Richards, Claire

Objective: Preeclampsia is a cardiovascular complication characterised by the new onset of hypertension and proteinuria or other end-organ dysfunction. Currently there are no effective treatments for preeclampsia except delivery of the placenta and the baby, often pre-term. Administration of mesenchymal stem cells (MSCs) has shown therapeutic potential in pre-clinical models of preeclampsia. In this study, we aimed to identify novel placental miRNAs in preeclampsia which could be targeted by MSCs or their extracellular vesicles (MSC-EVs). Design and method: Human MSCs were isolated from abdominal fat tissue during caesarean section and cultured for 48 h. Human umbilical cord endothelial cells (HUVEC) were co-cultured with MSCs from pregnancies with or without preeclampsia (n = 3) up to 90 h and angiogenesis assessed using tubule formation assay in IncuCyteu live cell imaging system. Using separate patient samples, miRNA was isolated from placentae from women with and without preeclampsia (n = 2) and miRNA next generation sequencing (miRNAseq) performed. The expression of two miRNAs identified in miRNAseq (miRNA-183–5p and miRNA-203a-3p) were measured in HUVEC cells exposed to 24 h hypoxia (1%) or normoxia (21%) in the presence of MSC conditioned medium (MSC-CM) or MSC-EVs. Results: MSCs isolated from women with preeclampsia demonstrated impaired pro-angiogenic profile compared to MSCs derived from normotensive pregnancies measured by the network length (mm/m2) of HUVECs following 66 h, 72 h, 78 h, 84 h and 90 h of exposure to MSC-CM (n = 3, p = 0.001). The results of miRNAseq identified a number of aberrantly expressed miRNAs including mir-183–5p (logFC = -2.8, p = 0.001) and mir-203a-3p (logFC = -6.7, p = 0.001). Following exposure of HUVECs to hypoxia, mir-183–5p was significantly increased by approximately 8-fold (p = 0.001) whereas mir-203a-3p showed no change in expression. MSC-CM and MSC-EVs were both capable of ameliorating this increase in mir-183–5p as a result of hypoxia (p = 0.01, MSC-CM; p = 0.001, MSC-EVs). Conclusions: In patients with preeclampsia, MSCs show impaired angiogenic function, potentially leading to inappropriate placental development and angiogenesis in pregnancy. Administration of healthy MSCs or associated MSC-EVs could have a therapeutic potential in the treatment of preeclampsia and the mechanism could involve novel mir-183–5p as a treatment target.