Efficacy of the combined use of donepezil with either quetiapine or sodium valproate in patients with Alzheimer's disease with behavioral and psychological symptoms of dementia, and their effects on vascular endothelial growth factors

Effect of recombinant irisin on recombinant human bone morphogenetic protein-2 induced osteogenesis and osteoblast differentiation

Osteoporotic fragility fractures substantially impact aging societies, necessitating long-term care and increasing healthcare costs. Myokine irisin, secreted by skeletal muscle, influences bone metabolism; however, a comprehensive understanding of the mechanisms by which irisin affects bone metabolism is still lacking. Therefore, this study aimed to explore the effects of irisin on osteogenesis and osteoblast differentiation triggered by bone morphogenetic protein-2 (BMP-2). We used 4-week-old male ICR mice and implanted polyethylene glycol pellets containing recombinant human BMP-2 (rh-BMP-2) into the left dorsal muscle pouch. Mice received weekly intraperitoneal injections of either phosphate-buffered saline or recombinant irisin (re-irisin). Ectopic bone formation was evaluated 3 weeks post-surgery using micro-computed tomography (μ-CT) and histological analysis. In vitro experiments, C2C12 cells were treated with or without rh-BMP-2 and re-irisin, and we assessed osteoblast differentiation markers, e.g., runt-related transcription factor 2, alkaline phosphatase, osteocalcin, and osteopontin, using real-time reverse transcription-polymerase chain reaction. The μ-CT analyses showed that re-irisin significantly increased bone mineral content and bone volume of ectopic bones newly formed by rh-BMP-2. The gene expressions of the osteoblast markers were significantly increased by rh-BMP-2 and further upregulated by re-irisin. The treatment of cyclic AMP response element-binding protein (CREB) small interfering RNA attenuated these effects, suggesting that CREB signaling pathway was involved in rh-BMP-2/re-irisin-induced osteoblastic differentiation. This study demonstrates the potential of irisin to enhance osteogenesis through BMP signaling, offering insights for osteoporosis treatment and highlighting irisin as a promising therapeutic target for improving bone health and extending a healthy lifespan.

Irisin reduces orthodontic tooth movement in rats by promoting the osteogenic potential in the periodontal ligament

OBJECTIVES

Positive effects of irisin on osteogenic differentiation of periodontal ligament (PDL) cells have been identified previously, this study aims to examine its effect on orthodontic tooth movement (OTM) in vivo.

MATERIALS AND METHODS

The maxillary right first molars of male Wistar rats (n = 21) were moved mesially for 14 days, with submucosal injection of two dosages of irisin (0.1 or 1 μg) or phosphate-buffered saline (control) every third day. OTM was recorded by feeler gauge and micro-computed tomography (μCT). Alveolar bone and root volume were analysed using μCT, and plasma irisin levels by ELISA. Histological characteristics of PDL tissues were examined, and the expression of collagen type I, periostin, osteocalcin (OCN), von Willebrand factor (vWF) and fibronectin type III domain-containing protein 5 (FNDC5) in PDL was evaluated by immunofluorescence staining.

RESULTS

Repeated 1 μg irisin injections suppressed OTM on days 6, 9, and 12. No significant differences were observed in OTM in the 0.1 μg irisin group, or in bone morphometric parameters, root volume or plasma irisin, compared to control. Resorption lacunae and hyalinization were found at the PDL-bone interface on the compression side in the control, whereas they were scarce after irisin administration. The expression of collagen type I, periostin, OCN, vWF, and FNDC5 in PDL was enhanced by irisin administration.

LIMITATIONS

The feeler gauge method may overestimate OTM.

CONCLUSIONS

Submucosal irisin injection reduced OTM by enhancing osteogenic potential of PDL, and this effect was more significant on the compression side.