Pericyte adhesion and growth onto polyhydroxymethylsiloxane surfaces nanostructured by plasma treatment and ion irradiation.

The study deals with the adhesion and proliferation of bovine retina pericytes onto surfaces of poly(hydroxymethylsiloxane) (PHMS) modified either by cold plasma or by low-energy ion beams. The surface treatment was able to convert the original polymer matrix into SiO2-like phases for O2-plasma or ion-mixed SiCxOy(Hz) phases for ion irradiation, respectively, with different modification levels of the surface free energy (SFE) and related surface wettability. Pericytes exhibited a negligible adhesion and proliferation onto untreated PHMS, an enhanced adhesion but not proliferation on plasma-treated PHMS, and great adhesion and proliferation to full confluence on ion-irradiated PHMS, as measured by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), quartz crystal microbalance, and optical microscopy. On the other hand, the adhesion and proliferation of GP8.39 endothelial cells (EC), which are strongly associated with pericytes in microvasculature, were very scarce onto both untreated and surface-modified PHMS. The surface-selective pericytal response was related to changes of physicochemical properties of PHMS film, from hydrophobic/neutral towards hydrophilic/negatively charged polymer layers, as well as to short- and long-time events of cell-surface interaction. We propose that surface properties can mediate and modulate cell-polymer matrix adhesion through the establishment of stereospecific chemical interactions and/or electrostatic repulsion, which can also explain the different behavior of pericytes compared to EC.