Long-Term Maintenance of Human Pluripotent Stem Cells on cRGDfK-Presenting Synthetic Surfaces.

Synthetic human pluripotent stem cell (hPSC) culture surfaces with defined physical and chemical properties will facilitate improved research and therapeutic applications of hPSCs. In this study, synthetic surfaces for hPSC culture in E8 medium were produced for screening by modifying two polymer brush coatings [poly(acrylamide-co-acrylic acid) (PAAA) and poly(acrylamide-co-propargyl acrylamide) (PAPA)] to present single peptides. Adhesion of hPSC colonies was more consistently observed on surfaces modified with cRGDfK compared to surfaces modified with other peptide sequences tested. PAPA-coated polystyrene flasks with coupled cRGDfK (cRGDfK-PAPA) were then used for long-term studies of three hPSC lines (H9, hiPS-NHF1.3, Genea-02). Cell lines maintained for ten passages on cRGDfK-PAPA were assessed for colony morphology, proliferation rate, maintenance of OCT4 expression, cell viability at harvest, teratoma formation potential, and global gene expression as assessed by the PluriTest™ assay. cRGDfK-PAPA and control cultures maintained on Geltrex™ produced comparable results in most assays. No karyotypic abnormalities were detected in cultures maintained on cRGDfK-PAPA, while abnormalities were detected in cultures maintained on Geltrex™, StemAdhere™ or Synthemax™. This is the first report of long term maintenance of hPSC cultures on the scalable, stable, and cost-effective cRGDfK-PAPA coating.

New Monoclonal Antibodies to Defined Cell Surface Proteins on Human Pluripotent Stem Cells.

The study and application of human pluripotent stem cells (hPSCs) will be enhanced by the availability of well-characterized monoclonal antibodies (mAbs) detecting cell-surface epitopes. Here, we report generation of seven new mAbs that detect cell surface proteins present on live and fixed human ES cells (hESCs) and human iPS cells (hiPSCs), confirming our previous prediction that these proteins were present on the cell surface of hPSCs. The mAbs all show a high correlation with POU5F1 (OCT4) expression and other hPSC surface markers (TRA-160 and SSEA-4) in hPSC cultures and detect rare OCT4 positive cells in differentiated cell cultures. These mAbs are immunoreactive to cell surface protein epitopes on both primed and naive state hPSCs, providing useful research tools to investigate the cellular mechanisms underlying human pluripotency and states of cellular reprogramming. In addition, we report that subsets of the seven new mAbs are also immunoreactive to human bone marrow-derived mesenchymal stem cells (MSCs), normal human breast subsets and both normal and tumorigenic colorectal cell populations. The mAbs reported here should accelerate the investigation of the nature of pluripotency, and enable development of robust cell separation and tracing technologies to enrich or deplete for hPSCs and other human stem and somatic cell types. Stem Cells 2017;35:626-640.

Defining synthetic surfaces for human pluripotent stem cell culture.

Human pluripotent stem cells (hPSCs) are able to self-renew indefinitely and to differentiate into all adult cell types. hPSCs therefore show potential for application to drug screening, disease modelling and cellular therapies. In order to meet this potential, culture conditions must be developed that are consistent, defined, scalable, free of animal products and that facilitate stable self-renewal of hPSCs. Several culture surfaces have recently been reported to meet many of these criteria although none of them have been widely implemented by the stem cell community due to issues with validation, reliability and expense. Most hPSC culture surfaces have been derived from extracellular matrix proteins (ECMPs) and their cell adhesion molecule (CAM) binding motifs. Elucidating the CAM-mediated cell-surface interactions that are essential for the in vitro maintenance of pluripotency will facilitate the optimisation of hPSC culture surfaces. Reports indicate that hPSC cultures can be supported by cell-surface interactions through certain CAM subtypes but not by others. This review summarises the recent reports of defined surfaces for hPSC culture and focuses on the CAMs and ECMPs involved.