Immune responses to biomaterials
Foreign body response
- Composed of giant cells and components of granulation tissue
- Macrophages, fibroblasts, capillaries, etc
- Response related physical and chemical factors
- Roughness
- Smooth surfaces have layer of macrophages one to two cells thick
- Rough surfaces have both macrophages and giant cells
- Surface-to-volume ratio
- More surface means more macrophages
- Fibrosis more common for bulk devices
- Response may persist for life of implant
- Long term activation level of macrophages and giant cells unknown
- Fibrosis, or fibrous encapsulation
- Isolates implant from local tissues