Fig. 2

Characterization of diPSCs. a A phase-contrast image of diPSC colonies, which were generated and cultured for 15 passages. b diPSC colonies at passage 15 were immunostained with representative pluripotency markers (Tra1-81, Tra1-60, SSEA4, Sox2, and Oct4) and were also stained for alkaline phosphatase. c Quantitative real-time RT-PCR was performed to detect the levels of multiple undifferentiated cell markers, such as Oct4, Nanog, DNMT3B, Zic3, and Rex1. *P < 0.01 (n = 3). d The expression levels of the representative marker genes for the ectoderm (Sox1, Pax6), mesoderm (GATA2, Brachyury), and endoderm (AFP, Sox17) lineages were measured by quantitative real-time RT-PCR. e G-banding analysis of diPSC1 at passage 13. f Bisulfite sequencing analysis to examine the methylation pattern of the Oct4 and Nanog promoters in H9-hESCs, disc cells, and diPSC. g, h The scatter plots compare gene expression levels between disc cells and diPSC1 (g) and between H9-hESCs and diPSC1 (h). i Pair-wise Pearson’s correlation coefficients among gene expression profile data for H9-hESCs, diPSC1, and disc cells are shown (top). Hierarchical clustering of the global expression profiles of H9-hESCs, diPSC1, and disc cells is shown (bottom). j A heatmap of the expression of the disc cell and hESC-enriched genes from H9-hESCs, diPSCs (p11), and disc cells (p3) (left). The list of disc cell and hESC-enriched genes is shown in Additional file 4. In addition, a heatmap of the expression of chondrogenic and hESC-enriched genes is shown on the right. The list of disc cell and hESC-enriched genes is shown in Additional file 5. The genes shown in green represent upregulation of expression, whereas the genes in red represent downregulation. diPSC disc cell-derived induced pluripotent stem cell, EB embryoid body, hESC human embryonic stem cell, NPC neural precursor cell, RT-PCR reverse transcription-polymerase chain reaction