The First Clone
Scientists have finally cloned a human embryo. The breakthrough promises cures for terrible diseases. Here's the inside story:
(5) Get the stem cells to specialize
The Challenges
(A) Any one of thousands of different "growth factors" may be involved in spurring a stem cell to become a brain cell or a blood cell.
(B) Even if the right chemicals are found, the stem cells may not respond unless the chemicals interact with the cells' DNA in precisely the right sequence.
(C) The body has over 200 types of specialized cells, and the recipe for growing certain types may remain a mystery for years.
Source: Jose Cibelli, Advanced Cell Technology
MILESTONES IN CLONING
February 1997
The first cloning of a mammal, Dolly the sheep, from an adult body cell is announced.
March 1997
President Clinton bans federal funding of human-cloning research.
1998-2000
Researchers clone mice, calves, goats, and pigs. A bull is "recloned" from a cloned bull.
April 2000
Scientists find that cloning can restore body cells to a youthful state.
October 2001
The first cloned human embryos are created at Advanced Cell Technology's lab in Worcester, Mass.
Source: Jose Cibelli, Advanced Cell Technology
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