Microfluidic Device Automatically Monitors Whole Blood Hemostasis

An assay has been devised for testing blood's clotting tendency, also known as hemostasis, which could one day prove lifesaving in a variety of clinical situations in which a patient's health is jeopardized by abnormal blood coagulation and platelet function.

The microfluidic based device assay can be used with blood samples or potentially be integrated into patients' blood flow lines; so that one day clinicians could have the foresight they need to prevent life-threatening events such as blood clotting or internal hemorrhaging.

Scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University (Boston, MA, USA) devised a microfluidic device that mimics a network of stenosed arteriolar vessels, permitting evaluation of blood clotting within small sample volumes under pathophysiological flow. By applying a clotting time analysis based on a phenomenological mathematical model of thrombus formation, coagulation and platelet function can be accurately measured in vitro in patient blood samples.

The devices were designed to fit on a standard (75 × 50 mm) microscope slide to simplify microscopic analysis using appropriate software and they used SU8 2075 master templates (MicroChem Corporation; Newton, MA, USA) fabricated on Si (100) wafers using photolithography. The devices were fabricated using soft lithography of polydimethylsiloxane (PDMS). The device contains hollow channels that mimic the pathology of the narrowing of small blood vessels, which occurs in patients as a side effect of medical conditions or treatments and can often cause a shift in the fluid mechanics of blood flow that can lead to life-threatening blood clots or internal bleeds.

In a large animal study already conducted, the team perfused blood directly from a living vessel into a microfluidic device to measure clinical clotting parameters over time, and they recorded precise predictions for clotting times for blood samples that were far more accurate and faster than currently-used clinical assays. The real-time monitoring ability of the device could also assess patients' coagulation status almost continuously, in stark contrast to today's standard of once or twice a day testing procedures, thereby reducing the likelihood of toxic side effects resulting from anticoagulation therapies. The team also demonstrated that the device can detect abnormal platelet function in patients with a rare bleeding disorder that cannot be easily identified using conventional assays.

Abhishek Jain, PhD, a postdoctoral fellow and lead author of the study, said, “The physics of what's happening inside our bodies is a major contributor to the reasons why blood clots form or why clotting fails during surgeries, traumas, or extracorporeal medical procedures. By mimicking the physics of blood clotting in our device more precisely, we hope this technology can one day be used to save lives.” The study was published on January 6, 2016, in the journal Nature Communications.

Related Links:
Wyss Institute for Biologically Inspired Engineering 
MicroChem Corporation