Correlation between ciliary beat frequency and metachronal wave disorder using image analysis method

Ciliary beating and metachronal waves are fundamental to effective mucociliary transport. The ciliary beat frequencies (CBFs) and metachronal wave directions of multiple cilia beating in culture media were measured simultaneously using digital microscopic images. The degree of synchronisation between ciliary beats was determined by the correlation between ciliary signals at two different locations. The wave propagation directions of cilia were determined from a two-dimensional correlation map by a principal axis method. The standard deviation of measured wave directions in a region of interest was defined as a measure of metachronal wave disorder (MWD). Considerable variation was found in the beat frequencies and metachronal wave directions of cilia beating on epithelium. The pooled mean of MWDs was 23.4 +/- 8.8 degrees, and the pooled mean of CBFs was 10.1 +/- 1.9 Hz on 120 cells from five healthy subjects. The means of the MWD and the CBF from subjects were highly correlated (correlation = -0.83). The higher the CBF, the lower the level of the MWD.