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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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Representative two dimensional tissue strain distributions on the surface of an engineered tissue. (a) Representative two dimensional strain (%) distribution in case of a 8.16 mm ring. (b) Representative two dimensional strain (%) distribution in case of a 7.47 mm ring
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Fig3: Representative two dimensional tissue strain distributions on the surface of an engineered tissue. (a) Representative two dimensional strain (%) distribution in case of a 8.16 mm ring. (b) Representative two dimensional strain (%) distribution in case of a 7.47 mm ring

Mentions: The strain fields at the surface of the strained engineered cardiovascular constructs (n = 6) were validated for two different strain rings (8.16 and 7.47 mm) after 2 weeks of dynamic culture. After 2 weeks of culture the average strain (%) measured 4.57 ± 1.34 and 8.04 ± 2.81, respectively. Typical strain fields after 2 weeks of culture for both ring heights (Figs. 3a and 3b, respectively) showed a more inhomogeneous distribution than the strain applied to the membrane without the tissue construct. The measured average applied strain in the tissue constructs is nearly equal to the membrane only situation (two dimensional), but the standard deviations are larger, reflecting the more inhomogeneous nature of the strain field. Furthermore, the major strain direction for both straining conditions (Fig. 3) is uniaxial.Figure 3


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)

Representative two dimensional tissue strain distributions on the surface of an engineered tissue. (a) Representative two dimensional strain (%) distribution in case of a 8.16 mm ring. (b) Representative two dimensional strain (%) distribution in case of a 7.47 mm ring
© Copyright Policy
Related In: Results  -  Collection

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

Fig3: Representative two dimensional tissue strain distributions on the surface of an engineered tissue. (a) Representative two dimensional strain (%) distribution in case of a 8.16 mm ring. (b) Representative two dimensional strain (%) distribution in case of a 7.47 mm ring
Mentions: The strain fields at the surface of the strained engineered cardiovascular constructs (n = 6) were validated for two different strain rings (8.16 and 7.47 mm) after 2 weeks of dynamic culture. After 2 weeks of culture the average strain (%) measured 4.57 ± 1.34 and 8.04 ± 2.81, respectively. Typical strain fields after 2 weeks of culture for both ring heights (Figs. 3a and 3b, respectively) showed a more inhomogeneous distribution than the strain applied to the membrane without the tissue construct. The measured average applied strain in the tissue constructs is nearly equal to the membrane only situation (two dimensional), but the standard deviations are larger, reflecting the more inhomogeneous nature of the strain field. Furthermore, the major strain direction for both straining conditions (Fig. 3) is uniaxial.Figure 3

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