[Show abstract][Hide abstract] ABSTRACT: Hematopoietic stem cells in the bone marrow have the capacity to both self-renew and to generate all cells of the hematopoietic system. The balance of these two activities is controlled by hematopoietic stem cell-intrinsic regulatory mechanisms as well as extrinsic signals from the microenvironment. Here we demonstrate that Meis1, a TALE family homeodomain transcription factor involved in numerous embryonic developmental processes, is selectively expressed in hematopoietic stem/progenitor cells. Conditional Meis1 knockout in adult hematopoietic cells resulted in a significant reduction in the hematopoietic stem/progenitor cells. Suppression of hematopoiesis by Meis1 deletion appears to be caused by impaired self-renewal activity and reduced cellular quiescence of hematopoietic stem/progenitor cells in a cell autonomous manner, resulting in stem cell exhaustion and defective long-term hematopoiesis. Meis1 deficiency down-regulated a subset of Pbx1-dependent hematopoietic stem cell signature genes, suggesting a functional link between them in the maintenance of hematopoietic stem/progenitor cells. These results show the importance of Meis1 in adult hematopoiesis.
PLoS ONE 02/2014; 9(2):e87646. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Human mesenchymal stem cells (hMSCs), which conventionally are isolated based on their adherence to plastic, are heterogeneous and have poor growth and differentiation, limiting our ability to investigate their intrinsic characteristics. We report an improved prospective clonal isolation technique and reveal that the combination of three cell-surface markers (LNGFR, THY-1, and VCAM-1) allows for the selection of highly enriched clonogenic cells (one out of three isolated cells). Clonal characterization of LNGFR(+)THY-1(+) cells demonstrated cellular heterogeneity among the clones. Rapidly expanding clones (RECs) exhibited robust multilineage differentiation and self-renewal potency, whereas the other clones tended to acquire cellular senescence via P16INK4a and exhibited frequent genomic errors. Furthermore, RECs exhibited unique expression of VCAM-1 and higher cellular motility compared with the other clones. The combination marker LNGFR(+)THY-1(+)VCAM-1(hi+) (LTV) can be used selectively to isolate the most potent and genetically stable MSCs.
[Show abstract][Hide abstract] ABSTRACT: Platelet-derived growth factor receptor α (PDGFR-α) and stem cell antigen 1 (Sca-1) have recently been identified as selective markers of mouse mesenchymal stem cells (MSCs). PDGFR-α(+)Sca-1(+) (PαS) MSCs have augmented growth potential and robust tri-lineage differentiation compared with standard culture-selected MSCs. In addition, the selective isolation of PαS MSCs avoids cellular contamination that can complicate other methods. Here we describe in detail our protocol to isolate PαS MSCs using flow cytometry. In brief, the tibia and femora are isolated and crushed using a pestle and mortar. The crushed bones are then chopped and incubated for 1 h at 37 °C in 20 ml of DMEM containing 0.2% (wt/vol) collagenase. The cell suspension is filtered before red blood cell lysis and incubated with the following antibodies: allophycocyanin (APC)-conjugated PDGFR-α, FITC-conjugated Sca-1, phycoerythrin (PE)-conjugated CD45 and Ter119. Appropriate gates are constructed on a cell sorter to exclude dead cells and lineage (CD45(+)Ter-119(+))-positive cells. Approximately 10,000 PαS MSCs may then be isolated per mouse. The total protocol takes ∼7 h to complete.
