NPPB and hydrops fetalis: There were several reasons to suggest that NP system could be involved it regulation of anti-fibrotic/pro-fibrotic potential of BM-MMSC in HF: first, there are the evidence on literature that BNP has a direct effect on cardiac fibroblast to inhibit fibrotic responses and prevent cardiac remodeling in pathological conditions [52]; second, it was demonstrated by the number of independent studies that NP system plays a very important role in regulation of cardiac development [39], cardiac hypertrophy and remodeling [47, 48, 52, 53].