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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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Related in: MedlinePlus

(a) Schematic cross-section of modified Flexcell system. This schematic shows the polycarbonate rings (gray) placed around the loading post, which limit the deformation of the membrane when a vacuum is applied. (b) Reinforcement of the polyglycolic acid scaffold with an elastic silicone layer. In the upper part a longitudinal cross-section of the PGA/P4HB scaffold embedded in an elastic silicone layer. A layer of 0.5 mm thick, consisting of MDX4-4210 (Dow Corning, USA). In the lower part rectangular scaffolds (34  ×  5 mm2 × ±1–1.2 mm) were attached to Bioflex culture wells (Flexcell Int. Corp., USA) by applying MDX4-4210 to the outer 5 mm of these constructs
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Fig1: (a) Schematic cross-section of modified Flexcell system. This schematic shows the polycarbonate rings (gray) placed around the loading post, which limit the deformation of the membrane when a vacuum is applied. (b) Reinforcement of the polyglycolic acid scaffold with an elastic silicone layer. In the upper part a longitudinal cross-section of the PGA/P4HB scaffold embedded in an elastic silicone layer. A layer of 0.5 mm thick, consisting of MDX4-4210 (Dow Corning, USA). In the lower part rectangular scaffolds (34  ×  5 mm2 × ±1–1.2 mm) were attached to Bioflex culture wells (Flexcell Int. Corp., USA) by applying MDX4-4210 to the outer 5 mm of these constructs

Mentions: In Fig. 1a a schematic overview of the modified straining setup is shown. When a vacuum is applied to the flexible membrane of the Bioflex plate, the membrane will deform at the locations where it is not supported by the loading post. Polycarbonate rings of varying height were placed around the original loading posts. When a maximum vacuum is applied in the presence of the polycarbonate rings, the rings limit the deformation of the flexible silicone membrane. By varying the height of these rings the deformation of the membrane can be varied.Figure 1


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)

(a) Schematic cross-section of modified Flexcell system. This schematic shows the polycarbonate rings (gray) placed around the loading post, which limit the deformation of the membrane when a vacuum is applied. (b) Reinforcement of the polyglycolic acid scaffold with an elastic silicone layer. In the upper part a longitudinal cross-section of the PGA/P4HB scaffold embedded in an elastic silicone layer. A layer of 0.5 mm thick, consisting of MDX4-4210 (Dow Corning, USA). In the lower part rectangular scaffolds (34  ×  5 mm2 × ±1–1.2 mm) were attached to Bioflex culture wells (Flexcell Int. Corp., USA) by applying MDX4-4210 to the outer 5 mm of these constructs
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211363&req=5

Fig1: (a) Schematic cross-section of modified Flexcell system. This schematic shows the polycarbonate rings (gray) placed around the loading post, which limit the deformation of the membrane when a vacuum is applied. (b) Reinforcement of the polyglycolic acid scaffold with an elastic silicone layer. In the upper part a longitudinal cross-section of the PGA/P4HB scaffold embedded in an elastic silicone layer. A layer of 0.5 mm thick, consisting of MDX4-4210 (Dow Corning, USA). In the lower part rectangular scaffolds (34  ×  5 mm2 × ±1–1.2 mm) were attached to Bioflex culture wells (Flexcell Int. Corp., USA) by applying MDX4-4210 to the outer 5 mm of these constructs
Mentions: In Fig. 1a a schematic overview of the modified straining setup is shown. When a vacuum is applied to the flexible membrane of the Bioflex plate, the membrane will deform at the locations where it is not supported by the loading post. Polycarbonate rings of varying height were placed around the original loading posts. When a maximum vacuum is applied in the presence of the polycarbonate rings, the rings limit the deformation of the flexible silicone membrane. By varying the height of these rings the deformation of the membrane can be varied.Figure 1

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