ABSTRACT
To find a new source of seed cells for constructing tissue-engineered intervertebral disc, nucleus pulposus (NP) cells and mesenchymal stem cells (MSCs) were isolated from New Zealand white rabbits. The nucleus pulposus cells population was fluorescence-laelled and co-cultured with MSCs with or without direct contact. Morphological changes were observed every 12 h. Semi-quantitative reverse transcriptase-polymerase chain reaction was performed to assess the expression levels of Sox-9, aggreacan and type II collagen every 24 h after the co-culture. MSCs treated with direct contact rounded up and presented a ring-like appearance. The expression of marker genes was significantly increased when cells were co-cultured with direct contact for 24 h. No significant change was found after coculture without direct contact. Co-culture of NP cells and MSCs with direct contact is a reliable method for generating large amount of NP cells used for cell-based tissue engineering therapy.
Subject(s)
Aggrecans/metabolism , Cell Differentiation , Cells, Cultured , Coculture Techniques , Collagen/metabolism , Gene Expression , Gene Expression Regulation , High Mobility Group Proteins/metabolism , Intervertebral Disc/cytology , Mesenchymal Stem Cells/cytology , Mesenchymal Stem Cells/metabolism , Models, Biological , Reverse Transcriptase Polymerase Chain Reaction , SOX9 Transcription Factor , Tissue Engineering/instrumentation , Tissue Engineering/methods , Transcription Factors/metabolismABSTRACT
Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 µM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30 per cent H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.