Tendon-like cellular and matrix maturation in scaffold-free three-dimensional tendon cell culture using mouse tendon cells

Tendons transmit mechanical forces between muscle and bone, and their biomechanical function requires high tensile strength, which is provided by highly organized collagen fibers. Tenocytes mainly drive tendon growth via extracellular matrix (ECM) production and organization. The biological mechanisms regulating tenocyte differentiation and morphological maturation have not been well established, partly due to the lack of a reliable in vitro system. Recent scaffold-free, cell-based tissue engineering approaches developed several unique in vitro tendon-like constructs. However, the application of these constructs is limited to the study of embryonic tendon development due to high cell density and immature matrix organization. In this study, we developed a scaffold-free, three-dimensional (3D) tendon culture system using mouse tendon cells and a differentially adherent growth channel. The 3D tendon constructs exhibited tissue maturation similar to the postnatal mouse tendon, including decreased cell density, increased thickness, and elongated cells between highly aligned extracellular matrix. The 3D tendon culture system is also feasible for genetic manipulation using adenovirus. Overall, the results suggest that the 3D tendon culture system using mouse tendon cells is a reliable in vitro system to study underlying biological mechanisms that regulate cellular and matrix maturation in postnatal tendon development. ### Competing Interest Statement The authors have declared no competing interest.