased in response to TNF exposure concomitant with an inhibition in regeneration. Caspase activation did not lead to apoptosis and did not involve caspase-3. Inhibition of caspase activity improved muscle regeneration in either the absence or the presence of TNF, revealing a nonapoptotic role for this pathway in the myogenic program. Caspase activity was localized to the interstitial cells, which also express Sca-1, CD34, and PW1. Perturbation of PW1 activity blocked caspase activation and improved regeneration. The restricted localization of Sca-1+, CD34+, PW1+ cells to a subset of interstitial cells with caspase activity reveals a critical regulatory role for this population during myogenesis, which may directly contribute to resident muscle stem cells or indirectly regulate stem cells through cell-cell interactions.

 

AbstractReferences |  Full Text: HTML, PDF (4512K)

Characterization of Bipotential Epidermal Progenitors Derived from Human Sebaceous Gland: Contrastin

Characterization of Bipotential Epidermal Progenitors Derived from Human Sebaceous Gland: Contrasting Roles of c-Myc and β-Catenin

Cristina Lo Celsoa, Melanie A. Bertab, Kristin M. Braunc, Michaela Fryed, Stephen Lylee, Christos C. Zouboulisf, Fiona M. Wattb,d

Abstract

The current belief is that the epidermal sebaceous gland (SG) is maintained by unipotent stem cells that are replenished by multipotent stem cells in the hair follicle (HF) bulge. However, sebocytes can be induced by c-Myc (Myc) activation in interfollicular epidermis (IFE), suggesting the existence of bipotential stem cells. We found that every SZ95 immortalized human sebocyte that underwent clonal growth in culture generated progeny that differentiated into both sebocytes and cells expressing involucrin and cornifin, markers of IFE and HF inner root sheath differentiation. The ability to generate involucrin positive cells was also observed in a new human sebocyte line, Seb-E6E7. SZ95 xenografts differentiated into SG and IFE but not HF. SZ95 cells that expressed involucrin had reduced Myc levels; however, this did not correlate with increased expression of the Myc repressor Blimp1, and Blimp1 expression did not distinguish cells undergoing SG, IFE, or HF differentiation in vivo. Overexpression of Myc stimulated sebocyte differentiation, whereas overexpression of β-catenin stimulated involucrin and cornifin expression. In transgenic mice simultaneous activation of Myc and β-catenin revealed mutual antagonism: Myc blocked ectopic HF formation and β-catenin reduced SG differentiation. Overexpression of the Myc target gene Indian hedgehog did not promote sebocyte differentiation in culture and cyclopamine treatment, while reducing proliferation, did not block Myc induced sebocyte differentiation in vivo. Our studies provide evidence for a bipotential epidermal stem cell population in an in vitro model of human epidermal lineage selection and highlight the importance of Myc as a regulator of sebocyte differentiation.

 

AbstractReferences |  Full Text: HTML, PDF (4400K)

Problems getting Full Text?

Molecular Mechanism of Systemic Delivery of Neural Precursor Cells to the Brain

Molecular Mechanism of Systemic Delivery of Neural Precursor Cells to the Brain: Assembly of Brain Endothelial Apical Cups and Control of Transmigration by CD44

Christine Rampona,b,c, Nicolas Weissa,b,c, Cyrille Debouxd,e, Nathalie Chaverota,b,c, Florence Millera,b,c, Delphine Buchetd,e, Hélène Tricoire-Leignela,b,c, Sylvie Cazaubona,b,c, Anne Baron-Van Evercoorend,e,f, Pierre-Olivier Courauda,b,c

Abstract

Systemically injected neural precursor cells (NPCs) were unexpectedly shown to reach the cerebral parenchyma and induce recovery in various diffuse brain pathologies, including animal models of multiple sclerosis. However, the molecular mechanisms supporting NPC migration across brain endothelium remain elusive. Brain endothelium constitutes the blood-brain barrier, which uniquely controls the access of drugs and trafficking of cells, including leukocytes, from the blood to the brain. Taking advantage of the availability of in vitro models of human and rat blood-brain barrier developed in our laboratory and validated by us and others, we show here that soluble hyaluronic acid, the major ligand of the adhesion molecule CD44, as well as anti-CD44 blocking antibodies, largely prevents NPC adhesion to and migration across brain endothelium in inflammatory conditions. We present further evidence that NPCs, surprisingly, induce the formation of apical cups at the surface of brain endothelial cells, enriched in CD44 and other adhesion molecules, thus hijacking the endothelial signaling recently shown to be involved in leukocyte extravasation. These results demonstrate the pivotal role of CD44 in the trans-endothelial migration of NPCs across brain endothelial cells: we propose that they may help design new strategies for the delivery of therapeutic NPCs to the brain by systemic administration.

 

AbstractReferences |  Full Text: HTML, PDF (1052K)

Problems getting Full Text?

