Lepton flavor violation in the triplet Higgs model

The triplet Higgs model, which is an extension of the standard model with a weak-scale triplet Higgs boson, is capable of generating small neutrino masses naturally. We investigate lepton flavor violation mediated by the triplet Higgs boson. We stress that various neutrino mass patterns could be distinguished by measuring the lepton flavor violating processes. \mu \to eee decay is significantly enhanced in the case of the degenerate masses or the inverted-hierarchical masses compared with that in the case of the hierarchical masses. On the other hand, the \mu \to e \gamma rate and the \mu - e conversion ratio in nuclei is almost insensitive to the mass spectra. We also emphasize that these decay rates tend to increase as the magnitude of U_{e3} increases. Lepton flavor nonconserving \tau decay modes are expected to be unobservable at planned experiments in the light of the current upper bounds of flavor violating muonic decay.Comment: 11 pages, 3 figures, typos correcte

Regenerative Effects of Mesenchymal Stem Cells: Contribution of Muse Cells, a Novel Pluripotent Stem Cell Type that Resides in Mesenchymal Cells

Mesenchymal stem cells (MSCs) are easily accessible and safe for regenerative medicine. MSCs exert trophic, immunomodulatory, anti-apoptotic, and tissue regeneration effects in a variety of tissues and organs, but their entity remains an enigma. Because MSCs are generally harvested from mesenchymal tissues, such as bone marrow, adipose tissue, or umbilical cord as adherent cells, MSCs comprise crude cell populations and are heterogeneous. The specific cells responsible for each effect have not been clarified. The most interesting property of MSCs is that, despite being adult stem cells that belong to the mesenchymal tissue lineage, they are able to differentiate into a broad spectrum of cells beyond the boundary of mesodermal lineage cells into ectodermal or endodermal lineages, and repair tissues. The broad spectrum of differentiation ability and tissue-repairing effects of MSCs might be mediated in part by the presence of a novel pluripotent stem cell type recently found in adult human mesenchymal tissues, termed multilineage-differentiating stress enduring (Muse) cells. Here we review recently updated studies of the regenerative effects of MSCs and discuss their potential in regenerative medicine

Morphologic and Gene Expression Criteria for Identifying Human Induced Pluripotent Stem Cells

<div><p>Induced pluripotent stem (iPS) cells can be generated from somatic cells by the forced expression of four factors, Oct3/4, Sox2, Klf4, and c-Myc. While a great variety of colonies grow during induction, only a few of them develop into iPS cells. Researchers currently use visual observation to identify iPS cells and select colonies resembling embryonic stem (ES) cells, and there are no established objective criteria. Therefore, we exhaustively analyzed the morphology and gene expression of all the colonies generated from human fibroblasts after transfection with four retroviral vectors encoding individual factors (192 and 203 colonies in two experiments) and with a single polycistronic retroviral vector encoding all four factors (199 and 192 colonies in two experiments). Here we demonstrate that the morphologic features of emerged colonies can be categorized based on six parameters, and all generated colonies that could be passaged were classified into seven subtypes in colonies transfected with four retroviral vectors and six subtypes with a single polycistronic retroviral vector, both including iPS cell colonies. The essential qualifications for iPS cells were: cells with a single nucleolus; nucleus to nucleolus (N/Nls) ratio ∼2.19: cell size ∼43.5 µm²: a nucleus to cytoplasm (N/C) ratio ∼0.87: cell density in a colony ∼5900 cells/mm²: and number of cell layer single. Most importantly, gene expression analysis revealed for the first time that endogenous Sox2 and Cdx2 were expressed specifically in iPS cells, whereas Oct3/4 and Nanog, popularly used markers for identifying iPS cells, are expressed in colonies other than iPS cells, suggesting that Sox2 and Cdx2 are reliable markers for identifying iPS cells. Our findings indicate that morphologic parameters and the expression of endogenous Sox2 and Cdx2 can be used to accurately identify iPS cells.</p> </div

Characterization of iPS cell colony G.

<p>(A–D) Immunocytochemistry for (A) Oct3/4, (B) Nanog, (C) Sox2, (D) TRA-1-81 in iPS cell colony G. Scale bar = 100 µm. (E, F) EBs generated from colony G were plated on gelatin coated dishes containing DMEM/F12 medium supplemented with 20% knockout serum replacement. After 10 days, cell differentiation was confirmed by immunocytochemistry for mesodermal (smooth muscle actin; SMA) (E), endodermal (alpha-fetoprotein; alpha-FP) (E) and ectodermal markers (neurofilament; NF) (F). Scale bar = 100 µm. (G) RT-PCR of differentiation markers in undifferentiated iPS cell colony G (Undifferentiation) and embryoid bodies derived from iPS cell colony G. Differentiation). (H–K) Hematoxylin and eosin staining of teratoma formed by transplantation of iPS cell colony G into immunodeficient mice testis. (H), Low magnification of the formed teratoma (12 weeks after injection). Endodermal (I), mesodermal (J) and ectodermal (K) tissue were observed in the teratoma.</p

Classification of morphologic characteristics in colonies generated from human fibroblasts using a single polycistronic viral vector.

<p>Each replicate represented 2×10⁵ GFP positive cells seeded onto a 60-mm dish containing feeder cells and cultured in Primate ES cell medium for thirty days.</p

RT-PCR and Q-PCR of typical examples in each colonies H∼L and iPS colony G and human ES cells.

<p>(A) RT-PCR analysis examined the expression of endogenous Oct3/4, Sox2, Nanog, Klf4, c-Myc, as well as FoxD3, Rex1, Dnmt3b, Abcg2 and Cdx2. Beta-actin was used as an internal control. (B) Q-PCR data for expression of endogenous Oct3/4, endogenous Sox2, Nanog, endogenous Klf4, endogenous c-Myc, FoxD3, Rex1, Dnmt3b, Abcg2 and Cdx2.</p

Morphometric analysis in colonies generated from human fibroblasts by using a single polycistronic Oct3/4-Klf4-Sox2-c-Myc-GFP expressing viral vector.

<p>(H–L, G) Photograph and parameters of colonies H∼L and G. Graphs shows parameters of each classified colony, including that of iPS cell colony G. The numerical value in the graph indicate the ratio to the maximum value (setting 100 for maximum value) in each parameter. Scale bars = 100 µm.</p