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.