A Scalable, Point-Of-Care, Microfluidic Approach For Assessing Thrombosis And Hemostasis
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 manual assembly using poly(dimethylsiloxane) (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 internally consistent and repeatable measurements of platelet and fibrin fluorescence intensity in clots forming under venous shear rate, using a bench-top LED microscope, and physiologically representative constant-pressure driven flow. We also demonstrate the ability to detect a strong, dose-dependent reduction in the fibrin fluorescence intensity signal in response to in vitro spiking of direct oral anticoagulants (DOACs). Further, we showed the ability to reverse this inhibition, through the addition of small quantities of drug reversal agents. In a separate study, the presence of DOACs in the blood of patients on the medications was clearly detected. Utilizing the previously obtained data from in vitro spiking, the relative response of DOAC patient blood with and without reversal agent was used to generate a quantitative prediction for the current concentration of drug in their system. The field of coagulation testing has lacked a definitive candidate for a fast, reliable means of accurately assessing patient anticoagulation status. Taken together, the ability to both identify the presence and predict the quantity of DOAC 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.