Modulating Inflammation in an Engineered Ligament Model

Musculoskeletal injuries account for the highest percent of time away from work and affect over 100 million people in the United States [1,2]. Ligament and tendon injuries account for approximately 50% of all musculoskeletal injuries [3]. Despite the prevalence of these injuries, current tendon and ligament research is lacking, with little advancement in the treatment of tendinopathies for decades. Tendinopathy describes an injured or diseased tendon/ligament. Underneath this umbrella term, tendinitis is used to describe an injured tendon/ligament that has signs of inflammation. There are many molecular pathways which have been explored in great lengths in muscle and bone; however, the same signals in tendon/ligament have significantly less research devoted to them – including the pro-inflammatory pathways upregulated in tendinitis. In this dissertation, we characterize an engineered ligament model, determine the effects of pro-inflammatory cytokines on engineered ligaments, and explore possible interventions to treat tendinitis such as anti-inflammatories and isometric loading.The in vitro engineered ligament model used throughout this dissertation was first developed by the Baar lab group [4]. In order to further validate the use of this model, we characterized the effect of passage number on cell gene expression and ligament function, as well as the ligament development over time. Despite previous studies suggesting multiple passages of fibroblasts led to decreased gene expression of typical tenoblast markers, our results found that there was no significant change in gene expression across multiple passages. Furthermore, from passage 4 to passage 11 there was no observed change in mechanical function or matrix composition of engineered ligaments. These results validate the use of this in vitro engineered ligament model using both early and later passage cells. We then characterized the development of engineered ligaments over the course of 5 weeks. The results sh