A tuneable microfluidic system for long duration chemotaxis experiments in a 3D collagen matrix

Abstract

In many cell types, migration can be oriented towards a chemical stimulus. In mammals, for example, embryonic cells migrate to follow developmental cues, immune cells migrate toward sites of inflammation, and cancer cells migrate away from the primary tumour and toward blood vessels during metastasis. Understanding how cells migrate in 3D environments in response to chemical cues is thus crucial to understanding directed migration in normal and disease states. To date, chemotaxis in mammalian cells has been primarily studied using 2D migration models. However, it is becoming increasingly clear that the mechanisms by which cells migrate in 2D and 3D environments dramatically differ, and cells in their native environments are confronted with a complex chemical milieu. To address these issues, we developed a microfluidic device to monitor the behaviour of cells embedded in a 3D collagen matrix in the presence of complex concentration fields of chemoattractants. This tuneable microsystem enables the generation of (1) homogeneous, stationary gradients set by a purely diffusive mechanism, or (2) spatially evolving, stationary gradients, set by a convection-diffusion mechanism. The device allows for stable gradients over several days and is large enough to study the behaviour of large cell aggregates. We observe that primary mature dendritic cells respond uniformly to homogeneous diffusion gradients, while cell behaviour is highly position-dependent in spatially variable convection-diffusion gradients. In addition, we demonstrate a directed response of cancer cells migrating away from tumour-like aggregates in the presence of soluble chemokine gradients. Together, this microfluidic device is a powerful system to observe the response of different cells and aggregates to tuneable chemical gradients.

Randomly Distributed K14+ Breast Tumor Cells Polarize to the Leading Edge and Guide Collective Migration in Response to Chemical and Mechanical Environmental Cues

“…In addition, we use primary tumor organoids with all their inherent heterogeneity, which preserves in vivo cell-cell and cell-matrix interactions. Prior studies using microfluidic devices have focused on forming 3D aggregates of homogeneous tumor cell lines or mixtures of cell lines (38,39), and thus do not account for the dynamic and differential response of an inherently heterogeneous cell population.…”

Nano-scale microfluidics to study 3D chemotaxis at the single cell level

“…Therefore, a number of cell culture systems have been developed to track cells migrating in 3D microenvironments [ 11 ]. Also, several microfluidic devices have been developed that allow exposure of cells cultured in 3D to soluble gradients [ 33 – 35 ]. However, spatiodeterministic retrieval of cells from these microfluidic chips was not possible in such setups.…”

Reconstitution of cell migration at a glance

“…The physical and chemical properties of each path can be well controlled and independently tuned. Consequently, research on directed migration of leukocytes and tumor cells pointed to sensitivity of the directional choice to very small force imbalances, such as the one introduced by hydraulic resistance (Moreau et al, 2018 preprint;Aizel et al, 2017;Cheng et al, 2007;Chung et al, 2009;Clark et al, 2018;Polacheck et al, 2011;Prentice-Mott et al, 2013;Sáez et al, 2018a) and the importance of the microtubule cytoskeleton in symmetry breaking and cell polarization towards the chosen path (Leithner et al, 2016;Mak and Erickson, 2014;Vargas et al, 2016).…”

“…Among leukocytes, directed migration of neutrophils towards an injured tissue and of dendritic cells towards the lymphatic vessels are key functions that involve the coordination between mechanosensing of the microenvironment and sensing of chemical cues (Théry, 2010;Vargas et al, 2017). To study chemotaxis through complex environments, it is possible to combine a 3D collagen meshwork and a well-controlled chemokine gradient (Aizel et al, 2017;Cheng et al, 2007;Chung et al, 2009;Clark et al, 2018;Maiuri et al, 2012;Polacheck et al, 2011;Sáez et al, 2018a). For example, a microfabricated chamber contains a central compartment with a collagen gel, open to a side chamber in which chemokines can be injected and diffuse through the gel (see poster).…”