A Calibration-Free Measurement for Monitoring Cellular Calcium Transients Adaptively

Ca 2 + plays an important role as an intracellular second messenger in the growth and development of cardiomyocytes (CMs), which can be visualized by calcium imaging and be quantified as calcium transient. Based on calcium imaging, the widely applied measurement method for cellular calcium transient requires laborious and inefficient calibration experiments, as well as affected by photobleaching. In this study, we presented a calibration-free method, based on calcium imaging, to calculate cellular calcium transient and correct photobleaching directly from the target video. We also set up image acquisition and calculation system on custom software, applied to calcium transients monitoring of neonatal rat cardiomyocytes. Results showed that the effect of the new method was similar to that of the traditional one with a Pearson correlation coefficient of 0.99 ± 0.01. Moreover, the residual sum of squares of the two methods was only 26.31 ± 26.28 when the area of the region of interest was greater than 8% of the image area. This result indicated that the new method provided a new concept of cellular Ca 2 + concentration quantification as well as a rapid and adaptive method for monitoring cellular calcium transient.