New series of online seminars: W MathBio!

• Speaker:  Chiara Giverso (Politecnico di Torino)
• Title: "From Cell Alignment to Axonal Guidance: Mechanics as a Guidance Signal"
• Date: The first seminar will take place on March 9, 2026
• Where: On Zoom

Abstract:

Cells are extremely sensitive to mechanical signals from their microenvironment, which play a fundamental role in regulating their orientation, cytoskeletal organization, and growth dynamics. In particular, cells and neurons cultured on substrates subjected to cyclic stretching have been shown to reorient themselves toward well-defined equilibrium angles relative to the direction of the main strain.

Cellular reorientation can be mathematically described by a linear viscoelastic model that captures the coupled evolution of intracellular stress and orientation under periodic stretching. The model predicts an oscillatory reorientation dynamic converging toward a stable equilibrium angle, which can be interpreted as the minimizer of a general orthotropic elastic energy. Bifurcation analysis and numerical simulations reveal a transition in the reorientation dynamics, governed by the interaction between the stretch frequency and the characteristic turnover time of cytoskeletal components and adhesions. Reorientation is faster at higher frequencies.

Building on this approach, the model is extended to neurons by coupling a viscoelastic growth cone reorientation model with a moving boundary description of tubulin-induced neurite growth. Numerical simulations, performed for different stretch frequencies and strain amplitudes, reproduce experimentally observed equilibrium orientations and demonstrate that the directionality and rate of axonal growth are strongly modulated by mechanical stimulation. In particular, higher stretch frequencies and amplitudes result in faster reorientation and more directional growth.

Overall, the proposed models highlight common physical principles underlying the mechanosensitive orientation of cells and neurons and establish a quantitative link between substrate mechanics, the viscoelastic cellular response, and long-term growth behavior.