Guidelines for ex vivo mechanical testing of tendon

Lake, Spencer P.; Snedeker, Jess G.; Wang, Vincent; Awad, Hani A.; Screen, Hazel R. C.; Thomopoulos, Stavros

doi:10.1002/jor.25647

Cited by 12 publications

(2 citation statements)

References 81 publications

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“…However, the compression test of tendon after enzyme treatment was not found. It may be because tendons are more influenced by uniaxial direction (that is, fiber direction) in vivo , and axial tension is a conventional mechanical test method ( Ristaniemi et al, 2021 ; Lake et al, 2023 ). Through uniaxial stretching, it is concluded that elastin has made a more significant contribution to the patellar tendon as an energy storage tendon.…”

Section: Discussionmentioning

confidence: 99%

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion

Liu,

Deng,

Liang

et al. 2024

Front. Bioeng. Biotechnol.

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Background: The treatment of patellar tendon injury has always been an unsolved problem, and mechanical characterization is very important for its repair and reconstruction. Elastin is a contributor to mechanics, but it is not clear how it affects the elasticity, viscoelastic properties, and structure of patellar tendon.Methods: The patellar tendons from six fresh adult experimental pigs were used in this study and they were made into 77 samples. The patellar tendon was specifically degraded by elastase, and the regional mechanical response and structural changes were investigated by: (1) Based on the previous study of elastase treatment conditions, the biochemical quantification of collagen, glycosaminoglycan and total protein was carried out; (2) The patellar tendon was divided into the proximal, central, and distal regions, and then the axial tensile test and stress relaxation test were performed before and after phosphate-buffered saline (PBS) or elastase treatment; (3) The dynamic constitutive model was established by the obtained mechanical data; (4) The structural relationship between elastin and collagen fibers was analyzed by two-photon microscopy and histology.Results: There was no statistical difference in mechanics between patellar tendon regions. Compared with those before elastase treatment, the low tensile modulus decreased by 75%–80%, the high tensile modulus decreased by 38%–47%, and the transition strain was prolonged after treatment. For viscoelastic behavior, the stress relaxation increased, the initial slope increased by 55%, the saturation slope increased by 44%, and the transition time increased by 25% after enzyme treatment. Elastin degradation made the collagen fibers of patellar tendon become disordered and looser, and the fiber wavelength increased significantly.Conclusion: The results of this study show that elastin plays an important role in the mechanical properties and fiber structure stability of patellar tendon, which supplements the structure-function relationship information of patellar tendon. The established constitutive model is of great significance to the prediction, repair and replacement of patellar tendon injury. In addition, human patellar tendon has a higher elastin content, so the results of this study can provide supporting information on the natural properties of tendon elastin degradation and guide the development of artificial patellar tendon biomaterials.

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Section: Discussionmentioning

confidence: 99%

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion

Liu,

Deng,

Liang

et al. 2024

Front. Bioeng. Biotechnol.

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“…Also, clamping could impose a strong compression force not represented by the constitutive law which is only valid in the tensile state and at low dispersion. As such, experimentally, clamping modifications (e.g., sinusoidal-shaped or serrated jaws, sandpaper) are employed to increase the contact area of the clamp across the sample ( Lake et al, 2023 ). Furthermore, incompressibility as a characteristic of soft tissues in computational biomechanics is not valid if the sample becomes dehydrated during an experiment.…”

Section: Discussionmentioning

confidence: 99%

Shape or size matters? Towards standard reporting of tensile testing parameters for human soft tissues: systematic review and finite element analysis

Lin,

Pirrung,

Niestrawska

et al. 2024

Front. Bioeng. Biotechnol.

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Material properties of soft-tissue samples are often derived through uniaxial tensile testing. For engineering materials, testing parameters (e.g., sample geometries and clamping conditions) are described by international standards; for biological tissues, such standards do not exist. To investigate what testing parameters have been reported for tensile testing of human soft-tissue samples, a systematic review of the literature was performed using PRISMA guidelines. Soft tissues are described as anisotropic and/or hyperelastic. Thus, we explored how the retrieved parameters compared against standards for engineering materials of similar characteristics. All research articles published in English, with an Abstract, and before 1 January 2023 were retrieved from databases of PubMed, Web of Science, and BASE. After screening of articles based on search terms and exclusion criteria, a total 1,096 articles were assessed for eligibility, from which 361 studies were retrieved and included in this review. We found that a non-tapered shape is most common (209 of 361), followed by a tapered sample shape (92 of 361). However, clamping conditions varied and were underreported (156 of 361). As a preliminary attempt to explore how the retrieved parameters might influence the stress distribution under tensile loading, a pilot study was performed using finite element analysis (FEA) and constitutive modeling for a clamped sample of little or no fiber dispersion. The preliminary FE simulation results might suggest the hypothesis that different sample geometries could have a profound influence on the stress-distribution under tensile loading. However, no conclusions can be drawn from these simulations, and future studies should involve exploring different sample geometries under different computational models and sample parameters (such as fiber dispersion and clamping effects). Taken together, reporting and choice of testing parameters remain as challenges, and as such, recommendations towards standard reporting of uniaxial tensile testing parameters for human soft tissues are proposed.

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Transcriptome‐Optimized Hydrogel Design of a Stem Cell Niche for Enhanced Tendon Regeneration

Zhang,

Rao,

Wong

et al. 2024

Advanced Materials

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Bioactive hydrogels have emerged as promising artificial niches for enhancing stem cell‐mediated tendon repair. However, a substantial knowledge gap remains regarding the optimal combination of niche features for targeted cellular responses, which often leads to lengthy development cycles and uncontrolled healing outcomes. To address this critical gap, an innovative, data‐driven materiomics strategy is developed. This approach is based on in‐house RNA‐seq data that integrates bioinformatics and mathematical modeling, which is a significant departure from traditional trial‐and‐error methods. It aims to provide both mechanistic insights and quantitative assessments and predictions of the tenogenic effects of adipose‐derived stem cells induced by systematically modulated features of a tendon‐mimetic hydrogel (TenoGel). The knowledge generated has enabled a rational approach for TenoGel design, addressing key considerations, such as tendon extracellular matrix concentration, uniaxial tensile loading, and in vitro pre‐conditioning duration. Remarkably, our optimized TenoGel demonstrated robust tenogenesis in vitro and facilitated tendon regeneration while preventing undesired ectopic ossification in a rat tendon injury model. These findings shed light on the importance of tailoring hydrogel features for efficient tendon repair. They also highlight the tremendous potential of the innovative materiomics strategy as a powerful predictive and assessment tool in biomaterial development for regenerative medicine.

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Guidelines for ex vivo mechanical testing of tendon

Cited by 12 publications

References 81 publications

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion

The alteration of the structure and macroscopic mechanical response of porcine patellar tendon by elastase digestion

Shape or size matters? Towards standard reporting of tensile testing parameters for human soft tissues: systematic review and finite element analysis

Transcriptome‐Optimized Hydrogel Design of a Stem Cell Niche for Enhanced Tendon Regeneration

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