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Synthesis and release of placental proteins by in vitro perfused human placental tissue
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Placenta (1986), Vol. 7
IMMUNOHISTOCHEMICAL DEMONSTRATION OF VIMENTIN, KERATINS, ACTIN AND DESMOPLAKIN IN HUMAN PLACENTAE A. Beham, H. Denk, G. Desoye & W. N. Franke (University of Graz, Austria) Vimentin, cytokeratins, actin and desmoplakin were demonstrated immunohistochemically in frozen tissue sections of human first-trimester and term placentae. Vimentin was found in amniotic epithelium, in mesenchymal cells of villi and of the chorionic plate as well as in endothelia and in smooth muscle cells of blood vessels. Cytokeratins could be demonstrated in amniotic epithelia and in the trophoblast. Antibodies to actin gave a positive reaction with vessel walls and mesenchymal cells within villi, with mesenchymal cells of the chorionic plate, with endothelial cells and with smooth muscle cells of blood vessels. Desmosomes (recognized as desmoplakin-positive structures) were found in the trophoblast and in amniotic epithelium. The co-expression of vimentin and cytokeratin filaments in amniotic epithelium is of particular interest. The presence of actin in stromal cells of villi and chorionic plate is consistent with their assumed myofibroblastic origin.
DIFFERENTIAL EFFECTS OF HISTAMINE ON THE PERMEABILITY OF THE DUALLYPERFUSED GUINEA-PIG PLACENTA TO ANIONIC AND CATIONIC HORSERADISH PEROXIDASE (HRP) A. Berhe, A. Harkes & C. Sibley (St Mary's Hospital, Manchester, UK) Effects of histamine on the permeability of the dually-perfused guinea-pig placenta to macromolecules of different charge have been investigated. Placentae were prepared and, after a short control period, i mg/ml cationic (cHRP) or anionic (aHRP) horseradish peroxidase (molecular radius 3.6 nm) and 4 #Ci 51Cr-ethylenediaminetetraacetic acid (diffusional marker) were added to the maternal side perfusate. Histamine was administered through the fetal circulation in the first or second halfofa 4o-min perfusion period. Samples from the fetal venous outflow were collected at 5-min intervals for measurement of the tracers and calculation of permeability surface area product (PS). Histamine, irrespective of whether it was perfused in the first or second 2o min, was associated with a significantly higher PS for aHRP. By contrast, histamine failed to have any significant effect on the PS for cHRP. The PS for 51CrEDTA did not change in response to histamine, irrespective of which HRP molecule was used, the overall permeability being lower in the cHRP experiments which were carried out secondly as a group. These results show that histamine can have similar effects on transplacental to those on capillary permeability in other vascular beds. The differential effect of histamine appears to be consistent with the different handling of the two tracers by the guinea-pig placenta.
SYNTHESIS AND RELEASE OF PLACENTAL PROTEINS BY IN VITRO PERFUSED HUMAN PLACENTAL TISSUE N. A. Bersinger & H. Schneider (University Hospital, Zurich, Switzerland) During pregnancy the human placenta releases a host of pregnancy-specific and pregnancyassociated proteins. These include the well-known human chorionic gonadotrophin (hCG) and human placental lactogen (hPL), as well as the new generation of pregnancy-associated plasma proteins (PAPPs). Molecular weights of the members of this heterogeneous group range from 21 ooo to i ooo ooo daltons. The biological function of most of the PAPPs is unknown. A major
Abstracts: European Placenta Group/Rochester Trophoblast Joint Conference
46s
point of controversy encountered in placental protein research is whether the synthesis of all these PAPPs is exclusively trophoblastic or ectopic (decidua, liver, plasma cells) upon stimulation by pregnancy (through hormones or other, currently unknown, pregnancy-specific factors). An in vitro perfusion system, with separate closed-circuit perfusion of fetal and maternal compartments in an isolated lobe of human term placenta, provides information on the placental synthesis of PAPPs in the absence of maternal tissue. At regular intervals, an aliquot of perfusing medium was removed from both circulations and assayed for hCG, hPL, Schwangerschafts protein i (SP1) , PAPP-A, and %-PAG by immunoassay. Oestradiol-I7//and oestriol were determined for control purposes. Before and after perfusion, an aliquot of placental tissue was extracted and the same analytes were determined in order to "distinguish between wash-out and synthesis. All the above-mentioned PAPPs were found to be produced during the 3-h perfusion. The release was predominantly into the maternal compartment, with only trace amounts found on the fetal side. When cycloheximide was added to the medium, the rates fell to levels between 5.5 (for %-PAG) and 62 per cent (for SP1) of the control experiments.
