Fig. 1. Microgroove substrates altered fibroblast morphology and improved iPSC generation.

a, Scanning electron micrograph (SEM) image of PDMS membranes with 10 μm groove width. All grooves were fabricated with a groove height of 3 μm. b, Top row shows phase contrast images of flat and grooved PMDS membranes with various width and spacing. Bottom row shows fibroblast morphology on various PDMS membranes. Images show fluorescence micrograph of the nucleus (DAPI, blue) and actin network (phalloidin, green) (scale bars, 100 μm). c, Reprogramming protocol. Colonies were subcultured and expanded or immunostained and quantified by day 12–14. d, Fluorescence micrograph shows the morphology of iPSC colonies generated on flat and grooved membranes (scale bar, 1mm). Groove dimensions were 10 μm width and spacing, denoted as “10 μm” in this and the rest of the figures. e, Reprogramming efficiency of fibroblasts transduced with OSKM and cultured on PDMS membranes with flat and grooved microtopography. The number of biological replicates, n, used for this experiment was equal to 6. Groove width and spacing were varied between 40, 20, and 10 μm. Differences of statistical significance were determined by a one-way analysis of variance (ANOVA), followed by a Tukey’s post-hoc test. * indicates significant difference (p<0.05) compared with the control flat surface. f, Reprogramming efficiency in fibroblasts transduced with OSK (n=4). * p<0.05 (two-tailed, unpaired t-test) compared with the control flat surface. g, Immunostaining of stable iPSC line expanded from colonies generated on 10 μm grooves. These cells express mESC-specific markers Oct4, Sox2, Nanog, and SSEA-1 (scale bar, 100 μm). h, The expanded iPSCs in g were transplanted into SCID mice to demonstrate the formation of teratomas in vivo (scale bar, 50 μm).