CBE PhD Dissertation Defense | A Scalable, Point-of-Care Microfluidic Approach for Assessing Thrombosis and Hemostasis

Abstract: 

Coagulation testing is an important diagnostic tool for the detection of excessive bleeding risk or obstructive clot formation (thrombosis), using blood samples from patients. Microfluidic flow devices have been well established to provide insights on the impacts of shear rate, drug action, and disease state on coagulation and platelet biology. The bulk of the microfluidic devices and assays used in the past have relied upon manufactured using polydimethyl siloxane (PDMS), a material and construction method not well suited to use in a clinical setting. This thesis describes the design and testing of a single-use, storage stable evolution of previous PDMS microfluidic designs, manufactured via injection molding and pressure-sensitive adhesive bonding. Using this device, we demonstrate the ability to make consistent and repeatable measurements of platelet and fibrin fluorescence intensity in a clot forming under venous shear rate, using a benchtop LED microscope and physiologically consistent constant-pressure driven flow. We also demonstrate the ability to detect a strong, dose-dependent inhibition in the fibrin fluorescence intensity signal to in vitro spiking of direct oral anticoagulants (DOACs). Further, we showed the ability to reverse this inhibition, through small quantities of reversal agents to the anticoagulant drugs. In addition, the presence of the direct oral anticoagulants in the blood of patients on the medications was clearly detected as well. By comparing the response of a DOAC patient’s blood to reversal agent with the dose response established via spiking of healthy blood, quantitation of the current level of DOAC present in the patient’s blood was demonstrated as well. The field of coagulation testing has lacked a fast, reliable means of accurately assessing patient anticoagulation status. Taken together, the ability to identify the presence of and quantitate the amount of DOAC present in a patient’s blood using a single-use microfluidic chip approach as described in this thesis represents a potential promising new direction for coagulation testing at the bed-side.