Low Doses of Simvastatin Potentiate the Effect of Sodium Alendronate in Inhibiting Bone Resorption and Restore Microstructural and Mechanical Bone Properties in Glucocorticoid-Induced Osteoporosis

Atorvastatin exerts a preventive effect against steroid-induced necrosis of the femoral head by modulating Wnt5a release

Steroid-induced osteonecrosis of the femoral head (SONFH) is a prevalent form of osteonecrosis in young individuals. More efficacious clinical strategies must be used to prevent and treat this condition. One of the mechanisms through which SONFH operates is the disruption of normal differentiation in bone marrow adipocytes and osteoblasts due to prolonged and extensive use of glucocorticoids (GCs). In vitro, it was observed that atorvastatin (ATO) effectively suppressed the impact of dexamethasone (DEX) on bone marrow mesenchymal stem cells (BMSCs), specifically by augmenting their lipogenic differentiation while impeding their osteogenic differentiation. To investigate the underlying mechanisms further, we conducted transcriptome sequencing of BMSCs subjected to different treatments, leading to the identification of Wnt5a as a crucial gene regulated by ATO. The analyses showed that ATO exhibited the ability to enhance the expression of Wnt5a and modulate the MAPK pathway while regulating the Wnt canonical signaling pathway via the WNT5A/LRP5 pathway. Our experimental findings provide further evidence that the combined treatment of ATO and DEX effectively mitigates the effects of DEX, resulting in the upregulation of osteogenic genes (Runx2, Alpl, Tnfrsf11b, Ctnnb1, Col1a) and the downregulation of adipogenic genes (Pparg, Cebpb, Lpl), meanwhile leading to the upregulation of Wnt5a expression. So, this study offers valuable insights into the potential mechanism by which ATO can be utilized in the prevention of SONFH, thereby holding significant implications for the prevention and treatment of SONFH in clinical settings.

Preclinical evaluation of methotrexate-loaded polyelectrolyte complexes and thermosensitive hydrogels as treatment for rheumatoid arthritis

This work proposes new methotrexate (MTX) loaded drug delivery systems (DDS) to treat rheumatoid arthritis via the intra-articular route: a poloxamer based thermosensitive hydrogel (MTX-HG), oligochitosan and hypromellose phthalate-based polyelectrolyte complexes (MTX-PEC) and their association (MTX-PEC-HG). MTX-PEC showed 470 ± 166 nm particle size, 0.298 ± 0.108 polydispersity index, +26 ± 2 mV and 74.3 ± 5.8% MTX efficiency entrapment and particle formation was confirmed by infrared spectroscopy and thermal analysis. MTX-HG and MTX-PEC-HG gelled at 36.7°C. MTX drug release profile was prolonged for MTX-HG and MTX-PEC-HG, and faster for MTX-PEC and free MTX. The in vivo effect of the MTX-DDSs systems was evaluated in induced arthritis rats as single intra-articular dose. The assessed parameters were the mechanical nociceptive threshold, the plasmatic IL-1β level and histological analysis of the tibiofemoral joint. MTX-HG and MTX-PEC-HG performance were similar to free MTX and worse than oral MTX, used as positive control. All DDSs showed some irritative effect, for which further studies are required. MTX-PEC was the best treatment on recovering cartilage damage and decreasing allodynia. Thus, MTX-PEC demonstrated potential to treat rheumatoid arthritis, with the possibility of decreasing the systemic exposure to the drug.

