Serum exosomal microRNA pathway activation in placenta accreta spectrum: pathophysiology and detection

Placenta Accreta Spectrum (PAS) disorders are a complex range of placental pathologies associated with significant maternal morbidity and mortality. Diagnosis of PAS relies on ultrasonographic findings with modest positive predictive value. Exosomal microRNA (miR) are small RNA molecules which reflect the cellular processes of origin tissues. We aimed to explore exosomal miR expression to understand PAS pathology and clinical utility for PAS detection. This study was a biomarker analysis of prospectively collected samples in two academic institutions from 2011-2022. Plasma specimens were collected from patients with suspected PAS, placenta previa or repeat cesarean section. Exosomes were quantified and characterized by nanoparticle tracking analysis and Western blot. MiR were assessed by PCR array and targeted single quantification. MiR pathway analysis was performed using Ingenuity® Pathway Analyses software. Placental biopsies were taken from all groups and analyzed by PCR and whole cell ELISA. ROC univariate analysis was performed for microRNA prediction of PAS. Clinically relevant outcomes were collected from abstracted medical records. Plasma specimens were analyzed from a total of 120 subjects (60 PAS, 30 placenta previa and 30 control). Isolated plasma exosomes had a mean size of 71.5 nm and were ten times greater in PAS specimens (20 vs 2 particles/frame). Protein expression of exosomes were positive for ICAM-1, Flotilin, Annexin and CD9. MiR analysis showed increased detection of three miRs (mir-92/103/192) in patients with PAS. Pathway interaction assessment revealed differential regulation of p53 signaling in PAS and ERBB2/HER2 in control specimens. These findings were subsequently confirmed in placental protein analysis. Placental miR paralleled plasma exosomal miR expression. Biomarker assessment of PAS-signature miR had an AUC=0.81 (p< 0.001, 95% CI [0.73-0.89]) with a sensitivity and specificity of 89.2% and 80%, respectively. In this large cohort, plasma exosomal miR assessment revealed differentially expressed pathways in PAS and are potential biomarkers for the detection of PAS.