Y. Chun, K. P. Mohanchandra, G. P. Carman, University of California, Los Angeles, Los Angeles, CA; D. S. Levi, Mattel Children's Hospital, UCLA, Los Angeles, CA; A. W. Tulloch, D. A. Rigberg, F. Vinuela, F. Vinuela Jr., P. F. Lawrence, David Geffen School of Medicine, UCLA, Los Angeles, CA
Objective: To fabricate and test micro-patterned superhydrophilic thin film NiTi endografts.
Methods: MEMS fabrication techniques were used to create patterned films and chemical processes were used to create a superhydrophilic surface. Thin film NiTi grafts were evaluated theoretically and experimentally in an in vitro pulsatile flow loop. In vitro platelet adhesion studies were conducted using platelet rich plasma (PRP) from a healthy adult donor. Micro-patterned superhydrophilic thin film NiTi grafts were mounted on commercially available self-expanding stents and deployed in swine.
Results: DSC and stress-strain plots confirmed the film’s superelastic properties at 36.5°C. A lift-off method was used to fabricate smooth micro patterns. A chemical treatment was used to created superhydrophilic surface in the film, which was not observed in bulk NiTi. In vitro tests showed a significant decrease in platelet/bacteria adhesion and aggregation compared to commercially available PTFE graft materials. In vivo, angiography two weeks after delivery confirmed the efficacy of thin film NiTi endografts in a swine model. SEM images showed uniformly promoted endothelial layer covering without thromobosis. Pathological studies were also performed to assess the endothelial tissue growth and the neointimal hyperplasia through the 30x60micron diamond shaped patterns on thin film NiTi.
Conclusion: Micro patterned superhydrophilic thin film NiTi may represent a novel alternative to PTFE for endograft construction.
