[Relevance of platelets in placental development and function].
The availability of mice with defined defects within the hemostatic system enabled researchers to identify a role the coagulation system for embryonic and placental development. However, the role of platelets during development has only recently been experimentally addressed, giving some insight into potential functions of platelets during development. Thus, a quantitative embryonic platelet defect (severe thrombopenia secondary to NF-E2 deficiency) is associated with an embryonic growth retardation and reduced vascularisation of the placenta. Maternal platelet deficiency is associated with placental haemorrhage, which, however, does not impair embryonic or maternal survival. In vitro studies established that platelets or platelet conditioned medium regulate the invasive properties of human extravillous trophoblast cells and induce a phenotypical switch of trophoblast cells. These data imply that platelets are of relevance during placentation. Conversely, platelets and the formation of platelet-fibrin aggregates are dispensable for the development of the embryo proper, establishing that the lethal phenotypes observed in some embryos lacking coagulation regulators does not result from an inability to form platelet-fibrin aggregates, but likely reflects altered protease dependent signaling during vascular development.
Isermann
B
B
Abteilung Innere Medizin I und Klinische Chemie, INF 410, Universität Heidelberg, 69120 Heidelberg. berend.isermann@med.uni-heidelberg.de
Nawroth
P P
PP
D001792:Blood Platelets / Q000502:physiology*; D047108:Embryonic Development / Q000502:physiology*; D005260:Female; D005312:Fetal Blood / Q000502:physiology; D006801:Humans; D008297:Male; D010920:Placenta / Q000502:physiology*; D011247:Pregnancy; D012098:Reproduction