STAP stem-cell conversion culture. For establishment of STAP stem-cell lines, STAP cell clusters were transferred to ACTH-containing medium36 on MEF feeder cells (several clusters, up to a dozen clusters, per well of 96-well plates). Four to seven days later, the cells were subjected to the first passage using a conventional trypsin method, and suspended cells were plated in ES maintain medium containing 20% FBS. Subsequent passaging was performed at a split ratio of 1:10 every second day before they reached subconfluency.
For clonal analysis of STAP stem cells, single STAP stem cells were manually picked by a thin-glass pipette, and plated into 96-well plates at one cell per well. The clonal colonies were cultured in ES medium containing 20% FBS, and expanded for subsequent experiments.
We next examined whether an alteration in culture conditions could induce in vitro conversion of STAP cells into cells similar to trophoblast stem cells 8,9, which can be derived from blastocysts during prolonged adhesion culture in the presence of Fgf4.
When we cultured STAP cell clusters under similar conditions (Fig. 2a; one cluster per well in a 96-well plate), flat cell colonies grew out by days 7–10 (Fig. 2b, left; typically in ,30% of wells). The Fgf4-induced cells strongly expressed the trophoblast marker proteins9–12 integrin a7 (Itga7) and eomesodermin (Eomes) (Fig. 2c, d) and marker genes (for example, Cdx2; Fig. 2e).
These Fgf4-induced cells with trophoblast marker expression could be expanded efficiently in the presence of Fgf4 by passaging for more than 30 passages with trypsin digestion every third day. Hereafter, these proliferative cells induced from STAP cells by Fgf4 treatment are referred to as Fgf4-induced stem cells. This type of derivation into trophoblast-stem-like cells is not common with ES cells (unless genetically manipulated)13 or STAP stem cells.
いづれにしろ、STAP細胞にESが混入した可能性と、故意の混入ねつ造行為は、関連づけられた事実ではないのです。 しかし、桂報告書30ページのせいで、以下の記載が書けたのです。 the mixup was probably not accidental. その前の、桂報告書には、何ページにもわたり複数個所で、幹細胞作製時にESが混じった可能性を指摘しているのです。
Haruko Obokata From Wikipedia Obokata announced her resignation from Riken in December 2014. ] In a year-end final report on the scandal, Riken concluded that she had indeed ‘falsified and fabricated data, that her so-called Stap cells were actually embryonic stem cells, and that the mixup was probably not accidental.’ Although Riken cleared her senior co-authors of ethics violations, it did criticize them severely for a failure to oversee her work sufficiently. Riken also ; however, it gave them a brutal drubbing for not properly checking her work. Riken also ‘promptly set about overhauling the CDB from top to bottom, stripping away half of its 500-odd staff, renaming it and installing a new management team.’