Immunotoxicity of absorbable silk fibroin biofilm on rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Silk fibroin, the main component of silk fibroin biofilm, is a natural protein, but it is still a heterologous protein to the body. Its immunogenicity/toxicity is an important factor in determining the development prospects. OBJECTIVE: To evaluate the toxicity of absorbable silk fibroin biofilm and its degradation products on the rat immune system by muscle implantation experiments in rats. METHODS: Ten Wistar rats from Beijing Weitong Lihua Experimental Animal Technology Co., Ltd. were implanted with a long strip of 1 mm× 10 mm in the right gluteal muscle to observe the implant absorption and determine the implantation cycle. Seventy-two Wistar rats were assigned into control and experimental groups (n=36/group, 18 in either sexes) . A long strip of 1 mm×10 mm was implanted into the rat right gluteal muscle in the experimental group, and the control group received no implantation. Some of the rats were taken for histological examination and calculate the organ/weight ratio, at 26 weeks postoperatively. The spleen lymphocyte proliferation ability, NK cell activity, cell classification of T lymphocytes, and levels of interleukin 2 and tumor necrosis factor α were detected. Another part of the animals was taken for macrophage phagocytosis of erythrocytes cell capacity and antibody producing cell count. RESULTS AND CONCLUSION: (1) Silk fibroin biofilm was completely absorbed after implanted into the rat muscle for 26 weeks. (2) In female or male Wistar rats, the immune organs in the experimental group showed no significant changes in the appearance, weight and histological examination. There were no significant differences in the hematological indexes (hemoglobin, red blood cell count, hematocrit, blood platelet count and white blood cell count and classification) , spleen lymphocyte proliferation, NK cell activity, the ratio of T lymphocytes and their subpopulations, and the levels of interleukin 2 and tumor necrosis factor α had no significant differences between two groups (P> 0.05) . (3) In female or male Wistar rats, the macrophage phagocytosis of chicken erythrocytes cell capacity and antibody producing cell count showed no significant differences between two groups (P> 0.05) . (4) These results indicate that silk fibroin biofilm causes no immunosuppression or immunostimulation on immune organs, immune cells and immune molecules (cytokines) of rats.