Newer implantable devices are coated with thin films of bioactive molecules that tamp down on clots and inflammation and aid device integration, but even these devices eventually need replacing. “Not only do they have a finite reservoir of bioactive agents, but the surface components of the thin films also degrade or lose their effectiveness when exposed to the physiological environment over time,” said Dr. Elliot Chaikof, the lead author of the study, in a statement.
In a novel approach, the Harvard team caused mutations in the enzyme Staphylococcus aureus Sortase A, resulting in a laboratory-evolved enzyme, dubbed eSrtA, that catalyzes the linking and breaking apart of peptides, and whose catalytic function is about 120 times the function of the unaltered enzyme. Using a two-step process of removing and replacing bioactive coatings, eSrtA could quickly and repeatedly regenerate thin film in the presence of whole blood, said David Liu, a professor of chemistry and chemical biology at Harvard, in the statement.
While the findings highlight a way to considerably extend the lifetime of device coatings and therefore the lifetime of devices such as stents, ventricular assist devices and heart valves, many questions remain. Because eSrtA is a bacterial enzyme, more research needs to be done to figure out just how it would interact with the immune system. How often a coating would need to be regenerated and how long it would last are also unknown. Other attempts to develop a coating that would help such implants withstand extended periods of time in the body have not come to fruition.
“Many thousands of people depend on implantable devices with bioactive constituents for their health and well-being, so finding a strategy that will ensure the long-term efficacy of these devices is of paramount importance,” Chaikof said in the statement. “While this research is relatively early stage, it opens the door to a new way of approaching and addressing this clinical challenge.”
REFERENCE: Fierce Medical Devices; 14 APR 2016; Amirah Al Idrus