問題詳情

It was nearly a decade in the making, but the first human trial using embryonic stem cells was approved on Friday. The trial, which will test a stem-cell-based treatment for spinal-cord injury, will begin later this summer and will use cells generated by Geron Corp. The approval marks the first time human stem cells, extracted and grown from embryos, will be transplanted into patients. Adult stem cells, which are present in many types of tissue, have been used in treatments for years — the most common being bone-marrow transplants in cancer care — but an embryonic study is a whole new thing. There's a good reason it's being greeted with so much excitement.Scientists believe that embryonic stem cells are more versatile than adult cells in generating the more than 200 different tissue types in the body. The need for healthy new cells is particularly acute in the case of spinal-cord injury, because once central-nervous-system tissue is destroyed, it does not regenerate — not in any significant way, at least. The Geron team began its work with what is known as a presidential stem-cell line — stem cells derived from discarded in vitro–fertilization embryos that already existed in 2001 when then President Bush decided to prohibit the use of federal funds to pursue human embryonic-stem-cell work. At the time, fewer than two dozen of these stem-cell lines were of good enough quality to use as a basis for human treatments.
How long have scientists been studying embryonic stem cells?
(A)One hundred years. 
(B)Ten years. 
(C)More than twenty years. 
(D)One year.

參考答案

答案：B
難度：適中0.664384
統計：A(25),B(194),C(52),D(21),E(0) #
個人：尚未作答書單：grin 、Einstein’s brain is now interactive iPad app 愛因斯坦的大腦現在成為iPad互動應用程式

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