[Expression and tissue localization of hemeoxygenase in human placenta].

ABSTRACT

OBJECTIVE: The purpose of this study was to investigate the expression and localization of the two known isoforms of hemeoxygenase (HO) in normal human first trimester placenta and third trimester placenta. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemistry were resorted to demonstrate the expression and localization of HO-1 and HO-2 in normal placenta tissue, obtained from 6 approximately 10 week gestation women (20 cases) and the third trimester woman (20 cases). RESULTS: Compared with glyceraldehydes-3-phosphate dehydrogenase (GAPDH), the expression of HO-1 was lower, there was no significant difference between the first trimester (0.31 +/- 0.19) and third trimester (0.28 +/- 0.14) (P > 0.05); the expression of HO-2 was higher, it is significantly higher at third trimester (1.12 +/- 0.58) compared with first trimester placenta (0.70 +/- 0.48) (P < 0.05). The result of immunohistochemistry demonstrated that HO-1 was predominantly localized in villous stroma cell and trophoblast; HO-2 predominantly localized in trophoblast as well as capillaries, with weak staining of villous stroma. The staining score were not normally distributed. The median staining scorse of HO-1 in trophoblast, villous stroma and capillaries at first trimester were 9.0, 2.6 and 2.8, respectively, at third trimester were 8.7, 2.0 and 1.4, there was no difference between the two groups (P > 0.05). The median staining score of HO-2 in capillaries at first trimester was 5.8, significantly lower than that of the third trimester (9.3) (P < 0.05). There was no significant difference between the staining score of HO-2 in trophoblast (10.5, 8.0) and villous stroma (3.6, 2.4) between the first trimester and the third trimester (P > 0.05). CONCLUSIONS: HO-1 and HO-2 as endogenous system may regulate feto-placental circulation, indicated their different roles in placental vascular development and regulation. They may offer protection against cyto-toxic damage in the placenta, and influence immunological function.