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Chorionic villus biopsy specimens were studied electron microscopically in six pregnancies at risk of the infantile type of neuronal ceroid lipofuscinosis (INCL). The biopsy was performed in all cases in the first trimester of pregnancy (8-10 gestation weeks) by the transcervical route. In one case, the biopsy was repeated at 17 weeks by the transabdominal procedure. In two pregnancies, the endothelial cells and, to a lesser extent, the mesenchymal cells of the chorionic villi contained unit membrane-bound inclusions typical of INCL. In both cases, the pregnancy was terminated and in one of them identical inclusions were found in the brains and kidneys of the fetus at 20 weeks of gestational age. The children from the remaining four pregnancies are healthy and have shown no signs of the disease.
Chorionic villi chromosome analysis was performed on 1,186 cases of induced abortion between the 5th and 11th week of gestation. The total incidence of major chromosome abnormalities, including numerical and structural chromosomal changes as well as mosaics and polyploids, was 4.5% (53 cases). The most common abnormalities were trisomy 21 (5 cases), trisomy 16 (4 cases), and monosomy X (4 cases). The incidence of chromosome abnormalities increased with the advancing age of the mother.
Human chorionic villi and choriomembrane proteins were analyzed by two-dimensional electrophoresis. The samples were obtained during the first trimester of pregnancy and were solubilized in buffer containing Triton X-100 and CHAPS. High molecular weight proteins with Mr above 200 KDa and proteins with basic pI were found to be better resolved in this buffer system that in solution containing Triton X-100 only. Nearly 200 protein spots could be visualized on the silver stained gels.
Analysis of the results of prenatal cytogenetic diagnosis carried out in the first and second pregnancy trimesters in more than 300 women permitted comparing the efficacies of two methodologic approaches, diagnostic amniocentesis and chorion sampling , with due consideration for the methodologic errors typical of these methods and of the tested biologic material. Up to 5% of the diagnoses are erroneous if the diagnosis is based on chorion sampling data, whereas in amniocentesis the share of diagnostic errors is lower by an order. The authors have given a theoretical rationale for and tried a methodologic approach, involving the employment of the 'direct' chromosomal preparations from villous chorion biopsy specimens and the so-called 'maintained' cell culture technique, that permits obtaining chromosomal preparations of higher quality and, consequently, helps improve the accuracy of chromosomal diagnosis.
Chorionic villus sampling (CVS) is now currently offered for first trimester prenatal diagnosis of genetic disorders. Chromosome analysis of CVS in direct and culture preparations is possible using modifications of standard banding techniques. We summarize our experience in applying QFQ, GTG, RBG, CBG, DA/DAPI, NOR, and SC differentiation protocols to direct preparations. Characteristic chromosome regions are properly labelled by these techniques, and analysis of 300 band stage karyotypes is consistently achievable on GTG banded direct preparations. However, banding of CVS direct chromosomes has proved to be difficult, and the analysis needs to be backed up by culture preparations.
Chorionic villus sampling (CVS) has a promising future about early detection of fetal abnormalities. It has the potential to become a major tool in the prenatal diagnosis and therapy of genetic disorders. Villus samples can be analyzed by means of cytogenetic, biochemical or molecular technics. Information available at present indicates fetal loss rate should be in the same proportion than amniocentesis. CVS appears to be a reasonably safe and reliable method of prenatal diagnosis in the first trimester of pregnancy. This procedure is setting as fast as it is possible like an excellent alternative to amniocentesis.
This report documents the first 262 cases of chorionic villus sampling (CVS) performed in parallel with cytogenetic and morphological investigations. Histomorphological examination of these CVS specimens gave suitable results in about 96% (251 cases). Of the latter, 201 samples (80.1%) exhibited villi and 176 (70.1%), maternal tissue. Viability and maturation of the chorionic villi were determined light microscopically even in cases with few villus trees. Smooth avascular villi with poorly defined margins observed under an inverted microscope, less than 10 mitoses after short-term incubation, and reduced growth of cell cultures were significantly correlated with sampling at the chorion laeve by means of histomorphologic criteria. Villi from cases exhibiting cytogenetically proved chromosomal abnormalities were characterized by molar degeneration or stromal fibrosis, or both, in 4 out of 9 cases, including 3 mosaics. In early abortions (within 3 weeks after CVS), an unexpectedly high rate of pathohistological changes within maternal tissue was evident. These results need further confirmation by investigation of a greater number of samples with immunohistochemical and morphometric methods.
