Cook designs long-term artificial lungs

Associate professor of biomedical engineering Keith Cook explains the need for artificial lungs. (credit: Abhinav Gautam/) Associate professor of biomedical engineering Keith Cook explains the need for artificial lungs. (credit: Abhinav Gautam/)

The production of useful artificial organs has long been a goal in the field of medical science, but it has not been achieved due to many restraints with current technology.
Keith Cook, an associate professor of biomedical engineering, recently received a four-year, $2.4 million grant from the National Institutes of Health (NIH) to study new technologies to develop artificial lungs that can be used for months at a time.

“Millions of people suffer from chronic lung disease,” Cook said. Unfortunately, there is a disparity between the number of people who need lung transplants and the number of lung donors. Additionally, patients are currently required to stay at the hospital to receive proper support. In this kind of situation, patients also need to find a donor quickly, or they risk further harm, and possibly death. This stark difference between supply and demand drives a very real need for artificial lungs. In his research, Cook looks at patients that ultimately might not receive lung transplants, as well as those who are too sick to get transplants and need some stabilization in order to receive them.

Cook’s planned artificial lung would help alleviate these problems by allowing those patients to rely on a device that would not clot for over three months, which could have applications for not only artificial lung devices but any device that uses blood.

In addition, he hopes to integrate these devices into patients’ homes, which would allow patients to avoid spending their time in a hospital ward while still receiving all the care they require. Patients would have little work, while the physicians or biomedical engineers could monitor the patient and intercede when the device nears failure. Cook estimated that the lungs could be used in hospitals in five to 10 years.

There are some working artificial lungs available now, but they prove useful for a month at most. One method currently used in hospitals involves extracorporeal membrane oxygenation (ECMO). In this process, a machine functions as an artificial lung by infusing oxygen into the blood, removing carbon dioxide, and returning the blood to the patient. However, this process is expensive and intensive. In order for the standard gas exchange to occur, a polypropylene membrane is used. The walls of the fibers are porous, allowing blood plasma to leak into the gas side or bubbles from the gas side to leak into the blood stream. Plasma leakage can destroy the gas exchange function of the lung, and air leakage can cause death in the patient.

A solid fiber such as polydimethylsiloxane (PDMS) eliminates plasma and gas leakage. However, the long-term function of these fibers is unknown. Because both of these materials provide advantages and problems that need to be overcome, Cook is currently working with both types to try to create a membrane that could last longer. For example, coating the polypropylene with PDMS may prove useful. However, neither of the methods are currently ready.

In a human body, endothelial cells keep the blood from coagulating. However, other materials run into many problems due to the lack of vascular endothelial cell linings in foreign materials. Although researchers have been attempting to create endothelial linings, it has been extremely difficult to do so. As a result, “people control or learn to live with it,” Cook said.

He explained that people largely deal with anticoagulants, which are drugs that slow down the blood clotting process, although this creates concerns such as making sure the patient doesn’t bleed more than usual. Because the endothelial cells have many complex properties, Cook is trying to mimic these properties one at a time. Cook believes that mimicking their properties may lead to better materials for the artificial lungs, and eliminate the challenge inherent in working with endothelial cells themselves.

As more work is done on the artificial lungs, Cook believes it will become a viable device for people with chronic lung disease and other lung problems. With Cook’s designs for the device, he hopes to increase the longevity of the device by decreasing coagulation on the foreign materials and using materials that would allow for successful lung function.