Elucidation of extracellular matrix mechanics from muscle fibers and fiber bundles.
TL;DR: A new method to quantify viscoelastic ECM modulus is presented by combining tests of single muscle fibers and fiber bundles, which demonstrate that ECM is a highly nonlinearly elastic material, while muscle fibers are linearly elastic.
About: This article is published in Journal of Biomechanics.The article was published on 2011-02-24 and is currently open access. It has received 156 citations till now. The article focuses on the topics: Skeletal muscle.
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TL;DR: Passive mechanics, myosin heavy chain, and collagen content were all unaffected while the titin protein degraded up to 80% over 7 days post-mortem, indicating that fresh cadaveric tissue may be used for passive mechanical testing and that certain biochemical properties are unchanged up to 7 days after death.
14 citations
Cites background from "Elucidation of extracellular matrix..."
...Interestingly, passive bundle mechanics were not affected by the marked titin degradation providing further evidence that bundle mechanics are dominated by the mechanical properties of the extracellular matrix rather than fiber properties (Meyer and Lieber, 2011)....
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TL;DR: The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering muscle–tendon behavior with the potential to modify contractile function.
Abstract: Introduction This study examined the effects of 24 wk of daily static stretching of the plantarflexors (unilateral 4 × 60-s stretching, whereas the contralateral leg served as a control; n = 26) on joint range of motion (ROM), muscle-tendon unit morphological and mechanical properties, neural activation, and contractile function. Methods Torque-angle/velocity was obtained in passive and active conditions using isokinetic dynamometry, whereas muscle-tendon morphology and mechanical properties were examined using ultrasonography. Results After the intervention, ROM increased (stretching, +11° ± 7°; control, 4° ± 8°), and passive torque (stretching, -10 ± 11 N·m; control, -7 ± 10 N·m) and normalized EMG amplitude (stretching, -3% ± 6%; control, -3% ± 4%) at a standardized dorsiflexion angle decreased. Increases were seen in passive tendon elongation at a standardized force (stretching, +1.3 ± 1.6 mm; control, +1.4 ± 2.1 mm) and in maximal passive muscle and tendon elongation. Angle of peak torque shifted toward dorsiflexion. No changes were seen in tendon stiffness, resting tendon length, or gastrocnemius medialis fascicle length. Conformable changes in ROM, passive dorsiflexion variables, tendon elongation, and angle of peak torque were observed in the nonstretched leg. Conclusions The present findings indicate that habitual stretching increases ROM and decreases passive torque, altering muscle-tendon behavior with the potential to modify contractile function.
13 citations
Cites background from "Elucidation of extracellular matrix..."
...Because structural connective tissue properties contribute to passive resistance (49), this finding may indicate that stretching has induced a change in structural properties of connective tissue, although the present data set cannot ascertain whether such change occurred....
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TL;DR: In this paper, the relevance of cross-helical fiber arrangement to muscles and surrounding fascial tissues is described, with the particular alignment of collagen fibres within their myofascial walls reflecting the most efficient distribution of mechanical stresses and coordinating these changes.
13 citations
TL;DR: The results demonstrate the strong meniscal modifications induced by ACLT at an early stage of OA and highlight the relationship between structural and chemical matrix alterations and mechanical properties.
