Upregulation of Adhesion Molecules Sustains Matrix-Free Growth of Human Embryonic Stem Cells

Despite recent advances in culture techniques for undifferentiated human Embryonic Stem Cells (hESCs), further improvements are required to facilitate research and translation of these cells in clinical settings. We have previously derived hESC lines that can be cultured in their undifferentiated state on regular plastic culture dishes, without the need for feeder cells or other coating supports, denoted Matrix-Free Growth hESCs (MFG-hESCs). In this study, we further characterize and compare MFG-hESCs to hESCs in order to understand the molecular differences responsible for the unique ability of MFG-hESCs. Microarray analysis demonstrated that MFG-hESCs highly resemble feeder-cultured hESCs in global gene expression profile. Two identified groups of genes with differential expression were those encoding for ribosomal proteins and attachment proteins, such as the RGD (Arg-Gly-Asp)-associated proteins. Real-time PCR and flow cytometry corroborated the microarray results. Culture of MFG-hESCs in the presence of RGD peptides resulted in decreased attachment ability compared to cells cultured in the presence of RGES (Arg-Gly-Asp-Ser) peptides. This study demonstrates that MFG-hESC lines overexpress cell attachment proteins but retain the typical characteristics of undifferentiated feeder-cultured hESCs. The ability to culture high-quality pluripotent stem cells in feeder- and matrix-free conditions creates a new opportunities for their large-scale manufacturing for experimental research and translational applications.