MSC Seminar. 17/03/2025. Gladys Massiera (Laboratoire Charles Coulomb, Univ. Montpellier): “Cilia beating coordination and mucus flow on airway epithelia”

The mucus lining the airway tissue is a visco-elastic gel trapping dust and pathogens present in the inhaled air and thus acts as a protective barrier. Its transport is a key element to ensure an efficient clearance of the respiratory system. It relies on two main elements: mucus rheology and cilia beating coordination. Our biophysical approach consists in understanding how mucus flows, by performing rheology at different length scales, and in understanding how cilia coordinate, by analyzing the cilia beating from videomicroscopy. As an experimental model, we use air-liquid interface (ALI) cultures of human bronchial epithelium (HBE), using either primary or induced pluripotent cells.

The mucus rheology and adhesion properties are measured at different scales using either standard rheometer or optical tweezers. We also develop an original experiment to measure mucus rheology directly on the HBE culture, preventing mucus collection bias and probing the rheological response at different height above the epithelium. We will discuss the flow properties of mucus in relation to its highly heterogeneous structure.

Cilia beating coordination is investigated by extracting the trajectory of each cilia. We quantify their coordination degree and the influence of various factors such as density and spatial distribution of the cilia. Maps of beating orientation and frequency are compared to mucus velocity field. These analysis tools allow to quantify and understand how beating coordination and metachronal waves emerge from the scale of a ciliated cell (tens of cilia) to the length scale of the tissue. These experimental results will be compared to theoretical models from statistical physics developed to describe cilia synchrony.