Experimental study on the effects of simvastatin in reversing the femoral metaphyseal defects induced by sodium valproate in normal and ovariectomized rats

The effects of simvastatin on the bone microstructure and mechanics of ovariectomized mice: a micro-CT and micro-finite element analysis study

BACKGROUND

Osteoporosis is a major health concern for postmenopausal women, and the effect of simvastatin (Sim) on bone metabolism is controversial. This study aimed to investigate the effect of simvastatin on the bone microstructure and bone mechanical properties in ovariectomized (OVX) mice.

METHODS

24 female C57BL/6J mice (8-week-old) were randomly allocated into three groups including the OVX + Sim group, the OVX group and the control group. At 8 weeks after operation, the L4 vertebral bones were dissected completely for micro-Computed Tomography (micro-CT) scanning and micro-finite element analysis (µFEA). The differences between three groups were compared using ANOVA with a LSD correction, and the relationship between bone microstructure and mechanical properties was analyzed using linear regression.

RESULTS

Bone volume fraction, trabecular number, connectivity density and trabecular tissue mineral density in the OVX + Sim group were significantly higher than those in the OVX group (P < 0.05). For the mechanical properties detected via µFEA, the OVX + Sim group had lower total deformation, equivalent elastic strain and equivalent stress compared to the OVX group (P < 0.05). In the three groups, the mechanical parameters were significantly correlated with bone volume fraction and trabecular bone mineral density.

CONCLUSIONS

The findings suggested that simvastatin had a potential role in the treatment of osteoporosis. The results of this study could guide future research on simvastatin and support the development of simvastatin-based treatments to improve bone health.

Trichostatin A enhances the titanium rods osseointegration in osteoporotic rats by the inhibition of oxidative stress through activating the AKT/Nrf2 pathway

The use of titanium implants as fixed supports following fractures in patients with OP can often result in sterile loosening and poor osseointegration. Oxidative stress has been shown to play a particularly important role in this process. While TSA has been reported to facilitate in vivo osteogenesis, the underlying mechanisms remain to be clarified. It also remains unclear whether TSA can improve the osseointegration of titanium implants. This study investigated whether TSA could enhance the osseointegration of titanium rods by activating AKT/Nrf2 pathway signaling, thereby suppressing oxidative stress. MC3T3-E1 cells treated with CCCP to induce oxidative stress served as an in vitro model, while an OVX-induced OP rat model was employed for in vivo analysis of titanium rod implantation. In vitro, TSA treatment of CCCP-treated MC3T3-E1 cells resulted in the upregulation of osteogenic proteins together with increased AKT, total Nrf2, nuclear Nrf2, HO-1, and NQO1 expression, enhanced mitochondrial functionality, and decreased oxidative damage. Notably, the PI3K/AKT inhibitor LY294002 reversed these effects. In vivo, TSA effectively enhanced the microstructural characteristics of distal femur trabecular bone, increased BMSCs mineralization capacity, promoted bone formation, and improved the binding of titanium implants to the surrounding tissue. Finally, our results showed that TSA could reverse oxidative stress-induced cell damage while promoting bone healing and improving titanium rods' osseointegration through AKT/Nrf2 pathway activation.

Fine-tuning osteoclastogenesis: An insight into the cellular and molecular regulation of osteoclastogenesis

Osteoclasts, the bone-resorbing cells, are essential for the bone remodeling process and are involved in the pathophysiology of several bone-related diseases. The extensive corpus of in vitro research and crucial mouse model studies in the 1990s demonstrated the key roles of monocyte/macrophage colony-stimulating factor, receptor activator of nuclear factor kappa B ligand (RANKL) and integrin αvβ3 in osteoclast biology. Our knowledge of the molecular mechanisms by which these variables control osteoclast differentiation and function has significantly advanced in the first decade of this century. Recent developments have revealed a number of novel insights into the fundamental mechanisms governing the differentiation and functional activity of osteoclasts; however, these mechanisms have not yet been adequately documented. Thus, in the present review, we discuss various regulatory factors including local and hormonal factors, innate as well as adaptive immune cells, noncoding RNAs (ncRNAs), etc., in the molecular regulation of the intricate and tightly regulated process of osteoclastogenesis. ncRNAs have a critical role as epigenetic controllers of osteoclast physiologic activities, including differentiation and bone resorption. The primary ncRNAs, which include micro-RNAs, circular RNAs, and long noncoding RNAs, form a complex network that affects gene transcription activities associated with osteoclast biological activity. Greater knowledge of the involvement of ncRNAs in osteoclast biological activities will contribute to the treatment and management of several skeletal diseases such as osteoporosis, osteoarthritis, rheumatoid arthritis, etc. Moreover, we further outline potential therapies targeting these regulatory pathways of osteoclastogenesis in distinct bone pathologies.

Aloe polysaccharide promotes osteogenesis potential of adipose-derived stromal cells via BMP-2/Smads and prevents ovariectomized-induced osteoporosis

BACKGROUND

Aloe polysaccharide (AP) is a type of an active macromolecule of Aloe vera, which contributes to its function. However, whether AP possesses anti-osteoporosis properties is unknown.

METHODS

Adipose-derived stromal cells were treated with different concentrations of AP. Early and late osteogenesis were, respectively, evaluated by ALP and Alizarin Red S staining. The effect of AP on the processes of adipogenesis inhibition in ADSCs was analyzed by oil red O staining. Western blot was used to assess the expression of osteogenic and adipogenic related factors. Then, Noggin was administered to further confirm the mechanism by which AP promotes the osteogenesis of ADSCs. Finally, 40 female SD rats were classified into a bilateral laparotomy group (Sham group) and three bilateral ovariectomy groups: OVX group, OVX + AP group, and OVX + AP + Noggin group. The bilateral rat femurs were collected to perform micro-CT scanning, HE, Masson trichrome, and Oil red O staining.

RESULTS

The results indicated that AP could increase ALP expression and calcium deposition. Through molecular mechanisms, AP promotes the protein expression of COL1A1, OPN, and ALP in ADSCs, but downregulates the expression of PPARγ. Also, AP directs ADSCs' fate by stimulating the BMP2/Smads signaling pathway. In vivo, the rat AP-treated had more trabecular bone than the OVX rat, indicating partial protection from cancellous bone loss after treatment with AP.

CONCLUSION

Our results show that AP may promote osteogenesis of ADSCs through BMP-2/Smads signaling pathway and inhibits lipogenic differentiation. Thus, AP might be a promising alternative medicine to treat postmenopausal osteoporosis.