Adhesion of human peripheral blood lymphocytes is dependent on surface wettability and protein preadsorption.

The influence of surface wettability and preadsorption of plasma proteins on cell adhesion was studied using human peripheral blood lymphocytes (PBL). Hydrophilic glass and hydrophobic octadecyl glass were used as model surfaces with known wettability. The adhesion of PBL was investigated under non-flow conditions that are considered as a model for the adhesion of migrating lymphocytes in the tissue. Furthermore, adhering lymphocytes were exposed to increasing shear forces to investigate the detachment under laminar flow conditions to simulate the situation during blood flow. The proteins used in this study were attachment proteins such as fibrinogen, fibronectin and vitronectin. Human serum albumin was used as a control. It was found under both conditions (static and dynamic) that PBL adhesion was strongly influenced by the wettability of the surfaces. Furthermore, it was shown that the properties of the underlying surface influenced the interaction between preadsorbed attachment proteins and PBL.

Protein adsorption, lymphocyte adhesion and platelet adhesion/activation on polyurethane ureas is related to hard segment content and composition.

Segmented polyurethane ureas with different hard segment content and composition were synthesized using 4,4'-diphenylmethane diisocyanate and polytetramethylene glycols. Using polyols with different molecular weights, it was possible to synthesize polyurethane ureas with either: (i) a constant ratio of urethane to urea bonds; (ii) a constant urethane content; or (iii) a constant urea content. Bulk properties were assessed by dynamic mechanical analysis. Surface properties were estimated by contact angle measurements and streaming potential measurements. Haemocompatibility was evaluated in vitro by measuring the adsorption of human serum albumin (HSA) and fibrinogen (Fg), the adhesion of human peripheral blood lymphocytes (PBL), and the presence of activated platelets on the biomaterial surfaces. Enzyme immuno assays (EIA) have been specially developed for this purpose for the detection of antibody-recognizable plasma proteins and platelet surface membrane proteins. No simple correlation between chemical structure of the polymers and surface properties was found. Parameters of haemocompatibility correlated more closely with hard segment content and chemical composition than with the surface characteristics of the polymers. Adsorption of plasma proteins, adhesion of lymphocytes and the adhesion/activation of platelets were found to increase with increasing hard segment content of the polyurethane ureas. However, the monoclonal-antibody recognisable fibrinogen and the platelet activation were nearly constant with increasing hard segment content, if the urea content was kept constant.