Implantation of a medical device induces an immune response that is characterized by protein deposits on the surface of the material and the recruitment of neutrophils and macrophages that attempt to degrade the materials with nitric oxide radicals. Subsequently, macrophages and fibroblasts deposit a dense fibrotic capsule that ultimately walls off the material from the body. While the immune system is imperative for pathogenic foreign bodies, for medical devices it can result in complications dependent upon the function of the device. Increasing our understanding of these responses to various biomaterials can lead to the improved rational design of materials that prevent immune recognition or induce immune tolerance to that device.

In the wound healing and tissue growth processes, there are specific patterns of immune activation that alter stem cell development and differentiation. Here, we seek to understand the mechanisms of immune patterning in tissue regeneration, while developing materials to help guide proper activation and inactivation of immune responses.

As previously mentioned, there are specific patterns of immune activation that can lead to either tissue development or pathogenesis. These patterns and activation states change for different tissue types that yield their own unique immune systems through the presence of tissue-resident immune cells. Further understanding of the differences in immune responses within these tissues (in the context of biomaterials) will create tissue-specific materials that are better tuned to the specific immunologic needs of each tissue.