In Vitro Biocompatibility Evaluation of Surface-modified Titanium Alloy

INTRODUCTION Ventricular Assist Devices (VADs) have become a means to both preserve and prolong the lives of patients with heart failure. By providing circulatory support, VADs lessen the load of the heart. Compared to traditional medical management of heart failure, VADs have a higher patient survival rate [1]. VADs are used as both a bridge to transport as well as form of destination therapy for patients requiring long-term or permanent circulatory support. While VADs do increase survival rate for heart failure patients, survival percentage of patients using this type of mechanical circulatory support for permanent or long-term support decreases significantly the longer the patient is reliant upon the device. In a study by Lietz K. et al., it was seen that the percent of patients still alive one-month post VAD implantation was 86.1%, but only 30.9% of patients with VADs were still alive twenty four months after implantation [2]. VADs do pose risks to patients since this implanted medical device can be thrombogenic. Blood cells in contact with the VAD can become activated, forming cell aggregates, which can lead to thrombosis, as well as other complications. To improve patient survival rates, many studies focus on improving the biocompatibility of the VAD material in contact with the blood. Platelet activation, since it is the initial step to thrombus formation is often used as a way to quantify material biocompatibility. A good indicator as to whether or not a material will cause the blood to clot, low platelet activation in blood samples corresponds to a biocompatible material. Material coatings or surface modifications have shown an increase in the biocompatibility of materials, as the coated materials display lower levels of platelet activation. A previous study was done by Ye et al. to assess the biocompatibility of a siloxane functionalized phosphorylcholine polymer coating. The study revealed the incorporation of the coating resulted in decreased platelet deposition on the coated titanium alloy surface as well as lower platelet activation levels than the unmodified titanium alloy. The results of this study suggests that an incorporation of a siloxane functionalized phosphorylcholine polymer coating onto a titanium alloy can improve the material’s biocompatibility [3].