Formation of three-dimensional cellular spheroids - combining mathematical modelling and experiments

Most cells in the human body are organised in three-dimensional structures. This leads to complex intercellular interactions that cannot be reproduced in two-dimensional monolayers of cell cultures. On the other hand, studying intercellular interactions in vivo is still rather complex. To bridge the gap, multicellular spheroids – three dimensional ball-shaped aggregates – have been developed as an in vitro model system for cellular interactions in tissues.

Since they are physiologically more relevant, multicellular spheroids are popular models in tissue engineering as well as drug development and toxicological tests [1]. In spite of these numerous applications of a fully formed spheroid, relatively little is known about the details of its formation. Various techniques for spheroid formation have been established of which almost all are based on the same principle (reviewed in [2]): The cells are cultured in a convex non-adhesive environment, in which they cluster due to gravity and then aggregate. Findings that E-Cadherin expression correlates with spheroid formation capacity [3], suggests that intercellular adhesion plays a key role in spheroid formation.

In this project we investigate how fundamental physical properties of the cell, primarily intercellular adhesion, contribute to the formation of cellular spheroids and the maintenance of the structure. To this end we apply a highly interdisciplinary approach combining cell biology, advanced microscopy, image analysis and mathematical modelling.

Different phases of spheroid formation. Snapshots of a 72 h time lapse of approximately 150 breast cancer cells (T-47D) in a round bottom well, recorded with a Zeiss Cell Observer and a 10x objective by Nariman Ansari. Scale bar: 50 µm. A: Individual cells and smaller cluster come together and aggregate into a flat discoid. B: The   discoid folds up. C: The cells form one three dimensional cluster. D: The cluster rounds up, becomes more compact and the cells form a basal membrane.

[1] Pampaloni F, Reynaud EG, Stelzer EHK (2007) The third dimension bridges the gap between cell culture and live tissue, Nat Rev Mol Cell Biol, 8:839-45.
[2] Pampaloni F, Ansari N, Stelzer EHK (2013) High-resolution deep imaging of live cellular spheroids
with light-sheet-based fluorescence microscopy, Cell Tissue Res, 352:161-77.
[3] Lin RZ, Chou LF, Chien CC, Chang HY (2006) Dynamic analysis of hepatoma spheroid formation: roles of E-cadherin and β1-integrin, Cell Tissue Res, 324:411-22.

People involved in this project:

Sabine Fischer
Biena Mathew
Nariman Ansari

Alexander Schmitz
Christian Mattheyer
Katharina Hötte
Isabell Smyrek
Francesco Pampaloni

Sakshi Garg, Group of Erin Schuman (MPI Brain Research, Frankfurt)