Bovine fetal fluid cells in vitro: fate and fetal sex prediction accuracy

The in vitro fate of bovine fetal fluid cells and the efficiency of fetal sex predication from cultures of these cells are studied using aspirates from live animals and pregnant uteri collected from the slaughterhouse. Over 70 percent of bovine amniotic fluid samples aspirated from pregnant uteri at the time of slaughter yielded cultures adequate for chromosome analysis whereas only 10 percent of allantoic fluid samples produced growth of cells satisfactory for chromosome analysis. Fetal sexing accuracy was 100 percent in all samples studied. Seven readily recognizable cell types were noted in cultures of fetal fluid cells obtained at various stages of gestation. In a majority of cases, the in vitro morphology of cells from both fetal cavities was similar to that observed in primary human amniotic fluid cell cultures.     

Epithelial cell differentiation in organotypic cultures of fetal rat lung

The purpose of this investigation was to examine the suitability of an organotypic lung-cell culture model for the study of factors influencing fetal lung-cell differentiation. It has been reported that the use of carbon-stripped (hormone-depleted) bovine fetal calf serum in monolayer cell cultures of fetal rat lung prevents continued epithelial cell differentiation in vitro. In this study, organotypic cultures of fetal rat lung cells taken at day 20 of gestation (late canalicular stage) were prepared with a carbon-stripped medium. These organotypic cultures were examined by light, scanning, and transmission electron microscopy for comparison with controls prepared with unstripped bovine fetal calf serum. Highly organized three-dimensional tubular epithelial structures resembling saccules of immature lung were observed within the gelatin sponge matrix. Morphometric analysis of day 20 carbon-stripped samples revealed that 74.6% of the epithelial cells in the tubular structures contained osmiophilic lamellar bodies characteristic of type II pneumonocytes. Control specimens had 71.2% cells with lamellar bodies and did not differ significantly from the experimental group. These data are similar to those obtained with organ cultures of fetal rat lung but are in contrast to findings with monolayer culture systems. The observations of this study suggest that 1) the hormones extracted from bovine fetal calf serum by carbon-stripping are not solely responsible for the continued fetal lung cell differentiation observed in vitro, and 2) that spatial relationships between lung cells in vitro may be a significant factor in the control of differentiation.     

Determination of bovine fetal sex by PCR using fetal fluid aspirated by transvaginal ultrasound-guided amniocentesis

Fetal sex can be determined by the polymerase chain reaction (PCR) using cells from fetal fluid collected by transvaginal ultrasound-guided amniocentesis. A total of 35 aspirates from 30 cows, 15 Holsteins and 15 Japanese Blacks at 59 to 250 d of pregnancy were used. Five cows were aspirated twice at a 10-d interval. A 5.0 MHz convex array transducer connected to a scanner was inserted into the vagina under caudal epidural anesthesia. The transducer was equipped with a 65-cm long, 21-g needle within the probe carrier. A bovine male-specific primer and a bovine gender-neutral primer were used. Fetal fluid was obtained from all except 2 cows in early pregnancy. Five animals aborted within 1 wk following aspiration. A total of 33 samples, 29 of amniotic fluid and 4 of allantoic fluid, was subjected to PCR analysis. Fetal gender was verified in 31 33 samples (18 females and 13 males). Gender was also determined by gross examination of external genitalia of offspring after calving or abortion. Fetal gender was correctly identified by PCR analysis of aspirated fetal fluid in 16 16 females and in 13 15 males. Transvaginal ultrasound-guided amniocentesis followed by PCR analysis of aspirated cell DNA can be used accurately to determine fetal sex in cows at 70 to 100 d of gestation. The procedure requires considerable skill and is not without some risk to fetal viability.     

