Numerical criteria for the diagnosis of placental chorangiosis using CD34 immunostaining

New era of trophoblast research: integrating morphological and molecular approaches

Many pregnancy complications are the result of dysfunction in the placenta. The pathogenic mechanisms of placenta-mediated pregnancy complications, however, are unclear. Abnormal placental development in these conditions begins in the first trimester, but no symptoms are observed during this period. To elucidate effective preventative treatments, understanding the differentiation and development of human placenta is crucial. This review elucidates the uniqueness of the human placenta in early development from the aspect of structural characteristics and molecular markers. We summarise the morphogenesis of human placenta based on human specimens and then compile molecular markers that have been clarified by immunostaining and RNA-sequencing data across species. Relevant studies were identified using the PubMed database and Google Scholar search engines up to March 2020. All articles were independently screened for eligibility by the authors based on titles and abstracts. In particular, the authors carefully examined literature on human placentation. This review integrates the development of human placentation from morphological approaches in comparison with other species and provides new insights into trophoblast molecular markers. The morphological features of human early placentation are described in Carnegie stages (CS), from CS3 (floating blastocyst) to CS9 (emerging point of tertiary villi). Molecular markers are described for each type of trophoblast involved in human placental development. We summarise the character of human trophoblast cell lines and explain how long-term culture system of human cytotrophoblast, both monolayer and spheroid, established in recent studies allows for the generation of human trophoblast cell lines. Due to differences in developmental features among species, it is desirable to understand early placentation in humans. In addition, reliable molecular markers that reflect normal human trophoblast are needed to advance trophoblast research. In the clinical setting, these markers can be valuable means for morphologically and functionally assessing placenta-mediated pregnancy complications and provide early prediction and management of these diseases.

Chorangiosis of Chorionic Villi: What Does It Really Mean?

Chorangiosis has been regarded as a result of low-grade placental hypoxia associated with pregnancy risk factors and abnormal outcomes. It is unknown whether these are a consequence of chorangiosis itself or of associated other placental pathology.Context.—

To prove that chorangiosis itself does not portend an increased risk for pregnancy unless associated with other placental pathology.Objective.—

This retrospective statistical study analyzes 1231 consecutive placentas with diffuse or focal hypervascularity of chorionic villi: 328 with preuterine pattern of chronic hypoxic placental injury (group 1), 297 with uterine type of chronic hypoxic placental injury (group 2), and 606 cases with chorangiosis (group 3) not fulfilling the inclusion criteria for groups 1 or 2.Design.—

Group 2, with 33 cases of chorangiosis (11.1%), featured 10 and 11 statistically significant highest percentages of abnormal clinical and placental variables, respectively; group 3 featured the highest percentages of multiple pregnancy, the heaviest placentas, and the most common acute chorioamnionitis, fetal inflammatory response; and group 1 had the highest proportion of mild erythroblastosis of fetal blood. When comparing groups 1 and 3, 21 of 29 clinical risk factors/outcomes (72.4%) and 30 of 41 placental variables (73.2%) were more common in group 1.Results.—

Presence of diffuse hypoxic patterns of placental injury adds prognostically negative significance to increased vascularity of chorionic villi. Chorangiosis without those patterns portends minimal risk for the pregnancy, and is associated with significantly fewer pregnancy risk factors, abnormal outcomes, and other placental abnormalities.Conclusions.—