title: Controlling matrix formation and cross-linking by hypoxia in cardiovascular tissue engineering.
abstract: In vivo functionality of cardiovascular tissue engineered constructs requires in vitro control of tissue development to obtain a well developed extracellular matrix (ECM). We hypothesize that ECM formation and maturation is stimulated by culturing at low oxygen concentrations. Gene expression levels of monolayers of human vascular-derived myofibroblasts, exposed to 7, 4, 2, 1, and 0.5% O(2) (n = 9 per group) for 24 h, were measured for vascular endothelial growth factor (VEGF), procollagen α1(I) and α1(III), elastin, and cross-link enzymes lysyl oxidase (LOX) and lysyl hydroxylase 2 (LH2). After 4 days of exposure to 7, 2, and 0.5% O(2) (n = 3 per group), protein synthesis was evaluated. All analyses were compared with control cultures at 21% O(2). Human myofibroblasts turned to hypoxia-driven gene expression, indicated by VEGF expression, at oxygen concentrations of 4% and lower. Gene expression levels of procollagen α1(I) and α1(III) increased to 138 ± 26 and 143 ± 19%, respectively, for all oxygen concentrations below 4%. At 2% O(2), LH2 and LOX gene expression levels were higher than control cultures (340 ± 53 and 136 ± 29%, respectively), and these levels increased even further with decreasing oxygen concentrations (611 ± 176 and 228 ± 45%, respectively, at 0.5% O(2)). Elastin gene expression levels remained unaffected. Collagen synthesis and LH2 protein levels increased at oxygen concentrations of 2% and lower. Oxygen concentrations below 4% induce enhanced ECM production by human myofibroblasts. Implementation of these results in cardiovascular tissue engineering approaches enables in vitro control of tissue development.
authors.affiliation: Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands. m.a.a.v.vlimmeren@tue.nl
authors.forename: Marijke A A
authors.initials: MA
authors.lastname: van Vlimmeren
authors.forename: Anita
authors.initials: A
authors.lastname: Driessen-Mol
authors.forename: Marloes
authors.initials: M
authors.lastname: van den Broek
authors.forename: Carlijn V C
authors.initials: CV
authors.lastname: Bouten
authors.forename: Frank P T
authors.initials: FP
authors.lastname: Baaijens
mesh_terms: D015687:Cell Hypoxia; D049109:Cell Proliferation; D048430:Cell Shape; D002470:Cell Survival; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D008875:Middle Aged; D058628:Myofibroblasts / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D012038:Regeneration; D013997:Time Factors; D023822:Tissue Engineering
chemical_list: D016326:Extracellular Matrix Proteins; D010100:Oxygen