Dr Deepak Srivastava, who directs cardiovascular and stem cell research at Gladstone Institutes in the US, agrees. He says that since iPS technology is so new, it is still critical to fund and conduct human embryonic stem cell research.

"Knowledge gained from research with embryonic stem cells, in part, helped Dr Yamanaka discover iPS technology. Researchers are still learning many important things about the safest and most efficient ways to create iPS cells for drug discovery, personalized medicine and tissue regeneration," he points out. "To further refine iPS technology for such promising purposes, scientists still need to measure iPS cells against the 'gold standard' of actual human embryonic stem cells."