ABSTRACT
@#Extracellular vesicles (EVs) are lipid bilayers secreted by a variety of cells that contain nucleic acids, proteins, etc. They can be used as a carrier for cell-to-cell communication. In related research on bone regeneration, mechanisms for transmitting regeneration signals to target cells to achieve the desired goal of osteogenesis have become one of the most important and unsolved topics. Therefore, this review aims to explore the role of mesenchymal stem cells and EVs derived from osteoblasts in bone regeneration in four processes, immunity, angiogenesis, osteogenesis and mineralization, and to provide new ideas for basic and clinical research.
ABSTRACT
@#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.
ABSTRACT
@#Bone is capable of regeneration after injury, but the process of properly restoring form and function is highly complex and prone to failure. The restoration process requires highly ordered and sequential interplay at the injury site between the host immune system and bone tissue. The dynamic process that occurs after bone injury includes the formation of a hematoma, the development of an inflammatory response and callus, and the remodeling of newly formed bone tissue. The inflammatory response at the injury site is essential for the onset of bone regeneration. This inflammatory response is tightly linked with the host immune system, in which various immune cells and molecules are involved. Recently, the relationship between T cells and bone regeneration has become a popular topic; however, currently, there are no summaries of the relationship between T cells and bone regeneration. Thus, this review aimed to elucidate the modulatory functions of T cells in bone regeneration.