title: Titanium particle-challenged osteoblasts promote osteoclastogenesis and osteolysis in a murine model of periprosthestic osteolysis.
abstract: The current study investigates the interactive behavior of titanium alloy particle-challenged osteoblastic bone marrow stromal cells (BMSCs) and macrophage lineage cells in a murine knee-prosthesis failure model. BMSCs were isolated from male BALB/c mice femurs and induced in osteogenic medium. At 24h after isolation, BMSCs in complete induction medium were challenged with 1, 3 or 5mgml(-1) titanium particles for 7days. Culture media were collected at 2, 4 and 6days and cells were harvested at 7days for alkaline phosphatase (ALP) assay/stains. Cell proliferation in the presence of Ti particles was periodically evaluated by MTT assay. Mice implanted with titanium-pin tibial implants were given an intra-articular injection of 50μl medium containing 5×10(5) Ti particles-challenged bone-marrow-derived osteoblastic cells, followed by a repeat injection at 2weeks post-operation. Control mice with titanium-pin implants received a naïve osteoblastic cell transfusion. After sacrifice at 4weeks, the implanted knee joint of each group was collected for biomechanical pin-pullout testing, histological evaluation and reverse transcriptase polymerase chain reaction analysis of mRNA extracted from the joint tissues. Ti particles significantly stimulated the proliferation of BMSC-derived osteoblastic cells at both high and low particle concentrations (p<0.05), with no marked differences between the particle doses. ALP expression was diminished following Ti particle interactions, especially in the high-dose particle group (p<0.05). In addition, the culture media collected from short-term challenged (48h) osteoblasts significantly increased the numbers of TRAP+ cells when added to mouse peripheral blood monocytes cultures, in comparison with the monocytes cells receiving naïve osteoblasts media (p<0.05). Intra-articular introduction of the osteoblastic cells to the mouse pin-implant failure model resulted in reduced implant interfacial shear strength and thicker peri-implant soft-tissue formation, suggesting that titanium particles-challenged osteoblasts contributed to periprosthetic osteolysis. Comparison of the gene expression profiles among the peri-implant tissue samples following osteoblast injection did not find significant difference in RunX2 or Osterix/Sp7 between the groups. However, MMP-2, IL-1, TNF-α, RANKL, and TRAP gene expressions were elevated in the challenged-osteoblast group (p<0.05). In conclusion, titanium alloy particles were shown to interfere with the growth, maturation, and functions of the bone marrow osteoblast progenitor cells. Particle-challenged osteoblasts appear to express mediators that regulate osteoclastogenesis and peri-prosthetic osteolysis.
authors.affiliation: Orthopaedic Research Institute, Via Christi Wichita Hospitals - St. Francis, 929 N St Francis Street, Wichita, KS 67214, USA.
authors.forename: Yunpeng
authors.initials: Y
authors.lastname: Jiang
authors.forename: Tanghong
authors.initials: T
authors.lastname: Jia
authors.forename: Weiming
authors.initials: W
authors.lastname: Gong
authors.forename: Paul H
authors.initials: PH
authors.lastname: Wooley
authors.forename: Shang-You
authors.initials: SY
authors.lastname: Yang
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage / Q000009:adverse effects; D002454:Cell Differentiation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D019544:Equipment Failure Analysis; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008422:Materials Testing; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000187:drug effects* / Q000473:pathology*; D010010:Osteoclasts / Q000187:drug effects / Q000473:pathology*; D010014:Osteolysis / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology*; D014025:Titanium / Q000008:administration & dosage / Q000009:adverse effects*
chemical_list: D001672:Biocompatible Materials; C009495:titanium dioxide; D014025:Titanium