Measuring Cell Circularity and Spreading On Thermoresponsive Surfaces

The use of thermoresponsive surfaces in cell culture to grow confluent cell monolayers has been investigated with two different thermoresponsive polymer systems: PNIPAM and PMO.  The cell-material interaction influences cell phenotype and biocompatibility of the substrate.   To assess biocompatibility, we evaluated metrics of cell circularity and spreading on each substrate.  Circularity, as defined by Wittmer, et al. 2006, is a measure of how rounded a cell is, ranging from 0 to 1.  Spreading is the percentage of cells exhibiting some form of cell protrusion observed using phase contrast microscopy.  Mouse fibroblasts were cultured on five different thermoresponsive surfaces with differing levels of hydrophobicity as well as a tissue culture plastic control for 48 hours, during which time microscopy images were taken at time points of 0h, 6h, 24h, and 48h.  These images were analyzed for circularity and spreading data.  It was hypothesized that cell circularity would decrease over time, thus indicating increased cell spreading.  The data for both circularity and spreading corroborate this theory from 0 to 48 hours, but present an unexpected finding at the time point of 6 hours.  Further research on gene expression will be conducted to explore this anomaly.