The force behind our strength: How mechanical processes regulate muscle development

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Skeletal muscles grow and regenerate as individual precursor cells—called myoblasts—fuse into long fibers from which mature muscle fibers develop. How they coordinate this process and form functional muscles is not yet fully understood.

A research team at the Max-Planck-Zentrum für Physik und Medizin (MPZPM) has now shown that mechanical stress influences the fusion of muscle cells. The results, published in Nature Communications, reveal an interaction between the organization of muscle cells, the surrounding intercellular space, mechanical stress and muscle growth. Skeletal muscle attaches to our bones and enables us to move or exert force.

It consists of long, multinucleated muscle fibers. Their precursors, the myotubes, are formed through the fusion of individual myoblasts. Previously, research into how this fusion is regulated had focused on understanding molecular signals.

More recently, however, it has become clear that cells also respond to physical forces and the mechanical properties of their environment. How such mechanical signals are organized in developing muscle tissue and whether they influence where myoblasts fuse has hardly been investigated. The team, led by Benoît Ladoux, head of the Tissue Mechanobiology division at MPZPM, describes the organization of myoblasts using concepts from physics.

This is because myoblasts do not arrange themselves randomly as they grow together. Instead, they self-organize into domains with distinct cellular orientations. Together, these domains form patterns.

So-called active nematics serve as model systems that help scientists understand this self-organizing process. In physics, active nematic systems include, for example, liquid crystals, in which molecules align parallel to one another, forming an ordered pattern. The myoblasts form comet- and cloverleaf-shaped patterns.