Surgical Modification of the Murine Calvaria Osteolysis Model

A study on the prevention and treatment of murine calvarial inflammatory osteolysis induced by ultra-high-molecular-weight polyethylene particles with neomangiferin

The present study aimed to examine the influence of neomangiferin on murine calvarial inflammatory osteolysis induced by ultra-high-molecular-weight polyethylene (UHMWPE) particles. Eight-week-old male C57BL/J6 mice served as an inflammatory osteolysis model, in which UHMWPE particles were implanted into the calvarial subperiosteal space. The mice were randomly distributed into four groups and treated with different interventions; namely, a sham group [phosphate-buffered saline (PBS) injection and no UHMWPE particles], model group (PBS injection and implantation of UHMWPE particles), low-dose neomangiferin group (UHMWPE particles +2.5 mg/kg neomangiferin), and high-dose neomangiferin group (UHMWPE particles +5 mg/kg neomangiferin). Following 3 weeks of feeding according to the above regimens, celiac artery blood samples were collected for an enzyme-linked immunosorbent assay (ELISA) to determine the expression of receptor activator of nuclear factor-κB ligand (RANKL), osteoclast-related receptor (OSCAR), cross-linked C-telopeptide of type I collagen (CTX-1); osteoprotegerin (OPG), tumor necrosis factor (TNF)-α, and interleukin (IL)-1β. Subsequently, the mice were sacrificed by cervical dislocation following ether-inhalation anesthesia, and the skull was separated for osteolysis analysis by micro-computed tomography (micro-CT). Following hematoxylin and eosin staining, tartrate-resistant acid phosphatase (TRAP) staining was performed to observe the dissolution and destruction of the skull. The micro-CT results suggested that neomangiferin significantly inhibited the murine calvarial osteolysis and bone resorption induced by UHMWPE particles. In addition, the ELISA results showed that neomangiferin decreased the expression levels of osteoclast markers RANKL, OSCAR, CTX-1, TNF-α and IL-1β. By contrast, the levels of OPG increased with the neomangiferin dose. Histopathological examination revealed that the TRAP-positive cell count was significantly reduced in the neomangiferin-treated animals compared with that in the positive control group, and the degree of bone resorption was also markedly reduced. Neomangiferin was found to have significant anti-inflammatory effects and to inhibit osteoclastogenesis. Therefore, it has the potential to prevent the aseptic loosening of a prosthesis following artificial joint replacement.

Tanshinone IIA protects against polyethylene particle-induced osteolysis response in a mouse calvarial model

The expression of β-catenin in detectable aseptic loosening after joint replacement and the surrounding osteolysis of the prosthesis is primarily caused by the abrasive particles introduced by the prosthesis, which results in a shortened service life of the prosthesis. Recent studies have shown that debris can induce many cytokines associated with osteolysis. In particular, RANKL directly stimulates osteoclast formation and activity. Thus, we hypothesize that the osteolysis induced by wear particles can be prevented by inhibiting the RANKL signaling pathway. In this study, we established a C57BL/J6 mouse calvarial model of PE granule induced osteolysis, and studied the inhibitory action of tanshinone IIA on osteoclast formation. Eight-week-old male c57BL/J6 mouse were randomly divided into four groups: Sham group (no PE particle-induced + PBS), positive group (PE particle-inducted + PBS), low dose group (PE particle-induced + 1 ug/g tanshinone IIA), and high-dose group (PE granule-induced + 2 ug/g tanshinone II). After 21 days, the mice were executed and the calvaria were collected and processed for micro-CT scan and histomorphometry analysis. Compared to the positive subgroup, Tanshinone IIA significantly reduced bone absorption induced by PE granules and inhibited the formation and activity of osteoclasts. In addition, ELISA test showed that tanshinone IIA significantly reduced OSCAR and CTX-1 expression. Further, tanshinone IIA enhanced the formation of OPG, thus reducing osteoclast damage to the bone around the implant. Overall, these data indicate that tanshinone IIA represents a promising drug for the treatment of bone absorption by particles and can be a new method of treatment for prophylaxis of aseptic loosening.

Cytokine expression in response to root repair agents

AIM

To evaluate the expression of TNF-α, IL-6, IFN-γ, TGF-β, IL-4, IL-10, RANKL, RANK and OPG on mouse calvarial bone treated with MTA, Geristore^® and Emdogain^® .

METHODOLOGY

Bone wounds were made on the heads of C57BL/6 mice, breaking the periosteum and the cortical surface of the calvaria. Each repair agent was inserted into sectioned Eppendorf microtubes and placed on the bone wound, and soft tissues were sutured. At 14 and 21 days, animals were sacrificed and the treated region was dissected. The calvaria bone was removed, and RNA was extracted. mRNA expression of the aforementioned cytokines was assessed using real-time PCR. Data were analysed by nonparametric methods, including the Mann-Whitney and Kruskal-Wallis tests (P < 0.05).

RESULTS

Following treatment with Emdogain^® and MTA, mRNA expression of RANKL, RANK and OPG increased significantly (P < 0.05) between days 14 to 21. Geristore^® did not alter the basal expression of these mediators during the same period of evaluation. Whilst treatment with Emdogain^® did cause a significant increase in TNF-α mRNA expression between days 14 and 21 (P < 0.05), treatment with MTA did not alter the basal expression of this cytokine at either experimental time point. However, TNF-α mRNA expression was down-regulated significantly at day 21 (P < 0.05) when Geristore^® was applied. A significant increase in the mRNA expression of IL-6, TGF-β, IL-10, IL-4 and IFN-γ was observed with Emdogain^® and MTA treatment between days 14 to 21, whereas Geristore^® reduced significantly the expression of IL-6, TGF-β and IL-4 (P < 0.05).

CONCLUSION

The clinical indication of these repair agents depends on the root resorption diagnosis. Whilst MTA and Emdogain^® induce a pro- and anti-inflammatory response early and late, respectively, Geristore^® was not associated with an inflammatory reaction when compared with both repair agents.