Objectives The implantable biomaterial devices are used for long term performance for the replacement of damaged or diseased tissues, especially for vascular grafts and artificial skin. Due to the rising number of patients with cardiovascular diseases (CVD) and the shortage of suitable autologous vessels, the demand for clinically effective synthetic small diameter vascular grafts is increasing. Improving biocompatibility of biomaterial is the goal of tissue engineering scientists attempt to minimise inflammatory responses into tolerance. Silk and Polyurethane (PU) are currently being trailed in the animal experiment as potential biomaterial used in different implantable medical device. Interleukin 1 beta (IL-1β) luciferase mouses are generated by incorporating the firefly luciferase gene driven by a 4.5-kb fragment of human IL-1β gene promoter (cHS4l-hIL-1β). In this study, IL-1β transgenic mice have been used to determine the IL-1β production after biomaterial implantation. The aim of this study is determine host responses to Silk or PU implants ± coating recombinant human tropoelastin (rhTE) in transgenic IL-1β mouse model.

Methods The back of each IL-1β mouse (n = 18) was subcutaneously implanted with received 4 different treated implants, control Silk, rhTE-coated Silk, control PU and rhTE-coated PU implants. The in vivo luciferase signal of IL-1β expression in each mouse was imaged daily for 5 days post-surgery, and then 9mice were euthanised at 10 days (10D) and 3 weeks (3W) post-surgery. The implants were harvested and stained with H&E and Milligan’s trichrome to assess inflammatory cell infiltration and collagen depositions. Performing immunohistochemistry stains, Von Willebrand factor (vWF) for neovascularisation, F480 for macrophage, Ly-6G and Ly-6C for neutrophil and proliferation maker Ki67 for proliferating cells.

Results Significantly reduced the levels of IL-1β production was observed in rhTE-coated Silk implants compared to control Silk implants at 2 and 3days post-surgery. Comparing to control implants, less number of total inflammatory cells were found in rhTE-coated Silk (∼47% 3W) and rhTE-coated PU (∼54.64% 10D). Also a reduction of neovascularisation (∼43% 3w) and less proliferating inflammatory cells (∼58% 3W) were observed in rhTE-coated Silk.

Conclusions Our results suggested that rhTE coating improves biocompatibility of Silk and PU, reducing inflammatory responses.