托福考试阅读练习题：ResearchersTurnHumanSkinCellsintoBloodCells

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生物医学领域科学家们的一个梦想如今终于成真。加拿大麦克马斯特大学的研究人员利用人的皮肤细胞和脱氧核糖核蛋白成功造出了血细胞。今天的托福考试阅读练习题要关注的就是此项最新研究成果。  
: Z6 A: N- A5 V' S　　One of the dreams of biomedical scientists is to be able to transform adult cells into other kinds of cells. And thus avoid some of the ethical concerns of working with embryonic stem cells. Now a research team from McMaster University in Ontario has announced that they’ve been able to transform human skin cells into blood cells. The work was published online on November 7th by the journal Nature. [Eva Szabo et al., "Direct conversion of human fibroblasts to multilineage blood progenitors"]
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　　Other research in this area has required that cells of one type first be returned to a more generally undifferentiated stem cell state, which can introduce fresh problems. Once there, the cell is then turned into the type of tissue the researchers seek. But in this case, the scientists avoided the middleman cell. The skin was changed directly into what appears to be functional adult human blood cells. The technique involves gene insertion by a virus vector and exposure to numerous regulatory proteins.

　　The cells have not been tested in humans to see if they’re truly indistinguishable from the home-grown kind. But the research is another step in the effort to create needed cell types from easily available ones.