Balgrist University Hospital, University of Zurich 1 article published in JoVE Bioengineering Engineering Tendon Assembloids to Probe Cellular Crosstalk in Disease and Repair Tino Stauber1,2, Maja Wolleb1,2, Jess G. Snedeker1,2 1Department of Orthopedics, Balgrist, University Hospital Zurich, University of Zurich, 2Department of Health Sciences and Technology, Institute for Biomechanics, ETH Zurich Here, we present an assembloid model system to mimic tendon cellular crosstalk between the load-bearing tendon core tissue and an extrinsic compartment containing cell populations activated by disease and injury. As an important use case, we demonstrate how the system can be deployed to probe disease-relevant activation of extrinsic endothelial cells.