Exosome Cell Origin Affects Markers of Tendon Repair in Ovine Macrophages and Tenocytes.

Tendon injuries and disease are resistant to surgical repair; thus, adjunct therapies are widely investigated, especially mesenchymal stromal cells (MSCs) and, more recently, their extracellular vesicles (MSCdEVs), for example, exosomes. Thought to act on resident and infiltrating immune cells, the role of MSCdEVs in paracrine signaling is of great interest. This study investigated how MSCdEVs differ from analogs derived from resident (tenocyte) populations (TdEV).

Biomechanical and histological changes secondary to aging in the human rotator cuff: A preliminary analysis.

The high failure rate of rotator cuff repair surgeries is positively correlated with age, yet the biomechanical changes to the tendons of the rotator cuff with age have not been described. As such, we sought to benchmark and characterize the biomechanical and histopathological properties with the accompanying gene expression of human rotator cuff tendons as a function of age and histopathological degeneration. All four rotator cuff tendons from fresh human cadaver shoulders underwent biomechanical, histopathological, and gene expression analyses.

Tendon midsubstance trauma as a means for the development of translatable chronic rotator cuff degeneration in an ovine model.

Background: Chronic degeneration of rotator cuff tendons is a major contributing factor to the unacceptably high prevalence of rotator cuff repair surgery failures. The etiology of chronic rotator cuff degeneration is not well understood, and current therapies are not effective, necessitating preclinical research to fill this knowledge gap. Unfortunately, current large animal models rely on enthesis disruption as a means of model generation, which is not representative of human patients with chronic rotator cuff degeneration prior to full-thickness tears.

Enthesis trauma as a means for the development of translatable chronic rotator cuff degeneration in an ovine model.

Background: Untreated rotator cuff tears lead to irreversible tendon degeneration, resulting in unacceptable repair prognosis. The inability of current animal models of degenerated rotator cuff tendons to more fully emulate the manifestation and degree of pathology seen in humans with a previously torn rotator cuff tendon (s) significantly impairs the development of novel therapeutics. Therefore, the objective of this study was to develop a large-animal translational model of enthesis damage to the rotator cuff tendons to mimic the chronic degenerative changes that occur in patients that demonstrate clinical manifestations of tendinopathy.

Partial Infraspinatus Tendon Transection as a Means for the Development of a Translational Ovine Chronic Rotator Cuff Disease Model.

Objective:  Rotator cuff tendon tears are the most common soft tissue injuries in the shoulder joint. Various animal models have been described for this condition, but all current translational animal models have inherent weaknesses in their ability to generate chronically degenerated rotator cuff tendons. The objective of this study was to evaluate a partial infraspinatus tendon transection model as a means of creating a chronically degenerated rotator cuff tendon in an ovine model and compare the injury characteristics of this model to those observed in human patients with severe chronic rotator cuff tendon injuries.