The HSC niche factor SCF is required for HSC maintenance. Using an Scf-GFP knockin mouse, we have identified a perivascular cell type in the bone marrow expressing high level of Scf.
Endothelial and perivascular cells maintain haematopoietic stem cells.
Specimen part
View SamplesThe hilum region of the mouse ovary, the transitional/junction area between OSE, mesothelium and tubal (oviductal) epithelium is identified as a previously unrecognized stem cell niche of the OSE. OSE cells with high ALDH1 activity have been predominantly detected in the hilum region by immunohistochemical staining.
Ovarian surface epithelium at the junction area contains a cancer-prone stem cell niche.
Age, Specimen part
View SamplesIt is generally believed that cerebellar granule neurons originate exclusively from granule neuron precursors (GNPs) in the external germinal layer (EGL). Here we identify a rare population of neuronal progenitors in the developing cerebellum that expresses Nestin. Although Nestin is widely considered a marker for multipotent stem cells, these Nestin-expressing progenitors (NEPs) are committed to the granule neuron lineage. Unlike conventional GNPs, which reside in the outer EGL and proliferate extensively, NEPs reside in the deep part of the EGL and are quiescent. Expression profiling reveals that NEPs are distinct from GNPs, and in particular, express markedly reduced levels of genes associated with DNA repair. Consistent with this, upon aberrant activation of Sonic hedgehog (Shh) signaling, NEPs exhibit more severe genomic instability and give rise to tumors more efficiently than GNPs. These studies identify a novel progenitor for cerebellar granule neurons and a novel cell of origin for medulloblastoma.
A population of Nestin-expressing progenitors in the cerebellum exhibits increased tumorigenicity.
Specimen part
View SamplesOverexpression of a caspase-resistant form of Bcl-2 (D34A) in human umbilical vein endothelial cells (EC) implanted into immunodeficient mice promotes the maturation of human EC-lined microvessels invested by vascular smooth muscle cells (VSMC) of mouse origin. In contrast, EC implants not overexpressing Bcl-2 form only simple, uncoated EC tubes. Here we compare the phenotypes of vessels formed in vivo and the transcriptomes in vitro of EC expressing different forms of Bcl-2. Wild type Bcl-2, like the caspase resistant D34A Bcl-2 mutant, is anti-apoptotic in vitro and promotes VSMC recruitment in vivo, whereas a G145E mutant that has diminished anti-apoptotic activity in vitro does not promote vessel maturation in vivo. The D34A and wild type forms of Bcl-2, but not the G145E mutant form of Bcl-2 significantly regulate RNA transcripts previously associated with EC-VSMC interactions and VSMC biology, including matrix Gla protein, insulin like growth factor binding protein (IGFBP)-2, matrix metaloproteinase-14 (MMP14), ADAM17 and Stanniocalcin-1. These effects of Bcl-2 on the transcriptome are detected in EC cultured as angiogenic 3-D tubes but are attenuated in EC cultured as 2-D monolayers. Bcl-2-regulated transcription in EC may contribute to vascular maturation, and support design of tissue engineering strategies using EC.
Antiapoptotic activities of bcl-2 correlate with vascular maturation and transcriptional modulation of human endothelial cells.
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