Perfusion of the Human Placenta with Red Blood Cells and Xanthine Oxidase Mimics Preeclampsia in-vitro

Abstract

Background and Purpose: Preeclampsia is a major obstetric problem of unknown etiology. The fact that removal of the placenta is the only cure for preeclampsia, has led to the well-established hypothesis, that the placenta is central in the etiology. Gene profiling and proteomics studies have suggested oxidative stress caused by reperfusion and free oxygen radicals as a potential pathophysiological mechanism in preeclampsia. In this study, the dual placental perfusion model was used in order to evaluate the damaging effects of oxidative stress induced by xanthine/xanthine oxides and free hemoglobin.

Material and Methods: The dual placenta perfusion model is a well-established in vitro model for functional placental studies. Placentas were perfused with medium containing either xanthine/xanthine oxidase or erythrocytes as a source of free hemoglobin. Concentration of free hemoglobin in the medium was measured by means of ELISA. Whole genome microarray technique and bioinformatics were used to evaluate the gene expression profile in the two groups.

Results: Substantial levels of free adult hemoglobin were detected in the perfusions. A total of 58 genes showed altered gene expression, the most altered were hemoglobin α, β and γ, tissue factor pathway inhibitor 2 and superoxide dismutase 2. Bioinformatics revealed that biological processes related to oxidative stress, anti-apoptosis and iron ion binding were significantly altered.

Conclusions: The results suggest that perfusion with xanthine/xanthine oxidase and free hemoglobin induce changes in gene expression similar to what has been described for the preeclamptic placenta.

Zusammenfassung

Hintergrund: Die Aetiologie der Praeeklampsie ist nach wie vor nicht geklärt. Die Tatsache, dass die Erkrankung allein durch die Entfernung der Plazenta geheilt werden kann, hat zu der Hypothese geführt, dass die Plazenta bei der Entstehung einer Praeeklampsie eine zentrale Rolle spielt. Untersuchungen des Genoms sowie Proteoms lassen auf oxidativen Stress infolge von Reperfusion mit Freigabe von reaktiven Sauerstoffmolekülen als potentiellen pathophysiologischen Mechanismus bei der Entwicklung einer Praeeklampsie schliessen. In dieser Arbeit wurde die doppelseitige in-vitro Perfusion eines Kotyledons der menschlichen Plazenta als Model benutzt, um die schädigenden Effekte von oxidativem Stress, hervorgerufen durch Xanthine/Xanthineoxiden und freies Hämoglobin, zu untersuchen.

Material und Methode: Die doppelseitige Perfusion hat sich als Model für in-vitro Studien verschiedener funktioneller Aspekte von meschlichem Plazentagewebe besonders bewährt. Plazenten wurden mit Medium nach Zugabe von Xanthine plus Xanthine Oxidase bzw. von Erythrozyten als Quelle von freiem Hämoglobin perfundiert. Die Konzentration von freiem Hämoglobin wurde im Medium mit einem ELISA gemessen. Gesamt Genom Mikroarray Technik und Methoden der Bioinformatik wurden verwendet, um das Gen Expressionsprofil in beiden Gruppen zu bestimmen.

Ergebnisse: Beachtliche Mengen freien Erwachsenen Hämoglobins wurden in den Perfusionen gemessen. Insgesamt fanden sich Expressionsveränderungen bei 58 Genen, mit den stärksten Veränderungen bei α-, ß- und γ-Hämoglobin, Gewebefaktor Reaktion Inhibitor 2 und bei Superoxiddismutase. Die Auswertung mit Hilfe von Bioinformatik ergab, dass biologische Prozesse im Zusammenhang mit oxidativem Stress, Anti-Apoptose und Bindung von Eisenionen signifikant verändert waren.

Konklusionen: Die Ergebnisse zeigen, dass durch die Perfusion mit Xanthine/Xanthineoxidase sowie freiem Hämoglobin Veränderungen in der Genexpression verursacht werden, die den in Plazentagewebe von Praeeklampsien beschriebenen Befunden ähneln.

Key words

hemoglobin - oxidative stress - dual placenta perfusion - microarray

Schlüsselwörter

Hämoglobin - oxidativer Stress - doppelseitige Plazentaperfusion - Mikroarray

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