Research progress in the regulation of macrophages in foreign body reaction in bone tissue repair

The foreign body reaction refers to a chronic inflammatory reaction and a wound-healing reaction that mainly involve macrophages and foreign body giant cells, which occur after a biological material is implanted into the body. Since macrophages in the foreign body reaction are recruited to the surface of the material after implantation of the material, subsequent secretion of a series of inflammatory factors and fusion into foreign body giant cells may lead to the degradation of the biological materials and environmental stress cracking. Moreover, the prolongation of macrophage polarization and the influence of related receptors may also lead to the phenomenon of fiber encapsulation, resulting in poor prognosis. Some scholars are committed to reducing the response of foreign bodies from the perspective of macrophages and foreign body giant cells, specifically by regulating the secretion of related inflammatory factors, reducing the subtypes of M1 macrophages, promoting their polarization to M2 macrophages, and regulating the fusion of macrophages and selective expression of macrophage-associated receptors to regulate fibrosis. The new immunological view holds that macrophages have the potential to repair bone tissue via angioplasts and osteogenesis in foreign body reactions. Therefore, the gold standard that has long been considered in regenerative medicine, which is that an inert material does not cause a foreign body reaction, is expected to be gradually replaced by tissue engineering that regulates tissue activity and function.