| Interactions of transplantable cells with synthetic polymers might influence the function of biohybrid artificial organs. This study explored growth and secretion of human insulin by transgenic βG I/17 insulinoma cells cultured on surfaces bearing diamine groups (N2), trifluoropropyl groups (F3), and mixtures of the two. Glass and untreated polystyrene served as controls. Composition of N2-F3 surfaces was controlled by the ratio of monomers in the silanization bath, as confirmed by electron spectroscopy for chemical analysis and by conjugation of surface amines with fluorescein-5-isothiocyanate. Atomic-force microscopy revealed that silanized surfaces were patchy, though their root-mean-square roughnesses did not differ significantly from that of smooth glass (0.3 nm). Surfaces richest in trifluoropropyl residues were the most hydrophobic, with advancing water-contact angles ≥90°. Cells cultured on pure F3 and pure N2 surfaces spread well, grew rapidly, and produced >1.8 moles lactate per mole glucose consumed, closely resembling cells grown on the permissive control, glass. On one mixed surface, 33 N2: 67 F3, cells had a lower lactate/glucose ratio, adopted a rounded form, grew slowly, and were quick to form emergent aggregates, similar to cultures on the inhibitory control, untreated polystyrene. Cultures on F3-rich surfaces secreted the most insulin, and, in the case of the pure F3 surface, showed improved responsiveness to secretagogues. F3 surfaces conditioned by βG I/17 cells stimulated insulin secretion by subsequent cultures. Incubation of conditioned surfaces with high concentrations of a polyclonal anti-laminin serum prior to re-plating partially abolished this improvement in secretory function. Together, these observations suggest that polymers bearing trifluoropropyl groups and coated with laminin might be attractive candidates for use in the artificial endocrine pancreas. |
