Researchers from ETH Zurich, the Friedrich Miescher Institute in Basel, and the Cantonal Hospital of Lucerne have successfully produced elastic ear cartilage in laboratory conditions using human cartilage cells. The engineered tissue demonstrated mechanical properties similar to natural cartilage and retained its shape and elasticity after six weeks when tested in animal models. The research builds on decades of work attempting to create replacement ears for patients who have lost them due to accidents or congenital conditions.
The development addresses a significant medical need, as microtia affects approximately four in every 10,000 children, causing congenital malformations of the outer ear. Current treatment involves reconstructing ears using the patient’s rib cartilage, a painful procedure that can cause scarring and often results in ears that are stiffer than natural ones. “We aren’t implanting soft tissue in the hope that it remains stable in the body. Instead, we want to achieve that stability in the laboratory,” says Philipp Fisch, lead author of the study published in Advanced Function Materials.
The researchers extracted cells from small cartilage samples removed during ear-shaping operations, then grew millions of cells in nutrient solutions before embedding them in bioink for 3D printing. After printing ear structures, the tissue underwent several weeks of maturation in laboratory incubators to promote the formation of type II collagen and other components found in natural ear cartilage. The team optimized four key factors: cell proliferation, material properties, cell density, and maturation environment control.
Despite the progress, researchers acknowledge that elastin production remains a significant challenge. This protein provides ears with their flexibility, but scientists have not yet determined the precise biological process needed to create stable elastin networks. “Despite this major success, elastin remains a challenge for us, as we were not able to mature it fully,” Fisch explained. The team hopes to solve this problem within the next five years before moving to clinical trials and regulatory approval processes.
Credit: ETH Zurich
