Osteoblastic lysosome plays a central role in mineralization

Mineralization is mediated by osteoblasts, which secrete mineral precursors through matrix vesicles (MVs) as a fundamental process in vertebrates. The vesicles are calcium and phosphate rich, containing organic materials such as acidic proteins. In a new study now published in Science Advances, Tomoaki Iwayama and colleagues at the departments of periodontology, biomedical research, oral science, biomaterials and oral anatomy development used scanning electron-assisted dielectric microscopy (SE-ADM) and super-resolution microscopy (SRM) to assess live osteoblasts during conditions of mineralization at nano-level resolution. They found the calcium-containing vesicles to be multi-vesicular bodies containing mineralizing nanovesicles or matrix vesicles (MVs). According to the observations, the MVs could be transported together with lysosomes and secreted by exocytosis. Iwayama et al. presented proof that the lysosomes could transport amorphous calcium phosphate in mineralizing osteoblast cells.