Role of RANKL in the regulation of NFATc1 and c‑Src mRNA expression in osteoclast‑like cells

Injectable Self-Healing Oxidized Starch/Gelatin Hybrid Hydrogel for Preventing Aseptic Loosening of Bone Tissue Engineering

Aseptic loosening presents a formidable challenge within the realm of bone tissue engineering, playing a pivotal role in the occurrence of joint replacement failures. The development of therapeutic materials characterized by an optimal combination of mechanical properties and biocompatibility is imperative to ensure the enduring functionality of bone implants over extended periods. In this context, this study introduced an injectable, temperature-sensitive irisin/oxidized starch/gelatin hybrid hydrogel (I-OG) system. The hierarchical cross-linked structure endows the I-OG hydrogel with controlled and adjustable physical and chemical properties, making it easy to adapt to different clinical environments. This hydrogel exhibits satisfactory injectable properties, excellent biocompatibility, and good temperature sensitivity. The sol-gel point of the I-OG hydrogel, close to the body temperature, allows it to cushion the shaking of the implant and maintain an intact state during compression of bone tissue. Significantly, the I-OG hydrogel effectively filled the gap between the implant and bone tissue, successfully inhibiting aseptic loosening induced by titanium particles, a result that confirmed the slow release of the irisin protein from the gel. Collectively, the findings from this study strongly support the proposition that functional hydrogels, typified by the I-OG system, hold substantial promise as an accessible and efficient treatment strategy for mitigating aseptic loosening.

The effects of vasoactive intestinal peptide on RANKL-induced osteoclast formation

Background

Congenital pseudarthrosis of the tibia is a rare disease characterized by an imbalance in bone remodeling. Vasoactive intestinal peptide (VIP) has been proven to modulate bone resorption and the formation of osteoclasts. This study aimed to explore the effects of VIP on the homeostasis of bone metabolism in diverse in vitro systems.

Methods

Bone marrow-derived macrophages (BMMs) were differentiated into tartrate-resistant acid phosphatase-positive cells through incubation with receptor activator of nuclear factor κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). In vitro resorption pit detection was carried out to assess the effects of VIP on osteoclastic activity. Rat osteosarcoma cell line ROS 17/2.8 was cultured alone or co-cultured with rat BMMs in the presence or absence of VIP at various concentrations. The expression levels of RANKL, RANK, OPG, NF-κB, IL-6, ERK, CAII, and GAPDH were determined by qRT-PCR and WB assay.

Results

VIP was observed to repress osteoclast differentiation without affecting the number of osteoclast precursor cells. Furthermore, the modulation of the RANKL/osteoprotegerin (OPG), nuclear factor-κB (NF-κB), and extracellular signal-regulated kinase (ERK) signaling pathways were involved in the inhibitive influence of VIP upon bone erosion. Additionally, VIP affected the expression levels of osteoclastic factors including RANKL, OPG, and interleukin-6 in osteoblast cells. Furthermore, the expression levels of RANKL and RANK were increased, while OPG expression was reduced after treatment with VIP in the co-culture of ROS 17/2.8 and rat BMMs. ERK and NF-κB signal pathways were demonstrated to be involved in the effect of VIP in the co-culture system.

Conclusions

VIP plays a critical role in bone remodeling and might serve as a potential target in the development of treatments for congenital pseudarthrosis of the tibia.