The Platelet Releasate is Altered in Human Pregnancy.

Purpose: Healthy pregnancy is characterized by an increase in platelet activation and a decrease in the number of circulating platelets with gestation. Despite this recognized importance, proteomic studies investigating platelets in healthy pregnancy have not been performed. As platelet cargo can be altered in different conditions, it is hypothesized that platelets may store a relevant and bespoke collection of molecules during pregnancy.

Experimental Design: Comparative label-free quantitative proteomic profiling of platelet releasates (PRs) is performed from 18 healthy pregnant and 13 non-pregnant women using an MS/MS approach.

Results: Of the 723 proteins identified, 69 PR proteins are found to be differentially released from platelets in pregnancy, including proteins only expressed during pregnancy such as pregnancy-specific glycoproteins and human placental lactogen. Moreover, the population of exosomal vesicles present in the PR is also modified in pregnancy. Receiver operating characteristic analysis shows the predictive ability of 11 PR proteins to distinctly classify pregnant and nonpregnant women with an area under the curve of 0.876, a sensitivity of 88.9%, and a specificity of 84.6%.

Conclusions And Clinical Relevance: Taken together this demonstrates that platelets and their released cargo are 'educated' in physiologic stressful conditions such as pregnancy and may represent a promising platform to study pregnancy complications.