Towards the joint on a chip: A microfluidic osteochondral model

Osteoarthritis (OA) is the most prevalent musculoskeletal disease, but no pharmacological treatment is yet available. This lack in anti-OA drugs finds among its causes the inadequacy of present OA in vitro models. OA is a multi-factorial disease leading to pathological changes not only in the cartilage but also in the subchondral bone and in the calcified hypertrophic interzone interfacing these two tissues. Classic in vitro systems do not capture this complexity. Here, building on our recently developed microfluidic techniques [1,2], we established a 3D microsystem (Fig. 1a) capable of hosting two directly interfaced microtissues and suitable for induction of OA traits through chemical or mechanical stimulation. Specifically, we aimed at generating a cartilaginous layer in contact with a layer mimicking the hypertrophic interzone.