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Effective ex vivo expansion of hematopoietic stem cells (HSCs) is a prerequisite for HSC transplantation. Growth and maintenance of HSC is dependent on cytokine and niche factors. We investigated whether mesenchymal stem cells (MSCs) or osteogenic cytokine-differentiated MSCs play a role in HSC expansion. We used the human HM3.B10 (B10) MSC cell line and the osteoblast-differentiated B10 (Ost-B10) as a feeder layer and examined ex vivo expansion of CD34(+)CD38(-) HSCs obtained from peripheral blood (PB) and cord blood (CB) with or without several growth cytokines. Both undifferentiated B10 and Ost-B10 cells exhibited similar effects on total HSC expansion; however, Ost-B10 demonstrated a higher potency in CD34(+)CD38(-) cell-specific proliferation in the presence of cytokines compared to undifferentiated B10 HSCs. Colony-forming cell assay and long-term culture initiating cell assay revealed that Ost-B10 displayed multipotent differentiation and enabled long-term ex vivo culture of HSCs. We next examined the relationship between HSC expansion and the presence of various chemokines. CXCL4 and CXCL12 expression were increased in Ost-B10 cells compared with the B10 cells. CD34(+)CD38(-) cells were significantly increased with CXCL12, but not CXCL4 treatment. siRNA inhibition of CXCL12 decreased CXCL12 secretion in both B10 and Ost-B10, whereas expansion of CD34(+)CD38(-) cells was decreased in Ost-B10 alone. These results demonstrated that ex vivo expansion of HSCs may be highly effective through osteoblast-differentiated MSCs acting as a feeder layer, and likely operates through the CXCL12 chemokines signaling pathway.

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Abstract-Effects of smoking on white matter lesions, such as lacunar infarction and leukoaraiosis, are still controversial.We hypothesized that the endothelial NO synthase (eNOS) genotype was a modulating factor for the effect of smoking on cerebral circulation. We took a cross-sectional population from the participants of a health examination to study the effects of smoking and a single-nucleotide polymorphism in the eNOS gene, T-786C. Smokers and nonsmokers were defined as having a smoking index (cigarettes per day times years) of Ն200 and 0, respectively. One hundred sixty-six male nonsmokers and 344 male smokers were recruited. Cerebral blood flow was measured by the 133 Xe inhalation method. Genotyping of T-786C was performed by using a newly developed allele-specific polymerase chain reaction. Smokers were exposed to greater oxidative stress, as estimated by urinary F 2 -isoprostane excretion. In smokers, CC homozygotes of T-786C showed a significant decrease of cerebral blood flow (56.6Ϯ13.3, 57.6Ϯ11.5, and 44.0Ϯ7.2 mL/min per 100 g tissue for TT, TC, and CC, respectively; Pϭ0.03 by ANOVA) and a significant increase of cerebrovascular resistance, whereas the eNOS genotype did not affect these parameters in nonsmokers. This result indicated that the eNOS genotype could modify cerebrovascular circulation in a general population by potentiating the adverse effect of smoking. Key Words: nitric oxide synthase Ⅲ polymorphism Ⅲ cross-sectional studies Ⅲ cerebral circulation S moking is an established risk factor for cardiovascular diseases. However, the adverse effect of smoking is controversial in some areas of cerebrovascular disease, such as lacunar infarction and white matter changes. 1-7 Such inconsistency may imply the importance of other environmental or genetic factors in modifying the effects of smoking. Because lacunar infarction and white matter changes are based on occlusive changes in small arteries perforating into the white matter and are characterized by decreased cerebral blood flow (CBF) and increased cerebrovascular resistance (CVR), the endothelial NO synthase (eNOS) gene is a good candidate for such a factor; eNOS constitutively produces NO, a potent vasodilator as well as an antitrophic factor for the arterial wall. 8 -11 Several reports have indicated that eNOS plays an essential role in the regulation of basal CBF in humans and in mice. 9,10 Furthermore, because smoking antagonizes the action of NO through the induction of oxidative stress, 12 it is logical to hypothesize that genetic alteration of eNOS activity may be a modifier of the effect of smoking on the cerebral circulation.Recently, the eNOS gene was studied extensively for genetic polymorphisms to elucidate its genetic role in cardiovascular diseases. As a result, a single-nucleotide polymorphism (SNP) in the promoter region, T-786C, was found to modify the promoter activity in vitro. 13 In addition, this SNP and a 27-bp repeat polymorphism in intron 4, called ecNOS4 a/b, were reported to influence eNOS mRNA and protein levels ...

We developed a low-coherence light source based on self-assembled InAs quantum dots (QDs) with controlled emission wavelengths and applied it to optical coherence tomography (OCT) imaging. A current-driven superluminescent diode (SLD) light source including four layers of QDs exhibits a broadband (80-nm-bandwidth) emission centered at approximately 1.2 µm with a Gaussian-like spectral shape at room temperature. Spectral-domain OCT (SD-OCT) using the QD-SLD as a light source was developed and imaging with the SD-OCT was demonstrated. The axial resolution was estimated to be approximately 8 µm in air and no apparent side lobes appeared beside the point spread function, indicating the effectiveness of the QD-SLD for high-resolution, noise-reduced OCT imaging.