The effectiveness of gender determination using polymerase chain reaction and radioimmunoassay methods in cattle

The aim of this study was to use polymerase chain reaction (PCR) by amplifying DNA from bovine (Bos taurus) fetal cells recovered through uterine puncture and subsequent amniotic fluid aspiration and to compare the effectiveness of the PCR method with amniotic dihydrotestosterone (DHT) levels in gender determination. Amniotic DHT levels between sexes were significantly higher in males than in females in all periods except the period 91 to 120 d. The differences among the amniotic DHT levels at different gestation periods (61 to 90, 91 to 120, 121 to 150, 151 to 180, 181 to 210 d) were not significant in females but were significant in males in the period 61 to 90 d compared with three other periods. Sensitivity was equal to 97.8% (95% CI = 88.2% to 99.6%), and specificity was equal to 85.4% (95% CI = 80.0% to 97.6%). These two values correspond with a cutoff of DHT in amniotic fluid. Distributions of the two sex groups were classified according to the 192.1 pg/mL cutoff value. A total of 93 amniotic fluid samples were examined by PCR analysis. The sex determination of 91 samples by PCR and electrophoresis was in agreement with the visual sexes of the fetuses. In two amniotic fluid samples, DNA was not isolated, and thus no sex determination was made. Fetal gender was correctly identified by PCR in 44 of 45 males and in 47 of 48 females. In PCR, one band (at the length of 102 bp) and two bands (at the lengths of 102 and 226 bp) were observed respectively for female and male fetuses. It may be concluded that the levels of amniotic DHT and PCR might be used for embryo sexing in pregnant cows.     

A noninvasive approach to studying fetal cells for prenatal diagnosis of chromosomal aneuploidies

Fetal cells isolated from maternal peripheral blood during the second trimester of pregnancy were analyzed. Blood samples were centrifuged in a Ficoll-Paque gradient, the mononuclear cell fraction was isolated and stained with fluorescent monoclonal antibodies against glycophorine A (GPA + PE), transferrin (CD71 + FITC), and Hoechst 33342. Fluorescence-activated cell sorting (FACS) was conducted on a Vantage flow cytofluorimeter (Becton Dickinson). Fluorescence in situ hybridization (FISH) with Y chromosome-specific DNA probe revealed fetal cells that exhibited Y signal in all 20 blood samples obtained from women pregnant with healthy male fetuses. The concentration of these fetal cells averaged about 1.34% and ranged from 0.1 to 4.2% in different blood samples. In six cases, blood samples were obtained from pregnant women, in which prenatal cytogenetic analysis revealed various fetal aneuploidies. Using FISH with DNA probes specific for chromosomes X, 18, and 13/21, Fetal cells with chromosomal aberrations were detected in these six maternal blood samples at a concentration from 1.5 to 5.6% (on average 3.7%). These results indicate the possibility of a new noninvasive approach, which is safe for both mother and fetus when used for isolation of fetal cells from pregnant women's blood samples and prenatal diagnosis of a broad spectrum of fetal cell chromosomal aberrations.     

Differential proteomic analysis of bovine conceptus fluid proteins in pregnancies generated by assisted reproductive technologies

Proteomic analysis of bovine conceptus fluid proteins during early pregnancy has the potential to expose protein species indicative of both the overall health of the fetal-maternal environment and fetal developmental status. In this study, we examined the differential abundance of bovine conceptus fluid proteins (5-50 kDa fraction) from naturally conceived, in vitro fertilisation (IVF) and somatic cell nuclear transfer (SCNT)-derived pregnancies at days 45 and 90 of gestation. In day 45 allantoic fluid (AllF) samples, an atypical cluster of low molecular weight ( approximately 14-16 kDa), low pI (between 3.0 and 4.5 pH units) protein species was increased in three of four IVF samples (30-100-fold increase in protein spot volumes compared to normal). These proteins were identified as paralogs of the bovine cathelicidin antimicrobial protein (CAMP) by MALDI-TOF MS peptide mass fingerprint and MALDI-TOF MS/MS peptide sequence analysis. Peptidoglycan recognition protein and serine (or cysteine) proteinase inhibitor clade B1, were also significantly increased in the corresponding IVF samples. In two of four SCNT AllF samples, a 2-10-fold increase in CAMP protein spot volumes were detected. No aberrant abundance levels of individual protein species were observed in amniotic fluid samples, or in day 90 IVF AllF samples. Identification of unique protein species present in the normal bovine AllF proteome at day 45 is also reported.     