[Show abstract][Hide abstract] ABSTRACT: Steroidogenic acute regulatory protein (StAR) facilitates cholesterol transfer into the inner mitochondrial membrane in the acute phase of steroidogenesis. Mice lacking StAR (Star(-/-)) share phenotypes with human individuals having congenital lipoid adrenal hyperplasia including compromised production of steroid hormones and florid accumulation of cholesterol esters in adrenal glands and gonads. To define a specific pattern of molecular changes with StAR deficiency, we performed transcriptome analysis of adrenal cells selectively isolated by fluorescent-activated cell sorting at embryonic d 17.5 or 18.5 in seven wild-type (Star(+/+)) or four Star(-/-) mice having the transgene targeting the enhanced green fluorescent protein to cell lineages that express StAR. A gene expression profile was obtained by whole-mouse genome microarray and confirmed by quantitative real-time PCR, identifying 1206 and 767 significantly up-regulated and down-regulated genes, respectively, in Star(-/-) mice compared with Star(+/+) mice (fold difference ≥ 2 and P value < 0.05 with false discovery rate < 0.2). In Star(-/-) mice, expression levels of genes involved in cholesterol efflux and the inflammatory response were significantly up-regulated, whereas those related to steroid hormone biosynthesis or cholesterol biosynthesis and influx were not significantly changed. Immunoreactive Iba1 or F4/80 (macrophage marker) in adrenal glands of Star(-/-) mice was detected not only in an increased number of resident macrophages but also in most adrenocortical cells. These findings expand our understanding of the pathophysiology of adrenal glands with the disruption of StAR and propose a reciprocal interaction between adrenocortical cells and resident macrophages inside adrenal glands of Star(-/-) mice.
[Show abstract][Hide abstract] ABSTRACT: Induced pluripotent stem (iPS) cells are generated from mouse and human somatic cells by the forced expression of defined transcription factors. Although most somatic cells are capable of acquiring pluripotency with minimal gene transduction, the poor efficiency of cell reprogramming and the uneven quality of iPS cells are still important problems. In particular, the choice of cell type most suitable for inducing high-quality iPS cells remains unclear.
Here, we generated iPS cells from PDGFRα+ Sca-1+ (PαS) adult mouse mesenchymal stem cells (MSCs) and PDGFRα⁻ Sca-1⁻ osteo-progenitors (OP cells), and compared the induction efficiency and quality of individual iPS clones. MSCs had a higher reprogramming efficiency compared with OP cells and Tail Tip Fibroblasts (TTFs). The iPS cells induced from MSCs by Oct3/4, Sox2, and Klf4 appeared to be the closest equivalent to ES cells by DNA microarray gene profile and germline-transmission efficiency.
Our findings suggest that a purified source of undifferentiated cells from adult tissue can produce high-quality iPS cells. In this context, prospectively enriched MSCs are a promising candidate for the efficient generation of high-quality iPS cells.
PLoS ONE 03/2011; 6(3):e17610. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Epigenetic gene regulation plays essential roles in differentiation of embryonic and tissue stem cells. In these benign undifferentiated cells, some polycomb targeted genes are kept in a state of DNA hypomethylation and they have a distinct chromatin signature termed bivalent chromatin structure to maintain their plasticity. We hypothesized that cancer stem cells (CSC), the malignant counterpart of these cells, are also under the control of epigenetics like benign stem cells. We compared the DNA methylation and chromatin structure in 10 tumor suppressor genes between CSC and differentiated cancer cells of MCF7 and Huh7 cells. We found that the level of DNA methylation was indeed significantly lower in CSC, while surprisingly, the bivalent chromatin structure was more ubiquitously seen in differentiated cancer cells compared to CSC. However, repressive marks of chromatin structure, namely H3K27me3 and EZH2, were significantly lower in CSC. As a consequence, CSC remained in a higher transcriptionally active chromatin state compared to differentiated cancer cells. We found that the differentiation of CSCs is also epigenetically regulated. These findings could help towards a comprehensive understanding of CSC, and also improve the development of eradicative therapies against human malignancies.
International Journal of Oncology 12/2010; 37(6):1537-46. · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We investigated the effect of irradiation on the lifespan of eight-week-old mice, the number of lymphocytes in bone marrow and the levels of p53 protein expression in the splenocytes.
Eight-week-old mice, wild-type p53 (p53(+/+)) and heterozygous p53 (p53(+/-)), were irradiated with 3 Gy. The cell numbers and cell cycle phases of bone marrow cells were determined by flow cytometry. The splenocyte proliferation was evaluated by a fluorescent cell viability assay. The p53 expression was evaluated by Western blotting.
