TGF-Β1 diminishes collagen production during long-term cyclic stretching of engineered connective tissue

Implication of decreased ERK signaling

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Abstract

Cyclic stretching and growth factors like TGF-Β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-Β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-Β1 samples had 101% higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-Β1 samples. However, at weeks 5 and 7, -TGF-Β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-Β1 samples. The collagen was better organized in -TGF-Β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-Β1 samples, which correlated with higher collagen deposition. The TGF-Β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-Β1 samples, respectively. The role of TGF-Β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-Β1 signaling during cyclic stretching. One advantage of TGF-Β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-Β1 to obtain improved tensile properties followed by TGF-Β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-Β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.

Original languageEnglish (US)
Pages (from-to)848-855
Number of pages8
JournalJournal of Biomechanics
Volume44
Issue number5
DOIs
StatePublished - Mar 15 2011

Fingerprint

Collagen
Connective Tissue
Elastin
Stretching
Tissue
Phosphorylation
Tensile Strength
Extracellular Matrix
Far-Western Blotting
Tensile strength
Fibrin
Mechanical properties
Intercellular Signaling Peptides and Proteins
Tensile testing
Fibroblasts
Western Blotting
Tensile properties
Staining and Labeling
Skin
Elastic moduli

Keywords

  • Collagen deposition
  • Cyclic stretching
  • ERK
  • P38
  • TGF-Β
  • Tissue engineering
  • Tissue growth and remodeling

Cite this

@article{3f700911e60d4a80b6a142f575b43fa2,
title = "TGF-Β1 diminishes collagen production during long-term cyclic stretching of engineered connective tissue: Implication of decreased ERK signaling",
abstract = "Cyclic stretching and growth factors like TGF-Β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-Β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-Β1 samples had 101{\%} higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-Β1 samples. However, at weeks 5 and 7, -TGF-Β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-Β1 samples. The collagen was better organized in -TGF-Β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-Β1 samples, which correlated with higher collagen deposition. The TGF-Β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-Β1 samples, respectively. The role of TGF-Β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-Β1 signaling during cyclic stretching. One advantage of TGF-Β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-Β1 to obtain improved tensile properties followed by TGF-Β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-Β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.",
keywords = "Collagen deposition, Cyclic stretching, ERK, P38, TGF-Β, Tissue engineering, Tissue growth and remodeling",
author = "Syedain, {Zeeshan H} and Tranquillo, {Robert T}",
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T1 - TGF-Β1 diminishes collagen production during long-term cyclic stretching of engineered connective tissue

T2 - Implication of decreased ERK signaling

AU - Syedain, Zeeshan H

AU - Tranquillo, Robert T

PY - 2011/3/15

Y1 - 2011/3/15

N2 - Cyclic stretching and growth factors like TGF-Β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-Β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-Β1 samples had 101% higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-Β1 samples. However, at weeks 5 and 7, -TGF-Β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-Β1 samples. The collagen was better organized in -TGF-Β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-Β1 samples, which correlated with higher collagen deposition. The TGF-Β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-Β1 samples, respectively. The role of TGF-Β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-Β1 signaling during cyclic stretching. One advantage of TGF-Β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-Β1 to obtain improved tensile properties followed by TGF-Β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-Β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.

AB - Cyclic stretching and growth factors like TGF-Β have been used to enhance extracellular matrix (ECM) production by cells in engineered tissue to achieve requisite mechanical properties. In this study, the effects of TGF-Β1 were evaluated during long-term cyclic stretching of fibrin-based tubular constructs seeded with neonatal human dermal fibroblasts. Samples were evaluated at 2, 5, and 7 weeks for tensile mechanical properties and ECM deposition. At 2 weeks, +TGF-Β1 samples had 101% higher collagen concentration but no difference in ultimate tensile strength (UTS) or modulus compared to -TGF-Β1 samples. However, at weeks 5 and 7, -TGF-Β1 samples had higher UTS/modulus and collagen concentration, but lower elastin concentration compared to +TGF-Β1 samples. The collagen was better organized in -TGF-Β1 samples based on picrosirius red staining. Western blot analysis at weeks 5 and 7 showed increased phosphorylation of ERK in -TGF-Β1 samples, which correlated with higher collagen deposition. The TGF-Β1 effects were further evaluated by western blot for αSMA and SMAD2/3 expression, which were 16-fold and 10-fold higher in +TGF-Β1 samples, respectively. The role of TGF-Β1 activated p38 in inhibiting phosphorylation of ERK was evaluated by treating samples with SB203580, an inhibitor of p38 activation. SB203580-treated cells showed increased phosphorylation of ERK after 1 hour of stretching and increased collagen production after 1 week of stretching, demonstrating an inhibitory role of activated p38 via TGF-Β1 signaling during cyclic stretching. One advantage of TGF-Β1 treatment was the 4-fold higher elastin deposition in samples at 7 weeks. Further cyclic stretching experiments were thus conducted with constructs cultured for 5 weeks without TGF-Β1 to obtain improved tensile properties followed by TGF-Β1 supplementation for 2 weeks to obtain increased elastin content, which correlated with a reduction in loss of pre-stress during preconditioning for tensile testing, indicating functional elastin. This study shows that a sequential stimulus approach - cyclic stretching with delayed TGF-Β1 supplementation - can be used to engineer tissue with desirable tensile and elastic properties.

KW - Collagen deposition

KW - Cyclic stretching

KW - ERK

KW - P38

KW - TGF-Β

KW - Tissue engineering

KW - Tissue growth and remodeling

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DO - 10.1016/j.jbiomech.2010.12.007

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