miR-351-3p promotes rat amniotic fluid-derived mesenchymal stromal cell proliferation via targeting the coding sequence of Abca4.

Amniotic fluid-derived mesenchymal stromal cells (AFMSCs) present different features, depending on the isolation timing and culture conditions. The lack of uniform experimental standards hinders the comparison of results from different studies on AFMSCs. Moreover, understanding the molecular mechanisms that underlie the features of AFMSCs isolated at different embryonic developmental stages might allow the obtention of more viable and highly proliferative AFMSCs through genetic modification. We isolated AFMSCs from pregnant rats at embryonic day (E)12, E15, E18, and E21 and compared their cell proliferation capacity and transcriptome. The cell counting kit-8 assay and RNA sequencing revealed that E12 and E15 AFMSCs showed different characteristics from E18 and E21 AFMSCs. Therefore, AFMSCs were divided into two groups: early (E12 and E15) and late (E18 and E21) pregnancy-stage groups. Next, we screened the gene/microRNA pair Abca4/miR-351-3p that was related to cell proliferation. Abca4 knockdown/overexpression suggested that this gene represses the proliferation of AFMSCs, which is a newly discovered function of this gene. Finally, dual luciferase reporter gene assays confirmed that miR-351-3p targeted the coding sequence of Abca4 and regulated AFMSC proliferation. miR-351-3p promotes AFMSC proliferation via targeting the coding sequence of Abca4. Our findings provide a molecular foundation for further research for obtaining AFMSCs with a higher proliferation capacity. © AlphaMed Press 2021 SIGNIFICANCE STATEMENT: The authors observed that the early passage amniotic fluid-derived mesenchymal stromal cells (AFMSCs) display significantly higher proliferation capacity. Through the further investigation, the authors found out a novel role for ABCA4 in the regulation of AFMSC proliferation, which was with the decreased expression of Abca4, AFMSCs exhibited an increased proliferation. Further understanding of the mechanism by which ABCA4 affects cell proliferation would benefit the screening of other proliferation-related factors and its use in the supplementation of culture medium for AFMSCs, which in turn would allow the development of an optimal culture scheme and the obtention of a high number of highly proliferative AFMSC in vitro.