Effect of dynamic compressive loading and its combination with a growth factor on the chondrocytic phenotype of 3-dimensional scaffold-embedded chondrocytes.
OBJECTIVE
Three-dimensionally (3D-) embedded chondrocytes have been suggested to maintain the chondrocytic phenotype. Furthermore, mechanical stress and growth factors have been found to be capable of enhancing cell proliferation and ECM synthesis. We investigated the effect of mechanical loading and growth factors on reactivation of the 3D-embedded chondrocytes.


METHODS
Freshly isolated chondrocytes from rat articular cartilage were grown in monolayer cultures and then in collagen gel. Real-time RT-PCR and histological analysis for aggrecan and type II and type I collagen was performed to evaluate their chondrocytic activity. Then, the 3D-embedded chondrocytes were cultured under either mechanical loading alone or in combination with growth factor. The dynamic compression (5% compression, 0.33 Hz) was loaded for 4 durations: 0, 10, 60, and 120 min/day. The growth factor administered was either basic fibroblast growth factor (bFGF) or bone morphogenetic protein-2 (BMP-2).


RESULTS
Mechanical loading statistically significantly reactivated the aggrecan and type II collagen expression with loading of 60 min/day as compared to the other durations. The presence of BMP-2 and bFGF clearly enhanced the aggrecan and type II collagen expression of 3D-embedded chondrocytes. Unlike previous reports using monolayer chondrocytes, however, BMP-2 or bFGF did not augment the chondrocytic phenotype when applied together with mechanical loading.


CONCLUSIONS
Dynamic compression effectively reactivated the dedifferentiated chondrocytes in 3D culture. However, the growth factors did not play any synergistic role when applied with dynamic compressive loading, suggesting that growth factors should be administered at different time points during regeneration of the transplantation-ready cartilage.
Ando
Kosei
K
Department of Orthopaedic Surgery, Shiga University of Medical Science, Otsu, Shiga, Japan. ando-ko@mx.scn.tv
Imai
Shinji
S
Isoya
Eiji
E
Kubo
Mitsuhiko
M
Mimura
Tomohiro
T
Shioji
Suguru
S
Ueyama
Hisao
H
Matsusue
Yoshitaka
Y
D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D019245:Compressive Strength; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical
D055396:Bone Morphogenetic Protein 2; D016222:Fibroblast Growth Factor 2