AT LONG last, researchers have proved that they can make human embryonic stem cells (hESCs) without destroying embryos. This may get round some moral objections to embryo research, but more importantly it has brought to light a substance that should help all stem-cell researchers improve their craft.
That substance is laminin – a protein found in the basement membranes underlying layers of skin. It made all the difference to work by Robert Lanza and his team at Advanced Cell Technology, a company in Worcester, Massachusetts, who last week reported creating hESCs from human embryos without destroying them (Cell Stem Cell, ).
Until now, hESCs have all been extracted from human embryos, which have perished in the process. Lanza avoided this by plucking out a single blastomere – one of the eight cells in an early-stage human embryo – and using it to generate a new colony of hESCs.
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When Lanza first attempted this a year ago, he proved that hESCs could be generated from blastomeres, but none of the embryos he took them from survived. Also, just 2 per cent of his blastomeres generated hESCs, so large numbers of embryos were needed. But when laminin was added to the dishes in which the embryos were grown, the majority of them survived the removal of a blastomere, and 20 to 50 per cent of the blastomeres went on to generate hESCs – about the same success rate as when taking hESCs directly from embryos.
Laminin appears to stop newly extracted blastomeres from turning into useless trophectoderm cells from which the placenta originates, and instead encourages them to turn into hESCs.
Lanza says the same trick might make it easier to create hESCs through other methods such as somatic cell nuclear transfer, the “cloning” technique which gave us Dolly the sheep. This would allow hESCs to be created from a patient’s own cells, making them less likely to be rejected if used therapeutically. To do this, doctors will have to make a “transient” embryo, by fusing an empty human egg with DNA extracted from one of the patient’s own cells – something not yet achieved in humans.
Other types of stem cell might reach the clinic first, such as those created by reprogramming adult cells. Even this technique could benefit from laminin, says Lyle Armstrong at the University of Newcastle upon Tyne in the UK. “Lanza’s paper contributes a great deal to the body of knowledge concerning hESC derivation,” he says.
Stem Cells – Learn more about the promise and the controversy in our cutting edge special report .
