Recombinant Adeno-Associated Virus-Mediated Osteoprotegerin Gene Therapy Inhibits Wear Debris-Induced Osteolysis

• Published in: Journal of bone and joint surgery. American volume Vol. 84; no. 8; pp. 1405 - 1412
• Main Authors: Ulrich-Vinther, Michael, Carmody, Emily E, Goater, J Jeffrey, Søballe, Kjeld, OʼKeefe, Regis J, Schwarz, Edward M
• Format: Journal Article
• Language: English
• Published: Boston, MA Copyright by The Journal of Bone and Joint Surgery, Incorporated 01-08-2002; Journal of Bone and Joint Surgery Incorporated; Journal of Bone and Joint Surgery AMERICAN VOLUME
• Edition: American volume
• Subjects: Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Applied cell therapy and gene therapy; Biological and medical sciences; Dependovirus; Genetic Therapy - methods; Genetic Vectors; Glycoproteins - administration & dosage; Glycoproteins - therapeutic use; Humans; Male; Medical sciences; Mice; Mice, Inbred C57BL; Osteolysis - prevention & control; Osteoprotegerin; Prosthesis Failure; Receptors, Cytoplasmic and Nuclear - administration & dosage; Receptors, Cytoplasmic and Nuclear - therapeutic use; Receptors, Tumor Necrosis Factor; Recombinant Proteins; Transduction, Genetic; Transfusions. Complications. Transfusion reactions. Cell and gene therapy; Immunopathology; Implant; Wear particle; Rodentia; Diseases of the osteoarticular system; Resorption; Bone disease; Osteoclast; Experimental study; Osteolysis; In vitro; Virus; In vivo; Vertebrata; Orthopedic surgery; Mammalia; Treatment; Mouse; Animal; Complication; Biological effect; Inhibition; Gene therapy; Vector
• ISSN: 0021-9355; 1535-1386
• DOI: 10.2106/00004623-200208000-00017

BackgroundAseptic loosening of orthopaedic implants secondary to wear debris-induced osteolysis is a serious problem. Osteoprotegerin (OPG) is a natural decoy protein that inhibits osteoclast activation and bone resorption. This study investigated whether gene therapy using a recombinant adeno-associated viral vector that expresses OPG can inhibit wear debris-induced osteolysis.MethodsA recombinant adeno-associated virus (rAAV) vector co-expressing OPG (rAAV-OPG-IRES-EGFP) was generated. A control vector expressing b-galactosidase (rAAV-LacZ) was also prepared. In vitro validation experiments were performed to determine rAAV-OPG-IRES-EGFP transduction efficiency, OPG expression level and function in bone wafer, and osteoclastic activity.The effect of rAAV-OPG-IRES-EGFP in vivo gene therapy on wear debris-induced osteolysis was then evaluated in a mouse calvarial model in which a single intramuscular injection of the vector was administered prior to the introduction of the wear debris. The effects of the rAAV-OPG-IRES-EGFP gene therapy on wear debris-induced osteoclastogenesis and bone resorption were determined by histomorphometry on day 10.ResultsIn vitro experiments revealed that 100% of human embryonic kidney 293 cells were transduced at a multiplicity of infection of 1000 with both rAAV-OPG-IRES-EGFP and rAAV-LacZ. At a rAAV-OPG-IRES-EGFP multiplicity of infection of 1000, an OPG concentration of 135 ng/mL of culture media was achieved after four days. Using a bone-wafer assay for osteoclast activity, we found that treatment with rAAV-OPG-IRES-EGFP reduced resorption sevenfold compared with parathyroid hormone-stimulated controls and elevenfold compared with rAAV-LacZ controls. Furthermore, a seventeenfold decrease in RANKL and macrophage colony-stimulating factor-induced splenocyte osteoclastogenesis was observed in co-cultures containing rAAV-OPG-IRES-EGFP-infected fibroblasts.In vivo administration of rAAV-OPG-IRES-EGFP resulted in detectable transduction of myocytes at the injection site and a significant increase in expression of serum OPG levels by the second day (p < 0.05). Maximal concentrations were obtained on day 6 and then leveled off throughout the observation period. In contrast, serum OPG could not be detected in the sham-treated, uninfected titanium-stimulated, or rAAV-LacZ-infected mice. In the control mice, titanium implantation resulted in a threefold increase in the mean number of osteoclasts adjacent to the sagittal suture as well as a twofold increase in the mean area of soft tissue in the sagittal suture compared with the sham-treated mice. In contrast, osteoclast numbers remained at basal levels, and the area of soft tissue in the sagittal suture was markedly reduced in titanium-implanted animals that received rAAV-OPG-IRES-EGFP treatment, demonstrating a complete inhibition of osteolysis in response to titanium particles.ConclusionsA single intramuscular injection of the rAAV-OPG-IRES-EGFP vector can efficiently transduce myocytes to produce high levels of OPG. The OPG effectively inhibits wear debris-induced osteoclastogenesis and osteolysis.Clinical RelevanceCurrently, there is no approved drug therapy to prevent or inhibit periprosthetic osteolysis. Although preclinical studies have identified potential drug therapies (i.e., bisphosphonates), there is no evidence that these drugs can effectively treat aseptic loosening in patients. This is the first evidence that in vivo OPG gene therapy can be used to prevent wear debris-induced osteolysis.