Angiogenic Factors in the Placentas of Women With COVID-19

Aim: There have been few studies since the beginning of the pandemic researching the histopathologies and conducting molecular investigations of the placentas of SARS-CoV-2 positive pregnant women. The aim of this study was to analyze the changes in the expression of angiogenic growth factors in the placentas of pregnant women infected with SARS-CoV-2 (the COVID-19 group), and to make comparisons with the placentas of non-infected pregnant women (the control group).

Methods: Placentas taken at birth from 20 healthy women (control) and 20 women with a positive test for COVID-19 were prepared for histopathological examination. Immunohistochemical staining was applied in placental tissues with ACE2 (Angiotensin-conversion enzyme-2), VEGF (Vascular Endothelial Growth Factor), VEGFR-1 (Vascular Endothelial Growth Factor Receptor 1) and PDGF (Platelet-Derived Growth Factor).

Results: First, the presence of COVID-19 in the placental tissue was assessed by the ACE2 immunohistochemical method. It was seen that ACE2 was expressed weakly in the placental syncytiotrophoblast cells of non-infected women, but in the syncytiotrophoblasts of the placentas of women infected with COVID-19, ACE2 expression was much higher. VEGF in the endothelial and stromal cells of the villi of the control group was very strong, but in the villi of infected placentas it was significantly weaker. VEGFR-1 was positive in the endothelial membranes of the villi of the control group, but was significantly weaker in the villi of infected placentas. PDGF expression was strong in the syncytiotrophoblast and stromal cells of the control group, but was significantly noticeably weaker in COVID-19 positive placentas.