A Passive Microfluidic Device for Chemotaxis Studies

Abstract

This work presents a disposable passive microfluidic system, allowing chemotaxis studies, through the generation of a concentration gradient. The device can handle liquid flows without an external supply of pressure or electric gradients, but simply using gravity force. It is able to ensure flow rates of 10 µL/h decreasing linearly with 2.5% in 24 h. The device is made of poly(methylmethacrylate) (PMMA), a biocompatible material, and it is fabricated by micro-milling and solvent assisted bonding. It is assembled into a mini incubator, designed properly for cell biology studies in passive microfluidic devices, which provides control of temperature and humidity levels, a contamination-free environment for cells with air and 5% of CO2. Furthermore, the mini incubator can be mounted on standard inverted optical microscopes. By using our microfluidic device integrated into the mini incubator, we are able to evaluate and follow in real-time the migration of any cell line to a chemotactic agent. The device is validated by showing cell migration at a rate of 0.36 µm/min, comparable with the rates present in scientific literature.

A Micro-Optic Stalk (μOS) System to Model the Collective Migration of Retinal Neuroblasts

“…In addition, small clusters exhibited a high directionality in the horizontal plane with an average value of DR = 0.72 ± 0.15 in response to FGF. These data suggest that the migration of smaller RNB clusters is more dependent on the concentration gradient field than the absolute concentration threshold, as supported by numerous studies [55,71,72] identifying gradient effects as dominant forces in chemotaxis. Further, previous study from our group used microdevices of much larger dimensions (>100 µm) to illustrate a similar preferred cluster migration of retinal progenitors in the 3-5 cell range [36].…”

“…Each loading channel is 75 µm in diameter and 3 × 10 3 µm in length to facilitate the convective transport of molecules into the µOS geometry. The Y-shape design was selected to minimize the volume to surface area of the loading regions [55,56]. The upper left and upper right loading ports concurrently flush solutions of reagent and cell media, independently, into the vertical compartments to generate tailored concentration fields within the adjoining microchannels via bulk diffusion [55].…”

“…The Y-shape design was selected to minimize the volume to surface area of the loading regions [55,56]. The upper left and upper right loading ports concurrently flush solutions of reagent and cell media, independently, into the vertical compartments to generate tailored concentration fields within the adjoining microchannels via bulk diffusion [55]. The BL reservoir filled with FGF is denoted as the source reservoir, and the EID reservoir filled with media is denoted as the sink reservoir in all experiments.…”

Remodeling of the Microvasculature: May the Blood Flow Be With You

“…But they come with limitations since they are not very versatile (fixed geometries and fluid properties) and they are expensive (disposable and non-reusable plates and consumables) (Roest et al, 2011). These type of 2D systems are mostly interesting to examine the role of shear stress exerted by different types of flow including laminar, pulsatile and reciprocating flow (Usami et al, 1993;Chien, 2007) but, in addition to the limitations already discussed, they do not incorporate the remodeling of the extracellular matrix (ECM) nor its mechanical properties, failing to fully recapitulate the complex 3D environment, geometries or the shear stress gradients found in vivo (Coluccio et al, 2019;Gordon et al, 2020).…”

A Disposable Passive Microfluidic Device for Cell Culturing

“…Microfluidic systems provide an excellent control of microenvironments [2][3][4], which is useful for high-performance cellular screenings [5][6][7][8], due to a high level of functional elements [9][10][11] and sensor integration [12][13][14][15][16], and for generating different types of gradients [17][18][19][20]. Moreover, microfluidic platforms offer the possibility to dynamically and automatically modify the microenvironment in different ways [21][22][23] for several applications [24][25][26][27].…”