Samples were seeded with smooth vascular muscle cells (VSMCs) derived from rat aorta by an explantation method (passage 7). VSMCs were seeded with the density 17,000 cells/cm2 BMS-777607 into 3 ml of Dulbecco’s modified Eagle’s minimum essential medium (DMEM, Sigma) supplement with

10% fetal bovine serum (FBS, Sebak GmbH, Aidenbach, Germany). The cells were cultivated for 2, 4, and 6 days at 37°C in a humidified air atmosphere containing 5% CO2. On the 2nd, 4th, and 6th day after seeding, the cells were rinsed in phosphate buffered saline (PBS) and fixed for 1 h in 70% cold ethanol (−20°C). The samples used for analysis by randomly chosen field were stained for 40 min with a combination of fluorescent membrane dye Texas Red C2-maleimide (Molecular probes, Invitrogen, Carlsbad, CA, USA) and a nuclear dye Hoechst no 33342 (Sigma). The number, morphology, and distribution of cells on substrate surface were then evaluated on photographs taken under an Olympus I×51 microscope using an Olympus DP 70 digital camera (Olympus America Inc., Center Valley, PA, USA). The number of cells was determined using image analysis software NIS Elements (Nikon Instruments Inc., Melville, NY, USA). Results and discussion Physical Paclitaxel concentration and chemical properties Figure 1 represents the dependence of the WCA of pristine, plasma-treated, and subsequently grafted samples on the aging time (time from treatment). It is evident

that immediately after plasma treatment (1 h), WCA decreases sharply to the minimal value which means the increasing the surface wettability. This effect corresponds with oxidation of the surface layer caused by creation of new polar groups [19]. Further, WCA increases with the increasing aging time, which can be explained by the rearrangement of the newly created functional polar groups of the macromolecular chains into the polymer bulk [19]. The saturated value of WCA of plasma-treated HDPE is higher than value of pristine HDPE, while at PLLA it is near the value of pristine PLLA. The time needed for the stabilization of the surface layer (for aging of the polymer) is 144 h for HDPE and these 96 h for PLLA.

From Figure 1, it is evident that immediately after the protein grafting, the samples have higher values of WCA in comparison with only plasma-treated samples. The value of WCA of grafted HDPE increases for the first 120 h faster than values measured on grafted PLLA. After reaching this time, the WCA value of grafted HDPE is not significantly changed and remains significantly lower than pristine or aged treated HDPE. The WCA of grafted PLLA is stabilized after approximately 244 h on the value higher than that of pristine or treated PLLA. Figure 1 Dependence of WCA of pristine, plasma-treated and subsequently grafted polymers on the aging time. The presence of grafted protein on modified samples was proved using mass spectrometry.