A novel, open source, low-cost bioreactor for load-controlled cyclic loading of tendon explants

Abstract

A major risk factor for tendinopathy is tendon overuse (i.e., fatigue loading). Fatigue loading of tendon damages the extracellular matrix and induces tissue degeneration. However, the specific mechanisms linking tendon fatigue damage with tissue degeneration are unclear. While explant models of tendon fatigue loading have been used to address this knowledge gap, they predominantly employ bioreactors that apply cyclic displacements/strains rather than loads/stresses, which are more physiologically relevant. This is because of the technical complexity and cost of building a load-controlled bioreactor, which requires multiple motors, load cells, and computationally intensive feedback loops. Here, we present a novel, low-cost, load-controlled bioreactor that applies cyclic loading to multiple tendon explants by offloading weights from a single motorized stage. Using an optional load cell, we validated that the bioreactor can effectively provide load-controlled fatigue testing of mouse and rat tendon explants while maintaining tissue viability. Furthermore, all the design files, bill of materials, and operating software are available "open source" (https://github.com/Szczesnytendon/Bioreactor) so that anyone can easily manufacture and use the bioreactor for their own research. Therefore, this novel load-controlled bioreactor will enable researchers to study the mechanisms driving fatigue-induced tendon degeneration in a more physiologically relevant and cost-effective manner.

Dynamic Load Model Systems of Tendon Inflammation and Mechanobiology

“…Variations in crosssectional area lead to differential load distribution across samples when stretched to the same strain as well. An ex vivo bioreactor was designed for this issue specifically, where researchers could characterize the link between tendon explant fatigue loading with tendon degeneration using cyclic loads and stresses instead of strains (Pedaprolu and Szczesny, 2021).…”

“…Overall, few studies have focused on gliding tendons and the role that compressive and shear forces play in tendon pathologies Example ex vivo systems are commonly developed in-house with whole tendon clamping systems that can be uniaxially stretched under set strains or loads (Wang et al, 2015;Tohidnezhad et al, 2020;Pedaprolu and Szczesny, 2021). (B) Tenocyte cell culture monolayers (2D in vitro systems) under static load, or no load, and dynamic loads have the greatest high-throughput capabilities.…”