Effect of dynamic compressive loading and its combination with a growth factor on the chondrocytic phenotype of 3-dimensional scaffold-embedded chondrocytes

Abstract

Background and purpose 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.Interpretation 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.

Opinion Statement of the Effect of Mechanical Stress on Cartilage Tissue Engineering~!2010-01-12~!2010-04-26~!2010-06-23~!

“…Elder et al [63] demonstrated that low amplitude cyclic compression at 0.33 Hz promoted GAG synthesis of mesenchymal cells from chick limb bud embedded in agarose gel. Furthermore, we also found that cyclic compressive loading of 5% amplitude in cycles of 3s stimulated cartilage-specific ECM synthesis by chondrocytes embedded in type I collagen gel [76].…”

Chondrocyte source for cartilage regeneration in an immature animal: Is iliac apophysis a good alternative?

“…The chondrogenic differentiation of mesenchymal stem cells from bone marrow, adipose tissue, and umbilical cord has been explored 41112. One of the major issues in chondrocyte expansion is the quality of the chondrocytes grown in vitro , mainly its ability to retain its phenotype in culture, if hyaline cartilage regeneration is to be achieved 411–13. There is a good source of autogenous chondrocyte in the iliac apophyseal growth plate in children, which can be potentially used for treating growth plate abnormality and articular cartilage defects 14.…”

Cartilage restoration in haemophilia: advanced therapies

“…But the difficulty of single-layer chondrocyte culture is that the cells undergo de-differentiation (they lose their specific characteristics), which results in failure to synthesize hyaline cartilage thereby losing therapeutic efficacy. To address this methodological problem, an attempt was made to culture these cells in 3D matrices, which did result in the secretion of growth factors, but exposed the chondrocytes to mechanical stress [16]. A solution for this, put forward by Maher et al [17], consisted in the incorporation of chondrocytes to biomaterials such as nanofiber hydrogels.…”