Problem: The purposes of this study were to investigate the presence of hepatocyte growth factor (HGF) in human milk, to identify the cells that produce HGF in human milk, and to determine the contribution of HGF to the growth of neonates.
Method of study: The HGF concentrations in serum and whey were determined with an enzyme-linked immunosorbent assay kit. The presence of HGF in whey was also examined by Western blot analysis. To determine which cells in human milk produce HGF, an immunohistochemical examination was conducted. The expression of HGF mRNA in the mononuclear cells in human milk was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). The effects of whey and of recombinant HGF (rHGF) on DNA synthesis by a rat small intestinal cell line, IEC-6, were examined by [3H]thymidine uptake.
Results: Human colostrum whey contained 2.22 +/- 1.02 ng of HGF/ml. Milk whey collected 1 month later contained 1.83 +/- 1.03 ng of HGF/ml. The presence of the heterodimeric form of HGF in colostrum whey was demonstrated by Western blot analysis. HGF was detected in the cytoplasm of human milk macrophages by an immunohistochemical examination, and the RT-PCR also revealed that HGF mRNA is expressed in the mononuclear cells of human milk. DNA synthesis by IEC-6 cells was increased by rHGF treatment and by whey treatment. The effect of whey on DNA synthesis by IEC-6 cells was partially, but significantly, decreased by anti-human HGF-neutralizing antibody treatment.
Conclusions: Human milk contains a large amount of the active form of HGF, produced by macrophages, and HGF in human milk induces the growth of intestinal cells. Our data suggest that HGF in human milk is one of the important factors regulating the growth of intestinal cells in neonates after birth.