Minimal mechanical load and tissue culture conditions preserve native cell phenotype and morphology in tendon—a novel ex vivo mouse explant model. Issue 5 (22nd November 2017)

• Record Type: Journal Article
• Authors: Wunderli, Stefania L.; Widmer, Jonas; Amrein, Niklaus; Foolen, Jasper; Silvan, Unai; Leupin, Olivier; Snedeker, Jess G.
• Is Part Of: Journal of orthopaedic research. Volume 36:Issue 5(2018)
• Page Start: 1383
• Page End: 1390
• Publication Date: 2017-11-22
• Subjects: tendon -- mechanobiology -- bioreactor -- mouse -- metabolic homeostasis; Orthopedics -- Periodicals; Musculoskeletal system -- Periodicals; 616.7
• DOI: 10.1002/jor.23769
• Languages: English
• ISSNs: 0736-0266

Abstract

ABSTRACT: Appropriate mechanical load is essential for tendon homeostasis and optimal tissue function. Due to technical challenges in achieving physiological mechanical loads in experimental tendon model systems, the research community still lacks well‐characterized models of tissue homeostasis and physiological relevance. Toward this urgent goal, we present and characterize a novel ex vivo murine tail tendon explant model. Mouse tail tendon fascicles were extracted and cultured for 6 days in a load‐deprived environment or in a custom‐designed bioreactor applying low magnitude mechanical load (intermittent cycles to 1% strain, at 1 Hz) in serum‐free tissue culture. Cells remained viable, as did collagen structure and mechanical properties in all tested conditions. Cell morphology in mechanically loaded tendon explants approximated native tendon, whereas load‐deprived tendons lost their native cell morphology. These losses were reflected in altered gene expression, with mechanical loading tending to maintain tendon specific and matrix remodeling genes phenotypic of native tissue. We conclude from this study that ex vivo load deprivation of murine tendon in minimal culture medium results in a degenerative‐like phenotype. We further conclude that onset of tissue degeneration can be suppressed by low‐magnitude mechanical loading. Thus a minimal explant culture model featuring serum‐free medium with low mechanical loads seems to provide a useful foundation for further investigations. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1383–1390, 2018. Abstract : Low‐magnitude mechanical loading in absence of serum suppresses the onset of tendon degeneration (as visualized in the frames). Murine tail tendon fascicles cultured in a bioreactor system for six days (B) approximate native tendon cell morphology (A), whereas load‐deprived tendons (C) loose their native phenotype (scale bar 50 µm). These changes were reflected in altered gene expression, with mechanical loading tending to maintain tendon specific and matrix remodelling genes at levels close to those of native tissue.