Adhesion and proliferation of rat vascular smooth muscle cells (VSMC) on polyethylene implanted with O+ and C+ ions

Polyethylene was implanted with 30-keV oxygen (PE/O+) or 23-keV carbon ions (PE/C+) at 10(13) to 5 x 10(15) ions cm(-2) doses in order to improve the adhesion of vascular smooth muscle cell (VSMC) to the polymer surface in vi tro because of its oxidation and carbon-enrichment. The concentration of -C O- groups in the PE/O+ and PE/C+ samples increased only up to doses of 3 x 10(14) and 10(15) ions cm(-2), respectively, and then declined. At the same time, the concentration of these groups, measured at a dose of 3 x 10(14) ions cm(-2), was higher in PE/O+ than in PE/C+ samples. Similarly, the numb er of initially-adhering rat VSMC (24 h after seeding) increased only up to a dose of 3 x 10(13) and 10(15) ions cm(-2) on PE/O+ and PE/C+ samples, re spectively. In addition, between doses of 10(13) and 10(14) ions cm(-2), th is number was about two to three times higher on PE/O+ samples. On the othe r hand, the surface wettability increased proportionally to the implanted i on dose, especially above a dose of 10(14) ions cm(-2). Thus, the number of initially-adhered cells appeared to be positively correlated with the amou nt of the oxygen group present at the polymer surface rather than with the surface wettability. The higher cell adhesion was accompanied by adsorption of fluorescent dye-conjugated collagen IV in larger amounts. The highest n umbers of initial ly-adhered cells were usually associated with the lowest rates of subsequent proliferation (measured by the doubling time, BrdU labe lling and MTT reduction assay) and the largest cell volumes. These results indicate that: (1) implantation of O+ and C+ ions significantly improved in itial adhesion of VSMC to polyethylene, (2) this effect was more pronounced in O+ irradiated samples, especially at a dose of 3 x 10(13) ions cm(-2); and (3) the latter sample seemed to be most suitable for tissue engineering where high initial densities, low subsequent proliferation, and high diffe rentiation are desirable, e.g. for vascular prostheses.