Introduction:Immature myeloid cells(IMCs) differentiate into granulocytes,macrophages and dendritic cells(DCs) in steady-state;their population expands in malignancy.IMCs have roles as immunosuppresors and in pathologies involving angiogenesis.We have previously shown that IMCs populate the placenta and promote angiogenesis.
DCs are coordinate immune responses.They promote angiogenesis during implantation and early pregnancy.
Aim:Determining whether alterations in myeloid-cell populations affect placental development will help to understand how aberrancies in placental pathologies affect pregnancy.
Materials and methods:Mouse experiments:placentas were harvested from timed pregnancies of C57Bl/6 mice.Human experiments:human placentas were obtained from normal-vaginal deliveries (NVD) and cesarean-sections (CS).Placentas were immunostained and analyzed using flow cytometry.
Results:The IMC population in the mouse placenta decreased throughout the latter part of pregnancy,conversely,the DC population in the mouse increased just before labor.
The DC population in the human placenta was higher in placentas derived from NVD compared to elective CS.
Placentas were collected from deliveries of pregnancy complicated by preeclampsia. The IMC population in placentas of preeclampsia was significantly higher(17.7%) as compared with those of healthy controls(9.4%,n=14,P=0.018).
Conclusions:In mice,our results indicate a reciprocal population shift between IMCs and DCs in the placenta during pregnancy.Similarly,in human pregnancies,the DC population increases prior to labor(NVD),as compared to placentas obtained in the absence of labor(CS). Additionally,in preeclampsia,we observed an increase in the IMC population within the placenta.The possibility that the onset of labor is preceded by the maturation of IMCs into DCs is intriguing.The roles of IMCs in other pregnancy complications such as IUGR are the subject of our current research.