Neural Stem Cell Targeting of Glioma Is Dependent on Phosphoinositide 3-Kinase Signaling

Neural Stem Cell Targeting of Glioma Is Dependent on Phosphoinositide 3-Kinase Signaling

Stephen E. Kendalla, Joseph Najbauerb, Heather F. Johnstonc, Marianne Z. Metzb, Shan Lia,c, Marisa Bowersb, Elizabeth Garciab, Seung U. Kimd,e, Michael E. Barishc, Karen S. Aboodyb,c, Carlotta A. Glackina

Abstract

The utility of neural stem cells (NSCs) has extended beyond regenerative medicine to targeted gene delivery, as NSCs possess an inherent tropism to solid tumors, including invasive gliomas. However, for optimal clinical implementation, an understanding of the molecular events that regulate NSC tumor tropism is needed to ensure their safety and to maximize therapeutic efficacy. We show that human NSC lines responded to multiple tumor-derived growth factors and that hepatocyte growth factor (HGF) induced the strongest chemotactic response. Gliomatropism was critically dependent on c-Met signaling, as short hairpin RNA-mediated ablation of c-Met significantly attenuated the response. Furthermore, inhibition of Ras-phosphoinositide 3-kinase (PI3K) signaling impaired the migration of human neural stem cells (hNSCs) toward HGF and other growth factors. Migration toward tumor cells is a highly regulated process, in which multiple growth factor signals converge on Ras-PI3K, causing direct modification of the cytoskeleton. The signaling pathways that regulate hNSC migration are similar to those that promote unregulated glioma invasion, suggesting shared cellular mechanisms and responses.

 

AbstractReferences |  Full Text: HTML, PDF (5164K)

Problems getting Full Text?

MSCs are Activated to Reduce Apoptosis in Part by Upregulation and STC-1

TISSUE-SPECIFIC STEM CELLS:

discussion_board.jpg

 

Multipotent Stromal Cells (MSCs) are Activated to Reduce Apoptosis in Part by Upregulation and Secretion of Stanniocalcin-1 (STC-1)

Gregory J. Block 1, Shinya Ohkouchi 1, France Fung 1, Joshua Frenkel 1, Carl Gregory 1,
Radhika Pochampally 1, Gabriel DiMattia 2, Deborah E. Sullivan 3, Darwin J. Prockop 1*

1 Tulane Center for Gene Therapy, Tulane University Health Sciences Center, New Orleans, LA, 70112
2 London Regional Cancer Program and the Dept. of Oncology, Biochemistry, The University of Western Ontario
3 Tulane University, Department of Microbiology and Immunology, New Orleans LA, 70112
* To whom correspondence should be addressed. E-mail: dprocko@tulane.edu

Stem Cells Express, First published online December 18, 2008


Abstract

Multipotent stromal cells (MSCs) have been shown to reduce apoptosis in injured cells by secretion of paracrine factors, but these factors were not fully defined. We observed that co-culture of MSCs with previously UV irradiated fibroblasts reduced apoptosis of the irradiated cells, but fresh MSC conditioned media was unable reproduce the effect. Comparative Microarray analysis of MSCs grown in the presence or absence of UV irradiated fibroblasts demonstrated that the MSCs were activated by the apoptotic cells to increase synthesis and secretion of stanniocalcin-1 (STC-1), a peptide hormone that modulates mineral metabolism and has pleiotrophic effects that have not been fully characterized. We showed that STC-1 was required but not sufficient for reduction of apoptosis of UV-irradiated fibroblasts. In contrast, we demonstrated that MSC-derived STC-1 was both required and sufficient for reduction of apoptosis of lung cancer epithelial cells made apoptotic by incubation at low pH in hypoxia. Our data demonstrate that STC-1 mediates the anti-apoptotic effects of MSCs in two distinct models of apoptosis in vitro.

 

AbstractReferences |  Full Text: HTML, PDF (908K)

Problems getting Full Text?

Thrombopoietin Inhibits Murine Mast Cell Differentiation

Thrombopoietin Inhibits Murine Mast Cell Differentiation

Fabrizio Martelli, Barbara Ghinassi, Rodolfo Lorenzini, Alessandro M. Vannucchi, Rosa Alba Rana, Mitsuo Nishikawa, Sandra Partamian, Giovanni Migliaccio, Anna Rita Migliaccioa

ABSTRACT

We have recently shown that Mpl, the thrombopoietin receptor, is expressed on murine mast cells and on their precursors and that targeted deletion of the Mpl gene increases mast cell differentiation in mice. Here we report that treatment of mice with thrombopoietin or addition of this growth factor to bone marrow-derived mast cell cultures severely hampers the generation of mature cells from their precursors by inducing apoptosis. Analysis of the expression profiling of mast cells obtained in the presence of thrombopoietin suggests that thrombopoietin induces apoptosis of mast cells by reducing expression of the transcription factor Mitf and its target antiapoptotic gene Bcl2. STEM CELLS 2008;26:912–919

 

Disclosure of potential conflicts of interest is found at the end of this article.

