We then tested differentiation into osteoblasts, a mesenchymal lineage that can be derived from fibroblasts1718. By alizarin red staining, a marker of osteogenic cells19, F-iPSC produced more sharply defined osteogenic colonies (Fig. 2b), deposited more elemental calcium (Fig. 2c), and showed higher expression of three osteoblast-associated genes (Fig. 2d) than B-iPSC. By these criteria, F-iPSC show enhanced osteogenic potential, reflecting a propensity to differentiate towards a mesenchymal lineage. In contrast, ntESC cells behaved comparably to fESC in hematopoietic and osteogenic assays.