In the last decade, chorionic villi sampling (CVS) has been widely accepted as a new technique in prenatal diagnosis. An inconsistency in karyotypes between CVS and fetal tissue was found in clinical practice, although the chorionic villi and the fetal tissues were from the same fertilized ovum. Karyotypes from direct chromosomal preparation of chorionic villi and cultured fetal tissues in 52 artificial abortion samples were compared. Results showed two cases with karyotypic inconsistency: (1) 46, XX/46, XY in the chorionic villus direct preparation and 46, XX in the fetal tissue; (2) 46, XY in the direct preparation of chorionic villi and 45,XY, t (15q21q) de novo in the fetal tissue. Our research demonstrates that karyotype from chorionic villus direct preparation does not always reflect the fetal karyotype.
Chorionic villi sampling (CVS) has become a first trimester alternative to amniocentesis for prenatal diagnosis. The cytogenetic findings in 150 experimental samples are presented. The ages of the mothers ranged from 12 to 35 years, but the majority of them were 18 and 19 years of age. Various parameters of culturing and processing the samples in order to improve the method, were investigated. Short term incubation for 48 h was the method routinely employed in processing the biopsies for cytogenetic analysis. In the first series of 100 cases one mosaic case (46,XX/45,X), one Robertsonian translocation (13;14), one marker chromosome and one fragment were found. The foetal tissues were not analysed for chromosomes. In the second series of 50 samples, one case of mosaicism was found in the chorionic villi (46,XX/47,XX, 18q-), but this abnormality was absent in the foetal tissue. One variant inv(9) was observed in the foetal tissue as well as in the chorionic villi. In all other cases the karyotypes from the chorionic villi samples matched those of the corresponding foetal samples. There was no maternal contamination in this series of 50 samples. The discrepancies in the cytogenetic results from other investigators are discussed.
Transabdominal CVS (chorionic villi sampling) was performed in 40 patients belonging to first or second trimester of pregnancy with 97.5% success, using a double and later single needle technique with no immediate complications. Karyotyping by direct method was successful in 75% of samples thus indicating the feasibility of cytogenetic analysis using villus tissue from first and second trimesters of pregnancy. It is a safe, simple, rapid and practical method of prenatal diagnosis in first and second trimesters of pregnancy with a potentially lower risk for fetal and maternal complications.
In long-term cultures of chorion villi the expression of cytoskeletal proteins--vimentin, cytokeratin, actin, tropomyosin and vinculin--was studied using immunoreactivity to antibodies. Vimentin was detected in all cells of chorionic villi cultures despite their morphological appearance. In comparison to fibroblast cultures from human skin biopsies with bundle-like vimentin structures, chorionic villi cells showed fine ramified vimentin filaments. Some of the chorionic villi cells with typical fibroblastoid appearance also had cytokeratin filaments. No differences were observed in the distribution of vinculin. Tropomyosin structure and actin filaments could be detected in cultures of chorionic villi whereas fibroblasts showed only an intense diffuse staining.
The activities of 14 lysosomal enzymes in chorionic villi at gestational ages of 6-12 weeks were assayed. Arylsulphatases A and B, alpha-glucosidase and beta-glucuronidase activities increased with advancing gestational age. When compared with the activity in cultured amniotic fluid cells, arylsulphatase A, beta-galactosidase, alpha-glucosidase, heparan N-sulphatase, alpha-L-iduronidase, alpha-mannosidase, neuraminidase, and sphingomyelinase showed significant differences. All except beta-glucuronidase showed lower activity in chorionic villi than in cultured amniotic fluid cells. Prenatal diagnosis using chorionic villi was possible except for alpha-L-iduronidase. Storage at -20 degrees C up to 42 days did not significantly affect activity. The results emphasize the importance of using fresh or frozen age-matched control tissue for diagnosis.
X-chromosome inactivation was investigated in human chorionic villi in the first trimester of pregnancy and cultured cells established from them. Expression of glucose-6-phosphate dehydrogenase (G6PD) was evaluated in these extraembryonic cells from four females heterozygous for the electrophoretic variants (AB) of G6PD. In each case the uncultured villi as well as derived cultured cells expressed the AB phenotype for G6PD with about equal intensity for the A and B bands. Single-cell-derived clones established from two of the four cases expressed either G6PD A or B. One clone expressing G6PD B was fused with mouse cells, and a hybrid clone retaining the inactive human X chromosome was isolated; there was no evidence of human G6PD expression in this clone retaining an inactive human X. DNA methylation in the first intron of the human gene for hypoxanthine phosphoribosyltransferase (HPRT) was evaluated in the four pairs of cultured villi and fetal cells. No differences were detected between the cultured villi and fetal cells as they all showed bands characteristic of an inactive X from somatic cells. These results show that there is no preferential inactivation of an X in the majority of cells that constitute human tertiary chorionic villi or in cultured cells derived from them. Long-term cultures established from chorionic villi appear to be no different from somatic cells with respect to X-chromosome inactivation.
