a modular bioreactor for mechanical conditioning …...a modular bioreactor for mechanical...
TRANSCRIPT
Tissue Engineering and Regenerative Medicine International Society – EU Meeting -2010Galway, Ireland
A Modular Bioreactor for Mechanical Conditioning of Tissue Engineered Constructs: AnApplication on Endothelial Cells
Yannis F Missirlis, Stergios C Dermenoudis,Corresponding Author: [email protected]
Laboratory of Biomechanics & Biomedical Engineering, Mechanical Engineering & Aeronautics Dept.,University of Patras, Rion, Greece
IntroductionTissue engineering offers the possibility ofdeveloping a biological substitute material invitro using bioreactors in which the in vivomechanical and biochemical conditions aresimulated.The hypothesis that drives our experimentalwork is that endothelial cells (EC) are able todifferentiate towards a specific phenotype whencultivated under a given set of mechanicalstimuli. To assess that, a novel bioreactorcapable of submitting ECs’ to 1) shear stresses(blood flow), 2) normal stresses (internalpressure), 3) mechanical stress (substrate strain)and 4) gravitational forces was constructed.
Materials and MethodsThe bioreactor was designed with Solidworks2008. The engineering drawings guided theconstruction of the device (fig.1).Ethylene Vinyl Acetate (EVA) tubular pieces(4mm inner diameter) were coated with 4%gelatine crosslinked with glutaraldehyde. Thetube was loaded on the bioreactor.Bovine capillary endothelial cells (BCE-HT+)were infused (50.000 cells/cm2) while therotation mode was activated (9rph). 4hrs later amechanical stimulus was superimposed.After 12hrs of exposure to a specific mechanicalenvironment, cell viability and morphologyresponse were evaluated by fluorescein diacetate(FDA)/propidium iodide (PI) staining. Images ofthe cells were acquired using confocalmicroscopy.
ResultsA shear rate of 103s-1 causes the cells to reorientparallel to the flow direction(1) (fig.2A). Cyclicuniaxial stretch of 6,7% at 1Hz induces a verticalorientation of the cell population(2) (fig.2B). Therotation of 1800rph results in elongated cells andthe creation of spiral formations (fig.2C). Whenrotation is combined with the other stimuli, it
suppresses the elongation of the cells but doesnot affect their orientation profile (fig.2D-E).
Fig. 1. A) Oscillating plate delivering theuniaxial substrate strain. B) Loaded biomaterialspecimen seeded with ECs. C) Rotationmechanism. D) Medium inflow and outflowdelivering the shear stress to the ECs
Fig. 2. FDA/PI staining of ECs
Discussion and ConclusionsThe use of the described modular bioreactor hasenabled us to observe the response of ECs to acombination of relevant mechanical stimuli.Experiments with different extra cellularmatrices (ECMs), primary ECs and forcemodalities are in progress.
References1. Kataoka N. (1998) Medical & BiologicalEngineering & Computing, 36(1), 122.2. Moretti M. (2004) J. of Materials Science:Materials in Medicine, 15, 1159.
DisclosuresAuthors have nothing to disclose.