Modification of human platelet adhesion on biomaterial surfaces by protein preadsorption under static and flow conditions (original) (raw)
Related papers
Proteins, platelets, and blood coagulation at biomaterial interfaces
Blood coagulation and platelet adhesion remain major impediments to the use of biomaterials in implantable medical devices. There is still significant controversy and question in the field regarding the role that surfaces play in this process. This manuscript addresses this topic area and reports on state of the art in the field. Particular emphasis is placed on the subject of surface engineering and surface measurements that allow for control and observation of surface-mediated biological responses in blood and test solutions. Appropriate use of surface texturing and chemical patterning methodologies allow for reduction of both blood coagulation and platelet adhesion, and new methods of surface interrogation at high resolution allow for measurement of the relevant biological factors.
Four plasma proteins have been shown to be able to mediate platelet adhesion to synthetic materials when they are adsorbed as purified proteins: fibrinogen (Fg), fibronectin (Fn), vitronectin (Vn), and von Willebrand factor (vWF). Among them, Fg is thought to play a leading role in mediating platelet adhesion to plasma-preadsorbed biomaterials, but this has been established for only three types of materials so far in our laboratory. Furthermore, the role of Fn, Vn, and vWF in mediating platelet adhesion to plasma-preadsorbed surfaces is still unclear. The aim of the current study was to assess the importance of Fg, Fn, Vn, and vWF in mediating platelet adhesion to a series of polystyrene based surfaces. The strategy applied in the present investigation was to compare platelet adhesion to surfaces preadsorbed with normal plasma, plasma selectively depleted in Fn or Vn or both Fn and Vn, plasma from donors who were genetically deficient in vWF, and serum. Few platelets adhered to the surfaces preadsorbed with serum, whereas depletion of Fn, Vn, or vWF from plasma did not decrease platelet adhesion significantly. Replenishment of exogenous Fg to serum before protein adsorption restored platelet adhesion to the surfaces, suggesting that Fg was the major plasma protein that mediated platelet adhesion. Also, we found that a surface density of adsorbed Fg far below the amount that usually adsorbs to synthetic surfaces was sufficient to support full-scale platelet adhesion.
Determination of blood compatibility is an important problem in blood contacting devices. In this study, two classes of materials including polyurethane (based on polyethylene glycol and poly tetrametylene oxide) and polyvinyl alcohol samples, with different hydrophilicity properties were synthesized and their physico-chemical properties were compared. Water uptake ratio, FTIR spectroscopy, and contact angle measurement were conducted. In vitro biocompatibility experiments were undertaken using L-929 fibroblast cell lines which demonstrated desired cell viability for all samples after 7 days. The adhesion of platelets from human plasma was studied by optical microscopy. Blood coagulation time were also determined which revealed polyurethane based poly tetramethylene oxide has better interaction by blood elements among all samples.
Procedure for quantification of platelet adhesion to biomaterials by radioscintigraphy
Thrombosis Research, 2004
Detection of adhered platelets on biomaterial surface that has blood-contacting application is an important test to assess its thrombogenicity. Usually, for measurement of platelet adhesion, after exposure to platelet-rich plasma (PRP) under standardized conditions the test surface is rinsed to remove non-adherent cells and is analyzed under scanning electron microscopy (SEM) to detect morphology of adhered cell and degree of aggregate formation. However, being a qualitative test it is unlikely to give an accurate estimate of platelets adhered to the surface. On the other hand, use of radiolabels enables quantification of platelets deposited on a material or device. Because of high gamma emission of 111 In, it can be used for radioscintigraphy, however, its short half life (2.5 days) is a major hurdle in using it for quantification of platelet adhesion. 125 I is a relatively strong radiolabel that is easily tagged to most of the proteins and has a relatively long half-life (60 days). The major objectives of this study are to standardize the labeling conditions to get good 125 I activity on platelets, while maintaining normal cell function after they are labeled. Considering all possible uncertainties, quantity of isotope and platelets to be used and the conditions of iodination reaction are established to get repeatable and reproducible labeling of platelets. Further, it is demonstrated that 125 I-platelets can be used to determine total number of cells adhered to titanium surface, which is known to be used as a blood-contacting biomaterial.