THE EFFECT OF MATERNAL SMOKING ON THE HUMAN PLACENTA AND ITS PRODUCTS G. M. Bouw, R. P. van Westering, P. A. de Jong, D. van Alten, H. P. van Geijn, P. H. J. Kurver, J. M. W. M. Merkus, J. I. Puyenbroek & F. J. Voorhorst (Prot. Christ. Streekziekenhuis, Bennekom, The Netherlands) In this investigation, placentae at term of smokers and non-smokers were examined by means of a histometric technique using point counting and mean linear intercepts measurements. The volume percentages of villous tissue, intervillous space, trophoblast and fibrinoid were determined. The surface density of the villous tissue, the exchange surface, was also measured. In addition, placental*'unction was also measured by means of estimation of placental products. Oestriol, human placental lactogen (hPL) and oxytocinase were estimated in maternal blood samples taken in the 24th , 32nd and 36th weeks of pregnancy and during delivery. Birthweight and placental volume were significantly higher in the group of non-smokers. The surface density of the villous tissue, as well as the total exchange surface, were also greater in the group of nonsmokers. In the non-smokers group, the level of the serum oestriol was higher in the 32nd and 36th week of pregnancy and during delivery. Almost the same pattern was seen for hPL in the 36th week and during delivery. Oxytocinase appeared to be higher only during the delivery. These findings suggest that placental volume, structure and function are detrimentally affected by maternal cigarette smoking, resulting in a lower birthweight of the baby.
INTRALOBULAR VARIATIONS IN VILLOUS MEMBRANE THICKNESS G. J. Burton & G. Critchley (University of Cambridge, UK) Vasculosyncytial membranes, a characteristic feature of mature terminal villi, are in general considered to be the principal site of gaseous exchange in the human placenta. The mechanism of their formation is still uncertain, however, although it has been suggested they may be stimulated to differentiate in organ culture under reduced oxygen tensions. It has recently been demonstrated that chronic hypoxia resultant upon living at altitude is associated with a reduction in the harmonic mean barrier thickness. To examine this effect further, advantage was taken of the naturally-occurring oxygen gradient that exists between the centre and periphery of
Placenta (1986), Vol. 7
IMMUNOHISTOCHEMICAL DEMONSTRATION OF VIMENTIN, KERATINS, ACTIN AND DESMOPLAKIN IN HUMAN PLACENTAE A. Beham, H. Denk, G. Desoye & W. N. Franke (University of Graz, Austria) Vimentin, cytokeratins, actin and desmoplakin were demonstrated immunohistochemically in frozen tissue sections of human first-trimester and term placentae. Vimentin was found in amniotic epithelium, in mesenchymal cells of villi and of the chorionic plate as well as in endothelia and in smooth muscle cells of blood vessels. Cytokeratins could be demonstrated in amniotic epithelia and in the trophoblast. Antibodies to actin gave a positive reaction with vessel walls and mesenchymal cells within villi, with mesenchymal cells of the chorionic plate, with endothelial cells and with smooth muscle cells of blood vessels. Desmosomes (recognized as desmoplakin-positive structures) were found in the trophoblast and in amniotic epithelium. The co-expression of vimentin and cytokeratin filaments in amniotic epithelium is of particular interest. The presence of actin in stromal cells of villi and chorionic plate is consistent with their assumed myofibroblastic origin.
DIFFERENTIAL EFFECTS OF HISTAMINE ON THE PERMEABILITY OF THE DUALLYPERFUSED GUINEA-PIG PLACENTA TO ANIONIC AND CATIONIC HORSERADISH PEROXIDASE (HRP) A. Berhe, A. Harkes & C. Sibley (St Mary's Hospital, Manchester, UK) Effects of histamine on the permeability of the dually-perfused guinea-pig placenta to macromolecules of different charge have been investigated. Placentae were prepared and, after a short control period, i mg/ml cationic (cHRP) or anionic (aHRP) horseradish peroxidase (molecular radius 3.6 nm) and 4 #Ci 51Cr-ethylenediaminetetraacetic acid (diffusional marker) were added to the maternal side perfusate. Histamine was administered through the fetal circulation in the first or second halfofa 4o-min perfusion period. Samples from the fetal venous outflow were collected at 5-min intervals for measurement of the tracers and calculation of permeability surface area product (PS). Histamine, irrespective of whether it was perfused in the first or second 2o min, was associated with a significantly higher PS for aHRP. By contrast, histamine failed to have any significant effect on the PS for cHRP. The PS for 51CrEDTA did not change in response to histamine, irrespective of which HRP molecule was used, the overall permeability being lower in the cHRP experiments which were carried out secondly as a group. These results show that histamine can have similar effects on transplacental to those on capillary permeability in other vascular beds. The differential effect of histamine appears to be consistent with the different handling of the two tracers by the guinea-pig placenta.
