Development of a reliable flow-based method for accurate measurement of mass density, size and weight of 3D tumor spheroids

Cells adjust their mass-to-volume ratio during important processes such as cell cycle progression, apoptosis, differentiation, disease state, and malignant transformation. Although methods for monitoring cell mass are emerging, there currently does not exist a means for measuring the cells density with meaningful precision.
Cell density, i.e. number of cells plated in ultra-low attachment plate when growing multicellular spheroids as free floating spheres, does not take into account the overall mass density of a spheroid. In addition, spheroids, even with similar volumes and homogeneous sizes, don’t necessarily have the same mass density, depending on how compact they are, thereby leading to
diverse biological responses to external stimuli and antitumor treatments.
The W8 system is a microfluidic device developed in collaboration with CellDynamics, an italian start up working on 3D biology models. The W8 system optically calculates the vertical fall speed of a floating spheroid, while measuring its morphology as well. By leveraging on Stokes’ law, spheroid mass density and weight are easily extracted. We can calculate mass density, weight on nanogram scale and morphological features (radius, surface area, volume).

Collaborators: Dr. Andrea Cristaldi (CellDynamics)
Dr. Azzurra Sargenti (CellDynamics)
Dr. Carola Cavallo (Istituto Ortopedico Rizzoli)

 

Confocal imaging of 3D tumor spheroid, clarified, labelled and observed with silicone oil immersion objective (30x – 1.05 NA, Olympus).