Cell migration in multicell spheroids: swimming against the tide

Area of Science:

• Oncology
• Cell Biology
• Biophysics

Background:

• Multicell spheroids are crucial in vitro models for solid tumor development due to their diffusion-limited geometry.
• Spheroids develop a static three-layered structure upon reaching dormancy, yet exhibit dynamic cellular activity.
• Cellular migration from nutrient-rich outer regions towards the necrotic core is observed but mechanistically unclear.

Purpose of the Study:

• To investigate the underlying mechanism driving cell migration within multicell spheroids.
• To determine if pressure gradients can explain the observed cell movement patterns.
• To elucidate the interplay between pressure gradients and chemotaxis in spheroid dynamics.

Main Methods:

• Analysis of recent experimental data on cell internationalization within spheroids.
• Mathematical modeling to implicate pressure gradients as the primary driver of cell movement.
• Comparison of the pressure gradient model with the role of chemotaxis.

Main Results:

• Pressure gradients, resulting from differential cell proliferation and death, adequately describe cell migration in spheroids.
• Cellular movement towards the necrotic core is primarily driven by these pressure differences.
• Chemotaxis was found to oppose, rather than drive, the passive cell movement.

Conclusions:

• Differential cell proliferation and death-induced pressure gradients are the main drivers of cell migration in multicell spheroids.
• The passive movement caused by pressure gradients is a dominant factor in spheroid cell dynamics.
• Understanding these mechanisms is vital for advancing cancer research and therapeutic strategies.