# Evaluation of the expression level of microRNA-21, microRNA-15a, microRNA-372 in human follicular fluid stem cells-derived oocyte-like cells (OLCs)

## TL;DR

This study evaluates the expression of specific microRNAs in oocyte-like cells derived from stem cells to understand their maturation stages.

## Contribution

The novel contribution is the analysis of miR-21, miR-15a, and miR-372 expression patterns in in vitro-derived oocyte-like cells to assess maturation.

## Key findings

- miR-21 and miR-15a expression decreased significantly on day 21 compared to day 7.
- miR-372 showed up-regulation on day 21 compared to day 14.
- Down-regulation of miR-372 may indicate differentiation of stem cells into germ cells.

## Abstract

Today, researchers have succeeded in achieving oocyte-like cells through the
in vitro differentiation of stem cells. MicroRNAs are key regulators of
oocyte development. In this study we decided to evaluate the expression
pattern of microRNA-21, microRNA-15a, and microRNA-372 in oocyte-like cells,
to determine the maturation stage of oocyte-like cells.

Human follicular fluid samples were collected and centrifuged, and their
cells were divided into 3 groups; day 7 as control group, days 14 and 21.
During this period, the cells were evaluated for their morphological
appearance and viability by inverted microscopy. RNA isolation was performed
and cDNA was reversely transcribed by specific stem-loop RT primers.
Real-time RT-PCR was used to detect microRNA expression.

The relative expression of microRNA-21 and microRNA-15a on day 21 was
significantly down-regulated compared to the control group (day 7), but
microRNA-372 did not show a significant difference. Also, on day 14 compared
to the control group (day 7), microRNA-21 did not show a significant
difference; but microRNA-15a and microRNA-372 were significantly
down-regulated. MicroRNA-21 and microRNA-15a on day 21 compared to day 14
revealed down-regulated levels, but microRNA-372 revealed up-regulated
levels.

Our results showed significant decreases in the expression of microRNA-21 and
microRNA-15a in oocyte-like cells, as well as in oocytes, which may lead to
cytoplasmic maturation, germinal vesicle break down and the completion of
meiosis І. In addition, down-regulation expression of microRNA-372 maybe a
confirmation that mesenchymal stem cells have differentiated into germ
cells, and these cells were differentiated into oocyte-like cells.