With additional functions of osteocytes being identified, the concept that osteocytes are just "static lacunar-dwelling cells" is no longer accepted. We reviewed most of the relevant literature on osteocyte's function in the direct remodeling of the perilucunar matrix, discussing the advantages and disadvantages. Special attention was paid to how the negative researchers argue about the "osteocytic osteolysis" principle, and how the positive side addressed the arguments. We also discussed the newly found data of osteocytic remodeling function from our group. With more biotechnology in hand, there is increased excitement in the prospect of now being able to answer the two important questions: do osteocytes have the capability to remove mineral from the perilacunar matrix and if so what are the molecular and cellular mechanisms? do osteocytes have the capability to deposit new mineral on the perilacunar matrix and if so what are the cellular and molecular mechanisms?
Animals ; Bone Matrix ; physiology ; Bone Remodeling ; physiology ; Humans ; Osteocytes ; physiology ; Osteogenesis ; physiology ; Osteolysis ; physiopathology

Peroxisome proliferator activated receptor gamma interacts with bone morphogenetic protein, Wnt, TAZ, and insulin-like growth factor-I, which are required for the process of osteoblast differentiation, regulating the mesenchymal stem cells (MSCs) into adipocytes and osteoblasts differentiation, thus impact on the osteoblast-mediated bone formation in bone remodeling, and, through RANKL and other factors directly or indirectly, regulate osteoclast-mediated bone resorption. This article reviews new researches for the influence of peroxisome proliferator activated receptor gamma on osteoblast and osteoclast function in bone remodeling.
Bone Remodeling ; physiology ; Humans ; Osteoblasts ; physiology ; Osteoclasts ; physiology ; PPAR gamma ; physiology

Animals ; Biomechanical Phenomena ; Bone Development ; Bone Remodeling ; Bone and Bones ; injuries ; Fracture Healing ; physiology ; Fractures, Bone ; pathology

At present, the numerical model of bone remodeling is inadequate to copy the physiological process of bone remodeling. According to the physiological mechanism of bone remodeling and the anisotropy of bone mechanics properties, an anisotropic bone modeling model with mechanostat was developed, and then was applied to a study on the remodeling evolution of 2D squareplate model. Good results were obtained. The model can be used in the study of implant, osteoporosis and other bone diseases.
Anisotropy ; Biomechanical Phenomena ; Bone Remodeling ; physiology ; Bone and Bones ; physiology ; Models, Biological ; Osteoporosis ; physiopathology

Osteogenesis and angiogenesis are two closely correlated processes during bone growth, development, remodelling and repair.Vascular endothelial growth factor (VEGF) is an essential mediator during the process of angiogenesis. Based on an extensive literature search, which was carried out using the PubMed database and the keywords of osteogenesis, VEGF, endochondral ossification and intramembranous ossification, this manuscript reviews the role of VEGF in ossification, with emphasis on its effect in endochondral and intramembranous ossification. Osteogenesis and angiogenesis are closely correlated processes. VEGF acts as an essential mediator during these processes. It not only functions in bone angiogenesis but also in various aspects of bone development.
Animals ; Bone Remodeling ; physiology ; Bone and Bones ; cytology ; physiology ; Calcification, Physiologic ; physiology ; Cartilage ; cytology ; physiology ; Humans ; Neovascularization, Physiologic ; physiology ; Osteoclasts ; physiology ; Osteogenesis ; physiology ; Vascular Endothelial Growth Factor A ; physiology

Bone is an active tissue in which the processes of remodeling are continuous to ensure normal bone integrity and strength. Steroids play an important role in regulating bone growth, development and remodeling. Glucocorticoids excess will induce bone damages especially osteoporosis. Otherwise, estrogen and androgen are bone protective steroids in both female and male. To develop a new selective steroid receptor modulator is one of the targets in future study to treat osteoporosis.
Adult ; Androgens ; physiology ; Bone Development ; Bone Remodeling ; Estrogens ; physiology ; Female ; Glucocorticoids ; physiology ; Humans ; Male ; Middle Aged ; Osteogenesis ; Osteoporosis ; prevention & control

