Single-cell mass cytometry reveals in vivo immunological response to surgical biomaterials

Abstract Adverse events related to surgical mesh implants such as mesh erosion and adhesion are inflammation-related and frequently reported in clinical use; thus, advanced real-time monitoring methods are required to evaluate the interactions between implants and host immune system in order to prevent any unfavorable events. Here, we performed single cell mass cytometry of the blood, characterizing two biomaterial-induced (silk and polypropylene) immune responses in a rodent ventral hernia model to systematically decipher the interactions between the host and implants. Compared to polypropylene, silk mesh induced less immune cell activation with lower proportions of macrophages, monocytes, and neutrophils in the innate system and lower proportions of CD4+ T cells and CD8+ T cells in the adaptive system at 3-week post-implantation. Functional markers (CD115, CD27, and CD62L) involved in the immune cell activation and migration were also downregulated in the silk group. Histological analysis of tissues confirmed that silk mesh implantation led to decreased neutrophils and macrophages recruitment, less fibrosis formation, and better tissue healing, suggesting silk mesh as a superior implant material. Importantly, in patients with abdominal hernia, the ratio of monocytes in blood in the silk group was also significantly lower when compared to the polypropylene group. Our study provides a systematical profile of the material-based foreign body response at single cell resolution, highlighting the impact of biomaterial implants on whole body immune system and introducing an innovative approach to monitor material-based immune response.