*ttps://ipscell.com/2014/02/are-stap-stem-cell-nature-papers-compromised/
Nimorula
February 25, 2014 at 7:19 pm .
In the paper “Bidirectional developmental potential…” besides the duplicated image in figures 1 and 2 there are things really hard to believe about the data they show in figure 1. First they should have done the analysis in chimaeric embryos previous to the chrorio-allantoic fusion (embryos before 6 somites, around E8) to conclude that only STAPs and not ES cells contribute to the placenta. Developing my point: After the allantois (derived from the embryonic mesoderm) fuses with the chorion (extraembryonic) the formation of the labyrinthine placenta occurs. In this, the trophoblast (extraembryonic) associates with the fetal blood vessels (embryonic) that have extensive villous branching. Then in an E12.5 placenta from a chimaera formed from a wildtype blastocyst injected with wildtype reporter Rosa26-GFP or CAG-GFP ES cells you should always find GFP positive cells in the placenta due to the contribution of the fetal blood vessels. Then is not possible that in the control chimaeras in figure 1a they didn’t find Rosa26-GFP cells (as stated in the text) / CAG-GFP (as stated in the figure). The same applies for the fetal membranes, the yolk sac mesoderm is derived from the embryo then in a chimaera you always have ES-derived cells (mesoderm) in the yolk sac. There is no way that control is real. Mild: the long exposure panel of the control embryo was not overexposed since the little piece of embryo in the far right of the panel is not overexposed.
nimorula
February 26, 2014 at 2:21 pm .
p.s. A nice example of chimaeric embryos analysing the contribution of ES cell derived tissue to the placenta in E12.5 embryos can be found in PNAS USA 100(26):15637-15642. (2003) see figure 4.
