Tissue Biocompatibility of Variously Treated DLC-coated NiTi Fragments using Rat Model

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Tissue Biocompatibility of Variously Treated
DLC-coated NiTi Fragments using Rat Model

• Shin JH1, Kim TH1, Kim EY1,
• Song HY1, Moon MW2, Lee KR2, Han DK3
• 1Department of Radiology, University of Ulsan,
  College of Medicine
• Asan Medical Center, Seoul, Korea
• 2Future Convergence Technology Lab.,
  3Biomaterials Research Center,
• KIST (Korea Institute of Science and Technology),
  Seoul, Korea

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Introduction
Introduction

• Problems with a biomedical device
• - Biocompatibility, hematocompatibility,
  cytotoxicity
• Ideal Biomaterials
• - Chemically and biologically inert to the
  surrounding tissues
• - Hard and wear-resistant with low friction
• - No release of toxic and carninogenic elements
• surface properties are very important

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Introduction

• DLC (diamond-like carbon) coatings
• - High hardness, low frictional coefficient,
  high wear corrosion resistance, chemical
  inertness, high electrical resistivity, and
  excellent smoothness
• - Promising as a hemocompatible material
• - Doping or surface treatment is helpful for
  better mechanical properties and biocompatibility

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Purpose
Purpose

• To evaluate tissue biocompatibility of the
  variously treated DLC coated NiTi fragments by
  in-vivo experiments using rat model

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Materials and Methods
Materials and Methods

• Test Specimens
• - Sample size 5mm x 5mm, rectangular
• -

NiTi-control (n6) NiTi/Si-DLC
(n6) NiTi/Si-DLC/PEG (n6) NiTi/Si-DLC/N2
(n6) NiTi/Si-DLC/CF4 (n6)
PEG
DLC
NiTi
Si
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Materials and Methods

• Animal Experiment
• - Six for each test specimen, so total 30
  specimens
• - Rat thigh muscle model (n15)
• - Anesthesia with intraperitoneal injection of
  ketamine (100mg/kg) and xylazine (15mg/kg)
• - Fixation of the hind leg
• - Bilateral thigh muscle dissection
• - Implantation of test specimens into muscle
  belly
• - Suture of the incision site

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Materials and Methods
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Materials and Methods

• Follow-up and Histopathology
• - 6 weeks of follow-up to allow tissue response
  to the implanted specimens
• - Sacrifice with removal of each specimen and
  surrounding skeletal muscle

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Materials and Methods

• - H E staining for the skeletal muscle
• - Measurement of fibrotic tissue thickness
  which indicates tissue response

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Materials and Methods

• Statistics
• - Measure fibrotic tissue thickness 3 times
  for each specimen
• - ANOVA test to evaluate significant difference
  of fibrotic tissue thickness between the five
  groups

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Results
Results

• All rats tolerated the surgery well
• Post-implantation period was uncomplicated
• Implantation site healed without any
  complications
• Implanted specimens could be removed easily
• Fibrotic tissue was observed as a capsule around
  the implantation site

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Results

• Fibrotic tissue thickness

sample Mean fibrotic tissue thickness
NiTi-control 85.40 ? (5th)
NiTi/Si-DLC 76.00 ? (4th)
NiTi/Si-DLC/PEG 61.60 ? (1st)
NiTi/Si-DLC/N2 72.70 ?(3rd)
NiTi/Si-DLC/CF4 69.10 ? (2nd)
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Results
(x100)
(x100)
(x100)
NiTi-control Mean - 85.40 ?
NiTi/Si-DLC Mean - 76.00 ?
NiTi/Si-DLC/PEG Mean - 61.60 ?
No significant difference between five groups
p0.063 (ANOVA)
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Results
NiTi/Si-DLC/PEG
(x200)
Minimal lymphocytic infiltration and fibrosis,
suggesting chronic inflammation
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Discussion
Discussion

• NiTi/Si-DLC/PEG showed the best tissue
  biocompatibility.
• - PEG is hydrophilic as a water-soluble polymer
• - PEG is flexible (high chain motility)
• - PEG has steric stabilization having exclude
  volume, - difficult for blood components to get
  close

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Conclusion
Conclusion

• NiTi/Si-DLC/PEG showed the best tissue
  biocompatibility.
• Variously treated DLC coated NiTi specimens
  showed less tissue reaction compared with
  NiTi-control.
• This observation provides basis for feasibility
  of application of the stents made of treated DLC
  coated NiTi.

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Acknowledgement

• Kim TH, Kim EY
• Dept. of Radiology, Asan Medical Center
• Park CS
• - Dept. of Pathology, Asan Medical Center
• Lee KR, Moon MW
• - Future Convergence Technology Lab., KIST
• Han DK, Park K
• - Biomaterials Research Center, KIST
• Thank you for your attention !