MATURE skin cells have been transformed into stem cells and then into beating
heart cells, claims a group of American scientists. This is the first time a
fully differentiated adult cell has been reprogrammed. The breakthrough gives
scientists a way to produce multipotent stem cells for treating conditions such
as heart disease or diabetes without creating an embryonic clone of the patient.
Therapeutic cloning has been attacked by anti-abortion campaigners.
Researchers at PPL Therapeutics of Blacksburg, Virginia, took adult skin
cells from cattle, 鈥渞everted鈥� them into stem cells and then transformed them
into heart cells. 鈥淲e were very pleased, because we didn鈥檛 expect it,鈥� says Alan
Coleman, director of research at PPL in Britain. PPL is part of the
Edinburgh-based team that produced Dolly the sheep.
鈥淭he major message from cloning was that an adult cell with a specialised
life could be reprogrammed. That was done by first making an embryo,鈥� says
Coleman.
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快猫短视频s can isolate stem cells from embryos and turn them into specific
tissues. Coleman says PPL is now en route to doing that without going through
the embryo stage. The advance comes just as 80 US Nobel laureates urged
President Bush last week not to block federal funding for experiments using
embryonic stem cells.
Coleman refuses to reveal exactly how the procedure was performed, because
the details are commercially sensitive. 鈥淭he holy grail is to reprogram a cell
by putting it in chemicals, but we can鈥檛 say if that鈥檚 what we鈥檝e done now,鈥� he
says.
Experiments in Britain in 1997, led by Azim Surani of the Institute of Cancer
Research in Cambridge, suggested that an adult mouse cell could be reprogrammed
by fusing it with a 鈥渃apsule鈥濃�攁n embryonic mouse stem cell stripped of its nuclear DNA
(快猫短视频, 29 January 2000, p 4). So a bank
of cultured stem cells could provide standardised capsules for reprogramming
patients鈥� own cells. 鈥淥ne of the ideas is to use the cytoplasm to reprogram the
nucleus of [another] cell,鈥� says Coleman. 鈥淚 can鈥檛 confirm or deny if that is
what we鈥檝e done here.鈥�
Ethicists concerned about the use of embryos in research welcomed the
advance. 鈥淭his is an encouraging breakthrough in the search for replacement
cells to treat serious diseases without the need to use human embryos. It鈥檚 too
early to say if this is the solution we鈥檝e been looking for, but it鈥檚 certainly
a step in the right direction,鈥� says Donald Bruce of the Church of Scotland.
The team now hopes to demonstrate that adult cells can be transformed into a
wide range of cells, and the big challenge is to repeat the procedure with human
cells.