Large, stratified, and mechanically functional human cartilage grown in vitro by mesenchymal condensation

The ability to regenerate functional cartilage from adult human mesenchymal stem cells would have tremendous clinical impact. Despite significant efforts, mechanically functional human cartilage has not been grown in vitro. We report engineering of functional human cartilage from mesenchymal stem cells, by mimicking the physiologic developmental process of mesenchymal cell condensation. Condensed mesenchymal bodies were induced to fuse and form mechanically functional cartilaginous tissue interfacing with bone, without using a scaffolding material. We demonstrate that this simple “biomimetic” approach can be used to generate centimeter-sized, anatomically shaped pieces of human cartilage with physiologic stratification and mechanical properties. Functional human cartilage grown from a patient’s own cells using this method could greatly accelerate the development of new therapeutic modalities for cartilage repair.