The effect of osteoprotegerin gene modification on wear debris-induced osteolysis in a murine model of knee prosthesis failure

Abstract

Using an in vivo adeno-associated virus (AAV)-mediated gene transfer technique, this study evaluated the therapeutic effects of an Osteoprotegerin (OPG) transgene against orthopaedic wear debris-induced osteolysis in a long-term murine model. A titanium pin was surgically implanted into proximal tibia of Balb/c mice to mimic a weight-bearing knee arthroplasty, followed by an intraarticular challenge with Ti-particles to provoke periprosthetic inflammation and osteolysis. rAAVhOPG or AAV-LacZ vectors were injected into the prosthetic joint at 3 weeks post-op. The tissues were harvested at 2, 4, 12 and 24 weeks after transfection for histological and molecular analyses. Successful transgene expression at the local site was confirmed by real-time PCR and ELISA. Inflammatory pseudo-membranes were ubiquitously presence at the interface between the Ti implant and the surrounding bone in both LacZ and virus-free control groups, while soft tissue was only observed sporadically at the bone-implant interface in the OPG group. A significant reduction in TRAP+ osteoclast numbers was observed in the OPG treatment group. MicroCT assessment indicated a marked reversal in the loss of peri-implant bone mineral density (BMD) in the OPGtransduced group, when compared with the LacZ and virus-free controls. Further, OPG gene modification appeared to reduce local bone collagen loss by a mean of 40%. Real time PCR examination confirmed that in vivo OPG gene transfer dramatically influenced the periprosthetic tissue gene expression profiles by diminishing the mRNA expression of TNF, IL-1, CPK and RANKL. There were no transgene-associated toxic effects apparent during the experiment, and the PCR detection of transgenes in remote organs such as lungs, kidneys, liver, and muscle of contralateral limb were consistently negative. Overall, rAAV-mediated OPG gene transfer effectively reversed Ti-particle induced bone resorption in this experimental model. The therapeutic effects may be due to the blockage of local osteoclastogenesis and possibly the down-regulation of RANKL expression.

Icariin protects against titanium particle-induced osteolysis and inflammatory response in a mouse calvarial model

“…As other studies indicate, we also confirmed that Ti particles induced an obvious inflammatory reaction and increased the expression of pro-inflammatory cytokines [7,9,11,13]. These cytokines, particularly TNF-a, IL-1b and IL-6, promote the activation of osteoclasts and eventually contribute to the osteolytic process.…”

New animal models of wear-particle osteolysis

“…However, this can be judged as a preliminary study, as no bone loss has been quantitatively proved (polystyrene particles used), only a few animals were included, the exact number of particles delivered could only be grossly extrapolated, and-surprisingly-no particles were observed on any histological bone section. We consider that major improvements were provided by Yang et al [48] and Zhang et al [49]. These authors used an effective long-term implant (pin implanted into proximal tibia to form a contiguous surface with the articular cartilage); an implant that stays well fixed after six months without particle challenge; monthly intra-articular injections for six months to achieve a long-term course (chronic reaction); pull-out tests as additional outcome measure; and most of all, in vivo gene transfer (using adenoassociated virus) to improve the delivery system of OPG-related therapy.…”

Polymethylmethacrylate and titanium alloy particles activate peripheral monocytes during periprosthetic inflammation and osteolysis

“…The parameters were 45 mm isotropic voxel size, 400 projections, 400 ms exposure time, 80 kW voltages, and 450 mA current as described previously. 22 The micro-CT scans were performed again after euthanasia. Following acquisition and reconstruction, image data were analyzed using GEHC MicroView 1 software to calculate the bone mineral densities (BMD) changes on the implanted bone chips.…”

“…22,23 The presence of dark purple staining granules in the cytoplasm was used to identify TRAP positive cells.…”