Quantitative study of dynamic behavior of cell monolayers during in vitro wound healing by optical flow analysis.

BACKGROUND In vitro wound healing assays are experimental models commonly used to analyze cell behavior during the migration process. A new approach is proposed for the quantification of cell motility based on an optical flow method. METHODS We assumed that cell-population dynamics can be defined by an a priori affine-motion model. Identified model parameters are used as motion descriptors quantifying both elementary and complex cell movements, either at the wound margins or within the cell monolayer. RESULTS When compared with the estimation of cell motility calculated from wound area temporal variation, it allows a more detailed and precise characterization of cell population movements. Comparative analysis of normal and cancerous cell lines revealed that typical measured velocities were about 2 microm/h and 7 microm/h for L929 and HeLa cells, respectively, at the beginning of the wound closure. The quantification of the effect of Hoechst 33342 on cell dynamics showed a similar behavior for control and stained cells within 20 h after wound scratching, but then a decreased velocity of stained cells. CONCLUSIONS The results demonstrate that this approach can be used to gain new insights into the dynamic changes induced by the extracellular environment and by anticancer drugs.