Exosomes secreted from Amniotic mesenchymal stem cells modify trophoblast activities by delivering miR-18a-5p and regulating HRK-p53 interaction

Background: Amniotic mesenchymal stem cells (AMSCs) have been demonstrated as effective in tissue repair and regeneration. Trophoblast dysfunction is associated with several types of pregnancy complications. The aim of this study is to investigate the effects of AMSCs on the biological activities of human trophoblasts, as well as their molecular mechanisms.

Methods: Exosomes were isolated from AMSC supernatants, and characterized and quantified by transmission electron microscopy (TEM) , nanoparticle tracking analysis (NTA) and Western blotting assay. Immunofluorescence assay was performed to detect the uptake of AMSCs-derived exomes (AMSC-Exos) by human trophoblasts. Human trophoblasts were subjected to transcriptome analysis after being co-cultured with AMSC-Exos. Lentiviral transfection was performed to construct the human trophoblast cell lines with stable HRK knockdown or overexpression. Immunohistochemistry was used to detect the HRK expression in preeclampsia (PE) patients. CCK8 and Transwell assays were respectively used to detect the trophoblast proliferation and migration. TUNEL flow cytometry assay was used to detect the apoptosis in trophoblasts. qRT-PCR and Western blotting assays were used to detect the mRNA and protein levels of the genes. Dual luciferase reporter assays were used to detect the changes in gene-transcript levels.

Results: AMSC-Exos could be absorbed by human trophoblasts. Transcriptome analysis showed that HRK was significantly reduced in human trophoblasts co-cultured with AMSC-Exos. HRK inhibited cell proliferation and migration in human trophoblasts and promoted their apoptosis via p53 upregulation. miR-18a-5p, present at high levels in AMSC-Exos, improved trophoblast proliferation and migration, and inhibited their apoptosis by inhibiting the HRK expression.

Conclusion: miR-18a-5p present in AMSC-Exos could be absorbed by trophoblasts, and in turn, improved their proliferation and migration and inhibited their apoptosis by HRK down-regulation.