Injury During Early Neonatal Development Leads to a Faster Repair Response When Compared to Later Injury in a Mouse Achilles Tendon

Abstract

During neonatal development, tendons undergo a well orchestrated process whereby extensive structural and compositional changes occur in synchrony to produce a normal tissue [1,2]. Similarly, during the repair response to injury, structural and compositional changes occur, but in this case, a mechanically inferior tendon is produced. As a result, the process of development has been postulated as a potential paradigm through which improved tissue healing may occur. By examining injury at distinctly different stages of development, we will obtain vital information into the structure-function relationships in tendon. Although the mouse is an intriguing model system due to the availability of assays and genetically altered animals, due to the small size and fragile nature of neonatal tendons, neonatal tendon injury has not been evaluated. Therefore, the objective of this study is to evaluate the differential healing response in neonatal tendon at two distinct stages of development. We hypothesized that when normalized, maximum stress and modulus will be significantly higher in early neonatal injury when compared to later neonatal injury. Also, when normalized, maximum stress, modulus and percent relaxation will be significantly increased over time in early neonatal injury but will remain low in later neonatal injury.