Hopes are held out for chorion villus sampling, a technique which is gaining more and more importance for the first trimester prenatal diagnosis of chromosomal aberrations and metabolic abnormalities. A variety of inherited skin diseases can be diagnosed postnatally and prenatally (in the second trimester) by ultrastructural diagnostic markers. For evaluation of prenatal diagnosis in the first trimester, we investigated chorionic villi derived from the trophoblast layer of the early pregnancy by light microscopy and conventional electron microscopy. The ultrastructure of the cellular layers covering the villi, i.e., the inner cytotrophoblast and the outer syncytiotrophoblast, as well as that of the connective tissue of the inner extraembryonic mesoderm, are thoroughly described in relation to the ultrastructural changes in certain genodermatoses including epidermolyses and keratinization disorders. We found that chorionic villi have only a few of the characteristics differentiated in skin, and none of the structures which are relevant to the diagnosis of genodermatoses. In our view, the ultrastructural approach is not suitable for first trimester prenatal diagnosis of genodermatoses in chorionic villi.
In 3,000 chorionic villi studies (CVS) 33 cases of mosaicism and 7 false-positive cell lines in all cells were seen. The mosaic cell lines were caused by aneuploidy of autosomes (13x), sex chromosomes (9x), and structural anomalies (11x). Mosaics of fetal origin were only 4 cases of trisomy 21 and one 47,XXY mosaic. In 7 cases abnormal karyotype of non-fetal origin was seen in all cells in direct studies, including trisomy 16 (3x) and trisomy 18 (2x). The combined use of direct CVS and cell cultures always uncovered the non-fetal origin of chromosome abnormalities and the study of cultured cells in all cases could have prevented 5 terminations. Complete follow-up studies demonstrated no false-negative results. Therefore, CVS can be nearly 100% accurate when both direct studies and cultures are examined in cases of mosaicism and other cell lines of possible non-fetal origin, such as trisomy 16, trisomy 18, translocation (21;21), and 45,X cells.
Full term placental chorionic villi cultured for 7 days in serum-free medium released hydrophilic folate-binding proteins (S-FBP(PCM) into the conditioned medium; in contrast, hydrophobic FBPs were the only form recovered from chorionic villi. Kinetic studies revealed that (i) S-FBP(PCM) was maximally released by the 3rd day, and this was associated with a proportionate decrease in hydrophobic FBPs; (ii) although cycloheximide inhibited de novo synthesis of [35S]methionine-labeled hydrophobic FBPs and S-FBP(PCM) by greater than 90%, unlabeled net S-FBP(PCM) release was only inhibited by 50%; (iii) EDTA markedly inhibited release of S-FBP(PCM) which was accompanied by a proportionate increase in hydrophobic FBPs; (iv) EDTA effects were completely reversed by 5-fold molar excesses of Mg2+ which led to a 50-fold greater release of S-FBP(PCM) compared to EDTA alone; (v) whereas Mg2+ alone stimulated S-FBP(PCM) release 4-fold greater than basal conditions, addition of cycloheximide to Mg2+ suppressed (by 4-fold) the expected increase observed with Mg2+ alone. Biochemical analyses of isolated S-FBP(PCM) revealed similarities to hydrophobic FBPs with respect to the ligand-binding domain and epitopes but differed in detergent-binding characteristics; furthermore, amino acid and carbohydrate analysis revealed a lower Mr = 25,500 with 12% carbohydrate. Based on kinetic analysis of S-FBP(PCM) release from chorionic villi-associated hydrophobic FBPs as well as structural analysis of S-FBP(PCM), these data continue to support the hypothesis that (a) a significant amount of maternal and probably fetal serum hydrophilic FBPs originate from placental hydrophobic FBPs, and (b) the endogenous hydrophobic FBP-directed Mg(2+)-dependent placental protease plays a major role in their release.
The cytogenetic findings were analysed in a series of 500 pregnancies in which chorionic villi sampling was performed. In all cases a direct method was used, karyotyping being successful in 481 cases (96.2%). The main indication for sampling was maternal age over 36 (412 cases; 82.4%). Abnormal laboratory findings resulted in 24 terminations of pregnancy (4.8%); in addition five unexpected balanced chromosome rearrangements were detected. Twelve of 15 cytogenetic discrepancies were detected at amniocentesis, two after termination, and one at spontaneous abortion. Complete follow up data were available for the first 250 patients, among whom nine pregnancies (3.6%) ended in spontaneous abortion before the 20th week. There were no false negative findings. Seventy additional chromosome studies were performed because of failure of chorionic villi sampling or equivocal results, or for confirmation. Counselling before chorionic villi sampling should include the possibility that subsequent amniocentesis may be needed should mosaicism or other unexpected abnormalities be found. The success rate and accuracy of karyotyping chorionic villi samples by the direct method are acceptable but distinctly less than those of karyotyping cultured amniotic fluid cells.