Simultaneous Application of Interstitial Flow and Cyclic Mechanical Strain to a Three-Dimensional Cell-Seeded Hydrogel

Abstract

The present study describes the design and validation of a simple apparatus to apply simultaneous mechanical and fluidic stress to three-dimensional (3D) cell-seeded collagen hydrogels. Constructs were formed in wells in a silicone substrate that could be stretched cyclically, and were also fitted with inlet ports to apply fluid flow. Acid etching was used to retain adhesion of the gels to the walls of the well, and an acellular layer of collagen hydrogel was used to distribute flow evenly. Finite element modeling showed that 5% uniaxial strain applied to the entire silicone substrate resulted in *6.5% strain in each of the gel constructs. Permeability testing and flow observation showed that acellular hydrogels were fourfold more permeable than cardiac fibroblast-seeded gels, and that the fluid distributed evenly in the acellular layer before entering the cell-seeded gel. Viability testing and imaging demonstrated that cells remained viable with expected fibroblast morphology for the 120 h duration of the experiments. These results demonstrate that this simple bioreactor can be used to study the effects of mechanical strain and interstitial flow in 3D protein hydrogels. Such 3D tissue models have utility in studying cell and tissue responses to their mechanical environment.

Microfluidics embedded within extracellular matrix to define vascular architectures and pattern diffusive gradients

“…Subsequently, 2D models were generated by importing device geometries directly from lithographic masks created in Adobe Illustrator. Model parameters including the permeability (5.5×10 −14 m 2 ) and porosity (99.6%) of the surrounding collagenous matrix, diffusivity (1×10 −9 m 2 /s) of the solute, and flow rates within the channels (10 nl/s) were defined 22,23 . Predicted steady state diffusive patterns are presented.…”

Injection of mesenchymal stromal cells into a mechanically stimulated in vitro model of cardiac fibrosis has paracrine effects on resident fibroblasts

“…In this study, fibroblast-seeded gels were prepared in custom-made polydimethylsiloxane (PDMS, Dow Corning, Midland, MI) wells, which prevented compaction of the gel matrix by the resident cells. This culture system has been developed and characterized previously and allows controlled application of 5% cyclic strain and/or perfusion with 10 μL/min cross flow [28]. These values of strain are relevant for cells in the heart wall in both rodent and human models, and are comparable values have been used in previous studies [29,30].…”

“…The apparatus used to apply cyclic mechanical strain and interstitial fluid flow to cell-seeded 3D collagen constructs has been described and characterized previously [28,31]. Briefly, constructs were cultured at 37 °C with 100% humidity and 5% CO 2 for 24 hours after gel polymerization (and 12 hours following MSC injection).…”

Mechanostimulation Protocols for Cardiac Tissue Engineering

“…In 2011, Galie and Stegemann [56] validated a device where simultaneous mechanical and fluidic stress was applied to a 3D cell construct. Cardiac fibroblasts were suspended in a collagen type I gel to obtain a 3D cell construct and subjected to cyclic strain (5%; 1 Hz) and interstitial flow (10 mL/min).…”