Thromboresistance of alkali- and heat-treated titanium metal formed with apatite

Fibrin deposition and platelet adhesion onto alkali- and heat-treated titanium metal (AH-Ti), alkali- and water-treated titanium metal (Wa-Ti), and alkali- and heat-treated titanium metal formed with apatite (Ap-Ti) in simulated body fluid (SBF) were evaluated by exposure to anticoagulated blood or washed platelet suspension (WPS) under static conditions and subsequent observation with scanning electron microscopy (SEM). The results were compared with those for commercially pure titanium metal (cp-Ti). Thrombus formation on AH-Ti and Wa-Ti, which were exposed to heparinized whole blood for 1 h, was significantly less than that on cp-Ti, on which pronounced depositions of fibrin-erythrocytes and lymphocytes were observed. No thrombus was observed on Ap-Ti, possibly because of a high adsorption of heparin. Morphological change of platelets attached to surfaces via adsorbed plasma proteins was found to a significant extent on AH-Ti and Wa-Ti exposed to WPS. However, there was almost no difference between cp-Ti and Ap-Ti in round morphology of adherent platelets. These findings suggested that Ap-Ti exhibits stronger antithrombogenic characteristics than cp-Ti and other materials examined in heparinized blood.