Although deoxyribonucleic acid (DNA) is the genetic coding for the very essence of life, these macromolecules or components thereof are not necessarily lost after a cell dies. There appears to be a link between extracellular DNA and biomineralization. Here the authors demonstrate that extracellular DNA functions as an initiator of collagen intrafibrillar mineralization. This is confirmed with in vitro and in vivo biological mineralization models. Because of their polyanionic property, extracellular DNA molecules are capable of stabilizing supersaturated calcium phosphate solution and mineralizing 2D and 3D collagen matrices completely as early as 24 h. The effectiveness of extracellular DNA in biomineralization of collagen is attributed to the relatively stable formation of amorphous liquid droplets triggered by attraction of DNA to the collagen fibrils via hydrogen bonding. These findings suggest that extracellular DNA is biomimetically significant for fabricating inorganic-organic hybrid materials for tissue engineering. DNA-induced collagen intrafibrillar mineralization provides a clue to the pathogenesis of ectopic mineralization in different body tissues. The use of DNase for targeting extracellular DNA at destined tissue sites provides a potential solution for treatment of diseases associated with ectopic mineralization.

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Nanohydroxyapatite (nHAP) has broad applications because of its nanoscopical dimension, large specific surface area, biocompatibility, and low cytotoxicity. Researchers recently discovered that nHAP synthesized in vitro inhibits the growth of different types of tumor cells. Nanohydroxyapatite with potent drug adsorption and loading capacity has potential applications in tumor diagnosis and treatment. Because local tumors and areas of tumor metastasis also produce pathological nHAP in vivo to promote progression and invasion, the role of nHAP in tumorigenesis and development is perceived literature by many as Janus, the double‐faced deity in ancient Roman mythology. In the present review, two types of nHAP (those synthesized in vitro and those produced in vivo) that are affiliated with tumors, their mechanisms in tumor progression as well as their applications in tumor treatment are elucidated to create a backdrop for future research in this exciting, yet controversial arena.

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Tooth biomineralization is a dynamic and complicated process influenced by local and systemic factors. Abnormal mineralization in teeth occurs when factors related to physiologic mineralization are altered during tooth formation and after tooth maturation, resulting in microscopic and macroscopic manifestations. The present Review provides timely information on the mechanisms and structural alterations of different forms of pathological tooth mineralization. A comprehensive study of these alterations benefits diagnosis and biomimetic treatment of abnormal mineralization in patients.

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Objective To investigate the significant role of fibrocytes in pathogenesis of fibrous epulis. Material Human epulis specimens and human peripheral blood mononuclear cells (PBMCs) were used in this study. Methods Different subtypes of human fibrous epulides and normal gingival tissue specimens were collected for histological and immunofluorescence analyses. Electron microscopy and elemental analysis were used to characterize the extracellular microenvironment in different subtypes of fibrous epulides. Human PBMCs were subsequently isolated from peripheral blood to identify the factor that trigger fibrocyte differentiation in vitro. Results We demonstrated the presence of circulation-derived fibrocytes in fibrous epulides. These fibrocytes differentiate into myofibroblasts or osteoblasts under the local inflammatory environment in fibrous epulides. TGF-β1 promotes fibrocytes differentiation into myofibroblasts in a concentration-dependent manner. The TGF-β1 along with a high calcium and phosphorus extracellular environment stimulates the fibrocytes to differentiate into osteoblasts. The fibrocytes-derived myofibroblasts and osteoblasts are responsible for the fibrogenesis and osteogenesis of fibrous epulides, respectively. The persistent local inflammatory environment drived the differentiation of circulation-derived fibrocytes and drived the recurrence of fibrous epulides. Conclusions Fibrocytes play an important role in the fibrogenesis and osteogenesis in fibrous epulis, and might serve as a therapeutic target for the recurrence of fibrous epulides.