Ruth Sager

Evolution of maternofetal transport of immunoglobulins during human pregnancy

PROBLEM: We determined the evolution of the maternal‐fetal transport of immunoglobulins during human pregnancy.

Maternal-fetal transport of immunoglobulin G and its subclasses during the third trimester of human pregnancy

PROBLEM: We determined the maternal‐fetal transport of immunoglobulin G (IgG) during the third trimester of human pregnancy.

Transport of proteins across the human placenta.

PROBLEM: The transport of various proteins across the human placenta was investigated by comparing maternal and fetal concentrations of tetanus antigen (TT‐AG), anti‐tetanus (TT)‐immunoglobulin G (IgG) (following maternal vaccination), IgA, human chorionic gonadotropin (hCG), human placental lactogen (hPL), and alpha‐fetoprotein (AFP) at term.

Lack of transport of erythropoietin across the human placenta as studied by an in vitro perfusion system.

The transfer of human recombinant erythropoietin (rhEPO) from the maternal to the fetal side was investigated using the technique of in vitro perfusion of an isolated cotyledon of human placenta, with recirculation of the perfusate (130 ml) in separate closed maternal and fetal circuits. rhEPO (221–512 U), together with [14C]BSA (bovine serum albumin, 44.8 kBq or 2,688,000 dpm), was added to the maternal circuit only. Despite a considerably lower molecular weight of EPO mol. wt.=30,400 Da) compared to BSA (mol. wt.= 69,000 Da), no difference was found in their transfer across the placenta from the maternal to the fetal side, which was very low for both macromolecules. The total transfer of rhEPO derived from the concentration measured in the samples taken from the fetal circuit at the end of 4–5 h of perfusion, was in the range of 0.04% of the amount initially added to the maternal compartment. A similar amount of transfer was determined for [14C]BSA (0.04–0.07%,n=12). In conclusion, by direct determination in a dually in vitro perfused human placental cotyledon, no significant transfer of rhEPO from the maternal to the fetal side could be shown.

Transport of immunoglobulin G and its subclasses across the in-vitro perfused human placenta

OBJECTIVE The transport of immunoglobulin G and its subclasses 1 to 4 was investigated in the in vitro-perfused isolated cotyledon of the human placenta. STUDY DESIGN An in vitro system with separate perfusion of the villous capillary system (fetal compartment) and the corresponding intervillous space (maternal compartment) was set up in an isolated cotyledon of human term placenta. After a 2-hour control phase with both compartments perfused in a closed circuit with NCTC-135 tissue culture medium together with Earls balanced salt solution (2:1), media were exchanged in both circuits and for the experimental phase immunoglobulin G (Sandoglobulin) together with carbon 14-labeled bovine serum albumin (5-10 microCi) was added to the maternal compartment at a concentration of 6 gm/L. During the experimental phase, lasting between 2 and 5 hours, samples were taken from the maternal and fetal compartments every 30 minutes up to 2 hours and every 60 minutes thereafter. RESULTS During the control phase immunoglobulin G appeared in the maternal perfusate and reached a plateau at 60 to 80 mg/L, whereas the concentration in the fetal perfusate did not exceed 20 mg/L. A similar pattern of release was observed for hemoglobin, suggesting a washout of remains of blood from the intervillous space and the villous vascular compartment. After addition of immunoglobulin G to the maternal circuit during the first 2 hours in three of four experiments, no change in immunoglobulin G concentration was seen in the fetal circuit, and only in the fourth and fifth hours did the fetal concentration increase to 0.6% of the maternal concentration. In contrast, carbon 14-labeled bovine serum albumin was already detectable in the fetal circuit after 1 hour, but the level remained constant at 0.1% of the maternal concentration. Total immunoglobulin G transfer was estimated at 0.5% of the amount added to the maternal circulation, which was five times higher than total transfer of bovine serum albumin. Transfer was shown for all four subclasses. At the end of the experiment the ratio of immunoglobulin G1 to immunoglobulin G2 in the fetal perfusate was significantly higher than in the maternal perfusate (3.8 vs 1.8), suggesting preferential transfer of immunoglobulin G1. CONCLUSION Transfer of all four immunoglobulin G subclasses of a commercially available immunoglobulin G preparation across the human placenta from the maternal to the fetal side was demonstrated by the dual in vitro perfusion system. There is a preferential transfer for immunoglobulin G1.

Protein Transport Across the In Vitro Perfused Human Placenta

PROBLEM: Placental transport of various proteins present in human serum, such as immunoglobulins (IgG, IgA), specific anti‐tetanus IgG (anti‐TT‐IgG), and tetanus toxoid‐antigen (TT‐AG), was investigated. In addition, the transport of IgG modified with biotin (IgG‐BT) and 14C‐bovine serum albumin (14C‐BSA, a permeability marker for macromolecules), was assessed.