Abstract: The aim of this study was to evaluate the effect of early osteoarthritis (OA) on the viscoelastic properties of rabbit menisci and to correlate the mechanical alterations with the microstructural changes. Anterior Cruciate Ligament Transection (ACLT) was performed in six male New-Zealand White rabbits on the right knee joint. Six healthy rabbits served as controls. Menisci were removed six weeks after ACLT and were graded macroscopically. Indentation-relaxation tests were performed in the anterior and posterior regions of the medial menisci. The collagen fibre organization and glycosaminoglycan (GAG) content were assessed by biphotonic confocal microscopy and histology, respectively. OA menisci displayed severe macroscopic lesions compared with healthy menisci (p=0.009). Moreover, the instantaneous and equilibrium moduli, which were 2.9±1.0MPa and 0.60±0.18MPa in the anterior region of healthy menisci, respectively, decreased significantly (p=0.03 and p=0.004, respectively) in OA menisci by 55% and 57%, respectively, indicating a global decrease in meniscal stiffness in this region. The equilibrium modulus alone decreased significantly (p=0.04) in the posterior region, going from 0.60±0.18MPa to 0.26±012MPa. This induced a loss of tissue elasticity. These mechanical changes were associated in the posterior region with a structural disruption of the superficial layers, from which the tie fibres emanate, and with a decrease in the GAG content in the anterior region. Consequently, the circumferential collagen fibres of the deep zone were dissociated and the collagen bundles were less compact. Our results demonstrate the strong meniscal modifications induced by ACLT at an early stage of OA and highlight the relationship between structural and chemical matrix alterations and mechanical properties.
12 citations
TL;DR: It was showed that immobilization of skeletal muscles in short positions produced contractile tissue atrophy, connective tissue thickening and alteration of passive mechanical behavior that were more damaging than the effects produced by a stroke.
Abstract: Patient management following a stroke currently represents a medical challenge. The presented study investigates the effect of immobilization on skeletal muscles in short positions after a stroke. A rat model was implemented in order to compare four situations within 14 days including control group, immobilization of one forelimb without stroke, stroke without immobilization and stroke with immobilization of the paretic forelimb. To analyze the changes of the mechanical properties of the passive skeletal muscle, the biological tissue is assumed to behave as a visco-hyperelastic and incompressible material characterized by the first-order Ogden’s strain energy function coupled with second-order Maxwell’s model. The material parameters were identified from inverse finite element method by using uniaxial relaxation tests data of skeletal muscle samples. Based on measurements of histological parameters, we observe that muscle immobilization led to microconstituents changes of skeletal muscles that were correlated with degradations of its mechanical properties. In the case of immobilization without stroke, the neurological behavior was also altered in the same manner as in the case of a stroke. We showed that immobilization of skeletal muscles in short positions produced contractile tissue atrophy, connective tissue thickening and alteration of passive mechanical behavior that were more damaging than the effects produced by a stroke. These results showed then that immobilization of skeletal muscles in short positions is highly deleterious with or without a stroke.
12 citations
References
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TL;DR: Naive mesenchymal stem cells are shown here to specify lineage and commit to phenotypes with extreme sensitivity to tissue-level elasticity, consistent with the elasticity-insensitive commitment of differentiated cell types.
12,204 citations
"Elucidation of extracellular matrix..." refers background in this paper
...Since substrate biomechanical properties have been shown to be critical in the biology of tissue development and remodeling (Engler et al., 2006; Gilbert et al., 2010), it is likely that mechanics are critical for ECM to perform its function....
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TL;DR: Using a bioengineered substrate to recapitulate key biophysical and biochemical niche features in conjunction with a highly automated single-cell tracking algorithm, it is shown that substrate elasticity is a potent regulator of MuSC fate in culture.
Abstract: Stem cells that naturally reside in adult tissues, such as muscle stem cells (MuSCs), exhibit robust regenerative capacity in vivo that is rapidly lost in culture. Using a bioengineered substrate to recapitulate key biophysical and biochemical niche features in conjunction with a highly automated single-cell tracking algorithm, we show that substrate elasticity is a potent regulator of MuSC fate in culture. Unlike MuSCs on rigid plastic dishes (approximately 10(6) kilopascals), MuSCs cultured on soft hydrogel substrates that mimic the elasticity of muscle (12 kilopascals) self-renew in vitro and contribute extensively to muscle regeneration when subsequently transplanted into mice and assayed histologically and quantitatively by noninvasive bioluminescence imaging. Our studies provide novel evidence that by recapitulating physiological tissue rigidity, propagation of adult muscle stem cells is possible, enabling future cell-based therapies for muscle-wasting diseases.
1,428 citations
"Elucidation of extracellular matrix..." refers background in this paper
...Since substrate biomechanical properties have been shown to be critical in the biology of tissue development and remodeling (Engler et al., 2006; Gilbert et al., 2010), it is likely that mechanics are critical for ECM to perform its function....
