| Description |
Platelet-surface interactions are a key mediator in a host's response to vascular biomaterials. Directly after implantation, a wide variety of serum proteins are adsorbed onto the surface of vascular devices, many of which activate platelets. Serving as the first step in the coagulation cascade, the local activation of platelets sets off a chain of events that can ultimately determine the fate of implanted vascular devices. Many material engineering approaches have been taken in an effort to reduce this activation; however, the most successful method to date remains the systemic delivery of antiplatelet and anticoagulant agents. The prevalence of antiplatelet pharmaceutics, coupled with a variation in efficacy across a diverse population, has led to an industry focused on the personalized assessment of platelet function. In this dissertation, methods were developed to address a deficiency in the current approach to platelet function testing. No current assays take into account the transient interactions of platelets with agonist surfaces, interactions that have the capability to prime a platelet population for enhanced adhesion and activation downstream of a stimulus. This phenomenon was leveraged here to create a flow cell in which the upstream priming of a platelet population by a surface-bound agonist could be assessed by downstream capture assay. It was demonstrated that this device is capable of determining the response of a platelet population to a variable priming stimulus, both alone and in the presence of common antiplatelet agents. To further investigate the priming response of platelets, it was of interest to develop a method by which to pattern multiple proteins on the same surface, thus enabling the measurement of the platelet population response to multiple surface bound agonists. Taking advantage of advances in microcontact printing and modern light microscopy, a new method by which to deposit multiple aligned patterns of agonists on a single substrate was developed. This patterning method was then used to investigate the ability of multiple agonists to prime platelets in flowing blood and observe the synergistic response that platelets exhibit when primed by multiple pathways. Taken collectively, these experiments contribute to the field of platelet activation by providing a controlled environment in which to study the priming response of platelets following transient exposure to surface bound agonists. This assay provides a platform in which the platelet response to a variety of surface coatings, biomaterials, and antiplatelet agents can be explored, and establishes a foundation for the further investigation of priming pathways in platelets. |
