Quantitative Scanning Electron Microscopy (SEM) to Study the Adhesion and Spreading of Human Endothelial Cells to Surface-Modified Poly(Carbonate Urethane)s

The polymers currently in use as vascular prostheses are, in the native state, poor substrates for endothelial cell (EC) adhesion and growth. This has a negative effect on the success of pre-seeding regimes. One attempt to improve the polymer substrate is to covalently couple reactive molecules to the surface, which can be used as anchorage points for EC or serve as spacer molecule to couple biological signal molecules such as oligopeptides. We have used a digitized image analysis system coupled to a scanning electron microscope to study the adhesion and spreading of human venous EC to unmodified poly(carbonate urethane) (uPCU), hydroxyl- functionalized PCU (mPCU) and to mPCU surfaces with succinyl or adipoyl dichloride coupled to it. Although the uPCU did not promote EC growth over a 5 day period, the early (30 minutes) adhesion and spreading behaviour on this surface was comparable to that of some modified surfaces which gave good promotion of EC growth in the longer term studies. Adhesion, but not spreading data at 4 hours gave a good correlation with the longer term studies of EC growth on the polymer surfaces. This study not only presents new directions in polymer development for vascular grafts, but also indicates the dangers associated with using early cell adhesion behaviour as a parameter of bifunctionality of biomaterial surfaces