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Effect of strain magnitude on the tissue properties of engineered cardiovascular constructs.

Boerboom RA, Rubbens MP, Driessen NJ, Bouten CV, Baaijens FP - Ann Biomed Eng (2007)

Bottom Line: To ultimately regulate the biochemical processes, it is essential to quantify the effect of mechanical loading on the properties of engineered cardiovascular constructs.The results suggest that when the tissues are exposed to prolonged mechanical stimulation, the production of collagen with a higher fraction of crosslinks is induced.In addition, dynamic straining induced a different alignment of cells and collagen in the superficial layers compared to the deeper layers of the construct.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Soft Tissue Biomechanics and Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands. r.a.boerboom@tue.nl

ABSTRACT
Mechanical loading is a powerful regulator of tissue properties in engineered cardiovascular tissues. To ultimately regulate the biochemical processes, it is essential to quantify the effect of mechanical loading on the properties of engineered cardiovascular constructs. In this study the Flexercell FX-4000T (Flexcell Int. Corp., USA) straining system was modified to simultaneously apply various strain magnitudes to individual samples during one experiment. In addition, porous polyglycolic acid (PGA) scaffolds, coated with poly-4-hydroxybutyrate (P4HB), were partially embedded in a silicone layer to allow long-term uniaxial cyclic mechanical straining of cardiovascular engineered constructs. The constructs were subjected to two different strain magnitudes and showed differences in biochemical properties, mechanical properties and organization of the microstructure compared to the unstrained constructs. The results suggest that when the tissues are exposed to prolonged mechanical stimulation, the production of collagen with a higher fraction of crosslinks is induced. However, straining with a large strain magnitude resulted in a negative effect on the mechanical properties of the tissue. In addition, dynamic straining induced a different alignment of cells and collagen in the superficial layers compared to the deeper layers of the construct. The presented model system can be used to systematically optimize culture protocols for engineered cardiovascular tissues.

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Histology and microstructure of 3-weeks-old engineered cardiovascular constructs. The straining direction is from left to right. (a–c) H&E staining of engineered cardiovascular constructs cultured at 0, 4, and 8% strain, respectively. (d–f) Multiphoton images of cells (blue) and collagen (green) visualized at the surface of the engineered constructs, approximately 3 μm into the tissue. (g–i) Multiphoton images of cells and collagen visualized approximately 25 μm into the engineered tissue constructs
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Fig5: Histology and microstructure of 3-weeks-old engineered cardiovascular constructs. The straining direction is from left to right. (a–c) H&E staining of engineered cardiovascular constructs cultured at 0, 4, and 8% strain, respectively. (d–f) Multiphoton images of cells (blue) and collagen (green) visualized at the surface of the engineered constructs, approximately 3 μm into the tissue. (g–i) Multiphoton images of cells and collagen visualized approximately 25 μm into the engineered tissue constructs

Mentions: The H&E stain was performed to obtain a general overview of matrix formation within the engineered cardiovascular constructs after 3 weeks of culture (Figs. 5a–c). In general the constructs showed a dense layer of cells and ECM at the surface of the construct. Deeper into the tissues less cells and a faint staining of the ECM was seen, which illustrates a reduced production of ECM per cell. The bottom of the engineered tissue, which was attached to the silicone support layer, did not show much production of matrix due to an insufficient supply of nutrients. Comparing the different straining conditions showed that the superficial layer appeared thinner in unstrained tissues relative to the strained tissues. In addition, the superficial layer of the 4% strained construct appeared more dense compared to the superficial layer of the 8% strained construct.Figure 5


Effect of strain magnitude on the tissue properties of engineered cardiovascular constructs.

Boerboom RA, Rubbens MP, Driessen NJ, Bouten CV, Baaijens FP - Ann Biomed Eng (2007)

Histology and microstructure of 3-weeks-old engineered cardiovascular constructs. The straining direction is from left to right. (a–c) H&E staining of engineered cardiovascular constructs cultured at 0, 4, and 8% strain, respectively. (d–f) Multiphoton images of cells (blue) and collagen (green) visualized at the surface of the engineered constructs, approximately 3 μm into the tissue. (g–i) Multiphoton images of cells and collagen visualized approximately 25 μm into the engineered tissue constructs
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2211363&req=5

Fig5: Histology and microstructure of 3-weeks-old engineered cardiovascular constructs. The straining direction is from left to right. (a–c) H&E staining of engineered cardiovascular constructs cultured at 0, 4, and 8% strain, respectively. (d–f) Multiphoton images of cells (blue) and collagen (green) visualized at the surface of the engineered constructs, approximately 3 μm into the tissue. (g–i) Multiphoton images of cells and collagen visualized approximately 25 μm into the engineered tissue constructs
Mentions: The H&E stain was performed to obtain a general overview of matrix formation within the engineered cardiovascular constructs after 3 weeks of culture (Figs. 5a–c). In general the constructs showed a dense layer of cells and ECM at the surface of the construct. Deeper into the tissues less cells and a faint staining of the ECM was seen, which illustrates a reduced production of ECM per cell. The bottom of the engineered tissue, which was attached to the silicone support layer, did not show much production of matrix due to an insufficient supply of nutrients. Comparing the different straining conditions showed that the superficial layer appeared thinner in unstrained tissues relative to the strained tissues. In addition, the superficial layer of the 4% strained construct appeared more dense compared to the superficial layer of the 8% strained construct.Figure 5

Bottom Line: To ultimately regulate the biochemical processes, it is essential to quantify the effect of mechanical loading on the properties of engineered cardiovascular constructs.The results suggest that when the tissues are exposed to prolonged mechanical stimulation, the production of collagen with a higher fraction of crosslinks is induced.In addition, dynamic straining induced a different alignment of cells and collagen in the superficial layers compared to the deeper layers of the construct.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, Soft Tissue Biomechanics and Engineering, Eindhoven University of Technology, PO Box 513, 5600 MB, Eindhoven, The Netherlands. r.a.boerboom@tue.nl

ABSTRACT
Mechanical loading is a powerful regulator of tissue properties in engineered cardiovascular tissues. To ultimately regulate the biochemical processes, it is essential to quantify the effect of mechanical loading on the properties of engineered cardiovascular constructs. In this study the Flexercell FX-4000T (Flexcell Int. Corp., USA) straining system was modified to simultaneously apply various strain magnitudes to individual samples during one experiment. In addition, porous polyglycolic acid (PGA) scaffolds, coated with poly-4-hydroxybutyrate (P4HB), were partially embedded in a silicone layer to allow long-term uniaxial cyclic mechanical straining of cardiovascular engineered constructs. The constructs were subjected to two different strain magnitudes and showed differences in biochemical properties, mechanical properties and organization of the microstructure compared to the unstrained constructs. The results suggest that when the tissues are exposed to prolonged mechanical stimulation, the production of collagen with a higher fraction of crosslinks is induced. However, straining with a large strain magnitude resulted in a negative effect on the mechanical properties of the tissue. In addition, dynamic straining induced a different alignment of cells and collagen in the superficial layers compared to the deeper layers of the construct. The presented model system can be used to systematically optimize culture protocols for engineered cardiovascular tissues.

Show MeSH
Related in: MedlinePlus