The lifespan of the irradiated mice was shorter than that of the non-irradiated mice. In irradiated 72-week-old p53(+/+) mice and 56-week-old p53(+/-) mice, the number of lymphocytes in bone marrow decreased as compared to that in the non-irradiated mice. In 56-week-old p53(+/-) mice, the S- and G2/M-phases of lymphocytes in the irradiated mice were increased compared to that in the non-irradiated mice. The splenocyte proliferation in p53(+/+) mice decreased with age, and the proliferation in the irradiated mice was much lower than that in the non-irradiated mice. In 72-week-old p53(+/+) mice after re-irradiation, the p53 protein expression in the splenocytes of the irradiated mice was delayed as compared to those from the non-irradiated mice.
We suggest that the decrease in the number of lymphocytes in bone marrow and the delayed p53 expression in splenocytes from the irradiated mice are related to the shortened lifespan after irradiation at a young age.
International Journal of Radiation Biology 11/2010; 86(11):927-34. · 1.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mucosal natural killer (NK) cells that produce interleukin (IL)-22 mediate intestinal homeostasis and inflammation in mice. However, their role in the pathogenesis of human inflammatory bowel diseases (IBDs) is not known. We investigated intestinal NK cells in intestinal mucosa samples of patients with Crohn's disease (CD).
We isolated lamina propria NK cells from intestinal mucosal samples of patients with IBD and subjects without IBD (controls) and analyzed expression patterns of cell surface molecules and cytokine production. Interactions between lamina propria NK cells and intestinal macrophages were examined.
In intestinal mucosa samples from controls, NKp44 and NKp46 were expressed differentially on CD3(-)CD56(+) NK cells, NKp44(+)NKp46(-) (NKp44(+)) NK cells expressed CD127 and the transcription factor retinoic acid-related orphan receptor C (RORC) and produced IL-22 whereas NKp44(-)NKp46(+) (NKp46(+)) NK cells did not express CD127 or RORC and produced interferon (IFN)-gamma. NKp46(+) NK cells were predominant in intestinal mucosa of patients with CD compared with controls or patients with ulcerative colitis. Upon interaction with intestinal inflammatory macrophages NKp46(+), NK cells from patients with CD were activated via IL-23 and produced IFN-gamma; this activation required cell-to-cell contact.
The balance of NKp44(+)/NKp46(+) NK cells is disrupted in intestinal mucosa of patients with CD. NKp46(+) NK cells might mediate the pathogenesis of CD by producing IFN-gamma.
[Show abstract][Hide abstract] ABSTRACT: Mesenchymal stem cells (MSCs) are defined as cells that undergo sustained in vitro growth and can give rise to multiple mesenchymal lineages. Because MSCs have only been isolated from tissue in culture, the equivalent cells have not been identified in vivo and little is known about their physiological roles or even their exact tissue location. In this study, we used phenotypic, morphological, and functional criteria to identify and prospectively isolate a subset of MSCs (PDGFRalpha+Sca-1+CD45-TER119-) from adult mouse bone marrow. Individual MSCs generated colonies at a high frequency and could differentiate into hematopoietic niche cells, osteoblasts, and adipocytes after in vivo transplantation. Naive MSCs resided in the perivascular region in a quiescent state. This study provides the useful method needed to identify MSCs as defined in vivo entities.
Journal of Experimental Medicine 10/2009; 206(11):2483-96. · 13.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The isolation of neural stem cells (NSCs) from the brain has been hampered by the lack of valid cell surface markers and the requirement for long-term in vitro cultivation that may lead to phenotype deterioration. However, few suitable specific cell surface antigens are available on NSCs that could be used for their prospective isolation. The present study demonstrated that the expression of complex type asparagine-linked oligosaccharide (N-glycans) was detected on brain cells dissociated from embryonic and adult brain using Phaseolus vulgaris erythroagglutinating lectin (E-PHA) which binds to biantennary complex type N-glycans, and demonstrated that E-PHA bound preferentially to purified NSCs, but not to neurons, microglia, or oligodendrocyte precursor cells. The labeling of dissociated mouse embryonic brain cells or adult brain cells with E-PHA enabled the enrichment of NSCs by 25-fold or 9-fold of the number of neurosphere-forming cells in comparison to that of unsorted cells, respectively. Furthermore, a lectin blot analysis revealed the presence of several glycoproteins which were recognized by E-PHA in the membrane fraction of the proliferating NSCs, but not in the differentiated cells. These results indicate that complex type N-glycans is a valuable cell surface marker for living mouse NSCs from both the embryonic and adult brain.