Betel leaf extract and its major component hydroxychavicol promote osteogenesis and alleviate glucocorticoid-induced osteoporosis in rats

Piper betle leaves possess several ethnomedicinal properties and are immensely used in traditional medicinal practices in regions of Asian and African subcontinents. However, their effects in treating skeletal complications are least known. In this study, we evaluated cellular and molecular effects of betel leaf extract (BLE) and its major phytoconstituent, hydroxychavicol (HCV) in promoting osteogenesis in vitro and alleviating glucocorticoid induced osteoporosis (GIO) in vivo. Both BLE and HCV markedly stimulated osteoblast differentiation of C3H10T1/2 cells with increased expression of RUNX2 and osteopontin through the GSK-3β/β-catenin-signaling pathway. Also, oral administration of BLE and HCV in GIO rats resulted in restoration of bone mass and tissue microarchitecture. Thus, with our findings we conclude that BLE and HCV promote osteogenesis of C3H10T1/2 cells via the GSK-3β/β-catenin pathway and alleviate GIO in rats.

High-fat diet and caffeine interact to modulate bone microstructure and biomechanics in mice

AIMS

Although excessive fat and caffeine intake are independent risk factors for bone microstructural and functional disturbances, their association remains overlooked. Thus, we investigated the impact of high-fat diet (HFD) and caffeine alone and combined on serum lipid profile, bone microstructure, micromineral distribution and biomechanical properties.

METHODS

Forty female C57BL/6 mice were randomized into 4 groups daily treated for seventeen weeks with standard diet (SD) or HFD (cafeteria diet) alone or combined with 50 mg/kg caffeine.

KEY FINDINGS

The association between HFD and caffeine reduced the weight gain compared to animals receiving HFD alone. Caffeine alone or combined with HFD increases total and HDL cholesterol circulating levels. HFD also reduced calcium, phosphorus and magnesium bone levels compared to the groups receiving SD, and this reduction was aggravated by caffeine coadministration. From biomechanical assays, HFD combined with caffeine increased bending strength and stiffness of tibia, a finding aligned with the marked microstructural remodeling of the cortical and cancellous bone in animals receiving this combination.

SIGNIFICANCE

Our findings indicated that HFD and caffeine interact to induce metabolic changes and bone microstructural remodeling, which are potentially related to bone biomechanical adaptations in response to HFD and caffeine coadministration.

Trans-fatty acids aggravate anabolic steroid-induced metabolic disturbances and differential gene expression in muscle, pancreas and adipose tissue

AIMS

Although anabolic steroids (AS) and trans-fatty acids overload exerts systemic toxicity and are independent risk factors for metabolic and cardiovascular disorders, their interaction remains poorly understood. Thus, we investigated the impact of a diet rich in trans-fatty acids (HFD) combined with AS on glycemic control, lipid profile, adipose tissue, skeletal muscle and pancreas microstructure and expression of genes involved in energy metabolism.

MAIN METHODS

Forty-eight C57BL/6 mice were randomized into 6 groups treated for 12 weeks with a standard diet (SD) or a diet rich in C18:1 trans-fatty isomers (HFD), alone or combined with 10 or 20 mg/kg testosterone cypionate (AS).

KEY FINDINGS

Our results indicated that AS improved glycemic control, upregulated gene expression of Glut-4 and CPT-1 in skeletal muscle, FAS, ACC and UCP-1 in adipose tissue. AS also reduced total and LDL cholesterol in mice fed a SD. When combined with the HFD, AS was unable to induce microstructural adaptations in adipose tissue, pancreatic islets and β-cells, but potentiated GCK and Glut-2 (pancreas) and Glut-4 and CPT-1 (skeletal muscle) upregulation. HFD plus AS also downregulated FAS and ACC gene expression in adipose tissue. Combined with HFD, AS increased triacylglycerol circulating levels, improved insulin sensitivity and glycemic control in mice.

SIGNIFICANCE

Our findings indicated that HFD and AS can interact to modulates glycemic control and lipid profile by a mechanism potentially related with a reprogramming of genes expression in organs such as the pancreas, adipose tissue and skeletal muscle.

