[Biomechanical tests of a new scaffold for the cultivation of chondrocytes].
OBJECTIVE
Scaffolds for the cultivation of chondrocytes are of increasing importance. So far, only little is known about their biomechanical properties. The present preliminary study addresses the biomechanical characteristics of a new collagen type I scaffold for the cultivation of chondrocytes.


METHODS
Human chondrocytes were amplified in a monolayer and then cultivated in a 3D-scaffold over a period of up to 6 weeks. The biomechanical tests addressed the properties under uniaxial compression including stiffness and viscoelastic characteristics (creep and retardation). The obtained values were normalized against the thickness of the specimens and expressed as ratios. In addition, we present histological and quantitative PCR results (for collagen type II and aggrecan).


RESULTS
The maximum force (or penetration force) revealed its highest values after a period of seven days. At this time the median value was 40 mN/mm. In the following period, a marked drop of the values was observed (19.8 mN/mm). With respect to the creep properties, we did not find any major changes over the period of six weeks. The median values were between 0.24 and 0.29 mm/mm. There were no significant differences between the samples seeded with chondrocytes and those which served as controls. A re-expansion of the samples was found with median values between 0.026 and 0.049 mm/mm (retardation). However, the original thickness was not reached after a period of 30 seconds with relief of the strain. Again, major differences of the values with respect to the duration of cultivation were not observed. Light microscopy revealed collagen type II and proteoglycans only in the pericellular region.


CONCLUSIONS
In this study not all of the biomechanical properties of the cultivated tissue were investigated. The limitation of the tests to stiffness and viscoelastic properties was reasonable in view of a potential routine use. In addition, it may facilitate a comparison between different matrix systems. In our study, the cultivation of cells within the collagen matrix did not alter the mechanical properties of the scaffold.
Schmidt-Rohlfing
B
B
Orthopädische Universitätsklinik, RWTH Aachen, Aachen. bernhard.scmidt@post.rwth-aachen.de
Gavenis
K
K
Erli
H J
HJ
Wiesemann
U
U
Schneider
U
U
D053674:Aggrecans; D001672:Biocompatible Materials / Q000378:metabolism; D001696:Biomechanical Phenomena / Q000379:methods; D018929:Cell Culture Techniques / Q000379:methods*; D002455:Cell Division / Q000502:physiology; D019902:Chondrocytes / Q000166:cytology* / Q000502:physiology*; D024042:Collagen Type I / Q000378:metabolism*; D024043:Collagen Type II / Q000378:metabolism*; D019245:Compressive Strength / Q000502:physiology; D004548:Elasticity; D016326:Extracellular Matrix Proteins; D006801:Humans; D037181:Lectins, C-Type; D008422:Materials Testing; D011509:Proteoglycans / Q000378:metabolism*; D023822:Tissue Engineering / Q000379:methods*; D014783:Viscosity
D053674:Aggrecans; D001672:Biocompatible Materials; D024042:Collagen Type I; D024043:Collagen Type II; D016326:Extracellular Matrix Proteins; D037181:Lectins, C-Type; D011509:Proteoglycans