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Mechanical strain stabilizes reconstituted collagen fibrils against enzymatic degradation by mammalian collagenase matrix metalloproteinase 8 (MMP-8).

Flynn BP, Bhole AP, Saeidi N, Liles M, Dimarzio CA, Ruberti JW - PLoS ONE (2010)

Bottom Line: It is found in bone, ligament, tendon, cartilage, intervertebral disc, skin, blood vessel, and cornea.These results have the potential to contribute to our understanding of many collagen matrix phenomena including development, adaptation, remodeling and disease.Additionally, tissue engineering could benefit from the ability to sculpt desired structures from physiologically compatible and mutable collagen.

View Article: PubMed Central - PubMed

Affiliation: Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States of America.

ABSTRACT

Background: Collagen, a triple-helical, self-organizing protein, is the predominant structural protein in mammals. It is found in bone, ligament, tendon, cartilage, intervertebral disc, skin, blood vessel, and cornea. We have recently postulated that fibrillar collagens (and their complementary enzymes) comprise the basis of a smart structural system which appears to support the retention of molecules in fibrils which are under tensile mechanical strain. The theory suggests that the mechanisms which drive the preferential accumulation of collagen in loaded tissue operate at the molecular level and are not solely cell-driven. The concept reduces control of matrix morphology to an interaction between molecules and the most relevant, physical, and persistent signal: mechanical strain.

Methodology/principal findings: The investigation was carried out in an environmentally-controlled microbioreactor in which reconstituted type I collagen micronetworks were gently strained between micropipettes. The strained micronetworks were exposed to active matrix metalloproteinase 8 (MMP-8) and relative degradation rates for loaded and unloaded fibrils were tracked simultaneously using label-free differential interference contrast (DIC) imaging. It was found that applied tensile mechanical strain significantly increased degradation time of loaded fibrils compared to unloaded, paired controls. In many cases, strained fibrils were detectable long after unstrained fibrils were degraded.

Conclusions/significance: In this investigation we demonstrate for the first time that applied mechanical strain preferentially preserves collagen fibrils in the presence of a physiologically-important mammalian enzyme: MMP-8. These results have the potential to contribute to our understanding of many collagen matrix phenomena including development, adaptation, remodeling and disease. Additionally, tissue engineering could benefit from the ability to sculpt desired structures from physiologically compatible and mutable collagen.

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Related in: MedlinePlus

P-value for degradation end time vs. RI for total edge intensity (o) and directional edge intensity (+).Note the differences between total and directional edge intensity methods. While both methods show significance (p<0.05) over a large range of RI, the total edge intensity is statistically different over almost the entire regime [.19, .81], while directional edge intensity is statistically different over the range from [.12, .53].
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pone-0012337-g004: P-value for degradation end time vs. RI for total edge intensity (o) and directional edge intensity (+).Note the differences between total and directional edge intensity methods. While both methods show significance (p<0.05) over a large range of RI, the total edge intensity is statistically different over almost the entire regime [.19, .81], while directional edge intensity is statistically different over the range from [.12, .53].

Mentions: A conservative quantitative edge detection algorithm (described in detail in Bhole et al [44]) was used to estimate the rate of degradation of the fibrils in the microbioreactor. Fig. 1 shows a sequence of images depicting regions of interest (ROIs) located in the strained portion of the collagen network (1A–C DIC image; 1D–F edge detected image) and in the unstrained portion (1G–I DIC image; 1J–L edge-detected image). The edge-detected, processed images were integrated to produce time varying edge intensity values reflecting the total quantity of fibrillar collagen, weighted to largest fibrils, in the ROI at any time (Fig. 3). The time required to degrade the observed fibrils to a fraction, RI, of the initial integrated DIC edge intensity varied significantly (p<0.05) between strained fibrils and unstrained control fibrils over RI [0.19, 0.81] for total edge intensity and over RI [0.12, 0.52] for directional edge intensity (Fig. 4). The data extracted from the quantitative analysis of separate unstrained and strained ROIs clearly indicates a faster degradation rate for the unstrained network as determined by both total and directional edge intensity methods. Degradation time (defined as RI  = 0.2) was 9822±3648 s (mean±std) (strained) and 7805±2321 s (unstrained) for directional edge intensity, and 9076±2769 s (strained) and 7467±1738 s (unstrained) for total edge intensity.