Ultrastructural and karyotypic examination of in vitro produced bovine embryos developed in the sheep uterus

This study examined whether development of bovine in vitro produced (IVP) blastocysts in the sheep uterus resulted in morphologically and karyotypically normal elongation stage bovine blastocysts. Seven day IVP bovine blastocysts, resulting from either in vitro maturation and fertilization, nuclear transfer (NT), or parthenogenic activation, were surgically transferred at the blastocyst stage into sheep uteri. Sheep were sacrificed after 7-9 days, and blastocysts were flushed from their uteri. One of each kind of IVP bovine blastocyst was recovered from sheep uteri for analysis by transmission electron microscopy, and nine NT blastocysts were used to establish cell cultures that were analysed for chromosome complement. TEM analysis of in vivo-derived elongation stage bovine and ovine blastocysts was done for comparative purposes. Most ultrastructural features of the 13-19 day blastocysts were similar to earlier stage blastocysts except that distinct alternative mitochondrial morphologies were found between epiblast and trophectoderm cells. Monociliated cells, presumably nodal cells, were observed in the bovine epiblast and hypoblast, and retrovirus-like particles were elaborated by cells in these same areas. Development in the sheep uterus of IVP bovine blastocysts resulted in the presence of crystalloid bodies in the trophectoderm cells, and apoptotic and necrotic cells were observed in the epiblast tissue. Thus, in vivo incubation in the sheep uterus allowed nearly normal development to the elongated blastocyst stage and may be useful for assessment of NT bovine blastocyst developmental competence. Cell cultures derived from the NT blastocysts had normal chromosome complements suggesting that activation by ionomycin and 6-dimethyl-aminopurine did not cause detrimental changes in ploidy in those blastocysts that developed.     

Prenatal fetal karyotyping and maternal serum alpha-fetoprotein screening.

Prenatal karyotyping was undertaken in 569 consecutive amniotic fluid samples where the indication for amniocentesis was two sequential raised maternal serum alpha-fetoprotein concentrations. In 475 successful cultures five chromosome abnormalities were found--four constitutional anomalies (47,XXY; 47,XYY; an inherited inv(8) (p23q11); and a de-novo translocation t(6;7) (p11;p22) and a culture-derived anomaly (trisomy 2) found in amniotic fluid cells but not in the fetus aborted because it had spina bifida. Of the pregnancies complicated by constitutional abnormalities, only the pregnancy in which the de-novo translocation was detected was terminated. No chromosome abnormalities were detected in the 17 pregnancies which miscarried after amniocentesis. These results provide little justification for including fetal karyotyping as an essential part of maternal serum alpha-fetoprotein screening programmes.     

Chromosome Analysis before Birth and its Value in Genetic Counselling

Chromosome analysis of amniotic cell cultures was achieved in 29 out of 30 consecutive patients who were referred for genetic counselling during pregnancy. Amniocentesis was performed without any apparent untoward maternal or fetal complication. The only pregnancy terminated was that of a carrier of X-linked granulomatous disease, in whom the amniotic cells showed that the fetus was male and also had Down''s syndrome (trisomy G). Chromosome analysis in the remaining 28 patients showed normal karyotypes. The interval between amniocentesis and a definitive karyotype varied from 7 to 31 (average 18·4) days.The reliability of chromosome analysis from amniotic cell culture and of fetal sex determination by means of the sex chromatin and Y-fluorescence techniques was studied further in amniotic fluid from cases of therapeutic abortion and of rhesus incompatibility. The fetal sex was correctly determined in all cases. It is concluded that antenatal diagnosis of genetic disease by amniocentesis now permits a more practical approach to genetic counselling.     

The combined QF-PCR and cytogenetic approach in prenatal diagnosis

In this study, the importance of quantitative fluorescence polymerase chain reaction (QF-PCR) aneuploidy diagnosis test which provides earlier and easier results were discussed. The cell cultures and DNA isolations were performed on 100 amniotic fluids. DNA isolations were made from peripheral blood samples of mothers who had blood-stained amniotic fluid samples. The reasons of references of these pregnant women to our division were increased maternal age, positive double/triple screening test and fetal anomaly history. QF-PCR applied to 19 short tandem repeat markers in the chromosomes 13, 18, 21 and genes X and Y chromosomes. All electropherogram peaks were evaluated on ABI3130. Thirty two (32 %) samples have high maternal age, seven (7 %) have fetal anomaly and the others have double/triple screening test positivity. Ninety-nine (99 %) of the 100 amniotic fluid samples were resulted, but one (1 %) of them could not examined because of the culture failure. The maternal contamination rates were determined as 3 %. Of 100 samples, 2 had trisomy 21 (2 %), 1 had trisomy 13 (1 %), 1 had structural abnormalities (1 %) and the others (97 %) have not any aneuploidy. The results of QF-PCR were in compatible with the results of cell culture and chromosome analysis. Although QF-PCR is an easier and an earlier test, it has a limitation of not to able to scan full genome. It is also sensitive for maternal contamination, so it should be tested together with maternal blood samples. QF-PCR aneuploidy test is the fastest diagnostic test for prenatal diagnosis and so it provides less stressful period for pregnant women.     

