• Vol. 33 No. 1, 121–127
  • 15 January 2004

The Rocky Road from Dolly to Human Embryonic Stem Cells: Has it Been a Worthwhile and Justifiable Scientific Pursuit?



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The announcement of the birth of Dolly the sheep, the world’s first adult cell somatic mammalian clone, in February 1997, caused excitement and concern in equal measure. Since then, the technique has been extended to 7 further species and has been refined to allow the introduction of new genes into clones as well as modification of existing ones. Health problems continue to be an issue of concern and the technique remains highly inefficient. This inefficiency is due to reprogramming difficulties in the donor nuclei, a problem that confounds immediate solution but one that is fuelling a lot of interesting basic research. Cloning could also be used to make embryonic stem (ES) cell lines from healthy cells taken from sick patients and after further manipulation, tissue made from these ES cells could be used to replace damaged tissue. Proof of principle of this concept, otherwise known as therapeutic cloning, has been obtained in mice, but its implementation in humans is a long way off.

The first mammal cloned from an adult cell was born in July 1996.1 The delivery of Dolly, a Finn Dorset sheep, was attended, unusually for a sheep, by a retinue of concerned animal handlers, technicians and vets.

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