title: In vitro and in vivo biocompatibility investigation of diamond-like carbon coated nickel-titanium shape memory alloy.
abstract: OBJECTIVE
  To investigate the biocompatibility of diamond-like carbon (DLC) coated nickel-titanium shape memory alloy (NiTi SMA) in vitro and in vivo.
  
  
  METHODS
  The in vitro study was carried out by co-culturing the DLC coated and uncoated NiTi SMA with bone marrow mesenchymal stem cells (MSCs), respectively, and the in vivo study was carried out by fixing the rabbits' femoral fracture model by DLC coated and uncoated NiTi SMA embracing fixator for 4 weeks, respectively. The concentration of the cells, alkaline phosphatase (AKP), and nickel ion in culture media were detected, respectively, at the first to fifth day after co-culturing. The inorganic substance, osteocalcin, alkaline phosphatase (ALP), and tumor necrosis factor (TNF) in callus surrounding fracture and the Ni(+) in muscles surrounding fracture site, liver and brain were detected 4 weeks postoperatively.
  
  
  RESULTS
  The in vitro study showed that the proliferation of MSCs and the expression of AKP in the DLC-coated group were higher than the uncoated group (P < 0.05), while the uncoated group released more Ni(2+) into the culture media than that in the coated group (P < 0.05). The in vivo study revealed that the inorganic substance and AKP, osteocalcin, and TNF expression were significantly higher in the DLC coated NiTi SMA embracing fixator than that in the uncoated group (P < 0.05). Ni(2+) in liver, brain, and muscles surrounding the fracture were significantly lower in the DLC coated groups than that in the uncoated group (P < 0.05).
  
  
  CONCLUSIONS
  Nickel-titanium shape memory alloy coated by diamond-like carbon appears to have better biocompatibility in vitro and in vivo compared to the uncoated one.
authors.affiliation: Department of Orthopedics, the Affiliated Hospital of Guilin Medical College, Guilin, Guangxi Zhuang Autonomous Region, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Ya-Yi
authors.initials: YY
authors.lastname: Xia
authors.forename: Ji-Cun
authors.initials: JC
authors.lastname: Tang
authors.forename: Ri-Ying
authors.initials: RY
authors.lastname: Wang
authors.forename: Chao-Yong
authors.initials: CY
authors.lastname: Bei
authors.forename: Yanjum
authors.initials: Y
authors.lastname: Zeng
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001853:Bone Marrow / Q000473:pathology; D017554:Carbon Compounds, Inorganic / Q000008:administration & dosage* / Q000009:adverse effects; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage* / Q000009:adverse effects; D005264:Femoral Fractures / Q000378:metabolism / Q000601:surgery / Q000628:therapy*; D006801:Humans; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009132:Muscles / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D009532:Nickel / Q000008:administration & dosage* / Q000009:adverse effects / Q000378:metabolism; D009984:Orthopedic Fixation Devices / Q000009:adverse effects; D015675:Osteocalcin / Q000378:metabolism; D011817:Rabbits; D014025:Titanium / Q000008:administration & dosage* / Q000009:adverse effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D017554:Carbon Compounds, Inorganic; D020099:Coated Materials, Biocompatible; D014409:Tumor Necrosis Factor-alpha; D015675:Osteocalcin; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium; D000469:Alkaline Phosphatase