SYNTHESIS AND RELEASE OF PLACENTAL PROTEINS BY IN VITRO PERFUSED HUMAN PLACENTAL TISSUE N. A. Bersinger & H. Schneider (University Hospital, Zurich, Switzerland) During pregnancy the human placenta releases a host of pregnancy-specific and pregnancyassociated proteins. These include the well-known human chorionic gonadotrophin (hCG) and human placental lactogen (hPL), as well as the new generation of pregnancy-associated plasma proteins (PAPPs). Molecular weights of the members of this heterogeneous group range from 21 ooo to i ooo ooo daltons. The biological function of most of the PAPPs is unknown. A major
Abstracts: European Placenta Group/Rochester Trophoblast Joint Conference
46s
point of controversy encountered in placental protein research is whether the synthesis of all these PAPPs is exclusively trophoblastic or ectopic (decidua, liver, plasma cells) upon stimulation by pregnancy (through hormones or other, currently unknown, pregnancy-specific factors). An in vitro perfusion system, with separate closed-circuit perfusion of fetal and maternal compartments in an isolated lobe of human term placenta, provides information on the placental synthesis of PAPPs in the absence of maternal tissue. At regular intervals, an aliquot of perfusing medium was removed from both circulations and assayed for hCG, hPL, Schwangerschafts protein i (SP1) , PAPP-A, and %-PAG by immunoassay. Oestradiol-I7//and oestriol were determined for control purposes. Before and after perfusion, an aliquot of placental tissue was extracted and the same analytes were determined in order to "distinguish between wash-out and synthesis. All the above-mentioned PAPPs were found to be produced during the 3-h perfusion. The release was predominantly into the maternal compartment, with only trace amounts found on the fetal side. When cycloheximide was added to the medium, the rates fell to levels between 5.5 (for %-PAG) and 62 per cent (for SP1) of the control experiments.
THE EFFECT OF MATERNAL SMOKING ON THE HUMAN PLACENTA AND ITS PRODUCTS G. M. Bouw, R. P. van Westering, P. A. de Jong, D. van Alten, H. P. van Geijn, P. H. J. Kurver, J. M. W. M. Merkus, J. I. Puyenbroek & F. J. Voorhorst (Prot. Christ. Streekziekenhuis, Bennekom, The Netherlands) In this investigation, placentae at term of smokers and non-smokers were examined by means of a histometric technique using point counting and mean linear intercepts measurements. The volume percentages of villous tissue, intervillous space, trophoblast and fibrinoid were determined. The surface density of the villous tissue, the exchange surface, was also measured. In addition, placental*'unction was also measured by means of estimation of placental products. Oestriol, human placental lactogen (hPL) and oxytocinase were estimated in maternal blood samples taken in the 24th , 32nd and 36th weeks of pregnancy and during delivery. Birthweight and placental volume were significantly higher in the group of non-smokers. The surface density of the villous tissue, as well as the total exchange surface, were also greater in the group of nonsmokers. In the non-smokers group, the level of the serum oestriol was higher in the 32nd and 36th week of pregnancy and during delivery. Almost the same pattern was seen for hPL in the 36th week and during delivery. Oxytocinase appeared to be higher only during the delivery. These findings suggest that placental volume, structure and function are detrimentally affected by maternal cigarette smoking, resulting in a lower birthweight of the baby.
INTRALOBULAR VARIATIONS IN VILLOUS MEMBRANE THICKNESS G. J. Burton & G. Critchley (University of Cambridge, UK) Vasculosyncytial membranes, a characteristic feature of mature terminal villi, are in general considered to be the principal site of gaseous exchange in the human placenta. The mechanism of their formation is still uncertain, however, although it has been suggested they may be stimulated to differentiate in organ culture under reduced oxygen tensions. It has recently been demonstrated that chronic hypoxia resultant upon living at altitude is associated with a reduction in the harmonic mean barrier thickness. To examine this effect further, advantage was taken of the naturally-occurring oxygen gradient that exists between the centre and periphery of