Fractal Analysis of Filamentous Actin Fluorescent Speckle Microscope Patterns in Cell Migration

The fluorescent speckle microscope pattern of newt lung epithelial cell filamentous actin during migration was analyzed using the Higuchi fractal method. The public domain datasets of 2004 PNAS Vallotton et al. were studied. The time series data from time lapsed images exhibited similar fractal dimensions (about 1.68 to 1.82) for various cell regions. Computer simulation of random time series data suggested an average fractal dimension of about 2 with a standard deviation of about 0.027. Speckle trend removals revealed pulsation features which were further studied using a sinusoidal signal model commonly used in gene regulatory studies. Gaussian noise models mixed with sinusoidal signal were used to simulate the observed fractal dimensions. The extracted constraints could be interpreted as polymerization and control pathway related. The administration of contractility promotion drug calyculin-A resulted in an increase of the overall image fractal dimension, which is consistent with the loss of correlation due to random direction contractions. It appears that high fractal dimension could be interpreted as being due to further randomization. Two doses of 20 nM calyculin-A increased cell noise by about 45%. Extension of this proof-of-concept fractal analysis to clinical treatment was also discussed.