Stojkovic’s team, including researchers from the University of Durham, UK, and at Sintocell, a company in Serbia, investigated 161 donated blastocysts in total, some of them normal and others in the so-called arrested form. Of the 119 blastocysts which arrested early – having multiplied to no more than 10 cells – none yielded viable embryonic stem cells.The last one didn't pan out, and there's no reason this one will, either, since its opponents promote the broadest criterion for "life."
The only successful line came from 13 “late-arrested” blastocysts, which had stalled after multiplying to between 16 and 24 cells.
The hESCs were retrieved and grown in the lab on a layer of human “feeder cells” and nutrients. “In countries with a non-flexible policy, arrested blastocysts provide a more ethical source for research and hESC derivation,” the team say. “Our opinion is that all surplus and consented arrested and developing embryos, whether of poor or good quality, should be used for research or derivation of hESCs and not discarded.”
The controversy continues, however. Not everyone thinks the blastocysts in question were indisputably dead. “They are arrested, but still metabolically active,” says Stephen Minger, a stem cell researcher at King’s College London, UK. “So technically they’re still alive, and to spin it bio-politically as an ethical source of hESCs is completely misleading,” he says.