Characterisation of the release of placenta-derived exosome in gestational diabetes mellitus

Abstract

Objectives: We have established that the release of placenta-derived exosomes (PdE) increases gradually during gestation in healthy normal pregnancies. The release and composition of exosomes from placentae of pregnancies complicated by GDM, however, remain to be fully elucidated. The aim of this study was to establish the gestational-age profile of PdE in maternal plasma of GDM pregnancies. Methods: Plasma samples were obtained from normal (n=20 per group) and GDM (n=7 per group) pregnancies in the first (FT 11-14 weeks), second (ST 22-24 weeks) and third (TT 32-36 weeks) trimester pregnancy. All samples were collected from Davila Clinic (Santiago, Chile). Exosomes were isolated from plasma by differential and buoyant density centrifugation. The total number of exosomes and PdE were determined by quantifying immunoreactive exosomal CD63 and placenta-specific marker (PLAP) by ELISA and fluorescence nanoparticle tracking analysis (NTA, NanoSight NS500). The PLAP/CD63 ratio (i.e. immunoractive PLAP content per exosome) was used as a measure of the contribution of PdE to total exosomes in maternal blood. Results: Variation in the concentration of PdE in maternal plasma was assessed by ANOVA with the variance partitioned between gestational age and pregnancy status (i.e. normal or GDM). Both gestational age and pregnancy status were identified as significant factors (ANOVA, p<0.05). Post-host analyses established that PdE concentrations increased during gestation (FT, ST and TT) in both normal and GDM pregnancies, however, the increase was significantly greater in GDM. (∼2.2-fold, ∼1.5-fold and ∼1.8-fold greater in the FT, ST and TT compared to normal pregnancies, respectively.) We observed that PLAP ratio was decreased dramatically in GDM pregnancies (p < 0.05). Conclusions: The concentrations of exosomes in maternal blood are higher in GDM than normal pregnancies. These characteristics could potentially be used for diagnostic markers for exosome profiling to screen asymptomatic populations.