Because the science is hard and the politics mean, progress in understanding human pluripotent cells has been slow. Biologists first trumpeted their discoveries of human embryonic stem cells (hESCs) and human embryonic germ cells (hEGCs) in 1998.1,2 ESCs come from the blastocyst's inner cell mass, whereas EGCs are derived later in development from the primordial germ cells that give rise to spermatozoa and ova. In the past four years, only about 25 published research papers have focused on human pluripotent cells, and just a handful of labs worldwide have become adept at extracting and culturing them.
Sluggish public funding has provided limited stimulus. In August 2001, the US National Institutes of Health (NIH) got the green light to support studies on existing hESC lines. Over the next 12 months, only four investigators secured funding, totaling $3.5 million (US), for new projects, says Della Hann, a senior policy advisor at NIH. ...
