MiR-449 overexpression inhibits osteogenic differentiation of bone marrow mesenchymal stem cells via suppressing Sirt1/Fra-1 pathway in high glucose and free fatty acids microenvironment.

Diabetic osteoporosis is a chronic complication caused by diabetes mellitus, and However, the exact mechanism of diabetes mellitus-induced osteoporosis is still unknown. In this study, we investigate the effect of miR-449 on osteogenic differentiation and its underlying mechanism in human bone marrow-derived mesenchymal stem cells (hBMSCs) with high glucose (HG) and free fatty acids (FFA) treatment. Results showed that after culturing for 14 days, high glucose (HG) and free fatty acids (FFA) treatment dramatically decreased mineralization of human bone marrow-derived mesenchymal stem cells (hBMSCs) compared with cells treated with osteogenic medium (OM) alone. We also found that miR-449 expression was up-regulated during osteogenic differentiation of hBMSCs with HG and FFA treatment. Moreover, during osteogenic differentiation of hBMSCs with HG and FFA treatment, miR-449 mimics notably decreased the alkaline phosphatase (ALP) activity and the mRNA and protein expression levels of runt-related transcription factor 2 (Runx2), ALP, collagen I, osteocalcin (OCN), and bone sialoprotein (BSP), which was remarkably increased by miR-449 inhibitors. Furthermore, miR-449 directly targets Sirt1 by binding to its 3'-UTR. Sirt1 overexpression reverses the suppressive effect of miR-449 mimics on Fra-1 mRNA and protein expression, which was also alleviated by Fra-1 overexpression. In addition, Fra-1 overexpression alleviates the inhibitory effect of miR-449 mimics on the ALP activity and the mRNA and protein of Runx2, collagen I, OCN and BSP. Taken together, our results indicated that miR-449 overexpression inhibited osteogenic differentiation of HG-FFA-treated hBMSCs through the Sirt1/Fra-1 signal pathway. It is conceivable that modulating miR-449 might provide a new therapy for intervention in diabetic osteoporosis.

Bone Turnover Markers and Bone Mineral Density to Predict Osteoporotic Fractures in Older Women: A Retrospective Comparative Study.

OBJECTIVE: To investigate the clinical significance of the detection of bone mineral density (BMD) and bone turnover markers (BTM) in older women with osteoporosis, and to compare their predictive power for osteoporotic fractures (OF). METHODS: In this retrospective study, 96 patients with OF and 107 patients with osteoporosis who were hospitalized in the Department of Orthopedics at the First Affiliated Hospital of Chengdu Medical College were examined from October 2017 to February 2019. All selected patients were divided into either the fracture group (96 cases, 47.3%) or the non-fracture group (107 cases, 52.7%). BMD was measured by dual-energy X-ray absorptiometry (DXA). BTM were detected by electrochemical luminescence: aminoterminal propeptide of type I procollagen (PINP), ß-cross-linked C-telopeptide of type I collagen (ß-CTX), and molecular fragment of osteocalcin N terminal (N-MID). Bone metabolism-related indicators were detected, including alkaline phosphatase (ALP), calcium (Ca), and phosphorus (P). Independent-samples t-tests were used to compare the measurement data between the two groups, one-way ANOVA to compare the gaps between groups, and binary logistic regression to analyze the correlation of BMD and BTM with OF. RESULTS: There were no significant differences in age, weight, height, body mass index, age, and time of menopause between the two groups. There were a total of 71 cases (35.0%) in group A (60-70 years), 80 cases (39.4%) in group B (71-80 years), and 52 cases (25.6%) in group C (81-90 years). The fracture group was compared with the non-fracture group for BMD in the lumbar (0.75 ± 0.05 vs 0.88 ± 0.13, 0.75 ± 0.16 vs 0.87 ± 0.09, 0.74 ± 0.21 vs 0.87 ± 0.12 g/cm2 ; P < 0.05), BMD in the hip (0.62 ± 0.16 vs 0.74 ± 0.14, 0.61 ± 0.15 vs 0.73 ± 0.0, 0.58 ± 0.13 vs 0.73 ± 0.08 g/cm2 ; P < 0.05), PINP (83.7 ± 5.7 vs 74.8 ± 5.0, 80.7 ± 4.1 vs 72.1 ± 5.1, 81.2 ± 7.0 vs 68.7 ± 6.3 ng/mL, P < 0.05), and ß-CTX (829.7 ± 91.5 vs 798.8 ± 52.2, 848.1 ± 71.2 vs 812.4 ± 79.0, 867.3 ± 53.1 vs 849.1 ± 67.2 pg./mL, P < 0.05). N-MID (19.0 ± 6.7 vs 21.3 ± 9.7, 16.2 ± 7.0 vs 18.0 ± 5.3 ng/mL, P < 0.05) in the fracture cases was lower than in the non-fracture cases for groups B and C, and there was statistical significance. Among the fracture cases, PINP in group A was higher than in group B and C, and ß-CTX in group C was higher than in group A and B (P < 0.05). There was no significant difference in the ALP, P, and Ca between the two groups (P > 0.05). Binary logistic regression analysis showed that for BMD in the lumbar and hip, ß-CTX and OF were significantly correlated (respectively, odds ratio [OR] = -4.182, 95% confidence interval [CI] 1.672-3.448; OR = 6.929, 95% CI 2.586-12.106; OR = 7.572, 95% CI 1.441-3.059), and the differences were statistically significant. PINP and N-MID were correlated with OF (respectively, OR = 4.213, 95% CI 0.978-1.005; OR = 2.510, 95% CI 1.070-1.134, P > 0.05), the difference was not statistically significant. CONCLUSION: Osteoporotic older women, with lower bone density and higher ß-CTX, are more likely to incur OF. ß-CTX is better than BMD at predicting OF and can help in its management and in implementing interventions in high-risk populations.