Sex differences in tendon structure and function

Abstract

Tendons play a critical role in the transmission of forces between muscles and bones, and chronic tendon injuries and diseases are among the leading causes of musculoskeletal disability. Little is known about sex-based differences in tendon structure and function. Our objective was to evaluate the mechanical properties, biochemical composition, transcriptome, and cellular activity of plantarflexor tendons from four month old male and female C57BL/6 mice using in vitro biomechanics, mass spectrometry-based proteomics, genome-wide expression profiling, and cell culture techniques. While the Achilles tendons of male mice were approximately 6% larger than female mice (P<0.05), the cell density of female mice was around 19% larger than males (P<0.05). No significant differences in mechanical properties (P>0.05) of plantaris tendons were observed. Mass spectrometry proteomics analysis revealed no significant difference between sexes in the abundance of major extracellular matrix (ECM) proteins such as collagen types I (P=0.30) and III (P=0.68), but female mice had approximately two-fold elevations (P<0.05) in less abundant ECM proteins such as fibronectin, periostin, and tenascin C. The transcriptome of male and female tendons differed by only 1%. In vitro, neither the sex of the serum that fibroblasts were cultured in, nor the sex of the ECM in which they were embedded, had profound effects on the expression of collagen and cell proliferation genes. Our results indicate that while male mice expectedly had larger tendons, male and female tendons have very similar mechanical properties and biochemical composition, with small increases in some ECM proteins and proteoglycans evident in female tendons.

Scleraxis is required for the growth of adult tendons in response to mechanical loading

“…Despite providing substantial new insight into the role of scleraxis in adult tendon adaptation, this study is not without limitations. We only studied male mice, as we previously demonstrated a general lack of differences between the Achilles tendons of male and female mice (36), and we anticipate the results are likely applicable to both sexes. Results from the plantaris tendon may not be applicable to all tendons, as different tendons display extensive divergence in their function and transcriptional profiles (37).…”

“…Proteomics. Label-free proteomics was performed as reported in previous studies (36,44) Raw spectra were converted to mgf files using Proteome Discovery (Thermo Fisher) and resulting files were searched against the UniProt mouse sequence database using a Mascot server (Matrix Science, London, UK). Search parameters used were: peptide mass tolerance, 10ppm; fragment mass tolerance, 0.01Da; +1,+2,+3 ions; unique peptides ≥2; missed cleavages 1; instrument type ESI-TRAP.…”

“…Variable modifications included carbamidomethylation of cysteine residues and oxidation of methionine. Label-free quantification was performed using ProgenesisQI software (Waters, Elstree Hertfordshire, UK) as described previously (36,44). In brief, the MS/MS peak list was searched against the UniProt mouse reviewed database on Mascot using the same search parameters as mentioned above.…”

Multiomics Analysis of the mdx/mTR Mouse Model of Duchenne Muscular Dystrophy

“…Proteomics. Proteomics was performed as reported in previous studies (3,27,40) Raw spectra were converted to mgf files using Proteome Discovery (Thermo Scientific, Loughborough, UK) and resulting files were searched against the UniProt mouse sequence database using a Mascot server (Matrix Science, London, UK). Search parameters used were: peptide mass tolerance, 10ppm; fragment mass tolerance, 0.01Da; +1,+2,+3 ions; missed cleavages 1; instrument type ESI-TRAP.…”

Prostaglandin D2Signaling is Not Involved in the Recovery of Rat Hindlimb Tendons from Injury

“…Mechanical properties were measured as modified from previous studies (Mendias et al, 2015a;Sarver et al, 2017). Prior to mechanical tests, tendons were thawed at room temperature and then placed in dish containing PBS.…”