Objective        To determine the role of osteopontin (OPN) in the differentiation of mouse marrow mesenchymal stem cells (MSCs) into epithelial cells (OPN) with knockout mice and wild type mice as experiment objects.       Methods         In vitro experiment: the MSCs were isolated and cultivated from wild type (WT) and knockout (KO) newborn mice (aged 1 day old) and identified for the purity. The cells at the third-generation were cultured to join epithelial transformation culture system. Microscopy

flow cytometry

immunofluorescence staining and Western blotting were used to observe and compare the expression levels of epidermal cells markers (CK14) of the 2 groups. Animal experiment: the experiment was divided into 4 groups

such as WT mice receiving GFP-MSCs injection around the wound (WT/MSCs group)

WT mice injected with PBS (WT/PBS group)

KO mice injected with GFP-MSCs (KO/MSCs group)

and KO mice injected with PBS (KO/PBS group). Each group had 8 male mice

at the age of 6 to 8 weeks and weighing 20 to 25 g. According to the grouping

cultivated GFP-MSCs and PBS were injected around the wound

and the wound healing and differentiation of GFP-MSCs into epithelial cells were observed.       Results       The isolated and cultured MSCs were seen in fusiform- or fibroblast-like. Flow cytometry confirmed the purity of separated MSCs was over 91%. CK14 was expressed in both WT and KO cells after induction for 12 and 17 d. Immunofluorescence staining also showed that the WT group had obviously higher expression level of CK14 than the KO group on the 17th day (0.936 3±0.009 5 vs 0.647 5±0.023 1

P0.01)

and so was Western blot analysis (0.614 6±0.015 3 vs 0.389 4±0.016 8

P0.01). Animal experiments also showed wound healing of WT/PBS group was significantly faster than the KO/PBS group (P0.05). Moreover

the wound healing of WT/MSCs group was faster than WT/PBS group (P0.05) and the capacity of injected GFP-MSCs to differentiate into epithelial WT/MSCs was also stronger than KO/MSCs (P0.05).       Conclusion       OPN induces MSCs to differentiate into epithelial cells in vitro and in vivo

and promotes the wound healing.