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1,224 citations
"Elucidation of extracellular matrix..." refers background in this paper
...Since substrate biomechanical properties have been shown to be critical in the biology of tissue development and remodeling (Engler et al., 2006; Gilbert et al., 2010), it is likely that mechanics are critical for ECM to perform its function....
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TL;DR: Avian integrin shows little specificity and appears to behave as a multifunctional, promiscuous receptor for extracellular matrix molecules, and post-translational modifications provide yet another mechanism for regulating integrin-ligand binding.
Abstract: Table 2 lists most of the extracellular matrix and related receptors identified to date. The wide range of binding affinities of these receptors for their ligands may be important to their function. The affinity of integrins for fibronectin is moderate, with a dissociation constant in the micromolar range. This affinity level leads to relatively rapid dissociation and reformation of receptor-ligand complexes. Thus changes in component concentration can shift binding equilibria within minutes (the time scale of many biologic phenomena) and change the number or organization of adhesive complexes. This type of interaction would be useful in motile cells, in which adhesions must form and dissociate rapidly. In contrast, the affinity of the 68-kDa laminin receptor for its ligand is three orders of magnitude higher. Such levels of affinity would be useful in stabilizing tissue. Members of the integrin family appear to recognize an RGD sequence on the ligands to which they bind. Since there are many ligands containing the RGD sequence, the question of specificity arises. Avian integrin shows little specificity and appears to behave as a multifunctional, promiscuous receptor for extracellular matrix molecules. Figure 1 summarizes our current view of the structural and functional features of avian integrin. In contrast, the mammalian receptors for vitronectin and fibronectin are specific for their respective ligands. More than one of these receptors may be present simultaneously on a cell surface, e.g. fibroblasts express receptors for fibronectin, laminin, and vitronectin at the same time. This multiplicity of receptors provides potential mechanisms for generating the adhesive differences among cells believed to play a prominent role in morphogenesis. Further adhesive differences may stem from the formation of different combinations of various alpha- and beta-subunits expressed in the cell. The mechanism of regulation of adhesive interactions with the extracellular matrix is only beginning to be explored. There are several levels at which this regulation might occur. Integrin appears to be more regionalized in more developed cells that are integral parts of tissue structures. Changes in receptor distribution could alter the relative strength of adhesive interactions. In certain instances, avian integrin disappears, or its concentration is reduced, e.g. during the development of embryonic lung (Chen et al 1986) and erythroid cells (Patel & Lodish 1985). Post-translational modifications provide yet another mechanism for regulating integrin-ligand binding.(ABSTRACT TRUNCATED AT 400 WORDS)
784 citations
"Elucidation of extracellular matrix..." refers background in this paper
...Extracellular matrix (ECM) is essential for the development, maintenance and regeneration of skeletal muscle (Buck and Horwitz, 1987; Purslow, 2002)....
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...The importance of the extracellular matrix (ECM) in muscle is widely recognized, since ECM plays a central role in proper muscle development (Buck and Horwitz, 1987), tissue structural support (Purslow, 2002), and transmission ofmechanical signals between fibers and tendon (Huijing, 1999)....
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...…r a c t The importance of the extracellular matrix (ECM) in muscle is widely recognized, since ECM plays a central role in proper muscle development (Buck and Horwitz, 1987), tissue structural support (Purslow, 2002), and transmission ofmechanical signals between fibers and tendon (Huijing, 1999)....
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TL;DR: The passive tension-sarcomere length relation of rat cardiac muscle was investigated by studying passive (or not activated) single myocytes and trabeculae and the contribution of collagen, titin, microtubules, and intermediate filaments to tension and stiffness was investigated.
587 citations
"Elucidation of extracellular matrix..." refers methods in this paper
...Previous studies used methods of subtraction, where the ECM was ‘‘preferentially’’ digested from muscle and its properties inferred from subtracting the digested state from the undigested state (see review by Fomovsky et al., 2010; Granzier and Irving, 1995)....
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