Fig. 1.

Stepwise protocol for the reprogramming of fibroblasts to human induced pluripotent stem cells (hiPSCs) using a single codon-optimized mini-intronic plasmid (CoMiP). Day of reprogramming represents the days at which the medium is changed. (a–d) Phase-contrast images of the five major stages of reprogramming demonstrating the progression from the fibroblast morphology, through early hiPSC colonies and cells ready for picking, and cells at passage 1. (e) Immunofluorescent staining of CoMiP-derived hiPSCs for the common pluripotency markers SOX2 and TRA-1-60. (f–g) Two different strategies for reprogramming of fibroblasts: one approach uses continued culture in fibroblast medium (containing FBS) up until day 9 of reprogramming before switching to E8 medium, and a second approach uses a gradual transfer from fibroblast medium through chemically defined E7 medium (E8 without TGFβ1) to E8 medium