Scientists have for the first time turned adult human skin cells into stem cells, which can grow into any type of tissue in the body, using cloning techniques.
Using the cloning technique which produced Dolly the sheep in 1996, researchers were able to turn skin cells from a 35-year-old man and a 75-year-old man into stem cells, raising the prospect that body parts could be regenerated in old age.
Last year, a team of researchers had created stem cells from the skin cells of babies but it was unclear whether it would work in adults because cells mutate with age.
Now, a team at the Research Institute for Stem Cell Research at CHA Health Systems in Los Angeles and the University of Seoul said they have achieved the same result with two adult males, 'The Telegraph' reported.
"The proportion of diseases you can treat with lab-made tissue increases with age. So if you can't do this with adult cells it is of limited value," said Robert Lanza, co-author of the research published in the journal Cell Stem Cell.
The technique works by removing the nucleus from an unfertilised egg and replacing it with the nucleus of a skin cell. An electric shock causes the cells to begin dividing until they form a 'blastocyst' - a small ball of a few hundred cells.
In IVF it is a blastocyst which is implanted into the womb, but with this technique the cells would be harvested to be used to create other organs or tissues.
Although the embryos created may not give rise to a human clone even if implanted in a womb, the prospect is now scientifically closer.
Reproductive biologist Shoukhrat Mitalipov of Oregon Health and Science University, who developed the technique last year said: "The advance here is showing that (nuclear transfer) looks like it will work with people of all ages.
"I'm happy to hear that our experiment was verified and shown to be genuine," he said.