SPP1 and hydrops fetalis: Since non-detectable OPN expression in cardiomyocytes was observed exclusively in the control group of our study, it can be hypothesized that the significantly increased OPN expression in cardiomyocytes already observed at the stage A HF of our study demonstrates how sensitive and balanced cellular molecular mechanisms of the remodeling are from the very beginning to react and compensate immediately for any intracellular dysfunctions caused by ischemia.