The technique has worked
previously using cells from babies, but it was thought that the natural
mutations that occur as they age would mean that it could not be achieved using
adult cells. But the researchers had success using skin cells from a 35-year-old
man and a 75-year-old man.
The research team removed the
nucleus from an egg cell and replaced it with the nucleus of an adult skin cell
in a process called somatic cell nuclear transfer (SCNT). SCNT is the process
that was used to create Dolly the sheep in 1996.
After shocking the cells with
electricity, they began dividing until they formed a ball of a few hundred
cells — a blastocyst — which has the potential to be grown into a number of
different tissue types. These tissues could one day be used to treat a range of
disorders including Parkinson's disease, heart disease and even spinal cord
'Therapeutic cloning has long
been envisioned as a means for generating patient-specific stem cells that
could be used to treat a range of age-related diseases', said Dr Robert Lanza, a
co-author of the study, from Advanced Cell Technology in Massachusetts, USA.
'However, despite cloning
success in animals, the derivation of stem cells from cloned human embryos has
proven elusive. Only one group has ever succeeded, and their lines were
generated using fetal and infant cells', he added.
Professor Shoukhrat Mitalipov, from
Oregon Health and Science University, who developed the technique, 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'.
There are ethical concerns
regarding the team's discovery, however. While the blastocysts created by the
current research would never give rise to a human embryo, the findings raise
the prospect of using a similar technique to create a cloned embryo. Dr Lanza
recognises the risk of attempting to do this, remarking that it would be 'unsafe
and grossly unethical' to NBC
Meanwhile, one of Dr Lanza's
colleagues, Dong-ryul Lee, from CHA University in South Korea, has found that
only relatively few human stem cell lines are needed to be able to treat
numerous people without fear of immunorejection.
Lee and his colleagues
discovered that 28 types of human embryonic stem cells developed in South Korea can
be transplanted into up to a quarter of Koreans without being rejected by the
body. This means theoretically that just 100 to 160 stem cell lines would need
to be generated in order to treat the whole of the South Korean population, they
The research was published in
Cell Stem Cell.