 

AbstractReferences |  Full Text: HTML, PDF (1690K)

Efficient Differentiation of Functional Hepatocytes from Human Embryonic Stem Cells

Efficient Differentiation of Functional Hepatocytes from Human Embryonic Stem Cells

Sadhana Agarwal, Katherine L. Holton, Robert Lanza

ABSTRACT

Differentiation of human embryonic stem cells (hESCs) to specific functional cell types can be achieved using methods that mimic in vivo embryonic developmental programs. Current protocols for generating hepatocytes from hESCs are hampered by inefficient differentiation procedures that lead to low yields and large cellular heterogeneity. We report here a robust and highly efficient process for the generation of high-purity (70%) hepatocyte cultures from hESCs that parallels sequential hepatic development in vivo. Highly enriched populations of definitive endoderm were generated from hESCs and then induced to differentiate along the hepatic lineage by the sequential addition of inducing factors implicated in physiological hepatogenesis. The differentiation process was largely uniform, with cell cultures progressively expressing increasing numbers of hepatic lineage markers, including GATA4, HNF4 alpha, alpha-fetoprotein, CD26, albumin, alpha-1-antitrypsin, Cyp7A1, and Cyp3A4. The hepatocytes exhibited functional hepatic characteristics, such as glycogen storage, indocyanine green uptake and release, and albumin secretion. In a mouse model of acute liver injury, the hESC-derived definitive endoderm differentiated into hepatocytes and repopulated the damaged liver. The methodology described here represents a significant step toward the efficient generation of hepatocytes for use in regenerative medicine and drug discovery.

 

AbstractReferences |  Full Text: HTML, PDF (2864K)

Problems getting Full Text?

Embryonic Stem Cells as a Platform for Analyzing Neural Gene Transcription

Embryonic Stem Cells as a Platform for Analyzing Neural Gene Transcription

Xiaodong Zhang, Scott A. Horrell, Deany Delaney, David I. Gottlieb

ABSTRACT

There is a need for improved methods to analyze transcriptional control of mammalian stem cell genes. We propose that embryonic stem cells (ESCs) will have broad utility as a model system, because they can be manipulated genetically and then differentiated into many cell types in vitro, avoiding the need to make mice. Results are presented demonstrating the utility of ESCs for analyzing cis-acting sequences using Olig2 as a model gene. Olig2 is a transcription factor that plays a key role in the development of a ventral compartment of the nervous system and the oligodendrocyte lineage. The functional role of an upstream region (USR) of the Olig2 gene was investigated in ESCs engineered at the undifferentiated stage and then differentiated into ventral neural cells with sonic hedgehog and retinoic acid. Deletion of the USR from the native gene via gene targeting eliminates expression in ventral neural cells differentiated in cell culture. The USR is also essential for regulated expression of an Olig2 transgene inserted at a defined foreign chromosomal site. A subregion of the USR has nonspecific promoter activity in transient transfection assays in cells that do not express Olig2. Taken together, the data demonstrate that the USR contains a promoter for the Olig2 gene and suggest that repression contributes to specific expression. The technology used in this study can be applied to a wide range of genes and cell types and will facilitate research on cis-acting DNA elements of mammalian genes.

 

AbstractReferences |  Full Text: HTML, PDF (2226K)

Problems getting Full Text?

Comprehensive MicroRNA Profiling Reveals a Unique Human Embryonic Stem Cell Signature Dominated by a

Comprehensive MicroRNA Profiling Reveals a Unique Human Embryonic Stem Cell Signature Dominated by a Single Seed Sequence

Louise C. Laurenta,b, Jing Chenc, Igor Ulitskyd, Franz-Josef Muellerb,e, Christina Lua,b, Ron Shamird, Jian-Bing Fanc, Jeanne F. Loringb

ABSTRACT

Embryonic stem cells are unique among cultured cells in their ability to self-renew and differentiate into a wide diversity of cell types, suggesting that a specific molecular control network underlies these features. Human embryonic stem cells (hESCs) are known to have distinct mRNA expression, global DNA methylation, and chromatin profiles, but the involvement of high-level regulators, such as microRNAs (miRNA), in the hESC-specific molecular network is poorly understood. We report that global miRNA expression profiling of hESCs and a variety of stem cell and differentiated cell types using a novel microarray platform revealed a unique set of miRNAs differentially regulated in hESCs, including numerous miRNAs not previously linked to hESCs. These hESC-associated miRNAs were more likely to be located in large genomic clusters, and less likely to be located in introns of coding genes. hESCs had higher expression of oncogenic miRNAs and lower expression of tumor suppressor miRNAs than the other cell types. Many miRNAs upregulated in hESCs share a common consensus seed sequence, suggesting that there is cooperative regulation of a critical set of target miRNAs. We propose that miRNAs are coordinately controlled in hESCs, and are key regulators of pluripotence and differentiation.

 

AbstractReferences |  Full Text: HTML, PDF (1003K)

Problems getting Full Text?

Pages

Subscribe to Stem Cells Portal - Stem Cells Journal Online Community RSS