The differential expression of hepatocyte growth factor and met in human placenta.

Met is the tyrosine kinase receptor for the ligand hepatocyte growth factor (HGF). Met/HGF plays an important role in epithelial cell proliferation, migration, and morphogenesis. HGF also plays a crucial role in placental development in the mouse. To determine whether HGF potentially has a similar role in human placental development, the production and localization of Met and HGF were determined in early second trimester and term placentas. Reverse transcription-PCR using specific primers demonstrated the expression of Met and HGF messenger ribonucleic acid in placental villi. HGF production was determined by enzyme-linked immunosorbent assay. HGF production over 48 h by second trimester placental villous explants in culture (810 pg/mg total protein x h) was 2.1-fold greater than that in term placental villous explants (380 pg/mg total protein x h; P < 0.01). Isolated trophoblast did not produce HGF, whereas isolated villous core tissues and villous core mesenchymal cells did produce HGF. Interleukin-1 beta treatment of placental villi or coculture of villous core mesenchymal cells with isolated trophoblast cells did not stimulate HGF production. Using immunohistochemistry, HGF localized to the villous core compartment with no localization to the trophoblast. In contrast, Met localized mainly to cytotrophoblast. These findings suggest that HGF produced by the villous core may act in a paracrine fashion to regulate trophoblast development or function through the HGF receptor, Met.