Foreign body reaction

Following biomaterial implantation, blood and body fluids contact the implant surface. Host blood proteins adsorb onto the implant surface and a fibrin matrix forms. Acute and chronic inflammation follow the initial blood protein deposition and matrix formation. The foreign body reaction can lead to device failure. and release of histamine from mast cells further recruits macrophages to the biomaterial. Foreign body giant cell formation depends on the biomaterial surface properties and on the presence of interleukin-4 and interleukin-13. Macrophages and foreign body giant cells release cytokines that attract fibroblasts. Fibroblasts create a collagenous fibrous capsule to separate the biomaterial from the surrounding tissue. The fibrous capsule may hinder the device's function, such as drug diffusion for drug delivery systems or normal tissue regeneration for tissue engineering implants. == Engineering biomaterial to resist the foreign body reaction ==

The foreign body giant cell formation and the fibrous encapsulation of the implanted device can affect the function of the implanted device and lead to its failure. Reducing the foreign body reaction can promote better device performance and durability. The sustained release of certain anti-inflammatory drugs from the biomaterial, such as dexamethasone, is shown to increase implant life by preventing inflammation and fibrosis. Biomaterials that mimic the extracellular matrix can significantly reduce the inflammatory response as well as reduce foreign body giant cell formation. Zwitterionic hydrogels also promote angiogenesis in surrounding tissues. Commonly used zwitterionic materials include sulfobetaine, carboxybetaine, and phosphorylcholine. Zwitterionic coatings can be covalently attached by "grafting to" and "grafting from" methods. With "grafting to" methods, the surface is modified with the polymer after synthesis, whereas with "grafting from" methods, polymer is directly synthesized on a modified surface. In this case, copolymer should contain a thiol group. Nazarova and coworkers synthesized MPC copolymers with 2-methacrylamido-D-glucose, N-vinylpyrrolidone, and N-vinyl-N-methyl-acetamide and grafted them onto the surface of carbon fibre biosorbent using γ-radiation. MPC copolymers with trimethoxysilylpropyl methacrylate can be thermally cured and self-crosslinked. Modian field alginates Alginates are widely used for their low cost, low toxicity, and tunability. Polypeptide materials Polyethylene glycol peptides and zwitterionic peptides have immunomodulatory functions that help to resist the foreign body reaction. ==Gallery==

File:Pulmonary talcosis low mag cropped.jpg|A foreign-body response to talc (talcosis) due to intravenous drug use. H&E stain. File:Suture material.jpg|Foreign body giant cell reaction to nylon suture material File:Foreign body granuloma (labeled).jpg|Foreign body granuloma ==See also==