Journal of Biomedical Materials Research Part A, 2005
Ten specially synthesized polyurethanes (PUs) were used to investigate the effects of surface properties on platelet adhesion. Surface composition and hydrophilicity, fibrinogen (Fg) and von Willebrand's factor (vWf) adsorption, monoclonal anti-Fg binding, and platelet adhesion were measured. PUs preadsorbed with afibrinogenemic plasma or serum exhibited very low platelet adhesion, while adhesion after preadsorption with vWf deficient plasma was not reduced, showing that Fg is the key plasma protein mediating platelet adhesion under static conditions. Platelet adhesion to the ten PUs after plasma preadsorption varied greatly, but was only partially consistent with Fg adsorption. Thus, while very hydrophilic PU copolymers containing PEG that had ultralow Fg adsorption also had very low platelet adhesion, some of the more hydrophobic PUs had relatively high Fg adsorption but still exhibited lower platelet adhesion. To examine why some PUs with high Fg ad-sorption had lower platelet adhesion, three monoclonal antibodies (mAbs) that bind to sites in Fg thought to mediate platelet adhesion were used. The antibodies were: M1, specific to ␥-chain C-terminal; and R1 and R2, specific to RGD containing regions in the ␣-chain N-and C-terminal, respectively. Platelet adhesion was well correlated with M1 binding, but not with R1 or R2 binding. When these mAbs were incubated with plasma preadsorbed surfaces, they blocked adhesion to variable degrees. The ability of the R1 and R2 mAbs to partially block adhesion to adsorbed Fg suggests that RGD sites in the alpha chain may also be involved in mediating platelet adhesion and act synergistically with the C-terminal of the ␥-chain.
Journal of Biomedical Materials Research Part A, 2005
Previous studies showed that platelet adhesion to biomaterials from static suspensions was greatly increased by the adsorption of even very small amounts (Ͻ5 ng/cm 2 ) of fibrinogen (Fg). In this study, the sensitivity of platelet adhesion to Fg was reexamined by measuring platelet adhesion under flow conditions. The role of adsorbed von Willebrand's factor (vWf) was also studied. Polyethylene (PE) tubing was preadsorbed with Fg, vWf, vWf-deficient plasma, and Fg-deficient plasma or serum with added Fg, and Fg adsorption measured with 125 I Fg. Platelets in a red blood cell suspension were passed through the tubes at either low (50 s Ϫ1 ) or high (500 or 1000 s Ϫ1 ) shear rates and adhesion measured with an improved LDH assay. Adhesion from flowing suspensions measured after preadsorption with afibrinogenemic plasma or serum was very low, but increased greatly with addition of Fg. Less than 10 ng/cm 2 of adsorbed Fg was enough to greatly enhance platelet adhesion. Adhesion at high shear was also strongly affected by vWf, as platelet adhesion at 500 s Ϫ1 to PE preadsorbed with vWf-deficient plasma decreased by more than tenfold compared to adhesion at 50 s Ϫ1 , but platelet adhesion to PE preadsorbed with normal plasma increased about eightfold when shear rate was increased. The results show that very low amounts of adsorbed Fg are able to support platelet adhesion under shear flow. However, adsorbed vWf also appears to play an important cofactor role in platelet adhesion to biomaterials, as its presence greatly augments platelet adhesion under high shear.
Comparison of microscopic methods for evaluating platelet adhesion to biomaterial surfaces
Acta of bioengineering and biomechanics / Wrocław University of Technology, 2009
Microscopic methods usable for sample surface imaging and subsequent qualitative and quantitative evaluation of platelet adhesion to the surface of the biomaterial studied were compared. It was shown, making use of the samples of medical steel (AISI 316L), that such tools as surface imaging with scanning electron microscopy (SEM), glutaraldehyde induced fluorescence technique (GIFT) and metallurgical microscopy (MM) are equivalent in evaluating surface platelet adhesion. The importance of biological variability of blood samples for a proper result assessment and the necessity of using internal standards were also considered.
Protein/platelet interaction with an artificial surface: Effect of vitamins and platelet inhibitors
Thrombosis Research, 1986
Protein adsorption and platelet adhesion are two important biological processes arising at the blood-prosthetic interface. The effect of Vitamins and antiplatelet drugs to modulate the surface induced platelet adhesion to polycarbonate was investigated using washed calf platelets in presence and absence of fibrinogen. This study also dgnonstrated the effects of Vitamins and antiplatelet drugs towards protein adsorption to an artificial surface. It seems Vitamin B Vitamin E, combinations of Aspirin-Persantine, Asp&-Vitamin C, a synthetic Polyelectrolyte and Galactosamine reduced the fibrinogen (fg) surface concentration from a mixture of proteins. These antiplatelet agents also enhanced the albumin surface concentration. This itself may be one of the parameters to reduce the platelet adhesion towards an artificial surface. A combination of Aspirin-Vitamin C-Vitamin B -Vitamin E inhibited the fibrinogen surface binding, wh P ch might be beneficial to improve the blood canpatibility of an artificial surface.