Overexpression of type IV collagen in chorionic villi in hydatidiform mole

To investigate the characteristic structure of hydatidiform mole, type IV collagen expression was determined in human villous tissues obtained from normal pregnancies (n = 17) and complete hydatidiform moles (n = 10). Indirect immunofluorescent staining was performed to detect type IV collagen with specific monoclonal antibody, and Northern blot analysis was performed to assess expression of messenger ribonucleic acid for the alpha1(IV) chain. In addition, serum levels of type I, III, and IV collagen were measured by RIA. Immunohistochemical staining for type IV collagen revealed stronger staining of the trophoblastic basement membrane in hydatidiform mole than in normal pregnancy. Northern blot analysis revealed that the villous expression of messenger ribonucleic acid for the alpha1(IV) chain was significantly increased in hydatidiform moles compared with normal pregnancy (P < 0.01). Although there were no differences in the serum type I and III collagen levels between hydatidiform mole and normal pregnancy, the type IV collagen level was significantly higher in patients with hydatidiform mole than in normal pregnancy (P < 0.05). These results suggest that type IV collagen might play an important role in determining the pathophysiology and structure of hydatidiform mole.