Now, President Barack Obama's administration has thrown that policy away according to the New York Times, allowing the first of many new embryonic stem cell lines to be approved.  The National Institutes of Health announced Wednesday that federal researchers now have legal access to 13 new embryonic stem cell lines.  Over 96 more lines are under review and may soon be approved.

Embryonic stem cells are typically derived from embryos left over at in vitro fertility clinics.  Opening more lines is significant for many reasons.  First, it is notoriously hard to keep stem cells growing and dividing in their original state for almost 10 years.  Genetic changes may skew test results and lead to misleading conclusions.

Secondly, it's important to have multiple lines accessible to verify that phenomena observed are applicable to all stem cells or just certain lines.  This information is essential if doctors are to ever hope to seriously treat diseases on a widespread basis with stem cells.

During the ban, researchers were able to finance some work on new lines via independent financing, but found themselves buried under mounds of government red tape, namely the necessity to keep the independently financed lines in separate areas.  Describes Ali H. Brivanlou, a researcher at Rockefeller University, "You can imagine what it meant not to be able to carry a pipette from one room to another.  They even had to repaint the walls to ensure no contamination by federal funds."

Two of the new lines were derived via private funding and through the work of Dr. Brivanlou's group.  Dr. George Daley of Children’s Hospital, Boston prepared the remaining 11 lines.  Dr. Francis S. Collins, director of the health agency, says that despite the fact that researchers can't derive their own lines, most understand that the decision to open up more lines is a major step forward.  He describes, "I’m not sure everyone is interested in deriving their own cell lines as long as they can get lines from others."

In recent years the controversy over the ban on new stem-cell lines has eased slightly with the discovery of induced pluripotent stem cells (iPSCs).  As time has passed, though, iPSCs now appear a less viable option than previously thought.  Like embryonic stem cells, they require complex chemical and physical stimuli to differentiate into the proper cell type.  However, unlike embryonic stem cells, they carry an additional tumorigenic (cancer) risk due to the mutagenic agents used to force the cells into pluripotency.  New methods of induction are being devised, but the risks largely remain to date.