Authors: Dorien Tiemessen Paul de Jonge Willeke Daamen Wout Feitz Paul Geutjes Egbert Oosterwijk
Publish Date: 2017/02/23
Volume: 35, Issue: 10, Pages: 1531-1539
Abstract
Preconditioning of a cell seeded construct may improve the functional outcome of a tissue engineered construct for augmentation cystoplasty The precise effects of mechanical stimulation on urinary bladder cells in vitro are not clear In this study we investigate the effect of a cyclic uniaxial strain culture on urinary bladder cells which were seeded on a type I collagen scaffoldIsolated porcine smooth muscle cells or urothelial cells were seeded on a type I collagen scaffolds and cultured under static and dynamic conditions A uniform cyclic uniaxial strain was applied to the seeded scaffold using a Bose Electroforce BioDynamic bioreactor Cell proliferation rate and phenotype were investigated including SEM analysis RTPCR and immunohistochemistry for αSmooth muscle actin calponin1 desmin and RCK103 expression to determine the effects of mechanical stimulation on both cell typesDynamic stimulation of smooth muscle cell seeded constructs resulted in cell alignment and enhanced proliferation rate Additionally expression of αSmooth muscle actin and calponin1 was increased suggesting differentiation of smooth muscle cells to a more mature phenotypeMechanical stimuli did not enhance the proliferation and differentiation of urothelial cells Mechanical stimulation ie preconditioning may improve the functional in vivo outcome of smooth muscle cell seeded constructs for flexible organs such as the bladderFor patients who need bladder reconstruction a tissue engineered bladder may be an alternative to current procedures in which autologous bowel tissue is used The first clinical studies with cell seeded bladdersized constructs illustrated that scaffolds implanted in patients who had a normal bladder cycle regenerated properly while patients with abnormal cycles responded poorly 1 Bladder regeneration studies in animals indicated slow smooth muscle cell ingrowth in scaffolds probably due to the limited migration from adjacent tissue 2 This suggests that adequate conditioning of the tissue engineered construct may be needed to improve the functional outcome of the regenerated tissue for flexible organsIt has become clear that mechanical stimulation is equally important in cellular behavior as genetic and chemical signals 3 By providing mechanotransduction cell proliferation and differentiation can be influenced and it may lead to extracellular matrix ECM production 4 5 6 Therefore it is important to investigate the behavior and phenotype of cells in constructs while under defined mechanical strain before implantationA bioreactor can apply mechanical stimuli under controlled in vitro conditions 7 8 Initially vacuum suction Seliktar et al 2000 and mechanical stretch was used 5 Thereafter different bioreactor systems using hydrostatic pressures have been developed and used to study urinary bladder tissue engineering 9 Hydrostatic pressure on human bladder smooth muscle cells on aligned nanofibrous scaffolds resulted in functional improvement of the engineered tissue 10 Although this setting simulated in vivo conditions the exact impact of the mechanical stimulation on the urinary bladder cells is not clear Moreover whether mechanical stimulation of cells seeded on other materials such as collagen also leads to functional improvement is currently unclear In this study we investigated the effect of a longterm controlled cyclic uniaxial strain on urinary bladder cells which were seeded on a type I collagen scaffold mimicking the filling and emptying of the bladder to assess whether this preconditioning step is beneficial in urinary bladder tissue engineering
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