First published online March 23, 2006
Development 133, 805e (2006)
© The Company of Biologists Limited
Cloning: trophoblast fails to get with the program
Nearly ten years after the first cloned mammal was born, nuclear transfer
into enucleated oocytes still rarely yields viable mammalian embryos –
most cloned embryos implant normally but die after the blastocyst stage.
Jouneau and co-workers now report that mouse embryos produced by the
transplantation of embryonic stem cell nuclei into enucleated mouse oocytes
(ES NT embryos) fail to develop primarily because of trophoblast defects
– defects that are characterised by trophoblast overgrowth and
subsequent placental abnormalities (see p.
1597). The researchers
use embryological studies, gene expression analyses and experiments with
chimeric embryos to investigate why ES NT embryogenesis fails. They show, for
example, that the peri-implantation death of ES NT embryos can be partly
rescued through the injection of normal ES cells or inner cell mass cells.
Based on their results, the researchers propose that ES NT embryos fail
because of defective epigenetic reprogramming in the trophoblast lineage.
Future work should determine whether the same is true for cloned embryos
produced by somatic cell nuclear transfer.
Related articles in Development:
- Developmental abnormalities of NT mouse embryos appear early after implantation
- Alice Jouneau, Qi Zhou, Anne Camus, Vincent Brochard, Linda Maulny, Jérôme Collignon, and Jean-Paul Renard
Development 2006 133: 1597-1607.
[Abstract]
[Full Text]
