Objective: To explore the role of osteopontin (OPN) in inhibiting fibrosis after intrauterine adhesions (IUA) in mice. Methods: Primary bone marrow mesenchymal stem cells (MSCs) of C57 BL/6 mice and OPN-/-C57 BL/6 mice were isolated and cultured

and the surface antigens of separated cells were detected by flow cytometry. Thirty female mice were randomized into sham operation group

model group

OPN-/-MSCs group

MSCs group

and solvent group

with 6 mice in each group. One week after modeling

MSCs and OPN-/-MSCs were injected into the left and right uterine horns of the mice respectively. Two weeks after the treatment

two-dimensional ultrasound was conducted for the diagnosis of mouse uterus morphology

HE staining and Masson staining for the detection of the morphological changes and fibrosis of the endometrium of the uterus

immunohistochemical staining for the detection of the expression of α-smooth muscle actin (α-SMA)

and Western blot for the detection of the protein expression of transforming growth factor-β1 (TGF-β1)

vascular endothelial growth factor (VEGF)

typeⅠcollagen α1 (COL1A1)

and typeⅢcollagen α1 (COL3A1). Results: MSCs and OPN-/-MSCs cells were successfully isolated and cultured

and expression of CD29

CD44 and CD90 were positive and expression of CD34 was negative in both groups. Compared with the model group

the morphological changes of the uterus in the OPN-/-MSCs group and the MSCs group were improved

the number of glands increased in varying degrees

the area of fibrosis decreased

and the positive expression of α-SMA decreased significantly (P=0.000). TGF-β1

VEGF

COL1A1 and COL3A1 protein expression levels were significantly decreased (all P=0.000). Compared with the OPN-/-MSCs group

the uterine morphology of the MSCs group improved more markedly

the number of glands increased

and the area of fibrosis decreased

the positive expression of α-SMA decreased significantly (P=0.000)

and the expression levels of TGF-β1

VEGF

COL1A1 and COL3A1 proteins also decreased significantly (all P=0.000). Conclusion: MSCs are more effective than OPN-/-MSCs in inhibiting intrauterine adhesions and endometrial fibrosis in mice

indicating that OPN has the effect of regulating bone marrow mesenchymal stem cells to inhibit endometrial fibrosis of intrauterine adhesions in mice.