[3-Dimensional microscopy as a method for volume measurement in cells undergoing apoptosis]

Different patterns of cell volume perturbations are commonly used for modes of cell death: necrosis (cell swelling) and apoptosis (cell shrinkage). In this study we employed recently developed three dimensional microscopy for the measurement of the volume of attached vascular smooth muscle cells transfected with E1A-adenoviral protein. These cells undergo rapid apoptosis in the absence of growth factors or in the presence of staurosporine. In 30-60 min of serum deprivation the volume of these cells is increased by -40% that corresponds to the time point of maximal activation of caspase 3 and chromatin cleavage. In 10-15 min swollen cells exhibit morphological collapse indicated by formation of apoptotic bodies. In contrast to serum-deprived cells, staurosporine leads to attenuation of cell volume by 30%. In this case, apoptotic bodies are detected in -2.5 hr after maximal shrinkage. Thus, our results show that cell shrinkage can not be considered as universal hallmark of apoptosis. The role of stimulus-specific cell volume perturbation in the triggering of the cell death machinery should be examined further.