title: A new method to address unmet needs for extracting individual cell migration features from a large number of cells embedded in 3D volumes.
abstract: BACKGROUND
  In vitro cell observation has been widely used by biologists and pharmacologists for screening molecule-induced effects on cancer cells. Computer-assisted time-lapse microscopy enables automated live cell imaging in vitro, enabling cell behavior characterization through image analysis, in particular regarding cell migration. In this context, 3D cell assays in transparent matrix gels have been developed to provide more realistic in vitro 3D environments for monitoring cell migration (fundamentally different from cell motility behavior observed in 2D), which is related to the spread of cancer and metastases.
  
  
  RESULTS
  In this paper we propose an improved automated tracking method that is designed to robustly and individually follow a large number of unlabeled cells observed under phase-contrast microscopy in 3D gels. The method automatically detects and tracks individual cells across a sequence of acquired volumes, using a template matching filtering method that in turn allows for robust detection and mean-shift tracking. The robustness of the method results from detecting and managing the cases where two cell (mean-shift) trackers converge to the same point. The resulting trajectories quantify cell migration through statistical analysis of 3D trajectory descriptors. We manually validated the method and observed efficient cell detection and a low tracking error rate (6%). We also applied the method in a real biological experiment where the pro-migratory effects of hyaluronic acid (HA) were analyzed on brain cancer cells. Using collagen gels with increased HA proportions, we were able to evidence a dose-response effect on cell migration abilities.
  
  
  CONCLUSIONS
  The developed method enables biomedical researchers to automatically and robustly quantify the pro- or anti-migratory effects of different experimental conditions on unlabeled cell cultures in a 3D environment.
authors.affiliation: Laboratory of Image Synthesis and Analysis, Faculty of Applied Science, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Ivan
authors.initials: I
authors.lastname: Adanja
authors.forename: Véronique
authors.initials: V
authors.lastname: Megalizzi
authors.forename: Olivier
authors.initials: O
authors.lastname: Debeir
authors.forename: Christine
authors.initials: C
authors.lastname: Decaestecker
mesh_terms: D000465:Algorithms; D002452:Cell Count; D018929:Cell Culture Techniques / Q000379:methods*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D003094:Collagen / Q000494:pharmacology; D005782:Gels / Q000494:pharmacology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D015203:Reproducibility of Results
chemical_list: D005782:Gels; D003094:Collagen