The iPSC lines MR31 (derived from IMR90 fetal lung fibroblasts) and MMW2 (derived from adult mesenchymal stem cells from bone marrow) were derived as described [11]. At passages 10 and 15, cells were adapted to a completely humanized-base medium consisting of StemPro hESC medium with 20% human Knockout Serum Replacement (hKSR), 1× StemPro protein cocktail and 8 ng/ml of basic fibroblast growth factor (FGF2) on culture dishes coated with CellStart, a xeno-free defined substrate (all from Invitrogen, Carlsbad, CA http://www.invitrogen.com) [5]. Cells were split every 4–6 days using a cell scraper and karyotyped every 10 passages. hESC culture was obtained as described previously [5].
