The specificity of each antibody was determined by immunoblotting or by inhibition in an enzyme-linked immunosorbent assay. After hypoxanthine-aminopterine-thymidine selection, positive hybrids were identified by enzyme-linked immunosorbent assay. The spleen cells of these mice were then hybridized with myeloma cells. In brief, BALB/c mice were immunized with each type of collagen after it had been extracted from human placentas. Preparation of the antibodies was described previously ( 7). Monoclonal antibodies (mAbs) against each α 1-chain of human type I, III, and VI collagen were used. Gestational age was determined from the date of the last menstrual period and by ultrasonographic measurements performed in early pregnancy.
We excluded necrotic villous tissue from analysis by histological examination. The pathological diagnosis of all 10 cases was complete hydatidiform mole. Molar tissues were obtained from 10 women, aged 22 to 41 yr, by dilatation and curettage at 7–13 weeks gestation. Normal villous tissues were obtained from 17 women, aged 20–38 yr, during early pregnancy (7–12 weeks) by dilatation and curettage for termination of pregnancy and were immediately frozen in liquid nitrogen. Informed consent was obtained from each subject, after the purpose and nature of the study were fully explained. This project was approved by the committee on investigations involving human subjects of Wakayama Medical College. The results were compared with those obtained during normal pregnancy. In the present study we investigated the distribution and composition of the various types of collagen, the major component of ECM, in hydatidiform moles by immunofluorescent staining and SDS-PAGE. There is marked proliferation of cyto- and syncytiotrophoblast ( 6). The edema displaces the mesenchymal stroma centrally, creating an acellular clear space called a central cistern. Microscopic examination discloses diffuse, marked villous enlargement due to massive stromal edema. The hydatidiform mole has such a characteristic macroscopic appearance that it may be diagnosed by the ultrasonographer, attendant at delivery, or the pathologist. The ECM of normal villous tissues has been studied ( 4, 5), but changes in the ECM in the villous tissues of hydatidiform mole are not fully understood. Synthesis, accumulation, and catabolism of the ECM occur during wound healing and during the initiation and progression of numerous diseases ( 3). THE EXTRACELLULAR matrix (ECM) is considered to play an important role in the stability of tissues and in regulating the growth and differentiation of cells ( 1, 2). These results suggest that alterations in the distribution and composition of collagen might play an important role in determining the pathophysiology and structure of hydatidiform mole. Both the ratios of type III to type I collagen and the ratios of type V to type I collagen in the villous tissues were significantly decreased ( P < 0.05) in molar pregnancy compared with those in normal pregnancy. Immunohistochemical staining for type I, III, and VI collagen revealed weak staining of the villous stroma in hydatidiform mole compared with that in normal pregnancy. Collagens were also extracted from the villous tissues obtained from normal pregnancy and hydatidiform mole by the salt precipitation method.
Indirect immunofluorescent staining was performed to detect type I, III, and VI collagen with specific monoclonal antibodies. To investigate the characteristic structure of hydatidiform mole, various types of collagen expression were determined in human villous tissues obtained from normal pregnancies (n = 17) and complete hydatidiform moles (n = 10).
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