DAS graphene-based feeder-free culture system for human induced pluripotent stem cells

Graphene has been selected as a candidate for synthetic feeder-free culture substrate guiding human/mouse multipotent stem cell lineage specification, and culturing pluripotent stem cells in a number of studies. However, conventional graphene is not an ideal biomaterial to maintain the pluripotency of human pluripotent stem cells (hPSC) including hESCs/hiPSCs due to its intrinsic hydrophobicity and relatively flat surface topography. Here, we applied morphology-controlled nanocrystalline graphene (NG) coating onto the culture substrates via diffusion-associated synthesis (DAS) process and cultivated hPSCs. It is found that enhanced hydrophilicity and controlled surface roughness of DAS-NG enabled tight focal adhesion of hPSCs onto the DAS-NG coated culture substrate and retained pluripotency for over 2 weeks. It is also found hPSCs grown on DAS-NG shared comparable global gene expression profile with hPSCs grown on mouse embryonic fibroblast (MEF). Importantly, the similarities in cell adhesion gene expression between hPSCs grown on DAS-NG and hPSCs on MEF suggest DAS-NG may provide comparable physical cues with MEF for sustaining pluripotency. Taken together, our findings show a new reliable method for culturing hPSCs in feeder-free condition using DAS-graphene. Human iPSCs and human ESC H9 were seeded onto DAS-NG coated glass, ITO or QU, CVD-grown graphene coated glass, uncoated glass and mitomycin-C treated CF1. Human pluripotent stem cells seeded on each culture substrate were cultured in human embryonic stem cell medium composed of knockout DMEM (GIBCO-10829) supplemented with 20% knockout serum replacement (GIBCO-10828), 1mM L-glutamine, 1% penicillin/streptomycin (PAA-P11-010), 1% MEM-non essential amino acid (PAA-M11-003), 0.1mM beta-mercaptoethanol, and 5ng/ml human basic fibroblast growth factor. 4 samples were analyzed: [1] hESC-MEF, H9 human embryonic stem cells (hESCs) grown on mitomycin-C treated MEF, 1 replicate. [2] hiPSC_MEF, human induced pluripotent stem cells (hiPSCs) grown on mitomycin-C treated MEF, 1 replicate. [3] hiPSC-DAS/GL, human induced pluripotent stem cells (hiPSCs) grown on diffusion-associated synthesis nanocrystalline graphene (DAS-NG) coated glass, 1 replicate. [4] hiPSC-w/o DAS, human induced pluripotent stem cells (hiPSCs) grown on uncoated glass, 1 replicate.