Microtissue size and cell-cell communication modulate cell migration in arrayed 3D collagen gels

Abstract

Cells communicate through the extracellular matrix (ECM) in many physiological and pathological processes. This is particularly important during cell migration, where cell communication can alter both the speed and the direction of migration. However, most cell culture systems operate with large volumes relative to cell numbers, creating low cell densities and diluting factors that mediate cell communication. Furthermore, they lack the ability to isolate single cells or small groups of cells. Droplet forming devices allow for an ability to embed single or small groups of cells into small volume segregated 3D environments, increasing the cell density to physiological levels. In this paper we show a microfluidic droplet device for fabricating 3D collagen-based microtissues to study breast cancer cell motility. MDA-MB-231 cells fail to spread and divide in small, thin chambers. Cell migration is also stunted as compared to thick 3D gels. However, larger chambers formed by a thicker devices promote cell spreading, cell division and faster migration. In the large devices, both cell-ECM and cell-cell interactions affect cell motility. Increasing collagen density decreases cell migration and increasing the number of cells per chamber increases cell migration speed. Furthermore, cells appear to sense both the ECM-chamber wall interface as well as other cells. Cells migrate towards the ECM-chamber interface if within roughly 150 μm, whereas cells further than 150 μm tend to move towards the center of the chamber. Finally, while cells do not show enhanced movement towards the center of mass of a cell cluster, their migration speed is more variable when further away from the cell cluster center of mass. These results show that microfluidic droplet devices can array 3D collagen gels and promote cell spreading, division and migration similar to what is seen in thick 3D collagen gels. Furthermore, they can provide a new avenue to study cell migration and cell-cell communication at physiologically relevant cell densities.

Digital light processing-based bioprinting of microtissue hydrogel arrays using dextran-induced aqueous emulsion ink

“…Microtissue arrays can be used to characterize the interaction between cells, between cells and the microenvironment, as well as the response of cells to external stimuli in the 3D local microenvironment, and to simulate the physiological state and possible response mechanism of cells. 42 This requires that the printed microtissue array fully ensures the viability of the cells. Cell migration is a crucial aspect of cell activity.…”

Time Sequential Single-Cell Patterning with High Efficiency and High Density

“…We compared the methods mentioned in other references in terms of throughput, capture rate, and single-cell rate, among which our device had the highest cell capture rate and the highest efficiency. There was one method for single-cell capture whose capture rate was higher than that of our device, whereas its cell damage rate was high, and its speed was very slow [ 29 ]. As the cells are trapped sequentially, cell loss will be reduced, which is crucial for manipulating some rare cells.…”

“…Some studies have designed trap structures along a main channel sequentially to capture single cells based on the principle of path of least flow resistance [ 27 , 28 , 29 , 30 , 31 ], and optimization of the geometric structures and flow field parameters was conducted to improve the single-cell capture efficiency. A recent study [ 32 ] proposed a single-cell trap structure which has an average single-cell capture efficiency of 90% on a large scale (100 × 100 trap sites).…”

Fibroblasts treated with macrophage conditioned medium results in phenotypic shifts and changes in collagen organization

“…Cell migration was imaged and analyzed using a previously described protocol. 43 Briefly, NIH/3T3 cells were imaged on an inverted microscope (ZEISS Axio Vert.A1, White Plains , NY) with a color camera (Canon, EOS Rebel T3i, Melville, NY). Images were taken every 2 min for 6 h using a 10× objective (NA= 0.25).…”