Journal of Neurochemistry 08/2009; 110(5):1575-84. · 4.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report here side population (SP) cells, a cancer stem cell enriched fraction from pancreatic cancer cell line, have enormous superior potential of the epithelial to mesenchymal transition (EMT), invasion, and metastasis. In an isolated SP cell culture, the cells rapidly expressed and up-regulated E-cadherin, an epithelial phenotypic marker, and the cells formed tightly contacted cell cluster, which is a representative epithelial phenotypic appearance. When the SP cells were incubated in the presence of TGF-beta, SP cells changed their shape into mesenchymal-like appearance including spindle shaped assembly. This alteration was associated with significant reduction of E-cadherin expression level. TGF-beta induced EMT-associated gene alteration such as reduction of E-cadherin mRNA and induction of Snail mRNA and matrixmetalloproteinase (MMP)-2 mRNA. Finally, SP cells exerted notable matrigel invasion activity in response to TGF-beta treatment, whereas MP cells did not respond to TGF-beta-mediated invasion. In conclusion, these results suggest that SP cells from pancreatic cancer cell line possess superior potentials of phenotypic switch, i.e., EMT/MET, micro-invasion, and in vivo metastasis, as compared to MP cells. Because micro-invasion and metastasis are key mechanisms of cancer malignant potential, SP cells would be the attractive target for preventing cancer progression.
International Journal of Cancer 03/2009; 124(12):2771-9. · 6.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mesenchymal stem cells (MSCs) are a heterogeneous subset of stromal stem cells isolated from many adult tissues. Previous studies reported that MSCs can differentiate to both mesodermal and neural lineages by a phenomenon referred to as ''dedifferentiation'' or ''transdifferentiation''. However, since MSCs have only been defined in vitro, much of their development in vivo is still unknown. Here, we prospectively identified MSCs in the bone marrow from adult transgenic mice encoding neural crest-specific P0-Cre/Floxed-EGFP and Wnt1-Cre/Floxed-EGFP. EGFP-positive MSCs formed spheres that expressed neural crest stem cell genes and differentiated into neurons, glial cells, and myofibroblasts. Interestingly, we observed MSCs both in the GFP(+) and GFP(-) fraction and found that there were no significant differences in the in vitro characteristics between these two populations. Our results suggest that MSCs in adult bone marrow have at least two developmental origins, one of which is the neural crest.
Biochemical and Biophysical Research Communications 02/2009; 379(4):1114-9. · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Adult bone marrow contains endothelial cells, adipocytes, stromal cells, and blood cells, such as erythro- cytes, lymphocytes, platelets. Stromal cells are a population of multipotent cells referred to as mesenchymal stem cells (MSCs), which not only support hematopoiesis, but also differentiate into multiple lineages, in- cluding fat, bone and cartilage. Because of this multipotency, MSCs are an attractive candidate for clinical application to promote repair or regeneration of damaged tissues of mesenchymal origin. However, the characteristics of bone marrow MSCs are still unclear, because of the lack of suitable markers for their prospective isolation. Here, we report the potential usefulness of CD271 (low-affinity nerve growth factor receptor: LNGFR) and CD133 (prominin1: AC133), as markers of the MSC population, for the prospective isolation of highly purified MSCs. This isolation method may provide hope for improving the starting population of stem cells for transplantation in diseases like spinal cord injury, cartilage repair and myocardial infarction.
Inflammation and Regeneration 01/2009; 29(1):73-78.