Biofabrication of Spatially Organized Temporo-mandibular Fibrocartilage Assembloids

The combination of mesenchymal stem cell (MSC) spheroids and polymeric scaffolds has been actively explored for engineering organized hyaline cartilage; however, its application to other types of cartilage remains under-explored. The temporo-mandibular joint (TMJ) fibrocartilage is a stratified tissue whose recapitulation remains challenging. In this study, the shape and growth orientation of assembloids are controlled by seeding early mature human adipose-derived MSC spheroids into scaffolds with a dual architecture of micron-scale fibers. This results in flattened asymmetric tissues with a single-sided articular surface. The engineered fibrocartilage mimics the histotypical organization of native human condylar fibrocartilage, featuring a thick fibrous zone with flattened cells. A native-like distribution of glycosaminoglycans, type I and II collagens, aggrecan core protein, and fibronectin is observed. Collagen organization is also found to be similar to that of native human tissue, up to the fibril level. Zonal-dependent micromechanical properties are identified in both the engineered and native tissues, although lower mechanical properties are observed in the fibrous zone of the engineered tissue. This work provides further evidence that the combination of MSC spheroids and micron-sized fiber scaffolds is a versatile approach for engineering stratified cartilage and a promising strategy for engineering biomimetic fibrocartilage grafts for TMJ reconstruction.