Regulation of Human Trophoblast GLUT1 Glucose Transporter by Insulin-Like Growth Factor I (IGF-I)

Glucose transport to the fetus across the placenta takes place via glucose transporters in the opposing faces of the barrier layer, the microvillous and basal membranes of the syncytiotrophoblast. While basal membrane content of the GLUT1 glucose transporter appears to be the rate-limiting step in transplacental transport, the factors regulating transporter expression and activity are largely unknown. In view of the many studies showing an association between IGF-I and fetal growth, we investigated the effects of IGF-I on placental glucose transport and GLUT1 transporter expression. Treatment of BeWo choriocarcinoma cells with IGF-I increased cellular GLUT1 protein. There was increased basolateral (but not microvillous) uptake of glucose and increased transepithelial transport of glucose across the BeWo monolayer. Primary syncytial cells treated with IGF-I also demonstrated an increase in GLUT1 protein. Term placental explants treated with IGF-I showed an increase in syncytial basal membrane GLUT1 but microvillous membrane GLUT1 was not affected. The placental dual perfusion model was used to assess the effects of fetally perfused IGF-I on transplacental glucose transport and syncytial GLUT1 content. In control perfusions there was a decrease in transplacental glucose transport over the course of the perfusion, whereas in tissues perfused with IGF-I through the fetal circulation there was no change. Syncytial basal membranes from IGF-I perfused tissues showed an increase in GLUT1 content. These results demonstrate that IGF-I, whether acting via microvillous or basal membrane receptors, increases the basal membrane content of GLUT1 and up-regulates basal membrane transport of glucose, leading to increased transepithelial glucose transport. These observations provide a partial explanation for the mechanism by which IGF-I controls nutrient supply in the regulation of fetal growth.

Stem Cells From Umbilical Cord Wharton’s Jelly From Preterm Birth Have Neuroglial Differentiation Potential

Objective: The aim of the study is to determine the neuroglial differentiation potential of human Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs) from preterm birth when compared to term delivery. Study Design: The WJ-MSCs from umbilical cords of preterm birth and term controls were isolated and induced into neural progenitors. The cells were analyzed for neuroglial markers by flow cytometry, real-time polymerase chain reaction, and immunocytochemistry. Results: Independent of gestational age, a subset of WJ-MSC displayed the neural progenitor cell markers Nestin and Musashi-1 and the mature neural markers microtubule-associated protein 2, glial fibrillary acidic protein, and myelin basic protein. Neuroglial induction of WJ-MSCs from term and preterm birth resulted in the enhanced transcription of Nestin and Musashi-1. Conclusions: Undifferentiated WJ-MSCs from preterm birth express neuroglial markers and can be successfully induced into neural progenitors similar to term controls. Their potential use as cellular graft in neuroregenerative therapy for peripartum brain injury in preterm birth has to be tested.

Effect of physiologic perfusion-fixation on the morphometrically evaluated dimensions of the term placental cotyledon.

Objective: To estimate the in vivo dimensions of the fetal villous tree of the normal term placenta. Methods: Dual-circuit perfusion-fixation of a cotyledon from eight normal term placentas was performed with random intra-cotyledon tissue sampling. Stereologic methods were used to derive estimates of villous (intermediate and terminal) surface area and volume, and star volume (a measure of villous volume). Results: Villous surface area (mean 20.9 m2 [standard deviation 1.8]), capillary surface area (12.8 m2 [1.5]), villous volume (469 mL [40]), and capillary volume (80 mL [10]) values were all approximately 50% higher than reported previously. Star volume estimates ranged from 480 to 1350 μm3. Conclusion: Tissue perfusion-fixation more accurately reconstructs the in vivo state, resulting in higher reference values than previously thought for the fetal villous tree dimensions. Up to one-quarter of fetoplacental blood volume is likely to be accommodated within the placenta at term.

Homing of placenta-derived mesenchymal stem cells after perinatal intracerebral transplantation in a rat model

OBJECTIVE The aim of this study is to assess early homing of placenta-derived stem cells after perinatal intracerebral transplantation in rats. STUDY DESIGN Neonatal Wistar rats (2-4 days old) were anesthetized, and 250,000 human placenta-derived mesenchymal stem cells (MSC) injected into the lateral ventricle or the paraventricular white matter using a stereotactic frame. Donor MSC were detected by immunohistochemistry using an antihuman HLA-ABC antibody. RESULTS In all, 84% of the animals survived the transplantation. Donor cells were detected in the brain ventricle 1-2 hours posttransplantation. After 4 hours, donor cells migrated throughout the ventricular system. At 1-4 weeks after transplantation, some cells had migrated into the periventricular white matter. CONCLUSION Human placenta-derived MSC were successfully transplanted into the lateral ventricles of neonatal rats. Donor cells survived, homed, and migrated in the recipient brains. Proliferation and differentiation analysis and functional tests will assess the therapeutic effects of stem cell transplantation.