Characterization of integrin engagement during defined human embryonic stem cell culture

Human embryonic stem (hES) cells are pluripotent, capable of differentiating into any cell type of the body, and therefore have the ability to provide insights into mechanisms of human development and disease, as well as to provide a potentially unlimited supply of cells for cell-based therapy and diagnostics. Knowledge of the adhesion receptors that hES cells employ to engage extracellular matrix (ECM) proteins is of basic biological interest and can enhance the design of cell culture and implantation systems to enable these biomedical applications. Although hES cells express a variety of cell surface receptors, little is known about which integrins are involved during subculture and passage. Matrigel is broadly used as a cell adhesive matrix for hES cell culture. Here, we sought to identify which integrins hES cells exploit for adhesion to Matrigel-coated surfaces in defined medium conditions. Using RT-PCR, flow cytometry, and fluorescence immunochemistry, we found that numerous integrins were expressed by H1 hES cells; however, antibody blocking assays indicated that only alpha(v)beta(3), alpha(6), beta(1), and alpha(2)beta(1) played a significant role in the initial adhesion of the hES cells to Matrigel in defined medium conditions. We subsequently identified a cohort of synthetic peptides that, when adsorbed to the culture surface, promoted H1 hES cell attachment and proliferation, as well as maintained a pluripotent phenotype. Peptides designed to engage with alpha(v)beta(3), alpha(6), beta(1), and alpha(2)beta(1) integrins and syndecan-1 were tested both individually and in various combinations. A combination of two integrin-engaging peptides (AG-10, C-16) and one syndecan-engaging peptide (AG-73) was sufficient to promote hES cell adhesion, maintenance, and proliferation. We propose that a specific integrin "fingerprint" is necessary for maintenance of hES cell self-renewal, and synthetic culture systems must capture this engagement profile for hES cells to remain undifferentiated.-Meng, Y., Eshghi, S., Li, Y. J., Schmidt, R., Schaffer, D. V., Healy, K. E. Characterization of integrin engagement during defined human embryonic stem cell culture.