Matrix architecture plays a pivotal role in 3D osteoblast migration: The effect of interstitial fluid flow

Abstract

Osteoblast migration is a crucial process in bone regeneration, which is strongly regulated by interstitial fluid flow. However, the exact role that such flow exerts on osteoblast migration is still unclear. To deepen the understanding of this phenomenon, we cultured human osteoblasts on 3D microfluidic devices under different fluid flow regimes. Our results show that a slow fluid flow rate by itself is not able to alter the 3D migratory patterns of osteoblasts in collagen-based gels but that at higher fluid flow rates (increased flow velocity) may indirectly influence cell movement by altering the collagen microstructure. In fact, we observed that high fluid flow rates (1 µl/min) are able to alter the collagen matrix architecture and to indirectly modulate the migration pattern. However, when these collagen scaffolds were crosslinked with a chemical crosslinker, specifically, transglutaminase II, we did not find significant alterations in the scaffold architecture or in osteoblast movement. Therefore, our data suggest that high interstitial fluid flow rates can regulate osteoblast migration by means of modifying the orientation of collagen fibers. Together, these results highlight the crucial role of the matrix architecture in 3D osteoblast migration. In addition, we show that interstitial fluid flow in conjunction with the matrix architecture regulates the osteoblast morphology in 3D.

3D Cell Migration Studies for Chemotaxis on Microfluidic-Based Chips: A Comparison between Cardiac and Dermal Fibroblasts

“…After several washes, cells were incubated with phalloidin-TRICT (1:100) and 4’,6-diamino-2-fenilindol (DAPI) (1:50) at 0.5% BSA/PBS for 3 h at room temperature in the dark and washed with PBS. Their maximum intensity projections were obtained from 3D images using confocal microscopy at 40× lens and cell shapes were analysed with a MatLab script developed in-house [ 23 ].…”

Primary Human Osteoblasts Cultured in a 3D Microenvironment Create a Unique Representative Model of Their Differentiation Into Osteocytes

“…For example, the use of optically transparent materials allowed the monitoring of osteoblast motility in a confined 3D environment (Movilla et al, 2018). The results of this study elucidated the effect of ECM degradation and its architecture on osteoblast migration, by applying growth factor gradients or interstitial fluid flow (Del Amo et al, 2018). Moreover, the culture chamber geometries facilitate the reproduction of 3D organ-level structures.…”

“…During the polymerization process, collagen fibers create an interpenetrating polymer network in presence of living cells (Rowe and Stegemann, 2006). The microarchitecture and the mechanical properties of the collagen fibrous hydrogels used in this study were characterized in previous studies (Moreno-Arotzena et al, 2015;Del Amo et al, 2018). In the present work, we selected the 6 mg/ml gel because its Young modulus (∼0.72 kPa, from Valero et al, 2018) was comparable to the one (∼0.58 kPa) that allowed a homogeneous cell distribution in a 3D matrix and enhanced osteocytic differentiation of MC3T3-E1 cells (McGarrigle et al, 2016).…”

Image-based Characterization of 3D Collagen Networks and the Effect of Embedded Cells

“…In this second case, collagen gels were not fluorescently labelled and were analysed by means of confocal reflection microscopy. These two methods are currently the most used for the study of collagen microstructures in 3D in biological laboratories (Chung et al, 2012;Cóndor et al, 2017;Del Amo et al, 2018;Kueng et al, 1989;Leclerc et al, 2003;Sung et al, 2009).…”

“…However, in vivo, the 3D ECM presents a more complex environment which leads to a wide variety of changes in cells in terms of their morphology, adhesion, migration or biological response (Del Amo et al, 2018;Pedersen & Swartz, 2005). Consequently, using in vitro 3D experiments reflects more realistically cell response in tissues and they are becoming crucial research tools.…”