Maternal or fetal origin of rhesus monkey (Macaca mulatta) amniotic fluid leukocytes can be identified by polymerase chain reaction using the zinc finger Y gene.

Leukocytes can be found in substantial numbers within the intrauterine tissues and amniotic fluid of women, and play a central role in the pathophysiology of infection-related preterm labor by their production of proinflammatory mediators. It remains unclear whether these leukocytes represent a fetal immune response, a maternal response, or a combination of the two. The objective of this study was to develop a test in the rhesus monkey (Macaca mulatta) suitable for determining the percentage of male fetal cells present in a population of leukocytes recovered from blood or amniotic fluid. We found inadequate specificity for rhesus monkey cells using commercial human Y-chromosome paint kits (fluorescence in situ hybridization (FISH)). Human-specific primers for the repetitive Y chromosome DYZ-1 locus employed in the polymerase chain reaction (PCR) produced an unacceptable percentage of false positives. However, we successfully developed a PCR-based test using rhesus-specific primers for the zinc finger Y (ZFY) locus. Densitometry of PCR products from known ratios of male and female adult peripheral leukocytes generated a linear standard curve which provided quantitative results and required only 400 cells per sample. The rhesus beta globin (RBG) gene served as an internal control. The PCR test correctly discriminated the sex of peripheral leukocytes in 20 adult males, 20 adult females, two male fetuses, and one female fetus. Serial samples of amniotic fluid from four chronically catheterized rhesus monkeys bearing male fetuses were used to confirm the utility of this assay for quantifying fetal cells in amniotic fluid. In conclusion, we have developed a PCR test which is suitable for distinguishing male from female cells in adult and fetal blood and in amniotic fluid, which lends itself to a variety of diagnostic and biologic applications in the rhesus monkey and potentially in other nonhuman primates.     

Cell morphology in long-term cultures of normal and abnormal amniotic fluids

Summary The cell morphology of long-term cultures of amniotic fluid cells from 10 fetuses with a neural tube defect (NTD) and three with omphalocele was examined and compared to 30 long-term cultures of normal amniotic fluids as well as a long-term culture of human fetal brain. Cultures from the amniotic fluids of the fetuses with NTD and omphalocele showed cells with the same general characteristics as normal amniotic fluid cells. However, the cultures of amniotic fluid cells from NTD pregnancies had an additional cell type also seen in fetal brain culture. This was a neuroblast-like cell, with small rounded refractile morphology and long branching processes forming clusters of varying sizes which lay on top of large flat cells. These neuroblast-like cells diminished in number with time in culture and were not present in subcultures. Their possible neuronal origin is discussed.     

The role of fetal urinary excretion in the transfer of ethanol into amniotic fluid after maternal administration of ethanol to the near-term pregnant ewe

The objective of this study was to determine whether fetal urinary excretion is a major route of ethanol transfer into the amniotic fluid surrounding the fetus following maternal administration of ethanol. Conscious instrumented pregnant ewes between 130 and 137 days' gestation (term, 147 days) with (n = 3) or without (n = 3) a catheter in the fetal bladder were administered 1 g ethanol/kg maternal body weight as a 1-h maternal intravenous infusion. Maternal blood, fetal blood, and amniotic fluid samples were collected at selected times, and fetal urine was collected continuously from the bladder-cannulated fetus during the 14-h study for the determination of ethanol concentrations. Fetal urinary excretion of ethanol occurred, and the total amount of ethanol excreted represented 0.30 +/- 0.07 (SD)% of the maternal ethanol dose. The renal clearance of ethanol by the fetus was 0.43 +/- 0.06 mL/min. The pharmacokinetics of ethanol in the maternal-fetal unit and the amniotic fluid for the bladder-cannulated fetal preparation were similar to the data for the nonbladder-cannulated preparation. The data indicate that fetal urinary excretion of ethanol is a secondary route of ethanol transfer into the amniotic fluid. It would appear that diffusion of ethanol across membranes from the maternal and fetal circulations is a major route of ethanol transfer into this intrauterine compartment.     

