First-Ever Built Magnetically Driven Micropump Using 3D Technology for VAD and ECMO Studies in a Mouse Model

Objectives: Despite many advantages represented by a murine model as the possibility to use knock-out mice for cardiac or lung studies as well as the availability of an immense spectrum of reagents to perform sophisticated molecular investigations, our previous design has been still based on CPB circuit implementing a peristaltic pump to drive blood via silicon capillary tubing. Unlikely to the clinical data reported for ECMO, we have observed marked hemolysis proven in all relevant lab values. As priming volume (PV) of the CPB or ECMO circuit in our mouse model was restricted to 0.6 to 0.8 mL, the construction of a clinically relevant centrifugal pump on a minor scale represents a considerable challenge. The smallest magnetically driven hydraulic micro-pump, available on the market, is only designed for water or oil drainage and carries a priming volume > 5 mL. Such device is designed for industrial purpose only, and induces even greater hemolysis compared to standard peristaltic pumps of CPB. The aim of our study was to design a magnetically driven centrifugal micro-pump with a priming volume below 0.2 mL for our mouse model of extracorporeal circulation.

Methods: Using a combination of 3D print technology and self-customization of parts via plastic micro-molding, we have successfully constructed a prototype of a world’s smallest, fully magnetically driven centrifugal blood pump with a PV of 0.15 mL which has been incorporated in our murine ECMO circuit. The micro impeller has been made from ring-shaped 6 × 4 × 2 mm NdFeB micro-magnet covered with a biologically compatible silicone.

Results: In vitro testing of the mouse ECMO circuit using standard priming solutions (Sterofundin and Tetraspan 1:1) and heparinized blood showed significantly improved parameters suitable for mouse hemodynamics at 1,000 to 3,500 rpm mimicking those parameters monitored in patients treated with ECMO and VAD. The flow and pressure generated by our micropump could be easily adjusted using an external magnetic driving device.

Conclusion: Thus, using 3D print technology combined with plastic molding allowed minimizing a disparity in a hemodynamic behavior between our previous design and clinically used pumps for VAD and ECMO therapy. We believe that our innovative solution will strengthen the results of clinically relevant translational studies focusing on VAD, ECMO, and ECLS using diverse murine protocols. Next set of in vivo murine experiments investigating SIRS, organ damage, and coagulation disorders upon VAD/ECMO treatment will be presented in prospective studies.