Organ size control via hydraulically gated oscillations

Area of Science:

• Biophysics
• Developmental Biology
• Tissue Engineering

Background:

• Hollow vesicular tissues in various organs require size and shape regulation for proper function.
• While chemical signaling is known, mechanical forces are increasingly recognized for their role in modulating tissue size and shape.
• Observed tissue cyst formation and size control exhibit simultaneous growth and oscillations, suggesting underlying dynamic mechanisms.

Purpose of the Study:

• To develop a minimal theoretical framework for the growth and dynamics of soft, fluid-permeable, spherical tissue shells.
• To investigate the role of mechanical forces and fluid dynamics in regulating tissue size and shape.
• To explain the observed oscillations in tissue growth and size control.

Main Methods:

• Creation of a minimal theoretical framework for spherical, fluid-permeable shells.
• Development of an in vitro experimental setup to monitor tissue spheroid growth and oscillations.
• Generalization of the theory to include irreversible deformations for analyzing experimental data.

Main Results:

• Demonstrated that tissue shells can relieve internal pressure by intermittent bursting, shrinking, and re-growing.
• Proposed a mechanism of hydraulically gated oscillations for size regulation in growing tissue shells.
• Explained the time scales and amplitudes of oscillations based on shell geometry and mechanical properties.

Conclusions:

• Soft hydraulics provide a simple mechanism for regulating the size of growing tissue shells.
• The theoretical framework and experimental observations elucidate the interplay between fluid pressure, mechanical properties, and tissue size dynamics.
• This study offers insights into fundamental principles governing biological tissue morphogenesis and size control.