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J Biomater Appl. 2017 Mar;31(8):1196-1202. doi: 10.1177/0885328216682691. Epub 2016 Dec 8.

An in vivo pilot study of a microporous thin film nitinol-covered stent to assess the effect of porosity and pore geometry on device interaction with the vessel wall.

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1 Department of Industrial Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
2 Department of Bioengineering, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
3 Advanced Development & Medical Affairs, NeuroSigma, Inc., Los Angeles, CA, USA.
4 Pediatric Cardiology, Mattel Children's Hospital, University of California, Los Angeles, CA, USA.
5 Division of Vascular Surgery, Ronald Reagan UCLA Medical Center, UCLA Surg-Vascular, Los Angeles, CA, USA.
6 Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA, USA.


Sputter-deposited thin film nitinol constructs with various micropatterns were fabricated to evaluate their effect on the vessel wall in vivo when used as a covering for commercially available stents. Thin film nitinol constructs were used to cover stents and deployed in non-diseased swine arteries. Swine were sacrificed after approximately four weeks and the thin film nitinol-covered stents were removed for histopathologic evaluation. Histopathology revealed differences in neointimal thickness that correlated with the thin film nitinol micropattern. Devices covered with thin film nitinol with a lateral × vertical length = 20 × 40 µm diamond pattern had minimal neointimal growth with well-organized cell architecture and little evidence of ongoing inflammation. Devices covered with thin film nitinol with smaller fenestrations exhibited a relatively thick neointimal layer with inflammation and larger fenestrations showed migration of inflammatory and smooth muscle cells through the micro fenestrations. This "proof-of-concept" study suggests that there may be an ideal thin film nitinol porosity and pore geometry to encourage endothelialization and incorporation of the device into the vessel wall. Future work will be needed to determine the optimal pore size and geometry to minimize neointimal proliferation and in-stent stenosis.


Coronary artery disease; neointimal hyperplasia; peripheral artery disease; restenosis; thin film nitinol

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