Mimicking physiological flow conditions to study alterations of bioactive glass surfaces in vitro

2017 ◽  
Vol 106 (1) ◽  
pp. 228-236 ◽  
Author(s):  
Miriam Höner ◽  
Frederik Böke ◽  
Michael Weber ◽  
Horst Fischer
Keyword(s):  
Bioactive Glass ◽  
Flow Conditions ◽  
Physiological Flow ◽  
Glass Surfaces

Surface Morphological Changes Accompanying Dissolution of Bioactive Glass: Effect of Residual Stress

2008 ◽  
Vol 47-50 ◽  
pp. 1302-1306 ◽  
Author(s):  
John A. Nychka ◽  
Ding Li
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Bioactive Glass ◽  
Morphological Changes ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
Mechanochemical Effect ◽  
Dissolution Behaviour ◽  
Glass Surfaces

We report our observations concerning the time evolution of surface morphology occurring during the in vitro immersion of bioactive glass surfaces in contact with phosphate buffer solution. We compare regions under intentionally produced residual stresses via micro-indentation to those where no indentation was performed. The sign of the residual stress is shown to be important for predicting dissolution behaviour; compression retards dissolution, whereas tension enhances dissolution. We analyze our results with a simple model for the work of bond dissociation. We report that a highly constrained residual compressive stress state, such as in an indent, leads to a work deficit in comparison to tension, which accounts for the slower dissolution rate of compressed bioactive glass. Such a mechanochemical effect suggests that the presence of residual stresses from the manufacture of biomedical implants and devices could lead to accelerated or delayed dissolution and that careful control of residual stresses should be sought for predictable performance in dissolvable materials.

scholarly journals A Novel Bioreactor for Mechanobiological Studies of Engineered Heart Valve Tissue Formation Under Pulmonary Arterial Physiological Flow Conditions

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Sharan Ramaswamy ◽  
Steven M. Boronyak ◽  
Trung Le ◽  
Andrew Holmes ◽  
Fotis Sotiropoulos ◽  
...  
Keyword(s):  
Shear Stress ◽  
Laminar Flow ◽  
Heart Valve ◽  
Tissue Formation ◽  
Flow Conditions ◽  
Physiological Flow ◽  
Valve Tissue ◽  
Engineered Tissue ◽  
Heart Valve Tissue

The ability to replicate physiological hemodynamic conditions during in vitro tissue development has been recognized as an important aspect in the development and in vitro assessment of engineered heart valve tissues. Moreover, we have demonstrated that studies aiming to understand mechanical conditioning require separation of the major heart valve deformation loading modes: flow, stretch, and flexure (FSF) (Sacks et al., 2009, "Bioengineering Challenges for Heart Valve Tissue Engineering," Annu. Rev. Biomed. Eng., 11(1), pp. 289–313). To achieve these goals in a novel bioreactor design, we utilized a cylindrical conduit configuration for the conditioning chamber to allow for higher fluid velocities, translating to higher shear stresses on the in situ tissue specimens while retaining laminar flow conditions. Moving boundary computational fluid dynamic (CFD) simulations were performed to predict the flow field under combined cyclic flexure and steady flow (cyclic-flex-flow) states using various combinations of flow rate, and media viscosity. The device was successfully constructed and tested for incubator housing, gas exchange, and sterility. In addition, we performed a pilot experiment using biodegradable polymer scaffolds seeded with bone marrow derived stem cells (BMSCs) at a seeding density of 5 × 106 cells/cm2. The constructs were subjected to combined cyclic flexure (1 Hz frequency) and steady flow (Re = 1376; flow rate of 1.06 l/min (LPM); shear stress in the range of 0–9 dynes/cm2) for 2 weeks to permit physiological shear stress conditions. Assays revealed significantly (P < 0.05) higher amounts of collagen (2051 ± 256 μg/g) at the end of 2 weeks in comparison to similar experiments previously conducted in our laboratory but performed at subphysiological levels of shear stress (<2 dynes/cm2; Engelmayr et al., 2006, "Cyclic Flexure and Laminar Flow Synergistically Accelerate Mesenchymal Stem Cell-Mediated Engineered Tissue Formation: Implications for Engineered Heart Valve Tissues," Biomaterials, 27(36), pp. 6083–6095). The implications of this novel design are that fully coupled or decoupled physiological flow, flexure, and stretch modes of engineered tissue conditioning investigations can be readily accomplished with the inclusion of this device in experimental protocols on engineered heart valve tissue formation.

scholarly journals Introduction of a new model for time-continuous and non-contact investigations of in-vitro thrombolysis under physiological flow conditions

BMC Neurology ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Florian C Roessler ◽  
Marcus Ohlrich ◽  
Jan H Marxsen ◽  
Marc Schmieger ◽  
Peter-Karl Weber ◽  
...  
Keyword(s):  
Flow Conditions ◽  
New Model ◽  
Physiological Flow ◽  
Contact Investigations

scholarly journals A surface acoustic wave-driven micropump for particle uptake investigation under physiological flow conditions in very small volumes

2015 ◽  
Vol 6 ◽  
pp. 414-419 ◽  
Author(s):  
Florian G Strobl ◽  
Dominik Breyer ◽  
Phillip Link ◽  
Adriano A Torrano ◽  
Christoph Bräuchle ◽  
...  
Keyword(s):  
Cellular Uptake ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Fluid Motion ◽  
Flow Profile ◽  
Flow Conditions ◽  
Particle Uptake ◽  
Physiological Flow ◽  
Static Conditions

Static conditions represent an important shortcoming of many in vitro experiments on the cellular uptake of nanoparticles. Here, we present a versatile microfluidic device based on acoustic streaming induced by surface acoustic waves (SAWs). The device offers a convenient method for introducing fluid motion in standard cell culture chambers and for mimicking capillary blood flow. We show that shear rates over the whole physiological range in sample volumes as small as 200 μL can be achieved. A precise characterization method for the induced flow profile is presented and the influence of flow on the uptake of Pt-decorated CeO2 particles by endothelial cells (HMEC-1) is demonstrated. Under physiological flow conditions the particle uptake rates for this system are significantly lower than at low shear conditions. This underlines the vital importance of the fluidic environment for cellular uptake mechanisms.

Sign in / Sign up

Export Citation Format

Share Document