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Current Osteoporosis Reports Feb 2018Solute transport in the lacunar-canalicular system (LCS) plays important roles in osteocyte metabolism and cell-cell signaling. This review will summarize recent studies... (Review)
Review
PURPOSE OF REVIEW
Solute transport in the lacunar-canalicular system (LCS) plays important roles in osteocyte metabolism and cell-cell signaling. This review will summarize recent studies that establish pericellular matrix (PCM), discovered inside the LCS, as a crucial regulator of solute transport in bone.
RECENT FINDINGS
Utilizing confocal imaging and mathematical modeling, recent studies successfully quantified molecular diffusion and convection in the LCS as well as the size-dependent sieving effects of the PCM, leading to the quantification of the effective PCM fiber spacing (10 to 17 nm) in murine adult bones. Perlecan/HSPG2, a large linear proteoglycan, was identified to be an essential PCM component. The PCM-filled LCS is bone's chromatographic column, where fluid/solute transport to and from the osteocytes is regulated. The chemical composition, deposition rate, and turnover rate of the osteocyte PCM should be further defined to better understand osteocyte physiology and bone metabolism.
Topics: Animals; Biological Transport; Bone and Bones; Female; Male; Osteocytes
PubMed: 29349685
DOI: 10.1007/s11914-018-0414-3 -
Current Osteoporosis Reports Dec 2019This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an... (Review)
Review
PURPOSE OF REVIEW
This review summarizes recently published data on the effects of pregnancy and lactation on bone structure, mechanical properties, and mechano-responsiveness in an effort to elucidate how the balance between the structural and metabolic functions of the skeleton is achieved during these physiological processes.
RECENT FINDINGS
While pregnancy and lactation induce significant changes in bone density and structure to provide calcium for fetal/infant growth, the maternal physiology also comprises several innate compensatory mechanisms that allow for the maintenance of skeletal mechanical integrity. Both clinical and animal studies suggest that pregnancy and lactation lead to adaptations in cortical bone structure to allow for rapid calcium release from the trabecular compartment while maintaining whole bone stiffness and strength. Moreover, extents of lactation-induced bone loss and weaning-induced recovery are highly dependent on a given bone's load-bearing function, resulting in better protection of the mechanical integrity at critical load-bearing sites. The recent discovery of lactation-induced osteocytic perilacunar/canalicular remodeling (PLR) indicates a new means for osteocytes to modulate mineral homeostasis and tissue-level mechanical properties of the maternal skeleton. Furthermore, lactation-induced PLR may also play an important role in maintaining the maternal skeleton's load-bearing capacity by altering osteocyte's microenvironment and modulating the transmission of anabolic mechanical signals to osteocytes. Both clinical and animal studies show that parity and lactation have no adverse, or a positive effect on bone strength later in life. The skeletal effects during pregnancy and lactation reflect an optimized balance between the mechanical and metabolic functions of the skeleton.
Topics: Adaptation, Physiological; Animals; Biomechanical Phenomena; Bone Density; Bone Remodeling; Bone and Bones; Calcium; Cancellous Bone; Cortical Bone; Female; Humans; Lactation; Osteocytes; Pregnancy; Weaning; Weight-Bearing
PubMed: 31755029
DOI: 10.1007/s11914-019-00555-5 -
Bone Dec 2010Bone geometry is commonly measured on computed tomographic (CT) and X-ray microtomographic (μCT) images. We obtained hundreds of CT, μCT and synchrotron μCT images of...
Bone geometry is commonly measured on computed tomographic (CT) and X-ray microtomographic (μCT) images. We obtained hundreds of CT, μCT and synchrotron μCT images of bones from diverse species that needed to be analysed remote from scanning hardware, but found that available software solutions were expensive, inflexible or methodologically opaque. We implemented standard bone measurements in a novel ImageJ plugin, BoneJ, with which we analysed trabecular bone, whole bones and osteocyte lacunae. BoneJ is open source and free for anyone to download, use, modify and distribute.
Topics: Animals; Bone and Bones; Image Processing, Computer-Assisted; Osteocytes; Reproducibility of Results; Software; Synchrotrons; X-Ray Microtomography
PubMed: 20817052
DOI: 10.1016/j.bone.2010.08.023 -
Physiological Research Nov 2021Parathyroid hormone (PTH) increases the release of serum calcium through osteoclasts, which leads to bone resorption. Primary, PTH stimulates osteoblasts leading to... (Review)
Review
Parathyroid hormone (PTH) increases the release of serum calcium through osteoclasts, which leads to bone resorption. Primary, PTH stimulates osteoblasts leading to increase RANKL (receptor activator for nuclear factor kappa-B ligand) expression and thus differentiation of osteoclasts. In kidneys, PTH increases calcium and decrease phosphate reabsorption. In kidneys, PTH stimulates 1alpha-hydroxylase to synthesize active vitamin D. Primary hyperparathyroidism (PHPT) is characterized by skeletal or renal complications. Nowadays, the classical form of PHPT is less seen and asymptomatic or subclinical (oligo symptomatic) forms are more frequent. Previously, it was thought that cortical bone is preferably affected by PHPT and that predispose bones to fracture at sites with a higher amount of cortical bone. However, an increased risk of vertebral fractures has been found by most of the studies showing that also trabecular bone is affected. Bone Mass measurement (BMD) at all skeletal sites is advised, but another specific tool for fracture assessment is needed. Trabecular bone score (TBS), an indirect measure of trabecular bone, maybe a useful method to estimate fracture risk. TBS is associated with vertebral fractures in PHPT regardless of BMD, age, BMI and gender. Furthermore, there is an association between TBS and high resolution peripheral quantitative computed tomography (HR-pQCT) parameters in the trabecular and cortical compartment. However, studies considering the effect of PHPT treatment on TBS are more conflicting. Secondary hyperparathyroidism caused by vitamin D deficiency was associated with impaired bone microarchitecture in all age categories, as measured by TBS and Hr-pQCT with further improvement after treatment with vitamin D.
