21 diciembre 2005


[Whether or not embryos should be cloned and then destroyed for their stem cells has been one of the hottest issues in science this year.

MercatorNet asked James Sherley, an associate professor of biological engineering at the Massachusetts Institute of Technology (MIT), to give his views

Sherley says:
  • The most profound drawback, which has not been adequately disclosed, is that human embryonic stem cells cannot be used directly to treat mature tissues and organs.
  • The tissues and organs of the body undergo constant cell turnover. Cells are born by cell division, they turn into functional cells (ie, “differentiate”), they function, they get old, they die, and finally they are lost or removed from their tissue or organ.
  • So, to treat mature tissues and organs by giving mature cells produced from embryonic stem cells is not enough.
  • The cells that normally sustain cell turnover are adult stem cells that reside in every tissue and organ which has this cell turnover process, and that is nearly all tissues.
  • This means that, in order to use embryonic stem cells for diseases in mature tissues, they must be turned into adult stem cells.
  • Another reason that embryonic stem cells cannot be used directly is that they form tumours when transplanted into mature tissues.
  • Knowing these facts, it is pure scientific folly to place such emphasis on embryonic stem cells research to the exclusion of support for adult stem cell research.
  • No matter what the hurdles are for success with adult stem cell-based therapy development, embryonic stem cell research faces the same hurdles and more.
Michael Cook is editor of MercatorNet. He writes from Melbourne.]

Vita Categoria-Eutanasia y Aborto

Michael Cook

MercatorNet: Professor Sherley, you have been outspoken in your opposition to therapeutic cloning. What’s wrong with destroying a human embryo, especially if this research might benefit people with terrible diseases?

James Sherley: Despite the confusion that some like to create on the questions of “are embryos human beings?” and “when does a human life begin?”, both scientists and physicians know very well that human embryos are alive and human. A human life begins when a diploid complement of human DNA is initiated to begin human development. Therefore, a life can be initiated by the fusion of sperm and egg or by the introduction of a diploid nucleus into an enucleated egg (ie, “cloning”). Given that embryos are human beings, they have a right to self and a right to life. Exploiting their parts (ie, cells) or killing them for research is moral trespass that society should not allow. Even if the research might, and let’s be clear, might benefit others, this trespass is not justified.



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