Coupling the activities of bone formation and resorption: a multitude of signals within the basic multicellular unit

Abstract

Coupling between bone formation and bone resorption refers to the process within basic multicellular units in which resorption by osteoclasts is met by the generation of osteoblasts from precursors, and their bone-forming activity, which needs to be sufficient to replace the bone lost. There are many sources of activities that contribute to coupling at remodeling sites, including growth factors released from the matrix, soluble and membrane products of osteoclasts and their precursors, signals from osteocytes and from immune cells and signaling taking place within the osteoblast lineage. Coupling is therefore a process that involves the interaction of a wide range of cell types and control mechanisms. As bone remodeling occurs at many sites asynchronously throughout the skeleton, locally generated activities comprise very important control mechanisms. In this review, we explore the potential roles of a number of these factors, including sphingosine-1-phosphate, semaphorins, ephrins, interleukin-6 (IL-6) family cytokines and marrow-derived factors. Their interactions achieve the essential tight control of coupling within individual remodeling units that is required for control of skeletal mass.

Osteoimmunology: oncostatin M as a pleiotropic regulator of bone formation and resorption in health and disease

“…This process maintains bone strength and quality throughout life by osteoclastic resorption of areas of old or damaged bone and replacement with a similar amount of new bone at the same site by osteoblasts. 10 Although early studies suggested that such coordination between osteoclast and osteoblast activity occurred in relative isolation in the basic multicellular unit, it is now clear that several important local accessory cell types influence bone metabolism through their paracrine secretions, 11 and may mediate many of the effects of drugs and cytokines on bone metabolism. These accessory cells include osteocytes, 12 bone marrow stromal cells and osteal macrophages; 13 some less well-delineated influences include those from local endothelial cells, 14 nerve cells 15,16 and cell populations of the bone marrow cavity such as lymphocytes, as discussed below.…”

Flexible Stem Trabecular Prostheses

“…The complexity of the human proximal femur morphological positioning of the trabecular bone in the proximal femur Fig. 2 and 3) is primarily determined by rearrangements where bone is retained only in the regions where it reaches a sufficient straining stimulus and, conversely, it is lost when not (Sims and Martin, 2014).…”

“…Coupling can be then considered a complex dynamic remodelling mechanism involving the interactions of different types of cells and controlling stimuli. Sinceremodelling of the bone occurs at many sites "asynchronously throughout the skeleton" (Sims and Martin 2014), control mechanisms comprising the mechanical stimulation are locally active (Fig. 6).…”

Effect of ovariectomy in bone structure of mandibular condyle

“…Osteoporosis is characterized by the substantial reduction of bone mass and development of more porous and thin bones, extremely fragile, compromising bone strength and subjecting them to fracture 2,3 . A deficiency of the hormone results in a high rate of bone remodeling, in which the resorption formation exceeds formation, thus resulting in a body bone mass loss 4,5 . The osteoprotegerin (OPG) is a nuclear factor kappa-B receptor ligand (RANKL) activator, which is necessary for cytokine regulation of bone formation and bone resorption.…”