Bone remodeling is balanced by bone formation and bone resorption as well as by alterations in the quantities and functions of seed cells, leading to either the maintenance or deterioration of bone status. The existing evidence indicates that microRNAs (miRNAs), known as a family of short non-coding RNAs, are the key post-transcriptional repressors of gene expression, and growing numbers of novel miRNAs have been verified to play vital roles in the regulation of osteogenesis, osteoclastogenesis, and adipogenesis, revealing how they interact with signaling molecules to control these processes. This review summarizes the current knowledge of the roles of miRNAs in regulating bone remodeling as well as novel applications for miRNAs in biomaterials for therapeutic purposes.
Animals ; Bone Remodeling ; physiology ; Cell Lineage ; Humans ; MicroRNAs ; physiology ; Osteoblasts ; cytology ; Transcription, Genetic

The prevailing model of osteology is that bones constantly undergo a remodeling process, and that the differentiation and functions of osteoblasts are partially regulated by leptin through different central hypothalamic pathways. The finding that bone remodeling is regulated by leptin suggested possible endocrinal effects of bones on energy metabolism. Recently, a reciprocal relationship between bones and energy metabolism was determined whereby leptin influences osteoblast functions and, in turn, the osteoblast-derived protein osteocalcin influences energy metabolism. The metabolic effects of bones are caused by the release of osteocalcin into the circulation in an uncarboxylated form due to incomplete gamma-carboxylation. In this regard, the Esp gene encoding osteotesticular protein tyrosine phosphatase is particularly interesting because it may regulate gamma-carboxylation of osteocalcin. Novel metabolic roles of osteocalcin have been identified, including increased insulin secretion and sensitivity, increased energy expenditure, fat mass reduction, and mitochondrial proliferation and functional enhancement. To date, only a positive correlation between osteocalcin and energy metabolism in humans has been detected, leaving causal effects unresolved. Further research topics include: identification of the osteocalcin receptor; the nature of osteocalcin regulation in other pathways regulating metabolism; crosstalk between nutrition, osteocalcin, and energy metabolism; and potential applications in the treatment of metabolic diseases.
Bone Remodeling/physiology ; Bone and Bones/*metabolism ; *Energy Metabolism ; Humans ; Leptin/metabolism ; Osteocalcin/genetics/*metabolism

Bidirectional Eph-Ephrin signaling as a focal point of research in cell-cell communications is critical for generation of nerves and vesssels as well as invation and metastasis of tumor cells. The roles for Ephrin-Eph bidirectional signaling in bone remodeling were important. EphrinB2 is expressed on osteoblasts and EphB4 is expressed on osteoclasts. Forward signaling through the EphB4 receptor into mesenchymal precursors promotes osteoblast differentiation, while reverse signaling through the EphrinB2 ligand into osteoclast suppresses differentiation. Signaling between the ligand EphrinB2 and the receptors EphB4 explains bidirectional signaling between osteoblasts and osteoclasts,bone absorption and remodeling, which may lay a theoretical foundation for identifying drug targeting and preventing and treating bone loss.
Animals ; Bone Remodeling ; physiology ; Ephrin-B2 ; physiology ; Humans ; Osteoblasts ; cytology ; Osteoclasts ; cytology ; Receptor, EphB4 ; physiology ; Signal Transduction ; physiology

A new method for the simulation of the mass distribution of cancellous bone is presented on the basis of finite element analysis (FEA). In this method,the process of bone remodelling is considered as a process of the topology optimization of a corresponding continuum structure. Fabric tensor is used to express the microstructure and the constitutive properties of cancellous bone. The effective volume fraction or the relative density of a point in the design domain is expressed by the invariables of the fabric tensor. A reference strain interval, which is corresponding to the strain dead zone of a bone in biomechanics, is applied to detect the the final topology of the structure. By the present approach, several numerical results are given, i. e., the simulation on the shape of the coronal plane of vertebrae, the predictions of the mass distributions of the two-dimensional and the three-dimensional proximal femurs. The validity and feasibility of this new method are verified by the comparison between the results of the present work and those in the published literatures.
Adaptation, Physiological ; Algorithms ; Biomechanical Phenomena ; Bone Density ; physiology ; Bone Remodeling ; physiology ; Bone and Bones ; physiology ; Computer Simulation ; Femur Head ; physiology ; Finite Element Analysis ; Humans ; Models, Biological ; Stress, Mechanical