Bioresorbable coronary scaffolds, designed to avoid the risks associated with the long-term implantation of metal stents, once captured the attention of medtech giants like Abbott (NYSE:ABT) and Boston Scientific (NYSE:BSX).
But companies have since linked the use of these biodegradable polymer-based devices to a heightened risk of myocardial infarction and thrombosis, prompting Abbott to pull its Absorb product from the market and Boston Scientific to terminate its Renuvia scaffold development program last year.
Researchers at Massachusetts Institute of Technology wanted to understand why these stents failed. Funded by Boston Scientific and the National Institutes of Health, they explored the microscopic structure of bioresorbable scaffolds, on the hunt for any clues as to why the devices didn’t hold up in patients.
The team discovered that degradable stents, which are made from the same polymer used in dissolvable sutures, have a heterogeneous (meaning non-uniform) inner structure. When the device is inflated, the internal layer is disrupted and rendered susceptible to structural failure.
“Because the nonuniform degradation will cause certain locations to degrade faster, it will promote large deformations, potentially causing flow disruption,” lead author Pei-Jiang Wang told MIT News.
The researchers, whose work was published last month in the journal Proceedings of the National Academy of Sciences, recommended that companies explore alternative methods to stent development to avoid the microscopic flaws seen with current-gen bioresorbable devices.
The reason this problem evaded companies for so long, according to the research team, is that it takes a long time for the microscopic structural flaws to manifest into visible problems. The companies weren’t using the proper analytical tools to be able to see these tiny problems.
“People have been evaluating polymer materials as if they were metals, but metals and polymers don’t behave the same way,” MIT health sciences and technology professor Elazer Edelman said. “People were looking at the wrong metrics, they were looking at the wrong timescales and they didn’t have the right tools.”