Silja Borring Låstad

• Låstad, Silja Borring; Abbasova, Nigar; Combriat, Thomas Michel Daniel & Dysthe, Dag Kristian (2026). Three Dimensional Dynamics of Epithelial Monolayers. BioaRxiv. doi: 10.64898/2026.03.10.710903. Full text in Research Archive Show summary

  Cells in epithelial monolayers are commonly quantified using a projected area and implicitly assuming constant cell volume and prism-shaped cells. These 2.5D assumptions ignore the volume and mass dynamics that may accompany density fluctuation in confluent space-filling tissues but remain inaccessible to the labelling- and intensity-based imaging techniques used to date. Here, we use time-lapse quantitative phase imaging (QPI) to obtain spatially and temporally resolved maps of height, volume, and dry mass in MDCK epithelial monolayers under physiological conditions. Three findings follow. (i) Cellular dry mass concentration is maintained to within ∼ 4.5 % across the monolayer and over time, even during large-amplitude pulsations, ruling out fluid (water) transport as the dominant driver of height and area dynamics. (ii) The mean height of the monolayer increases from ∼ 5.5 to ∼ 9 µm and the mean cell volume decreases by ∼ 25 % as the cell density doubles, evidence of contact inhibition of cell size rather than constant cell volume. Cell heights vary up to 30%, oscillate with a ∼ 5 h period, and follow gamma-shaped distributions. (iii) At cellular scales, both segmented-cell tracking and continuum mass-flux analysis show that projected cell volume is not conserved; mass conservation is recovered only after coarse-graining over ∼ 2 cell diameters and ∼ 1.6 h. Two non-exclusive mechanisms may explain this: non-prismatic cell geometry produces apparent volume fluctuations even at constant true volume, and periodic mass exchange between cells and the ECM produces genuine cyclic changes in cellular dry mass. A propagating elastic mode in the dry-mass structure factor ( c s ∼ 15 µm/h) further indicates that the monolayer behaves as a viscoelastic active medium rather than a plug-flow fluid. Each of these results requires simultaneous, time-resolved access to height and dry mass at the cellular scale and is therefore newly visible with QPI applied to epithelial monolayers. Together, they question the common 2.5D assumptions of prism-shaped cells, constant volume, plug-flow kinematics, and argue that quantitative continuum and cell-based models of epithelial dynamics must incorporate dry-mass-density regulation and 3D cell geometry.

• Låstad, Silja Borring; Abbasova, Nigar; Combriat, Thomas Michel Daniel & Dysthe, Dag Kristian (2026). Quantitative Phase Imaging of the Dynamics of Epithelial Monolayers. SPIE Quantitative Phase Imaging XII. 13861. doi: 10.1117/12.3084036. Full text in Research Archive Show summary

  This study uses two different quantitative phase imaging techniques (QPI) and for the first time measures the height, volume, and mass dynamics of Madin-Darby Canine Kidney (MDCK) monolayers. We demonstrate novel methods to determine the height of confluent monolayers of cells from 2D and 3D QPI data and validate that the two methods agree. We developed a novel cell segmentation method adapted to QPI images of confluent cell layers and present a robust measure of relative error. We also demonstrate that height statistics of cells can be obtained without segmenting the images. We obtain the following precisions of cell density (1 %), height (3 %), area (5 %) and volume (6 %). Cell height varies 15-25 % over a monolayer and increases 50-100 % when cell density doubles. The average refractive index and the dry mass fraction of the cells, on the other hand, are constant over the entire density range.

• Låstad, Silja Borring & Mitarai, Namiko (2025). Triggered and spontaneous dormancy in bacteria during feast-famine cycles with stochastic antibiotic application. Physical Review E (PRE). ISSN 2470-0045. 112(2). doi: 10.1103/lyfw-zn4j. Full text in Research Archive
• Combriat, Thomas Michel Daniel; Olsen, Petter Angell; Låstad, Silja Borring; Malthe-Sørenssen, Anders; Krauss, Stefan Johannes Karl & Dysthe, Dag Kristian (2024). Acoustic Wave-Induced Stroboscopic Optical Mechanotyping of Adherent Cells. Advanced Science. 11(16). doi: 10.1002/advs.202307929. Full text in Research Archive Show summary

  In this study, a novel, high content technique using a cylindrical acoustic transducer, stroboscopic fast imaging, and homodyne detection to recover the mechanical properties (dynamic shear modulus) of living adherent cells at low ultrasonic frequencies is presented. By analyzing the micro-oscillations of cells, whole populations are simultaneously mechanotyped with sub-cellular resolution. The technique can be combined with standard fluorescence imaging allowing to further cross-correlate biological and mechanical information. The potential of the technique is demonstrated by mechanotyping co-cultures of different cell types with significantly different mechanical properties.

• Låstad, Silja Borring & Haerter, Jan O. (2022). The geometry of evolved community matrix spectra. Scientific Reports. 12(1). doi: 10.1038/s41598-022-17379-6. Full text in Research Archive

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• Låstad, Silja Borring; Abbasova, Nigar; Combriat, Thomas Michel Daniel & Dysthe, Dag Kristian (2026). Three Dimensional Dynamics of Epithelial Monolayers. Full text in Research Archive
• Låstad, Silja Borring; Abbasova, Nigar; Ho, Richard David Jun-Geet; Combriat, Thomas Michel Daniel & Dysthe, Dag Kristian (2025). Segmentation-free measurement of cell motion from quantitative phase imaging. Full text in Research Archive
• Låstad, Silja Borring; Abbasova, Nigar; Combriat, Thomas Michel Daniel & Dysthe, Dag Kristian (2025). Cell height, area and volume fluctuations in MDCK monolayers. Full text in Research Archive

View all works in NVA