Scientists have used cloning technology to make embryonic stem cells that carry a diabetic woman's genes and turned them into insulin-producing beta cells that could cure her disease.
The team reported clearing an big hurdle in the quest to make "personalised stem cells" for use in disease therapy, but a bioethicist said it also highlighted the need for better regulation of lab-grown embryos.
"We are now one step closer to being able to treat diabetic patients with their own insulin-producing cells," said Dieter Egli of the New York Stem Cell Foundation, who led the study published in the journal Nature.
Egli and a team had transplanted the nuclei of cells taken from the woman's skin into human eggs to create stem cells, which they could then coax into becoming beta cells - a shortage of which causes insulin deficiency and high blood-sugar in diabetics.
In doing so, the team confirmed a potentially important source for future cell-replacement therapy. It was not the first study to create stem cells in this way, but it was the first to use cells sourced from a diseased adult person with the aim of producing therapy-specific cells.
Insoo Hyun, a bioethicist from the Case Western Reserve University's school of medicine in Cleveland, Ohio, said the research, the latest to produce embryonic stem cells that carry the genomes of living people, raised red flags. "This repeated cloning of embryos and generation of stem cells, now using cells collected from adults, increases the likelihood that human embryos will be produced to generate therapy for a specific individual," he wrote in a comment carried by Nature.
"Regulatory structures must be in place to oversee it."
Embryonic stem cells - neutral, primitive cells that can develop into most of the specialised tissue cells of the body - are viewed as a potential source for rebuilding organs damaged by disease or accident. But they are controversial, as until recently, stem cells could be obtained only from human embryos. They can be grown in the lab by transferring the nucleus of a cell from tissue like the skin, which contains a person's DNA, into a human egg from which the nucleus has been removed.
The egg is then given an electrical pulse to start dividing until it forms a blastocyst, a hollow, early-stage embryo made up of about 150 cells with the DNA of the donor of the tissue cell.
Technically known as somatic-cell nuclear transfer, the technique is used for therapeutic research but is also the first step in cloning, and was used to create Dolly the sheep.