TGF-β1 and IGF-1 influence the re-differentiation capacity of human chondrocytes in 3D pellet cultures in relation to different oxygen concentrations
To prevent de-differentiation of chondrocytes in vitro, the 3D environment, growth factors and different oxygen concentrations were considered. In this in vitro study, we quantified the influence of insulin-like growth factor (IGF)-1 and/or transforming growth factor (TGF)-β1 under differing oxygen (5/21% O2) levels on the proliferation and synthesis rates of hyaline extracellular matrix (ECM) components in chondrogenic pellet cultures. Human chondrocytes isolated from articular cartilage were transferred into conical tubes to form pellets. Pellets were stimulated with TGF-β1 and/or IGF-1. After 2 and 5 weeks of cultivation the DNA concentration and expression of pro-collagen type 1, type 2 and aggrecan were analysed. Under hypoxia the DNA content remained stable. In contrast, under normoxia, cells showed an increase of DNA concentration after stimulation with TGF-β1/IGF-1 and TGF-β1. Nevertheless, DNA contents under normoxia did not reach the values of hypoxic-cultivated cells. Under both culture conditions a reduced synthesis of pro-collagen type 1 could be determined. Although the expression of pro-collagen type 2 was significantly higher under normoxia, a decrease in the case of TGF-β1/IGF-1- and IGF-1-stimulated cells was observed. Under hypoxia pro-collagen type 2 contents remained stable or increased for TGF-β1/IGF-1-stimulated cells. Furthermore, incubation with growth factors resulted in aggrecan accumulation under hypoxia, while a reduced expression under normoxia could be determined for TGF-β1/IGF-1- and IGF-1-stimulated cells. Our results demonstrate that the treatment with growth factors causes differences in the expression of ECM compounds within pellet cultures. While under normoxia TGF-β1 alone leads to a positive effect of the expression of hyaline cartilage-specific ECM components, an additive effect of both growth factors was only determined under hypoxia.
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Document Type: Research Article
Affiliations: Department of Orthopaedics, Biomechanics and Implant Technology Research Laboratory, University Medicine Rostock, Rostock, Germany
Publication date: January 1, 2012
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- The International Journal of Molecular Medicine is a monthly, peer-reviewed journal devoted to the publication of high quality studies related to the molecular mechanisms of human disease. The journal welcomes research on all aspects of molecular and clinical research, ranging from biochemistry to immunology, pathology, genetics, human genomics, microbiology, molecular pathogenesis, molecular cardiology, molecular surgery and molecular psychology.
The International Journal of Molecular Medicine aims to provide an insight for researchers within the community in regard to developing molecular tools and identifying molecular targets for the diagnosis and treatment of a diverse number of human diseases.
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