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Tissue Biocompatibility of Variously Treated DLC-coated NiTi Fragments using Rat Model. Shin JH 1 , Kim TH 1 , Kim EY 1 , Song HY 1 , Moon MW 2 , Lee KR 2 , Han DK 3 1 Department of Radiology, University of Ulsan, College of Medicine Asan Medical Center, Seoul, Korea
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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
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
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
Purpose Purpose To evaluate tissue biocompatibility of the variously treated DLC coated NiTi fragments by in-vivo experiments using rat model
Materials and Methods Materials and Methods 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) Test Specimens - Sample size: 5mm x 5mm, rectangular - PEG DLC NiTi Si
Materials and Methods 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 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
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
Results Fibrotic tissue thickness
Results (x100) (x100) (x100) NiTi-control Mean - 85.40 ㎛ NiTi/Si-DLC Mean - 76.00 ㎛ NiTi/Si-DLC/PEGMean - 61.60 ㎛ No significant difference between five groups ; p=0.063 (ANOVA)
Results NiTi/Si-DLC/PEG (x200) Minimal lymphocytic infiltration and fibrosis, suggesting chronic inflammation
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.
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 !