Mapping Structure and Biological Functions within Mesenchymal Bodies using Microfluidics

Abstract

Organoids that recapitulate the functional hallmarks of anatomic structures comprise cell populations able to self-organize cohesively in 3D. However, the rules underlying organoid formation in vitro remain poorly understood because a correlative analysis of individual cell fate and spatial organization has been challenging. Here, we use a novel microfluidics platform to investigate the mechanisms determining the formation of organoids by human mesenchymal stromal cells that recapitulate the early steps of condensation initiating bone repair in vivo. We find that heterogeneous mesenchymal stromal cells selforganize in 3D in a developmentally hierarchical manner. We demonstrate a link between structural organization and local regulation of specific molecular signaling pathways such as NF-κB and actin polymerization, which modulate osteo-endocrine functions. This study emphasizes the importance of resolving spatial heterogeneities within cellular aggregates to link organization and functional properties, enabling a better understanding of the mechanisms controlling organoid formation, relevant to organogenesis and tissue repair.! 3!

Individual Control and Quantification of 3D Spheroids in a High-Density Microfluidic Droplet Array

“…The structural organization that emerged from these spheroid fusions was identical to the self-arrangement obtained when the different cell populations were seeded together in the same droplet (Sart et al, 2020). However, those experiments could not distinguish between kinetic effects, related to the speed of aggregation of the different cell types, and the biophysical effects, related to the affinity of different cells.…”

Cyclical aggregation extends in vitro expansion potential of human mesenchymal stem cells

“…However, these effects can be mitigated through the MSC's 3D aggregation process in which cells are integrated into a new cellular environment with a lower modulus similar to human tissue [19][20][21][22][23] . Additionally, aggregation promotes cell-cell interactions, which create new cell signaling events from either paracrine or biomechanical stimulation [24][25][26] . Both mechanisms may contribute to how aggregated MSCs have been shown to enhance multiple cellular functions, such as anti-inflammatory and regenerative potential 27,28 , stem cell genes 29,30 , and the increased ISR response 31 .…”

A Multiscale Immuno-Oncology on-Chip System (MIOCS) establishes that collective T cell behaviors govern tumor regression

“…The complete experiments rely on a microfluidic device that consists of a droplet generating region followed by a droplet trapping region that serves to culture the cells and observe them (Fig. 1a,b) [15, 17]. This trapping region is patterned with 234 microfluidic anchors [18], that allow the droplets to be held in place even in the presence of an external flow.…”