The effects of cross-linking of collagen-glycosaminoglycan scaffolds on compressive stiffness, chondrocyte-mediated contraction, proliferation and biosynthesis.
The healing of articular cartilage defects may be improved by the use of implantable three-dimensional matrices. The present study investigated the effects of four cross-linking methods on the compressive stiffness of collagen-glycosaminoglycan (CG) matrices and the interaction between adult canine articular chondrocytes and the matrix: dehydrothermal treatment (DHT), ultraviolet irradiation (UV), glutaraldehyde treatment (GTA), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC). The degree and kinetics of chondrocyte-mediated contraction, chondrocyte proliferation, and protein and glycosaminoglycan synthesis were evaluated over a four-week period in vitro. Cell-mediated contraction of the matrices varied with cross-linking: the most compliant DHT and UV matrices contracted the most (60% reduction in matrix diameter) and stiffest EDAC matrices contracted the least (30% reduction in matrix diameter). All cross-linking protocols permitted cell proliferation and matrix synthesis as measured by DNA content and radiolabeled sulfate and proline incorporation, respectively. During the first week in culture, a lower level of proliferation was seen in the GTA matrices but over the four-week culture period, the GTA and EDAC matrices provided for the greatest cell proliferation. On day 2, there was a significantly lower rate of 3H-proline incorporation in the GTA matrices (p<0.003) although at later time points, the EDAC and GTA matrices exhibited the highest levels of matrix synthesis. With regard to cartilage-specific matrix molecule synthesis, immunohistochemistry revealed a greater amount of type II collagen in DHT and UV matrices at the early time points. These findings serve as a foundation for future studies of tissue engineering of articular cartilage and the association of chondrocyte contraction and the processes of mitosis and biosynthesis.
Lee
C R
CR
Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge 02139, USA. psyn@mit.edu
Grodzinsky
A J
AJ
Spector
M
M
D000818:Animals; D002455:Cell Division; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D003094:Collagen / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004285:Dogs; D006025:Glycosaminoglycans / Q000737:chemistry / Q000378:metabolism; D007150:Immunohistochemistry
D006025:Glycosaminoglycans; D003094:Collagen; D004247:DNA