Word: blastocysts
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...report in the journal Science sounded last week--at least at first blush. Woo Suk Hwang and Dr. Shin Yong Moon, from Korea's Seoul National University, announced that they had created more than 200 embryos by cloning mature human cells and had grown 30 of them to the blastocyst stage of development, each more than 100 cells strong. This isn't the first time cloned human embryos have been produced: in 2001 the Massachusetts biotech firm Advanced Cell Technology made several. They all died quickly, but in a sense the first cloned human cells are actually old news...
Sandel first explained that a week-old embryo, or blastocyst, is killed when stem cells—embryonic cells that can be developed into any kind of tissue—are extracted from...
Despite Krauthammer's protestations, cows are not people. Teasing stem cells from microscopic blastocysts is not in any way analogous to a "brave new world of fetal farming." Research cloning, more appropriately termed therapeutic nuclear transfer, carries enormous potential for alleviating dreaded human diseases. There is a very clear line between this research and what Krauthammer terms the inevitable next step: implanting such a blastocyst into a human womb. There is no reason to believe that this will necessarily occur. But even if such a procedure might eventually be performed in some renegade scientist's lab, should that be reason...
...cloning advocates. We would never countenance such work in humans, they say. Cows, yes, but we would never implant a cloned human embryo in the uterus of a woman and grow it to the stage of a fetus. We solemnly promise to grow human clones only to the blastocyst stage, a tiny 8-day-old cell mass no larger than the period at the end of this sentence, so that we can extract stem cells and cure diseases that way. Nothing more. No fetuses. No implantation. No brave new world of fetal farming...
This is all very nice. But curing with stem cells is extremely complicated. First, you have to tease out the stem cells from the blastocyst. Then you have to keep the stem cells alive, growing one generation after another while retaining their pluripotentiality (their ability to develop into all different kinds of cells). Then you have to take those stem cells and chemically tweak them in complex ways to make them grow into specialized tissue cells--say, neurons for a spinal-cord injury. Then you inject the neurons into the patient and get your cure...