High‐Throughput Measurements of Intra‐Cellular and Secreted Cytokine from Single Spheroids Using Anchored Microfluidic Droplets. Issue 49 (13th November 2020)

• Record Type: Journal Article
• Authors: Saint‐Sardos, Adrien; Sart, Sébastien; Lippera, Kevin; Brient‐Litzler, Elodie; Michelin, Sébastien; Amselem, Gabriel; Baroud, Charles N.
• Is Part Of: Small. Volume 16:Issue 49(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-13
• Subjects: 3D cell culture -- lab‐on‐a‐chip -- organoid -- secretome -- single‐cell -- spheroids -- vascular endothelial growth factor; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202002303
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: While many single‐cell approaches have been developed to measure secretions from anchorage‐independent cells, these protocols cannot be applied to adherent cells, especially when these cells require to be cultured in 3D formats. Here, a platform to measure secretions from individual spheroids of human mesenchymal stem cells, cultured within microfluidic droplets is introduced. The platform allows to quantify the secretions from hundreds of individual spheroids in each device, by using a secondary droplet to bring functionalized micro‐beads in proximity to each spheroid. Vascular endothelial growth factor (VEGF‐A) is measured on and a broad distribution of secretion levels within the population of spheroids is observed. The intra‐cellular level of VEGF‐A on each spheroid, measured through immuno‐staining, correlates well with the extra‐cellular measurement, indicating that the heterogeneities observed at the spheroid level result from variations at the intra‐cellular level. Further, the molecular accumulation within the droplets is modeled and it is found that physical confinement is crucial for measurements of protein secretions. The model predicts that the time to achieve a measurement scales with droplet volume. These first measurements of secretions from individual spheroids provide several new biological and technological insights. Abstract : The secretion of soluble molecules is measured on hundreds of individual spheroids, using microfluidic droplets coupled with microbeads for fluorescent immune‐assays. The ability to combine intracellular and secretion measurements on each spheroid shows that these parameters strongly correlated for the case of VEGF. A mathematical model of the measurement dynamics demonstrates that droplet size determines the secretion measurement dynamics.