IFPA Meeting 2010 Workshops Report II: Placental pathology; trophoblast invasion; fetal sex; parasites and the placenta; decidua and embryonic or fetal loss; trophoblast differentiation and syncytialisation

Workshops are an important part of the IFPA annual meeting. At IFPA Meeting 2010 diverse topics were discussed in twelve themed workshops, six of which are summarized in this report. 1. The placental pathology workshop focused on clinical correlates of placenta accreta/percreta. 2. Mechanisms of regulation of trophoblast invasion and spiral artery remodeling were discussed in the trophoblast invasion workshop. 3. The fetal sex and intrauterine stress workshop explored recent work on placental sex differences and discussed them in the context of whether boys live dangerously in the womb.4. The workshop on parasites addressed inflammatory responses as a sign of interaction between placental tissue and parasites. 5. The decidua and embryonic/fetal loss workshop focused on key regulatory mediators in the decidua, embryo and fetus and how alterations in expression may contribute to different diseases and adverse conditions of pregnancy. 6. The trophoblast differentiation and syncytialisation workshop addressed the regulation of villous cytotrophoblast differentiation and how variations may lead to placental dysfunction and pregnancy complications.

Trophoblast differentiation: progenitor cells, fusion and migration -- a workshop report

Challenge lies ahead in unravelling the role played by trophoblast and its repertoire of expressed genes in normal human placental development, growth and pathology. Specific technical advances will clearly be required for characterisation of function. In particular, improvements in our repertoire of in vitro models are needed before many of the key questions can be answered. Recent advances in the study of human trophoblast differentiation are discussed.

Infarction of solid Hodgkin's tumors in mice by antibody-directed targeting of tissue factor to tumor vasculature

We demonstrated previously that selective thrombosis of the blood vessels of solid tumors in mice can be achieved by targeting the extracellular domain of tissue factor by means of an antibody to an experimentally induced marker on tumor vascular endothelium. In the present study, we extend this finding to a naturally occurring marker of tumor vascular endothelium, vascular cell adhesion molecule-1 (VCAM-1). VCAM-1 is expressed by vascular endothelial cells in Hodgkin's disease and various solid tumors in mice and humans. It is absent from vascular endothelial cells in normal tissues in mice, with the exception of the heart and lungs, where it is present on venules. A monoclonal antibody to murine VCAM-1 was covalently linked to the extracellular domain of human tissue factor to create a "coaguligand." After i.v. administration to severe combined immunodeficient mice bearing human Hodgkin's tumors, the coaguligand localized selectively to VCAM-1-expressing vessels, caused thrombosis of those vessels, and retarded tumor growth. The coaguligand also localized to VCAM-1-expressing vessels in the heart and lungs of the mice but did not induce thrombosis in these sites. An immunohistochemical evaluation of the distribution of a monoclonal anti-phosphatidylserine (PS) antibody in the mice showed that the VCAM-1-expressing vessels in the tumor expressed PS, whereas the VCAM-1-expressing vessels in the heart and lungs lacked PS. The lack of thrombotic effect of the coaguligand on heart and lung vessels may be because PS is needed to provide the procoagulant surface upon which coagulation complexes can assemble. The requirement for coincident expression of the targeted marker and PS on tumor endothelium probably contributes to the selectivity of thrombotic action and the safety of coaguligands.

Monoclonal antiphosphatidylserine antibodies react directly with feline and murine central nervous system

OBJECTIVE

Antiphospholipid antibodies (aPL), especially against phosphatidylserine and cardiolipin, are associated with a variety of neurological disorders. While it is believed aPL react with endothelial cells to cause cerebral thrombosis, it is not known to what degree aPL react with neural tissue nor which particular aPL specificities may be more relevant. We investigated direct aPL reactivity with the central nervous system (CNS) using 3 monoclonal IgM aPL that differentiate between cardiolipin and phosphatidylserine dependent antigens.

METHODS

Brain and spinal cord from normal cat Felis domesticus and brain from CD-1 mice were reacted with aPL using indirect immunoperoxidase techniques. Monoclonal aPL were reacted with whole brain myelin by dot immunoblots.

RESULTS

Monoclonal D11A4, reactive with cardiolipin and not phosphatidylserine (CL+/PS-), did not react with any portion of the tissue. Both monoclonal 3SB9b (CL-/PS+) and BA3B5C4 (CL+/PS+) reacted in feline and murine CNS. Both labeled myelinated fibers in grey and white matter of brain and spinal cord in an identical pattern with positive control antibody against myelin basic protein and reacted with whole human brain myelin by dot immunoblot. 3SB9b (CL-+PS+) additionally reacted with ependyma and epithelium of the choroid plexus.

CONCLUSION

aPL, especially those reactive with phosphatidylserine dependent antigens, react directly with epitopes associated with myelin, brain ependyma, or choroid epithelium. Direct reactivity of aPL with nervous tissue may be relevant to neurological disorders.