Evaluation of Lucilia sericata and Its Excretion/Secretion Products in Terms of Biocompatibility

Abstract

Aim: Larval debridement therapy (LDT) is been used for the treatment of chronic wounds especially in patients with diabetic foot and decubitus ulcers, as well as in those with venous and arterial stasis. Using their proteolytic enzymes excreted with the saliva, larvae of the green bottle fly, Lucilia sericata debride the necrotic tissue found inside the wound, first extracorporeally and later fully digest it by ingesting to their digestive system. Biocompatibility is the relevance of any medical material designed for human use in its mechanical behavior in body tissues and cells, its chemical, physical and biological consistency. The larvae used for LDT are considered as medical device and should be produced according to ISO 13485. In our study, we aimed to investigate the effects of living and dead L. sericata larvae as well as of their excretion/secretion (E/S) products on healthy cells according to international standards for biocompatibility assays. Methods: MTT cell viability test, which is the in-vitro cytotoxicity method according to EN ISO 10993-5 and used for determining the active substance concentration on medical devices, was used. Physiological saline and Dulbecco's Modified Eagle's Medium (DMEM) were used for analyses of living/dead maggots and their E/S products. L929 Fibroblast Cells were chosen as healthy cells as they are the dominant cells of the wound healing process and also commonly used in the biocompatibility tests. Fibroblasts were exposed to 1, 2, 3, 5 and 10 specimens of live or dead larvae. Results: Using the MTT test, fibroblast cells were exposed to different concentrations of E/S products and to living and dead larvae. According to TS EN ISO, the applied material is considered biocompatible if the cell viability is above 70% after exposure to the tested material. The viability of the fibroblasts was 81.6±5.4% in the saline medium and 93.6±6.04% in DMEM when they were exposed to different concentrations of E/S products. It was 92.6±1.6% when approximately 10,000 cells were exposed to 10 dead larvae, and 85.94 ± 2.09% when they were exposed to 10 life larvae. No adverse effects were detected on biocompatibility when the fibroblasts were exposed to the different E/S concentrations and number of dead/live larvae. Conclusion: These data show that living and dead specimens of L. sericata larvae, and their E/S fluids do not have a toxic effect on healthy L929 Fibroblast Cells and accordingly would not harm healthy tissue when used for the treatment of patients.