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, Korea2Future Convergence Technology Lab., 3Biomaterials Research Center,
KIST (Korea Institute of Science and Technology), Seoul, Korea
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
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
Introduction
To evaluate tissue biocompatibility of the
variously treated DLC coated NiTi fragments
by in-vivo experiments using rat model
Purpose
Purpose
Materials and Methods
Test Specimens
- Sample size: 5mm x 5mm, rectangular
- NiTi-control (n=6)
NiTi/Si-DLC (n=6)
NiTi/Si-DLC/PEG (n=6)
NiTi/Si-DLC/N2 (n=6)
NiTi/Si-DLC/CF4 (n=6)
NiTiSi
DLC
Materials and Methods
PEG
Animal Experiment
- Six for each test specimen, so total 30 specimens
- Rat thigh muscle model (n=15)
- 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
Materials and Methods
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
Materials and Methods
- H & E staining for the skeletal muscle
- Measurement of ‘fibrotic tissue thickness’ which indicates tissue response
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
Materials and Methods
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
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)
Results
NiTi-control
Mean - 85.40 ㎛NiTi/Si-DLC
Mean - 76.00 ㎛NiTi/Si-DLC/PEG
Mean - 61.60 ㎛
No significant difference between five groups
; p=0.063 (ANOVA)
(x100) (x100)(x100)
Results
Results
Minimal lymphocytic infiltration and fibrosis, suggesting chronic inflammation
(x200)
NiTi/Si-DLC/PEG
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
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.
AcknowledgementKim 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 !