title: Dynamic compressive strain influences chondrogenic gene expression in human mesenchymal stem cells.
abstract: This study tests the hypothesis that dynamic compressive strain selectively enhances chondrogenic differentiation by human mesenchymal stem cells (MSCs). Primary MSCs were isolated and expended in monolayer culture. The cells were seeded in alginate constructs or in pellet culture. The time course of chondrogenic differentiation was assessed by real-time QPCR of mRNA expression analysis for cartilage specific markers. Collagen types II and X mRNA, not present in undifferentiated MSCs, were detectable by 2-4 days of chondrogenic induction and continued to rise significantly throughout the culture period of 10 days (p < 0.001). Basal levels of gene expression for Sox-9 and aggrecan were evident in undifferentiated MSCs, although chondrogenic induction for a period of 8 days resulted in an increased trend in the gene expression levels. The alginate system was also used in mechanical conditioning studies. Dynamic compression was applied, in an intermittent regimen, at a strain amplitude of 15% and frequency of 1 Hz in the presence and absence of 10 ng/ml TGFbeta3, for a period of 8 days. Results indicated significant changes in the levels of mRNA expression for the chondrogenic markers. For example, by day 8, the application of the strain regimen alone caused an up-regulation in all the chondrogenic markers compared to the control samples (no TGFbeta, no compression). However, the combined effects of strain and TGFbeta on these markers were more complex than purely additive.
authors.affiliation: Medical Engineering Division and IRC in Biomedical Materials, Department of Engineering, Queen Mary University of London, London, UK.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Campbell
authors.forename: David A
authors.initials: DA
authors.lastname: Lee
authors.forename: Dan L
authors.initials: DL
authors.lastname: Bader
mesh_terms: D000464:Alginates; D002454:Cell Differentiation / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D020219:Chondrogenesis / Q000235:genetics / Q000502:physiology*; D003094:Collagen / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006609:High Mobility Group Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D040542:Mechanotransduction, Cellular / Q000235:genetics / Q000502:physiology*; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D055758:SOX9 Transcription Factor; D013314:Stress, Mechanical; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D006609:High Mobility Group Proteins; D012333:RNA, Messenger; D055758:SOX9 Transcription Factor; C527932:SOX9 protein, human; D014157:Transcription Factors; D020723:Glucuronic Acid; D003094:Collagen