CELL BIOLOGY Correction for “Combined hydrogels that switch human pluripotent stem cells from self-renewal to differentiation,” by James E. Dixon, Disheet A. Shah, Catherine Rogers, Stephen Hall, Nicola Weston, Christopher D. J. Parmenter, Donal McNally, Chris Denning, and Kevin M. Shakesheff, which was first published March 27, 2014; 10.1073/pnas.1319685111 (Proc Natl Acad Sci USA 111:5580–5585).
The authors wish to note the following: “The corresponding authors were recently made aware of errors in Figs. 2 and S9 that required investigation. The journal editor was informed immediately and the University of Nottingham conducted an investigation into the cause(s) of the errors, their implications for the validity of the conclusions of the paper, and whether appropriate corrections could be submitted. This investigation was overseen by a member of the University Executive Board and was independent of the authors. The investigation concluded that the errors were caused by accidental mistakes in the preparation of the figures. The author who prepared the figures selected incorrect images from the data archive. By investigating the original data archives, it was concluded that (1) the correct images were available at the time of figure preparation, (2) the correct images were similar in key features of scientific relevance to the experiments, (3) the correct and original data was available to use or it was appropriate to remove that figure section, and (4) the university evaluated the matter and determined a correction was appropriate and should be submitted to the journal for peer review. Accordingly, we have replaced the image in Fig. 2B with the correct original image and removed the 2-hour data point from Fig. S9A.”
Fig. 2.
Switching HPSC self-renewal to differentiation. (A) Quantitative gene expression of pluripotency markers OCT4 and NANOG in HUES7 HESCs cultured in hydrogels (containing Matrigel and PVA) compared with those grown as conventional monolayers or as EBs (23). Relative expression levels for constructs over a 21-d period cultured in HPSC maintenance medium (CM). (Bars are SE; n = 6.) (B) Light microscopy of HUES7 HESCs cultured in composite hydrogels (containing Matrigel and PVA) with or without switching at day 0 (postcross-linking of hydrogel) cultured in CM or DIFF medium (23). HUES7 cells within unswitched hydrogels cultured in CM retained HESC morphology and proliferated to fill the gel volume, which was inhibited if cultured in DIFF medium. HUES7 cells in switched hydrogels, especially those cultured in DIFF medium, rapidly lost HESC morphology and proliferation. Images were taken at 14 d postcross-linking. (Bar: 50 µm.) (C and D) Quantitative gene expression analyses for the culture conditions described in B. OCT4 and NANOG (at day 14) (C) and T (at day 5; D, Left) and SOX17 (at day 14; D, Right) gene expression is shown. (Bars are SE; n = 6.)
Fig. S9.
Interaction of HPSCs and composite hydrogels with or without switching. (A) Switching hydrogel microenvironment alters the interaction of HUES7 HESCs to alginate/collagen hydrogels. HUES7 were seeded onto hydrogels, and the morphological character of cells was assessed (switching was carried out preseeding). After switching alginate/collagen hydrogels interact with HUES7 HESCs similarly to collagen-only gels (all hydrogels also contained Matrigel and PVA). (Bar: 50 μm.) (B) HPSC/hydrogel interaction influences cell roundness (p2 /[4πA]), perimeter (p), and area (a), which can be controlled by switching (n = 6).