Researchers at MIT have developed a biodegradable material that can act as a scaffold within which cardiac muscle can grow, potentially allowing for regenerative treatment of heart tissue damaged by infarcts or cardiomyopathy.
The scaffold has three principal advantages over its predecessors. First, its mechanical properties closely match those of native heart tissue. For example, it is stiffer when stretched circumferentially as compared to longitudinally.
Engelmayr found that he could essentially “dial in” specific mechanical properties for the polymer scaffold by varying the time it is allowed to set, or cure. He noted that with this ability, coupled with the flexibility of the laser technique, “we might be able to come up with even better pore shapes with better mechanical properties.”
In a second advantage, the team found that a patch of tissue created from neonatal rat heart cells cultured on the scaffold showed directionally dependent electrophysiological properties similar to native tissue. In other words, when an electrical field was applied the engineered patch contracted more readily in one direction than in another.
In a third advantage, “the scaffold itself has an intrinsic ability to guide the orientation of cultured heart cells,” Freed said (in 2004, Freed was part of another MIT team that showed that heart cells cultured on a traditional scaffold could also be coaxed into alignment, but only with electrical stimulation).
The researchers note that the scaffold used in the experiments described above has some limitations. For example, they write, it is “too thin to address reconstruction of full-thickness myocardium.” However, as they report in Nature Materials, they have already begun addressing those problems by creating new honeycomb scaffolds that, among other things, allow much thicker, multi-layered tissue structures.
Abstract: Accordion-like honeycombs for tissue engineering of cardiac anisotropy Nature Materials I doi:10.1038/nmat2316
Press release: Mending broken hearts with tissue engineering …
Image: Scanning electron micrograph of an accordion-like honeycomb scaffold for cardiac tissue engineering. Original magnification =100 X