Assessment of tissue reaction of rat to materials used in vascular grafts. Gholam Hosein Kazemzadeh 1 , Nafiseh Jirofti 2 , Davod Mohebbi-Kalhori 2 , Reza Taheri 3* 1 Department of Vascular Surgery, Vascular and Endovascular Surgery Research Center, Mashhad University of Medical Sciences, Mashhad, Iran 2 Department of Chemical Engineering, University of Sistan and Baluchestan, Zahedan, Iran 3 Surgical Oncology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran Abstract Background: Vascular grafts are used common in surgery. Some patients have no native vessels for auto- graft so we should use vascular graft. In this study we assessed tissue reaction of rats to materials used in vascular grafts. Materials and methods: We prepared 8 types of grafts with electro-spinning method from different materials such as polycaprolactone (PCL), polyurethane (PU) and polyethylene terephthalate (PET) in sporadic and mixture patterns. After sterilisation with ethylene oxide, grafts were implanted in subcutaneous layer of 32 rats (divided into 8 groups of 4 rats). Rats assessed for local and general responses in 45 d. Histopathological responses were assessed by pathologist after 45 d. Results: There is no mortality during study. There are no local and systemic responses. Surgical site Infection not found. Tissue reactions to polyethylene terephthalate (PET) was higher than PET (Bio). Tissue reactions to polyurethane (PU) and PU (Bio) were about equal. PU had lower reactions in comparison with (PET) and polycaprolactone (PCL). PU+PET (Bio) had lower reaction in comparison with PET+PCL (Bio) Conclusions: It seems polyurethane has lesser reaction in compared with other materials in both single and mixture Keywords: Rat, Electro-spinning, Vascular graft, Tissue reaction. Accepted on June 11, 2018 Introduction Biomaterial implants are used in different anatomic locations. It has been recognized that maintaining a controlled biological reaction in the peri-implant region is essential. Although the ultimate device designs are regularly used in their target anatomical location, the biocompatibility of polymer components is often evaluated subcutaneously or intramuscularly. Subcutaneous tissue implant in the rat model has proven to be a high-throughput, relatively low-cost screening technique for testing tissue responses to new materials [1,2]. The healing characteristics surrounding polymer implants in subcutaneous tissues are often extrapolated to other tissues; expecting that the observed healing is similar in other locations. This model also allows the initial evaluation of the effects of materials used in vascular grafts on tissue responses in a more relevant environment than the in vitro assay. The aim of this study was to assess the tissue reaction to materials used in vascular grafts in the rat model. Materials and Methods This research has started in 2015. We contributed to the planning, design, gathering, analysis and interpretation of all data about artificial vessels. In this team working project, research group from Sistan and Balouchestan University started making artificial vessels by electro-spinning method since 2015. We use nano technique for production of artificial vessel. We product nano fiber by electro-spinning; this method have many advantages such as scalability, repeatability and control of nano fiber diameter; One reason for usage of nano fiber is that red blood cells cannot transmit from their holes. The electro-spinning method was used first to manufacture eight samples of multi-layer and single layer polycaprolactone (PCL), polyurethane (PU) and polyethylene terephthalate (PET) biopolymer nano-fibers. For assessment histopathological response to substances used in tissue vascular grafts rats were chosen. Coordination with the animal lab Mashhad medical faculty was done to provide rat. The rats were about 45 d old and had the mean weight of 170 gm. After ensuring proper preparation of rats, artificial blood samples with ethylene oxide in the clean sterile room (CSR) were sterile for 14 h. Rats with a mixture of ketamine (1.5 cc) and ISSN 0970-938X www.biomedres.info Biomed Res 2018 Volume 29 Issue 13 2794 Biomedical Research 2018; 29 (13): 2794-2796