Amniotic fluid exerts a neurotrophic influence on fetal neurodevelopment via the ERK/GSK-3 pathway

Background

The fetus is surrounded by the amniotic fluid (AF) contained by the amniotic sac of the pregnant female. The AF is directly conveyed to the fetus during pregnancy. Although AF has recently been reported as an untapped resource containing various substances, it remains unclear whether the AF could influence fetal neurodevelopment.

Results

We used AF that was extracted from embryos at 16 days in pregnant SD rat and exposed the AF to the neural cells derived from the embryos of same rat. We found that the treatment of AF to cortical neurons increased the phosphorylation in ERK1/2 that is necessary for fetal neurodevelopment, which was inhibited by the treatment of MEK inhibitors. Moreover, we found the subsequent inhibition of glycogen synthase kinase-3 (GSK-3), which is an important determinant of cell fate in neural cells. Indeed, AF increased the neural clustering of cortical neurons, which revealed that the clustered cells were proliferating neural progenitor cells. Accordingly, we confirmed the ability of AF to increase the neural progenitor cells through neurosphere formation. Furthermore, we showed that the ERK/GSK-3 pathway was involved in AF-mediated neurosphere enlargement.

Conclusions

Although the placenta mainly supplies oxygenated blood, nutrient substances for fetal development, these findings further suggest that circulating-AF into the fetus could affect fetal neurodevelopment via MAP kinases-derived GSK-3 pathway during pregnancy. Moreover, we suggest that AF could be utilized as a valuable resource in the field of regenerative medicine.     

Decrease in gamma-glutamyl transpeptidase activity in early amniotic fluid in fetal trisomy 18 syndrome.

A study was carried out in which activity of gamma-glutamyl transpeptidase was measured in 259 samples of amniotic fluid obtained at various weeks of pregnancy. Two hundred and twenty-eight of the babies subsequently delivered had no chromosome abnormality and served as controls, while in 31 various chromosome abnormalities were detected. Mean activity of gamma-glutamyl transpeptidase in the control samples at 15 weeks was 602 U/l. Activity in the samples obtained in cases of fetal chromosome abnormality was generally below this: it was below the 10th percentile in 74% of the samples and below the 2.5th percentile in 52% of the cases. It is concluded that assay of gamma-glutamyl transpeptidase activity is a rapid preliminary test for prenatal diagnosis of chromosomal abnormalities.     

Maternal DDAVP-induced hyponatremia preserves fetal urine flow during acute fetal hemorrhage

Maternal administration of DDAVP induces maternal and fetal plasma hyponatremia, accentuates fetal urine flow, and increases amniotic fluid volume. Fetal hemorrhage represents an acute stress that results in fetal AVP secretion and reduced urine flow rate. In view of the potential therapeutic use of DDAVP for pregnancies with reduced amniotic fluid volume, we sought to examine the impact of maternal hypotonicity during acute fetal hemorrhage. Chronically catheterized pregnant ewes (130 +/- 2 days) were allocated to control or to DDAVP-induced hyponatremia groups. In the latter group, tap water (2,000 ml) was administered intragastrically to the ewe followed by DDAVP (20 microg bolus, 4 microg/h) and a maintenance intravenous infusion of 5% dextrose water for 4 h to achieve maternal hyponatremia of 10-12 meq/l. Thereafter, ovine fetuses from both groups were continuously hemorrhaged to 30% of estimated blood volume over a 60-min period. DDAVP caused similar degree of reductions in plasma sodium and osmolality in pregnant ewes and their fetuses. In response to hemorrhage, DDAVP fetuses showed greater reduction in hematocrit than control fetuses (14 vs. 10%). Both groups of fetuses demonstrated similar increases in plasma AVP concentration. However, the AVP-hemorrhage threshold was greater in DDAVP fetuses (22.5%) than in control (17.5%). Hemorrhage had no significant impact on plasma osmolality, electrolyte levels, or cardiovascular responses in either group of fetuses. Despite similar increases in plasma AVP, DDAVP fetuses preserved fetal urine flow rates, with values threefold those of control fetuses. These results suggest that under conditions of acute fetal stress of hemorrhage, maternal DDAVP may preserve fetal urine flow and amniotic fluid volume.     

