Let-7f-5p regulates TGFBR1 in glucocorticoid-inhibited osteoblast differentiation and ameliorates glucocorticoid-induced bone loss.

Previous studies indicated that let-7 enhances osteogenesis and bone formation of human adipose-derived mesenchymal stem cells (MSCs). We also have confirmed that let-7f-5p expression was upregulated during osteoblast differentiation in rat bone marrow-derived MSCs (BMSCs) and was downregulated in the vertebrae of patients with glucocorticoid (GC)-induced osteoporosis (GIOP). The study was performed to determine the role of let-7f-5p in GC-inhibited osteogenic differentiation of murine BMSCs in vitro and in GIOP in vivo. Here, we report that dexamethasone (Dex) inhibited osteogenic differentiation of BMSCs and let-7f-5p expression, while increasing the expression of transforming growth factor beta receptor 1 (TGFBR1), a direct target of let-7f-5p during osteoblast differentiation under Dex conditions. In addition, let-7f-5p promoted osteogenic differentiation of BMSCs, as indicated by the promotion of alkaline phosphatase (ALP) staining and activity, Von Kossa staining, and osteogenic marker expression (Runx2,Osx, Alp, and Ocn), but decreased TGFBR1 expression in the presence of Dex. However, overexpression of TGFBR1 reversed the upregulation of let-7f-5p during Dex-treated osteoblast differentiation. Knockdown of TGFBR1 reversed the effect of let-7f-5p downregulation during Dex-treated osteogenic differentiation of BMSCs. We also found that glucocorticoid receptor (GR) mediated transcriptional silencing of let-7f-5p and its knockdown enhanced Dex-inhibited osteogenic differentiation. Further, when injected in vivo, agomiR-let-7f-5p significantly reversed bone loss induced by Dex, as well as increased osteogenic marker expression (Runx2, Osx, Alp, and Ocn) and decreased TGFBR1 expression in bone extracts. These findings indicated that the regulatory axis of GR/let-7f-5p/TGFBR1 may be important for Dex-inhibited osteoblast differentiation and that let-7f-5p may be a useful therapeutic target for GIOP.

IGF-1R/ß-catenin signaling axis is involved in type 2 diabetic osteoporosis.

Insulin-like growth factor-1 receptor (IGF-1R) is involved in both glucose and bone metabolism. IGF-1R signaling regulates the canonical Wnt/ß-catenin signaling pathway. In this study, we investigated whether the IGF-1R/ ß-catenin signaling axis plays a role in the pathogenesis of diabetic osteoporosis (DOP). Serum from patients with or without DOP was collected to measure the IGF-1R level using enzyme-linked immunosorbent assay (ELISA). Rats were given streptozotocin following a four-week high-fat diet induction (DOP group), or received vehicle after the same period of a normal diet (control group). Dual energy X-ray absorption, a biomechanics test, and hematoxylin-eosin (HE) staining were performed to evaluate bone mass, bone strength, and histomorphology, respectively, in vertebrae. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting were performed to measure the total and phosphorylation levels of IGF-1R, glycogen synthase kinase-3ß (GSK-3ß), and ß-catenin. The serum IGF-1R level was much higher in patients with DOP than in controls. DOP rats exhibited strikingly reduced bone mass and attenuated compression strength of the vertebrae compared with the control group. HE staining showed that the histomorphology of DOP vertebrae was seriously impaired, which manifested as decreased and thinned trabeculae and increased lipid droplets within trabeculae. PCR analysis demonstrated that IGF-1R mRNA expression was significantly up-regulated, and western blotting detection showed that phosphorylation levels of IGF-1R, GSK-3ß, and ß-catenin were enhanced in DOP rat vertebrae. Our results suggest that the IGF-1R/ß-catenin signaling axis plays a role in the pathogenesis of DOP. This may contribute to development of the underlying therapeutic target for DOP.

Plastrum Testudinis Extracts Promote BMSC Proliferation and Osteogenic Differentiation by Regulating Let-7f-5p and the TNFR2/PI3K/AKT Signaling Pathway.

BACKGROUND/AIMS: Plastrum testudinis extracts (PTE) show osteoprotective effects on glucocorticoid-induced osteoporosis in vivo and in vitro. However, the underlying molecular mechanism of PTE in promoting osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is unclear. METHODS: BMSC proliferation was investigated using the Cell Counting Kit-8 assay. BMSC differentiation and osteogenic mineralization were assayed using alkaline phosphatase and Alizarin red staining, respectively. The mRNA expression levels of Let-7f-5p, Tnfr2, Traf2, Pi3k, Akt, ß-catenin, Gsk3ß, Runx2, and Ocn were measured using real time quantitative polymerase chain reaction. Protein levels of TNFR2, TRAF2, p-PI3K, p-AKT, p-ß-CATENIN, and p-GSK3ß were analyzed by western blotting. The functional relationship of Let-7f-5p and Tnfr2 was determined by luciferase reporter assays. RESULTS: The optimum concentration for PTE was 30 µg/ml. PTE significantly promoted BMSC osteogenic differentiation and mineralization after 7 and 14 days in culture, respectively. The combination of PTE and osteogenic induction exhibited significant synergy. PTE upregulated Let-7f-5p, ß-catenin, Runx2, and Ocn mRNA expression, and downregulated Tnfr2, Traf2, Pi3k, Akt, and Gsk3ß mRNA expression. PTE inhibited TNFR2, TRAF2, and p-ß-CATENIN protein expression, and promoted p-PI3K, p-AKT, and p-GSK3ß protein expression. In addition, Tnfr2 was a functional target of Let-7f-5p in 293T cells. CONCLUSIONS: Our results suggested that PTE may promote BMSC proliferation and osteogenic differentiation via a mechanism associated with the regulation of Let-7f-5p and the TNFR2/PI3K/AKT signaling pathway.