Mechanical strain stabilizes reconstituted collagen fibrils against enzymatic degradation by mammalian collagenase matrix metalloproteinase 8 (MMP-8).

Flynn BP, Bhole AP, Saeidi N, Liles M, Dimarzio CA, Ruberti JW - PLoS ONE (2010)

P-value for degradation end time vs. RI for total edge intensity (o) and directional edge intensity (+).Note the differences between total and directional edge intensity methods. While both methods show significance (p<0.05) over a large range of RI, the total edge intensity is statistically different over almost the entire regime [.19, .81], while directional edge intensity is statistically different over the range from [.12, .53].
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2925882&req=5

pone-0012337-g004: P-value for degradation end time vs. RI for total edge intensity (o) and directional edge intensity (+).Note the differences between total and directional edge intensity methods. While both methods show significance (p<0.05) over a large range of RI, the total edge intensity is statistically different over almost the entire regime [.19, .81], while directional edge intensity is statistically different over the range from [.12, .53].
Mentions: A conservative quantitative edge detection algorithm (described in detail in Bhole et al [44]) was used to estimate the rate of degradation of the fibrils in the microbioreactor. Fig. 1 shows a sequence of images depicting regions of interest (ROIs) located in the strained portion of the collagen network (1A–C DIC image; 1D–F edge detected image) and in the unstrained portion (1G–I DIC image; 1J–L edge-detected image). The edge-detected, processed images were integrated to produce time varying edge intensity values reflecting the total quantity of fibrillar collagen, weighted to largest fibrils, in the ROI at any time (Fig. 3). The time required to degrade the observed fibrils to a fraction, RI, of the initial integrated DIC edge intensity varied significantly (p<0.05) between strained fibrils and unstrained control fibrils over RI [0.19, 0.81] for total edge intensity and over RI [0.12, 0.52] for directional edge intensity (Fig. 4). The data extracted from the quantitative analysis of separate unstrained and strained ROIs clearly indicates a faster degradation rate for the unstrained network as determined by both total and directional edge intensity methods. Degradation time (defined as RI  = 0.2) was 9822±3648 s (mean±std) (strained) and 7805±2321 s (unstrained) for directional edge intensity, and 9076±2769 s (strained) and 7467±1738 s (unstrained) for total edge intensity.

Bottom Line: It is found in bone, ligament, tendon, cartilage, intervertebral disc, skin, blood vessel, and cornea.These results have the potential to contribute to our understanding of many collagen matrix phenomena including development, adaptation, remodeling and disease.Additionally, tissue engineering could benefit from the ability to sculpt desired structures from physiologically compatible and mutable collagen.

View Article: PubMed Central - PubMed

Affiliation: Mechanical and Industrial Engineering, Northeastern University, Boston, Massachusetts, United States of America.

ABSTRACT

Background: Collagen, a triple-helical, self-organizing protein, is the predominant structural protein in mammals. It is found in bone, ligament, tendon, cartilage, intervertebral disc, skin, blood vessel, and cornea. We have recently postulated that fibrillar collagens (and their complementary enzymes) comprise the basis of a smart structural system which appears to support the retention of molecules in fibrils which are under tensile mechanical strain. The theory suggests that the mechanisms which drive the preferential accumulation of collagen in loaded tissue operate at the molecular level and are not solely cell-driven. The concept reduces control of matrix morphology to an interaction between molecules and the most relevant, physical, and persistent signal: mechanical strain.

Methodology/principal findings: The investigation was carried out in an environmentally-controlled microbioreactor in which reconstituted type I collagen micronetworks were gently strained between micropipettes. The strained micronetworks were exposed to active matrix metalloproteinase 8 (MMP-8) and relative degradation rates for loaded and unloaded fibrils were tracked simultaneously using label-free differential interference contrast (DIC) imaging. It was found that applied tensile mechanical strain significantly increased degradation time of loaded fibrils compared to unloaded, paired controls. In many cases, strained fibrils were detectable long after unstrained fibrils were degraded.

Conclusions/significance: In this investigation we demonstrate for the first time that applied mechanical strain preferentially preserves collagen fibrils in the presence of a physiologically-important mammalian enzyme: MMP-8. These results have the potential to contribute to our understanding of many collagen matrix phenomena including development, adaptation, remodeling and disease. Additionally, tissue engineering could benefit from the ability to sculpt desired structures from physiologically compatible and mutable collagen.

Show MeSH
Related in: MedlinePlus