Hofbauer cells in early human placenta: possible implications in vasculogenesis and angiogenesis.

The stroma of the placental villi contain numerous macrophages, so-called Hofbauer cells which are of mesenchymal origin and are thought to function in many processes. Although there are many studies concerning placental vasculogenesis and angiogenesis, there has been a lack of evidence on the possible roles of Hofbauer cells in these processes. In this study we hypothesized that Hofbauer cell locations and numbers might be correlated with the vascular structures within the placental villi core and therefore may be implicated to play roles in placental vasculogenesis and angiogenesis. Placental tissues were obtained from normal first-trimester pregnancies. Tissues were prepared for light microscopic investigations. Double immunohistochemistry staining with CD31/PECAM1 and CD68 was applied to placental tissues. In placental villous core, majority of the Hofbauer cells were found to be either in close contact with angiogenic cell cords and primitive vascular tubes or located in between them. Moreover, the number of Hofbauer cells and vasculogenic structures were found to be significantly correlated. The findings of this study suggest for the first time that Hofbauer cells might be involved in the processes of vasculogenesis and angiogenesis in the placenta.