Transdermal delivery of fluvastatin loaded nanoemulsion gel: Preparation, characterization and in vivo anti-osteoporosis activity

The objective of present study was to develop hydrogel based nanoemulsion (NE) drug delivery system for transdermal delivery and evaluate its potential in in vivo anti-osteoporotic activity. NE was prepared using aqueous phase titration method and characterized for droplet size, zeta potential and morphology. It was then formulated into hydrogel based NE gel using carbopol 940 as gelling agent. NE gel was evaluated for pH, viscosity, in vitro/ex vivo permeation studies and in vivo anti-osteoporotic activity. The results indicated formation of spherical, nano sized globules of NE ranging from 11.17 ± 0.24 to 128.8 ± 0.16 nm with polydispersity of <0.5. In vitro and ex vivo permeation studies showed significantly higher permeation of NE as well as NE gel in comparison to fluvastatin solution indicating that NE gel can effectively penetrate through skin layers. In vivo anti-osteoporotic results demonstrated formation of new bone in trabecular region of osteoporotic rat femurs through micro-CT scanning radiographs. Biomechanical strength testing demonstrated greater load bearing capacity of rat femurs in the treated animals in comparison with the osteoporotic group. Thus, developed NE gel formulation of fluvastatin demonstrated greater potential for transdermal delivery and in the treatment of osteoporosis.

Is bone loss a physiological cost of reproduction in the Great fruit-eating bat Artibeus lituratus?

During mammalian pregnancy and lactation, the maternal demand for calcium is increased to satisfy fetus and newborn skeletal growth. In addition to the dietary intake, females use the calcium contained in their bones to supply this increased demand, leading to a decrease in maternal bone mineral content. In reproductive insectivorous female bats, bone loss has been described as a physiological cost of reproduction, due to the reported increased risk of bone fracture. This physiological cost may be the mechanism underlying the conflict between increasing litter size and maintaining wing skeletal integrity, which would help to explain the small litter size of most bat species. If bone loss is a linking cost between reproduction and survival in bats, and most bat species have small litter sizes, one would expect to find a loss of bone and an increasing probability of bone fracture during pregnancy and lactation in other non-insectivorous bats. In this study, we tested for the existence of this cost in the Great-fruit eating bat, Artibeus lituratus. We analyzed trabecular structure, bone strength and bone mineral content for the humerus bone, hypothesizing that bone loss during reproduction in females would increase the risk of fracture. Our results showed a decrease of 22-31% in bone trabecular area in lactating females, rapidly compensated following weaning. Bone strength did not differ among reproductive and non-reproductive groups and seems to be more influenced by bone organic components rather than mineral contents. Since we observed bone loss during reproduction yet the humerus strength seems to be unaffected, we suggest that bone loss may not represent a physiological cost during reproduction for this frugivorous bat.

Porous Chitosan/Nano-Hydroxyapatite Composite Scaffolds Incorporating Simvastatin-Loaded PLGA Microspheres for Bone Repair

The combination of bone tissue scaffolds with osteogenic induction factors is an effective strategy to facilitate bone healing processes. Here, chitosan (CS)/nano-hydroxyapatite (HA) scaffolds containing simvastatin (SIM)-loaded PLGA microspheres were fabricated by combining a freeze-drying technique with a modified water-oil-water emulsion method. The CS/HA weight ratio of 1:2 was selected by analyzing the effect of HA content on the micro-architecture, mechanical strength, and biocompatibility of the scaffold. Drug release kinetics showed that the SIM encapsulated in the scaffold was released in a sustained manner for up to 30 days. In vitro bioactivity study in rat bone marrow-derived mesenchymal stem cells showed that the SIM-loaded scaffolds had a strong ability in accelerating cell proliferation and inducing osteogenic differentiation. Moreover, an in vivo experiment using a rat calvarial defect model also documented that the SIM-loaded scaffolds had a remarkable effect on bone-promoting regeneration. The results of this study suggest that the SIM-loaded CS/HA scaffold is feasible and effective in bone repair and thus may provide a promising route for the treatment of critical-sized bone defects.