Microfiltration platform for continuous blood plasma protein extraction from whole blood during cardiac surgery

Abstract

This report describes the design, fabrication, and testing of a cross-flow filtration microdevice, for the continuous extraction of blood plasma from a circulating whole blood sample in a clinically relevant environment to assist in continuous monitoring of a patient’s inflammatory response during cardiac surgeries involving cardiopulmonary bypass (CPB) procedures (about 400 000 adult and 20 000 pediatric patients in the United States per year). The microfiltration system consists of a two-compartment mass exchanger with two aligned sets of PDMS microchannels, separated by a porous polycarbonate (PCTE) membrane. Using this microdevice, blood plasma has been continuously separated from blood cells in a real-time manner with no evidence of bio-fouling or cell lysis. The technology is designed to continuously extract plasma containing diagnostic plasma proteins such as complements and cytokines using a significantly smaller blood volume as compared to traditional blood collection techniques. The microfiltration device has been tested using a simulated CPB circulation loop primed with donor human blood, in a manner identical to a clinical surgical setup, to collect plasma fractions in order to study the effects of CPB system components and circulation on immune activation during extracorporeal circulatory support. The microdevice, with 200 nm membrane pore size, was connected to a simulated CPB circuit, and was able to continuously extract ~15% pure plasma volume (100% cell-free) with high sampling frequencies which could be analyzed directly following collection with no need to further centrifuge or modify the fraction. Less than 2.5 ml total plasma volume was collected over a 4 h sampling period (less than one Vacutainer blood collection tube volume). The results tracked cytokine concentrations collected from both the reservoir and filtrate samples which were comparable to those from direct blood draws, indicating very high protein recovery of the microdevice. Additionally, the cytokine concentration increased significantly compared to baseline values over the circulation time for all cytokines analyzed. The high plasma protein recovery (over 80%), no indication of hemolysis and low level of biofouling on the membrane surface during the experimental period (over 4 h) were all indications of effective and reliable device performance for future clinical applications. The simple and robust design and operation of these devices allow operation over a wide range of experimental flow conditions and blood hematocrit levels to allow surgeons and clinicians autonomous usage in a clinical environment to better understand the mechanisms of injury resulting from cardiac surgery, and allow early interventions in patients with excessive postoperative complications to improve surgical outcomes. Ultimately, monolithic integration of this microfiltration device with a continuous microimmunoassay would create an integrated microanalysis system for tracking inflammation biomarkers concentrations in patients for point-of-care diagnos...

Characterization of thermoplastic microfiltration chip for the separation of blood plasma from human blood

“…adhesive into the ring-shaped structure and the major aim was to prevent leakage during the filtration process. Compared to other microfluidic chips, [2][3][4][5][6][7][8][9][10][11][12][13][19][20][21] the onsite blood filtration could be realized with this device by inserting the tip of the plastic syringe into this device. The bonding technique, two-step injection and curing of UV adhesive, would ensure an efficient filtration process and no leakage would happen during the filtration process.…”

“…Microfluidic devices can even be integrated with other components toward a lab-on-a-chip (LOC). Blood analysis [2][3][4][5][6][7][8][9][10][11][12][13] involves separating blood plasma from whole human blood to prevent blood cells from affecting final assay results. The conventional approach for plasma separation involves fitting commercial centrifuge tubes with a filter to separate the blood plasma from the whole human blood; however, the centrifugal forces induced by high speed rotation are difficult to be realized on microfluidic platforms.…”

Microfluidic devices for stem cell analysis

“…11.28b) (Hosokawa et al ., 2010;Hur et al ., 2011;Mach et al ., 2011;Mohamed et al ., 2009;Tan et al ., 2009;Zheng et al ., 2007). Additionally, there are reports of microfl uidic devices that continuously monitor a patient's inflammatory response during cardiac surgery involving cardiopulmonary bypass (CPB) procedures (Aran et al ., 2011) and remove bacteria from human blood (Aran et al ., 2011;Mach and Di Carlo, 2010;Wu et al ., 2009b). The development of novel, microscale cell sorting strategies, such as microfl uidics-based cell sorters, have paved the way to a better understanding of cell biology.…”

An integrated dielectrophoresis-active hydrophoretic microchip for continuous particle filtration and separation

“…Therefore, the problem of jamming is avoided. Cross-flow filtration suffers from membrane fouling, which limits the device to one-single use due to the sterility issue in most biological applications 30,31 . The membrane-free property of our technique allows repetitive use, which is cost-effective for many applications.…”