To create the degrading core, Karp's team recommended the use of an extra-stiff, biocompatible polymer that begins to erode on its surface following implantation. The polymer itself is made of components that already exist in the human body.

"By adjusting the polymer's composition, we can tune the core to degrade predictably over a pre-determined amount of time," says Karp, co-senior author on the study.


Based on the promising in vivo experimental data presented by del Nido and Karp's team, the biomedical device company CryoLife Inc., is already developing their concept into a growth-accommodating annuloplasty ring implant for pediatric heart valve repair.

"In combination with the braided sleeve exterior, this two-part implant concept could have many medical applications beyond the most obvious ones to enhance cardiac valve surgery in children," says del Nido.

The proprietary design of the braided sleeve developed by del Nido and Karp's team doesn't just share resemblance to a Chinese finger trap but also to an organic structure engineered by nature itself. "We solved this problem of growth accommodation with a concept that already exists in nature: the octopus has a special ability to stretch its arms into confined cracks and spaces between rocks, in search of its prey," says Yuhan Lee, PhD, co-first author on the study and a materials researcher at BWH. "It can do this because of unique, braid-like crossfibers of connective tissue that enable the simultaneous elongation and shrinking diameter of its arms, allowing it to extend its reach two to three times beyond the original arm length."

This type of elongating movement is also found in natural tissue structure of the mammalian intestines and esophagus. "This concept could be adapted for many different clinical applications, with exciting potential to be converted into an actively -- rather than a passively -- elongating structure that could act as a tissue scaffold encouraging growth," says Feins.

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