Foreign body response induced by tissue expander implantation

Abstract

The foreign body response (FBR) is described as the host's response to implanted biomaterials, which involves a complex cascade of immune modulators. The dynamic changes of immune cells, inflammatory cytokines and the formation of a fibrous capsule remain to be elucidated. In the present study, a model of subcutaneous implantation of a tissue expander was used. The results revealed that macrophages, the main immune cells in FBR, infiltrated into the expanded tissue and located at the tissue-material interface from day 1-90. Following the decrease of the number of macrophages, collagen deposited and fibroblasts transformed into myofibroblasts at the tissue-material interface, leading to the formation of a fibrous capsule from day 14. The persistent existing macrophages led to a high expression of proinflammatory cytokines, including tumor necrosis factor-α and interleukin-1β, both of which initiated the NK-κB and JNK inflammatory pathways, mediating the FBR to tissue expander implantation.