Effect of osteoporosis induced by ovariectomy on vertebral bone defect/fracture in rat.

Osteoporotic vertebral fracture (OVF) is a worldwide health concern and lacks sufficient basic studies. Suitable animal models should be the foundation for basic study and treatment of OVF. There have been few studies on the development of animal models of osteoporotic vertebral bone defects. OVF models using various animal species should be developed to evaluate the therapeutic strategy in preclinical testing. We developed an OVF model in rats. Rat osteoporosis was induced by ovariectomy (OVX), and 3 months after OVX, a 3 mm diameter hemispheric vertebral bone defect was developed in lumbar vertebra 6 (L6). Sagittal plain X-rays of the rats, their bone quantity, bone microarchitecture, and histomorphology were analyzed: 3 months after OVX, rats showed significantly lower bone quantity, relative bone volume, and total volume bone mineral density. After the vertebral bone defect had developed for 16 weeks, no significant indication of self-healing could be observed from the sagittal plain X-rays, three-dimensional images, and histomorphology. These results indicate that the rat model of osteoporotic vertebral bone defect, induced by OVX and a 3 mm diameter hemispheric vertebral bone defect, can sufficiently mimic OVF patients in clinic and provide a sound basis for subsequent studies.

[Trilobate technique, a new principal to repair cleft lip].

OBJECTIVE: To develop a new method for reparation of cleft lip, and to evoke more colleagues for advance practices and study, in order to determine her indication and contraindication as soon as possible. METHODS: 48 cases were included into this study. Trilobate flap were designed in floor of nose and lip area in cleft side, rotate two of the three flaps upwards, respectively to elevate the tip of nose, and to reconstruct the floor of nose. As for the left flap, it was derived transversally to opposing side, sutured with the flap of non-cleft-side. RESULTS: With this technique, less tissue was lost, better vertical lengthening and good formed cuspids-bow was achieved, and the scar was a parallel line being symmetry to the philtrum column opposite. Meanwhile, because the tension was mainly located in the area where there was no mini flaps, the blood supply was good enough, rarely occur any necrosis in the tip of flaps. All cases in this study obtained perfect healing, with good appearance at nostrils and floor of nose. CONCLUSIONS: In use of the method of trilobate flap, we can draw down the peak of the cuspids bow effectually, hence avoid the addition cut in the lower part of the lip, decrease the scar on skin, as well as nice reconstruction of floor of nose, philtrum column and nostril. Because lack of long term study, we evoke more colleagues for cooperation in advance study.

[Collagen changes of allografting an acellular dermal matrix].

OBJECTIVE: To evaluate the collagen changes of allografting an acellular dermal matrix (allo-ADM). METHODS: The allo-ADM was grafted underneath the skin of SD rats. The content of collagen and the proportion of type I to III collagen was examined with a biochemical assay. RESULT: The content of collagen and the proportion of type I to III collagen in the allo-ADM group showed no significant changes. CONCLUSION: The allo-ADM could keep long time in the body and it may be an ideal material for soft tissue filling.

[Clinically analyzing the possible side-effects after injecting hydrophilic polyacrylamide gel as a soft-tissue filler].

OBJECTIVE: To evaluate the possible side-effects after injecting hydrophilic polyacrylamide gel for augmentation of the soft-tissue. METHODS: Fifteen patients with some side-effects after injecting the hydrophilic polyacrylamide gel had been undergoing for the treatment in our unit from 2000 to 2001. Their symptoms were analyzed and the specimen of the tissue was also removed for pathologic examination. RESULTS: The major complaints of the patients after injecting hydrophilic polyacrylamide gel were feeling pain(60.00%), uncomfortable (13.33%), no cosmetic improvement results (33.33%), secondary deformity (20.00%), long-lasting swelling (6.67%), and nodules (80.00%). The pathologic examination was showing the capsule formation (53.33%), macrophagocyte infiltration (60.00%) and granuloma producing (20.00%). CONCLUSION: Clinical application of the hydrophilic polyacrylamide gel may result in some serious side-effects. It should be cautious to the physicians who may apply the product for clinic use.