Proliferation of endothelial cells on the plasma-treated segmented-polyurethane surface: attempt of construction of a small caliber hybrid vascular graft and antithrombogenicity.

To prepare a porous segmented-polyurethane (SPU) tube, a solution of SPU containing different concentrations of NaCl was coated on a glass rod and the coated SPU was immediately immersed in water. When the surface of the porous SPU, where bovine aortic endothelial cells are not normally capable of adhering and proliferating, was modified by plasma treatment, the proliferation of endothelial cells could be drastically improved. The cells proliferated confluently on the porous SPU surface prepared at low concentrations of NaCl below 10 g per 100 ml, but poorly on the porous surface prepared at high concentrations of NaCl. The construction of a hybrid vascular graft consisting of a porous SPU tube (2 mm in inner diameter, 5 cm in length) and endothelial cells was attempted. The cells cultured on the inner surface of the tube proliferated to confluency everywhere. From an in vitro antithrombogenic evaluation test, which involved the use of human blood, the present hybrid graft can be considered to provide an inert surface against thrombus formation and blood coagulation. Negligible changes in shape of human leukocytes in contact with bovine aortic endothelial cell surface occurred, suggesting that the bovine aortic endothelial cells used are immunologically less active against human blood.

Ion implantation into collagen-coated surfaces for the development of small diameter artificial grafts.

Ion implantation into collagen (Type I) coated inner surfaces of test tubes with a length of 50 mm and an inner diameter of 2 and 3 mm were performed to develop hybrid type small diameter artificial vascular grafts. To obtain information about the cellular response and chemical and physical structure of those collagen surfaces, several experiments such as platelets adhesion test, endothelial cell culture, analysis of amino acids and animal study were performed. He(+) ion implanted collagen coated specimen exhibited cell attachment and inhibit platelet adhesion. From these results, it was assumed that He(+) ions broke the ligands that correspond to platelet, and the ligands that correspond to endothelial cell adhesion still existed after ion implantation. It was suggested that platelets and cell attachment could be control individually by ion implantation into collagen.

Oxygen ion implantation at 20 to 2000 keV into polysulfone for improvement of endothelial cell adhesion.

The irradiation effects of oxygen on polysulfone have been investigated at energies of 20 keV, 150 keV and 2 MeV. The strong improvement of endothelial cell adhesion and proliferation is found on ion irradiated polysulfone at 20 keV. Such improvement is declined with increasing ion energy. The changes of surface color and free energy are strongly dependent on ion energy and dose. The formation of amorphous carbon phase is demonstrated by Raman spectroscopy and its degree is correspondent to the color changes observed. The formations of hydroxyl and carboxyl groups are confirmed by the attenuated total reflectance (ATR) FTIR spectroscopy. The depletions of heteroatoms are conjectured by detail analysis of X-ray photoelectron spectroscopy (XPS). Since no single one of these changes can be related directly to the improved adhesion and proliferation of endothelial cells on irradiated surface, we argue that the distribution of functional groups is crucial in promoting the adhesion of endothelial cells. Although the distribution cannot directly be detected at present, the irradiation effects were related to the results of TRIM simulation. The surface changes can be controlled by adjusting the size energy and dose of irradiating ion for the optimum morphology to cell adhesion.

Development of a biologically active Guglielmi detachable coil for the treatment of cerebral aneurysms. Part I: in vitro study.

BACKGROUND AND PURPOSE: Stronger cellular adhesion on the surface of endovascular devices promotes accelerated healing of aneurysms. The purpose of this in vitro study was to study the cellular interaction on the surface of bioactive Guglielmi detachable coils (GDCs) after using the surface-modification technology, ion implantation. METHODS: Polystyrene (PS) dishes and platinum plates were used to simulate a GDC surface. They were treated with either simple collagen coating or collagen coating followed with ion implantation. Bovine endothelial cells (2-2.5 x 10(4) cells in 1 mL) were suspended in medium supplemented with 10% fetal bovine serum on the PS dishes or platinum plates. Five days after cell seeding, the strength of cell adhesion was evaluated by trypsin treatment and flow shear stress. The cell detachment from the PS and platinum surfaces was observed microscopically. RESULTS: Five days after cell seeding, both simple collagen-coated surfaces and collagen-coated ion-implanted surfaces showed uniform endothelial proliferation. After trypsin treatment, or under flow shear stress, stronger cell adhesion against chemical and flow shear stress was observed on the ion-implanted collagen-coated surface. In contrast, the endothelial cells were detached easily from the non-ion-implanted collagen-coated surface. CONCLUSION: Ion implantation in combination with protein coating improves the strength of surface cell adhesion when exposed to flow shear stress and proteolytic enzymes. Strong endothelial cell adhesion is reported to be important to achieve earlier endothelialization across the neck of an embolized aneurysm with bioactive GDCs. This new technology may improve long-term anatomic outcome in cerebral aneurysms treated with GDCs.

Development of biologically active GDC for the treatment of cerebral aneurysms.

In Vitro Study: The surface of polystyrene dishes were treated either by: 1) collagen coating without ion implantation, or 2) collagen coating with ion implantation. Ne(+) implantation was performed on area 2 with fluences of 1 x 10(15) at an energy of 150 keV Bovine endothelial cells were cultured on the dishes and the resistance to detachment of cells was evalated with trypsin treatment. Experimental Aneurysm Study: GDCs were coated with either type I collagen, fibronectin, vitronectin, laminin or fibrinogen. Ion implantation was then performed on these protein-coated GDCs. 56 experimental aneurysms were constructed microsurgically in the bilateral common carotid arteries of 28 swine. The aneurysms were embolized with standard GDCs or with ion-implanted protein-coated GDCs. The animals were sacrificed at day 14 after coil placement. The aneurysmal orifice was observed microscopically. In vitro study showed that endothelial cell proliferation and strength of cell attachment were accerelated by ion implantation. On specimens examined 14 days post-embolization, greater fibrous tissue coverage at the neck of the aneurysm was observed macroscopically and microscopically with ion implanted GDCs, whereas only a fibrin-like thin layer covered the standard GDC surfaces. These in vitro and in vivo studied indicate that ion implantation combined with protein coating of GDCs improves cellular adhesion/proliferation. This technology may provide an improvement in clinical outcome of cerebral aneurysms.