Objective. To investigate the effects of miR-144-3p-targeted regulation of phosphatase and tensin homolog deleted on chromosome ten (PTEN) gene on proliferation, apoptosis, and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) under retraction force. Methods. The BMSCs of rats were randomly divided into the tension MSC group with detrusor stimulation and the MSC group without detrusor stimulation, after which osteogenic differentiation of BMSCs was induced in both groups. Alkaline phosphatase (ALP) staining and alizarin red staining were used to detect the osteogenic differentiation ability of the two groups of cells. Real-time quantitative reverse transcription PCR (qRT-PCR) was used to detect the expression of miR-144-3p and PTEN in the two groups of cells after osteogenic differentiation. Bioinformatics website and dual luciferase reporter were used to detect the relationship between miR-144-3p and PTEN. The tension MSC group was used as a control group, and miR-144-3p mimics (miR-144-3p mimic group), mimic controls (mimic-NC group), PTEN interferers (si-PTEN group), and interference controls (si-NC group) were transfected into BMSCs. The BMSCs were then continuously stimulated for 24 h using a Flexercell in vitro cellular mechanics loading device, applying a draft force at a frequency of 1 Hz and a deformation rate of 18%. The cell proliferation was detected by Cell Counting Kit-8 (CCK-8) colorimetric assay; the expression levels of cyclin, cyclin-dependent kinases (CDK), BCL2-associated X (BAX), B-cell lymphoma-2 (BCL-2), and other cell cycle and apoptosis related proteins were detected by western blot (WB); and the osteogenic differentiation ability of MSC cells was detected by ALP staining and alizarin red staining. Results. Compared with the MSC group, the level of miR-144-3p was significantly lower and the level of PTEN was significantly higher in the tension MSC group. ALP staining showed normal activity in the MSC group and decreased ALP activity in the tension MSC group compared to the MSC group. Alizarin red staining in the MSC group showed scattered calcium nodule formation, and alizarin red staining showed red nodules with a more uniform color distribution. Compared to the MSC group, the tension MSC group showed fewer, smaller, and lighter staining mineralized nodules. Compared with the tension group and mimic-NC group (si-NC group), the proliferation rate of cells in the miR-144-3p mimic group (si-PTEN group) was significantly higher; the expression levels of PTEN and BAX were significantly lower; and the expression levels of cyclin, CDK, and BCL-2 protein were significantly higher. ALP staining results revealed that the miR-144-3p mimic group (si-PTEN group) showed significantly higher osteogenic differentiation ability and ALP activity of MSC than the tension group and mimic-NC group (si-NC group). Conclusion. miR-144-3p may inhibit apoptosis and promote proliferation and osteogenic differentiation of BMSCs under tension by targeting and regulating PTEN.

Purpose. To discuss effects of phosphatase and tensin homolog protein (PTEN)-mediated transforming growth factor-β (TGF-β)/Smad homologue 2 (Smad2) pathway on osteogenic differentiation in osteoporotic (OP) tibial fracture rats and bone marrow mesenchymal stem cell (BMSC) under tension. Methods. A tibial fracture model was established. The rats were divided into sham-operated group and model group, and tibia tissue was collected. Purchase well-grown cultured rat BMSC, and use the Flexercell in vitro cell mechanics loading device to apply tension. The expression of PTEN was detected by qRT-PCR. After the BMSCs were transfected with si-PTEN and oe-PTEN, the force was applied to detect cell differentiation. The expression of TGF-β/Smad2 protein was detected by Western blot. The formation of calcium nodules in BMSC was detected by alkaline phosphatase (ALP) staining and alizarin red (AR) staining. Results. The expression of PTEN was higher in the model group and tension MSC group, and the expression of TGF-β and Smad2 protein was lower. The expression of TGF-β and Smad2 protein in oe-PTEN group was lower than the oe-NC group and control group. The expression of TGF-β and Smad2 protein in si-PTEN group was higher than the si-NC group and control group. The results of ALP staining and AR staining also confirmed the above results. Conclusion. PTEN-mediated TGF-β/Smad2 pathway may play a key role in the osteogenic differentiation of OP tibial fracture rats. Downregulation of PTEN and upregulation of TGF-β/Smad2 signal can promote the osteogenic differentiation of BMSC under tension.