Serum-free cryopreservation of human amniotic epithelial cells before and after isolation from their natural scaffold

Amniotic epithelial cells are a promising source for stem cell-based therapy through their potential capacity to differentiate into the cell lineages of all three germ layers. Long-term preservation is necessary to have a ready-to-use source of stem cells, when required. Reduced differentiation capability, decrease of viability and use of fetal bovine serum (FBS) are three drawbacks of clinical application of cryopreserved stem cells. In this study, we used human amniotic fluid instead of animal serum, and evaluated viability and multipotency of amniotic epithelial cells after cryopreservation in suspension and compared with those cryopreserved on their natural scaffold (in situ cryopreservation). There was no significant difference in viability of the cells cryopreserved in amniotic fluid and FBS. Also, the same results were achieved for expression of pluripotency marker OCT-4 when FBS was replaced by amniotic fluid in the samples with the same cryoprotectant. The cells cryopreserved in presence of scaffold had a higher level of viability compared to the cells cryopreserved in suspension. Although, the number of the cells expressed OCT-4 significantly decreased within cryopreservation in suspension, no decrease in expression of OCT-4 was observed when the cells cryopreserved with their natural scaffold. Upon culturing of post-thawed cells in specific lineage differentiating mediums, the markers of neuronal, hepatic, cardiomyocytic and pancreatic were found in differentiated cells. These results show that replacement of FBS by amniotic fluid and in situ cryopreservation of amniotic epithelial cells is an effective approach to overcome limitations related to long-term preservation including differentiation during cryopreservation and decrease of viability.     

Chromosome lesions in amniotic fluid cell cultures

Summary The frequencies of chromosome lesions were determined on 3537 mitoses in samples of varying sizes from cultures of 25 amniotic fluid specimens taken from patients at cytogenetic risk. The average percentage values of aberrant cells, including and excluding gaps, were 12.5 and 4.9, respectively. The corresponding values for fibroblasts and peripheral blood lymphocytes from normal adult donors, calculated under the same laboratory conditions, were 5.0 (including gaps) and 2.4 (excluding gaps) and 2.4 (including gaps) and 1.0 (excluding gaps), respectively. The hypothesis of a correlation between the increased incidence of chromosome lesions and the occurrence of abnormal karyotypes in amniotic fluid cell cultures is discussed.     

Composition of the fetal fluids in African antelopes

Twenty-four samples of amniotic and allantoic fetal fluids were collected from 15 African antelopes of 11 species and subspecies. Two samples were taken from delivered placentas and the rest were from animals that died during pregnancy or parturition. Data on the sex, development (crown-rump length) and age (trimester of pregnancy) of fetuses, fluid volumes, pH, and 18 biochemical parameters were obtained wherever conditions permitted. Collecting data on fetal fluids in zoo and wild animals may help evaluate both normal and pathological pregnancies.     

The influence of androgen status on metabolic activity in the rat epididymis

Forty-two bovine fetal fluid samples (29 by transsacrosciatic amniocentesis, 2 by transischiorectal amniocentesis, 11 from slaughter-house material) were set up in tissue culture. Thirteen cultures failed due to either incubator failure, bacterial or fungal contamination, or the paucity of culturable cells. Sufficient growth for sex chromosome analysis was obtained in 29 smaples. Twenty-four of these were correctly sexed, three could not be verified and two were incorrectly sexed.Contamination of fetal fluid samples with maternal cells was found to be a major problem which could lead to the misinterpretation of results. To minimize this possibility: the first 1–2 ml of aspirated fetal fluids must be discarded; multiple cultures should be initiated from each sample; and when male cells are not observed, numerous metaphase spreads from each culture and from several passages must be analyzed.