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A New Strategy For Prevention Of Anastomotic Stricture By Using Tacrolimus eluting Biodegradable Nanofiber
M. Mutsuga1, Y. Narita1, A. Yamawaki2, Y. Suematsu3, H. Oshima1, A. Usui1, S. Takamoto*3, Y. Ueda1. 1Nagoya University, Graduate School of Medicine, Department of Cardiothoracic Surgery, Nagoya, Japan, 2Department of Clinical Cell Therapy and Tissue Engineering, Nagoya University School of Medicine, Nagoya, Japan, 3Department of Cardiac Surgery, The University of Tokyo Graduate School of Medicine, Tokyo, Japan,
BACKGROUND:The thrombus formation and neointimal hyperplasia of the vascular anastomosis remains to be major complications of coronary artery bypass surgery. Despite of advanced technical improvement in cardiac surgery, these complications could not be avoided completely and it will induce anastomotic stricture. We developed novel controlled drug delivery device to prevent anastomotic stricture. It consisted of nano-scaled “cotton-wool” configuration fiber which composed biodegradable polymer and Tacrolimus of immunosuppressive agent. The current study demonstrates the effects of Tacrolimus-eluting biodegradable nano-fiber (TEBN) for prevention of anastomotic stricture in a rat model.
METHODS:TEBN was fabricated by electrospining technique. Tacrolimus was incorporated into poly(L-lactide-co-glycolide) with L:G molar ratio of 50:50. Nano-fiber is easy to handle to any type of vascular anastomosis flexibly. TEBN was placed around the end-to-end anastomotic site in our rat model of infra-renal aortic anastomosis. Rats were randomly divided into five groups (n=5 in each groups); without TEBN (as a control), 5mg of nano-fiber only, 5mg of TEBN Tacrolimus containing 0.04wt%, 0.1wt% and 1.0wt% respectively. Morphometric analysis and histological analaysis including immunohistochemistry were performed at two-weeks.
RESULTS:The ratio of intimal width (intimal width divided by the intimal and medial width) was significantly reduced in 1wt% of TEBN placed group compared with other groups (0.51, 0.47, 0.48, 0.47 and 0.23 in control, 0wt%, 0.04wt%, 0.1wt% and 1wt%, respectively, p<0.05). (Fig 1) The cells, which constitutes of intimal hyperplasia, were alpha smooth muscle actin and SMemb positive in immunohistochemistry. Immunohistochamical stain of factor VIII revealed endothelial cells were covered on the surface of the aortic lumen even in 1wt% of TEBN placed group, in which neointimal hyperplasia was significantly inhibited.
CONCLUSIONS:The cotton-wool shaped TEBN reduced neointimal hyperplasia and preserved endothelialization. These results strongly suggest that this material is useful in vascular anastomosis. 
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