Structural Characterization of Scaffold-Free Tendons Constructs

Tendons are connective tissues that connect muscles to bones allowing for joint movement. Musculoskeletal injuries have become more prominent in the United States during the last years as they often occur in athletes and patients with moderate physical activity. Currently, tendon injuries are mostly treated by therapy or using another tendon source such as autologous or allogeneic grafts. The therapy treatment requires long periods of rehabilitation, and the success of the surgery is patient specific. Nevertheless, these replacements do not allow the tendons to regain its native properties. This concern generates a significant clinical interest in developing a tissue engineered tendon construct that can replicate the mechanical and biological structure of tendons. Previously developed engineered tissue replacements have proved to be unsuccessful because the traditional scaffold-based approach does not replicate the normal tendon development. In contrast, the scaffold-free approaches have succeeded to replicate early embryonic tendons. However, they fail to match the mechanical and structural properties of late embryonic tendons. A critical barrier stopping the development of tendon constructs is the lack of knowledge regarding the key mechanobiological mechanisms that influence the tendon maturation. This project aimed to establish a working lab protocol to build scaffold-free tendon constructs with the goal of characterizing the construct structural properties and compare them with a day fourteen chicken embryo tendon. For this, tendon constructs were formed using embryonic chicken tenocytes and relied on the cells’ own self-assembly properties. Then, the constructs were subjected to analysis of structural properties through the use of confocal microscopy to visualize the cells’ collagen deposition, alignment, and density. Approximately 72% of the tendon constructs exhibited high collagen alignment thus mimicking the 14-day chicken embryo showing a parallel organization along the direction of the long axis of construct. Consequently, scaffold-free tendons constructs were similar and comparable to the E-14 chicken embryo, suggesting an efficient lab protocol and practice. The outcomes from this study will be used to improve the in vitro maturation of tendon constructs through the activation of essential mechanotransduction signaling pathways, which play a crucial role in the development of embryonic tendons.