Three human embryonic stem cell lines once eligible for federal funding are "on hold" until further notice because they were derived from embryos that were too early.
Human embryonic stem cells
Image: Wikimedia commons,
Nissim Benvenisty
"These lines were derived from early embryos -- those consisting of 6, 8, or 16 cells -- and thus formally did not fit the official definition of ES cells by the NIH," linkurl:George Daley,; who derived these particular lines and submitted them for approval to the NIH last year, told The Scientist in an email. The current definition is limited to "cells that are derived from the inner cell mass of blastocyst-stage human embryos" -- a stage that the three lines on hold "failed to reach," said an NIH spokesperson. Last February, the NIH published a linkurl:notice in the Federal Register; that proposed a change in the formal definition of human embryonic stem cell...

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