Elsevier

Placenta

Volume 32, Supplement 1, February 2011, Pages S49-S54
Placenta

Placental and trophoblastic in vitro models to study preventive and therapeutic agents for preeclampsia

https://doi.org/10.1016/j.placenta.2010.11.023Get rights and content

Abstract

In the field of preeclampsia, enormous efforts are ongoing to identify biomarkers predicting the syndrome already in the first trimester of pregnancy. At the same time, there is the need for in vitro models to test such biomarkers prior to their use in clinical trials. In addition, in vitro models may accelerate the development and evaluation of the benefit of any putative therapeutics. Therefore, in vitro systems have been established to evaluate the release of biomarkers and measure the effect of putative therapeutics using placental villous explants as well as the choriocarcinoma cell line BeWo. For explants, a cryogenic method to freeze, transport and thaw villous explants was developed to use such tissues for a multi-site tissue culture evaluation.

Here we focus on three out of many in vitro models that have been established for human placental trophoblast. (1) Choriocarcinoma cell lines such as BeWo, Jeg-3 and Jar cells (2) isolated primary trophoblast cells, and (2) villous explants from normal placentas delivered at term. Cell lines were used to assess the effect of differentiation and fusion on the expression and release of a preeclampsia marker (placental protein 13; PP13) and beta-hCG. Moreover, cell lines were used to study the effect of putative preeclampsia therapeutics such as vitamins C and E, heparin and aspirin on marker release and viability. Cryopreservation of villous explants enabled shipment to a remote laboratory and testing of parameters in different countries using explants from one and the same placenta.

Recently published data make it tempting to speculate that the choriocarcinoma cell line BeWo as well as fresh and cryogenically stored placental villous explants may well serve as in vitro models to study preventive and therapeutic agents in the field of preeclampsia.

Introduction

Placental insufficiency plays a crucial role in the development of preeclampsia and fetal growth restriction, pregnancy pathologies with still unknown etiologies [1]. Preeclampsia is one of the leading causes for maternal and neonatal mortality and morbidity. Therefore, major efforts are ongoing to identify markers for the early prediction of preeclampsia. Such markers will assist in developing appropriate management tools and preventive therapies to finally find agents to eliminate preeclampsia.

The last years have shown an enormous progress in the availability of predictive markers and the usefulness of their combination in either concurrent or contingent approaches [2]. This progress has prepared the ground to consider screening, and in fact screening for preeclampsia with different sonographic and biomarker assays is currently offered in a limited number of centers of excellence.

The development of preeclampsia prevention and management is lagging behind novel drug development for other multifactorial diseases. The use of animal models to study placental alterations in preeclampsia was considered dubious in view of the very different processes of placentation between human and other mammals. As a result, most candidate therapeutics were tested directly on human. However, due to ethical constrains, and often in conjunction with financial limitations, studies lack sufficient power or failed due to limitations of design in the absence of suitable model systems to better substantiate them. The benefit of a research approach based on in vitro models combined with the use of disease screening and diagnosis markers proved very effective in developing treatment of diabetes, hyper-cholesterol, or leukemia, to name a few.

In this paper we review two in vitro models in the context of evaluating drug candidates in preventing and treating preeclampsia using preeclampsia markers as monitoring tools to evaluate drug benefit. Such in vitro systems include placental villous explants and trophoblast derived choriocarcinoma cells, which are first tested on the effects of putative therapeutics and second on the effects of blood samples from healthy and preeclamptic women in combination with the putative therapeutics. The criteria of evaluating the performance of such systems include viability, proliferation and morphological criteria of tissues and cells as well as expression and release of disease-related screening and diagnostic biomarkers. The value of marker changes known to have a value in predicting preeclampsia in the presence of putative preventive and managing anti-preeclampsia agents is then reviewed.

Section snippets

In vitro models

To leverage the progress in biomarker development, in vitro models are required for the assessment of preventive means before such putative therapeutics can be incorporated in large scale clinical trials.

First line models are animal models. Indeed, a number of animal models have been developed to mimic preeclampsia. Most models make use of rodents such as rats and mice. However, these rodent models lack the profound invasion of trophoblast into the endometrium and myometrium as well as the

Conclusions

The last few years have seen an enormous progress in terms of marker development to predict and diagnose preeclampsia. On the other hand, the introduction of these effective markers into routine prediction of preeclampsia progresses very slowly due to the lack of effective therapeutics or other agents. The benefit of a research approach based on in vitro models combined with the use of disease screening and diagnosis markers proved very effective in developing treatment of diabetes,

Contributors

B.H. and H.M. supervised the experiments, participated in data analysis and jointly wrote the manuscript. K.O. and V.K. performed cell culture, cryoprotection and biochemical experiments, M.S. and Y.G. E.L. developed the procedure for placenta system processing, culturing and explant sampling, E.L. developed the methodology for cryopreservation and cryoprotectant selection, and R.G. obtained patient informed consent, built the patient information system, audited clinical outcome, collected

Role of funding source

This work was supported by a research grant of the European Union (FP6-grant # 037244, project title Pregenesys).

Conflict of interest

H.M. is CEO & director of Diagnostic Technologies Ltd (DTL), and has options for ordinary shares on the company accounting for 3.5% in the company shares on a fully diluted basis. M.S., V.K. and Y.G. are employees of DTL and their salary is paid from the grant sponsored by this research.

Acknowledgements

This work was supported by a research grant of the European Union (FP6-grant #037244, project title Pregenesys). K.O. was funded by the EU (FP6-Grant #037244) within the PhD program Molecular Medicine of the Medical University of Graz.

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