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Different mechanisms activated by mild versus strong loading in rat Achilles tendon healing
- Source :
- PLoS ONE, PLoS ONE, Vol 13, Iss 7, p e0201211 (2018)
- Publication Year :
- 2018
- Publisher :
- Linköpings universitet, Avdelningen för Kirurgi, Ortopedi och Onkologi, 2018.
-
Abstract
- Background Mechanical loading stimulates Achilles tendon healing. However, various degrees of loading appear to have different effects on the mechanical properties of the healing tendon, and strong loading might create microdamage in the tissue. This suggests that different mechanisms might be activated depending on the magnitude of loading. The aim of this study was to investigate these mechanisms further. Methods Female rats had their right Achilles tendon cut transversely and divided into three groups: 1) unloading (calf muscle paralysis by Botox injections, combined with joint fixation by a steel-orthosis), 2) mild loading (Botox only), 3) strong loading (free cage activity). Gene expression was analyzed by PCR, 5 days post-injury, and mechanical testing 8 days post-injury. The occurrence of microdamage was analyzed 3, 5, or 14 days post-injury, by measuring leakage of injected fluorescence-labelled albumin in the healing tendon tissue. Results Peak force, peak stress, and elastic modulus of the healing tendons gradually improved with increased loading as well as the expression of extracellular matrix genes. In contrast, only strong loading increased transverse area and affected inflammation genes. Strong loading led to higher fluorescence (as a sign of microdamage) compared to mild loading at 3 and 5 days post-injury, but not at 14 days. Discussion Our results show that strong loading improves both the quality and quantity of the healing tendon, while mild loading only improves the quality. Strong loading also induces microdamage and alters the inflammatory response. This suggests that mild loading exert its effect via mechanotransduction mechanisms, while strong loading exert its effect both via mechanotransduction and the creation of microdamage. Conclusion In conclusion, mild loading is enough to increase the quality of the healing tendon without inducing microdamage and alter the inflammation in the tissue. This supports the general conception that early mobilization of a ruptured tendon in patients is advantageous. Funding Agencies|Swedish Research Council; Swedish Research Council for Sports Science; Ostergotland County (ALF)
- Subjects :
- Fysiologi
Physiology
Immunology
Toxic Agents
Bacterial Toxins
lcsh:Medicine
Gene Expression
Botulinum Toxin
Pathology and Laboratory Medicine
Toxicology
Achilles Tendon
Blood Plasma
Rats, Sprague-Dawley
Tendons
Random Allocation
Signs and Symptoms
Tendon Injuries
Diagnostic Medicine
Elastic Modulus
Tissue Repair
Medicine and Health Sciences
Genetics
Animals
Toxins
lcsh:Science
Immune Response
Inflammation
Wound Healing
lcsh:R
Biology and Life Sciences
Cell Biology
Biomechanical Phenomena
Body Fluids
Extracellular Matrix
Disease Models, Animal
Biological Tissue
Blood
Gene Expression Regulation
Connective Tissue
lcsh:Q
Female
Anatomy
Cellular Structures and Organelles
Physiological Processes
Research Article
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- PLoS ONE, PLoS ONE, Vol 13, Iss 7, p e0201211 (2018)
- Accession number :
- edsair.pmid.dedup....870c4b3821f54051452d4024eb3d4f10