Institute of Biomedical Systems developed antithrombogenic coating for heart pumps

The improvement of the Sputnik series circulatory assist devices, which was developed at MIET and implanted into more than 50 patients, has pushed scientists to do new research in related fields. It resulted in the development of high-quality coating based on collagen and carbon nanotubes and designed for implantable devices that control blood flow. The engineers also developed a special microfluidic chip that allows to study the properties of such coatings using a minimum amount of blood.

The main interested partner of the study was Sechenov University. The results of the study were published in the highly credible international journal Micromachines.

Scientists of the Institute of Biomedical Systems (BMS) at MIET and Sechenov University developed the first heart pump more than ten years ago; it was the first domestically produced circulatory assist device for the left ventricle of the heart. Such devices are implanted into patients who have end-stage heart failure, which often allows them to survive until their heart transplantation.

However, complications caused by implants continued to be a pressing problem, increased blood clotting (thrombosis) in particular, as it not only affects the long-term performance of the implant, but also threatens the life of the patient, since a clot detachment can cut off the blood supply to vital organs. Therefore, the development of stable and antithrombogenic coatings for heart pumps has become of particular social importance.

During the scientific study that began in 2018, scientists of the BMS Institute proposed a method for the layer-by-layer formation of hemocompatible nanocomposite coatings based on multi-walled and single-walled carbon nanotubes in a collagen matrix (you can find the academic paper here).

“We have recently started to use carbon nanoscale material for such purposes, but they have already proved to be an excellent basis for biocompatible functional coatings,” says Alexander Gerasimenko, head of the Nanotechnology Laboratory. “Collagen is an important structural and building protein for various tissues, and it is often used as component for tissue-engineered frameworks. It is known that collagen can provide anticoagulant effect, but at the moment there is almost no data regarding the antithrombogenic effect of collagen coating coming into contact with blood flow. Our study proves that collagen is a suitable candidate for the development of a coating that prevents thrombosis.”

To investigate the properties of the new coating the scientists developed a reusable microfluidic device that simulates the operation of a functioning circulatory assist device. The new device is based on a chip with microchannels, which can be used to test the resistance and thrombogenicity of the material using a minimum amount of blood, no more than 100 ml. For comparison, 4-5 liters of blood are usually consumed in a traditional device that simulates human circulatory system.

“The synergy of collagen and carbon nanotube nanostructure in our coating improved its physical properties – the coating is able to withstand blood flow's shear similar to real blood flow in circulatory assist devices,” explains Kristina Popovich, one of the key researchers in the project team, a master's student at MIET. “We recreated the same shear stress in the microfluidic device to conduct tests. It is known that the degree of thrombosis is highly dependent on this factor, which is why the microfluidic chip is designed to withstand high shear stresses without leakage. In addition, our device makes it possible to dispense with a large volume of pumped fluid and to conserve blood for numerous tests.”

Tests of the nanocomposite coating conducted with the new device have confirmed that it is a suitable candidate for cardiovascular implants. Scientists believe that in future both the coating and the method of testing might be used by both domestic implant manufacturers and manufacturers of blood purification systems and similar devices. The microfluidic device will be useful for simulating kidney, liver and other processes.

The scientists are planning to develop a number of microfluidic devices that simulate complex processes in circulatory assist devices with real-time detection of blood values, as well as presenting new compositions of long–lasting hemocompatible nanocoating.