Compartment Specific Mechanical Loading of Bi-Layered Osteochondral Micro-Tissues in a Joint-on-Chip System suggests routes for Osteoarthritis pathogenesis investigation

In this work we engineered an osteochondral unit (OCU) on-chip model where osteoarthritis (OA) phenotype is recapitulated through the application of hyper-physiological mechanical loading. After a functional and biological validation of the device, we aimed to better characterize the diversity of the human articular chondrocytes (hACs) population present in our in vitro model and identify subpopulations responsible for the pathological loading response. As a method, we applied single-cell RNA sequencing (scRNA-seq) to hACs from both on-chip single cultures and co-cultures with bone marrow derived mesenchymal stromal cells (bmMSCs), i.e. in osteochondral construct, and either exposed or not to cyclic mechanical loading. Single cell RNA-seq (scRNA-seq) was performed on hACs after 21 days of culture on-chip (i.e. 14 days of static maturation and 7 days of mechanical stimulation, with constructs cultured statically for 21 days used as controls). hACs were cultured either in a single culture (in cartilaginous constructs) or in a co-culture with bmMSCs (in osteochondral constructs). ***Submitter states that raw files are not provided due to data sensitivity***