Topics: Bone Density; Bone and Bones; Humans; Parathyroid Hormone; Tomography, X-Ray Computed
PubMed: 34918524
DOI: 10.33549/physiolres.934779 -
Tissue Engineering. Part B, Reviews Dec 2011Inflammation is an immediate response that plays a critical role in healing after fracture or injury to bone. However, in certain clinical contexts, such as in... (Review)
Review
Inflammation is an immediate response that plays a critical role in healing after fracture or injury to bone. However, in certain clinical contexts, such as in inflammatory diseases or in response to the implantation of a biomedical device, the inflammatory response may become chronic and result in destructive catabolic effects on the bone tissue. Since our previous review 3 years ago, which identified inflammatory signals critical for bone regeneration and described the inhibitory effects of anti-inflammatory agents on bone healing, a multitude of studies have been published exploring various aspects of this emerging field. In this review, we distinguish between regenerative and damaging inflammatory processes in bone, update our discussion of the effects of anti-inflammatory agents on bone healing, summarize recent in vitro and in vivo studies demonstrating how inflammation can be modulated to stimulate bone regeneration, and identify key future directions in the field.
Topics: Anti-Inflammatory Agents; Bone Regeneration; Bone and Bones; Humans; Inflammation; Wound Healing
PubMed: 21615330
DOI: 10.1089/ten.TEB.2011.0182 -
European Spine Journal : Official... Oct 2001The principal role of the skeleton is to provide structural support for the body. While the skeleton also serves as the body's mineral reservoir, the mineralized... (Review)
Review
The principal role of the skeleton is to provide structural support for the body. While the skeleton also serves as the body's mineral reservoir, the mineralized structure is the very basis of posture, opposes muscular contraction resulting in motion, withstands functional load bearing, and protects internal organs. Although the mass and morphology of the skeleton is defined, to some extent, by genetic determinants, it is the tissue's ability to remodel--the local resorption and formation of bone--which is responsible for achieving this intricate balance between competing responsibilities. The aim of this review is to address bone's form-function relationship, beginning with extensive research in the musculoskeletal disciplines, and focusing on several recent cellular and molecular discoveries which help understand the complex interdependence of bone cells, growth factors, physical stimuli, metabolic demands, and structural responsibilities. With a clinical and spine-oriented audience in mind, the principles of bone cell and molecular biology and physiology are presented, and an attempt has been made to incorporate epidemiologic data and therapeutic implications. Bone research remains interdisciplinary by nature, and a deeper understanding of bone biology will ultimately lead to advances in the treatment of diseases and injuries to bone itself.
Topics: Adaptation, Physiological; Animals; Bone Remodeling; Bone and Bones; Extracellular Matrix; Humans
PubMed: 11716022
DOI: 10.1007/s005860100283 -
Arthritis Care & Research Jan 2012
Topics: Bone and Bones; Humans; Muscle, Skeletal; Prognosis; Rheumatic Diseases
PubMed: 22213720
DOI: 10.1002/acr.20511 -
Frontiers in Bioscience (Scholar... Jan 2013Bone defects that cannot "heal spontaneously during life" will become an ever greater health problem as populations age. Harvesting autografts has several drawbacks,... (Review)
Review
Bone defects that cannot "heal spontaneously during life" will become an ever greater health problem as populations age. Harvesting autografts has several drawbacks, such as pain and morbidity at both donor and acceptor sites, the limited quantity of material available, and frequently its inappropriate shape. Researchers have therefore developed alternative strategies that involve biomaterials to fill bone defects. These biomaterials must be biocompatible and interact with the surrounding bone tissue to allow their colonization by bone cells and blood vessels. The latest generation biomaterials are not inert; they control cell responses like adhesion, proliferation and differentiation. These biomaterials are called biomimetic materials. This review focuses on the development of third generation materials. We first briefly describe the bone tissue with its cells and matrix, and then how bone cells interact with the extracellular matrix. The next section covers the materials currently used to repair bone defects. Finally, we describe the strategies employed to modify the surface of materials, such as coating with hydroxyapatite and grafting biomolecules.
Topics: Animals; Biocompatible Materials; Biomimetic Materials; Bone Regeneration; Bone Substitutes; Bone and Bones; Humans
PubMed: 23277057
DOI: 10.2741/s378 -
Physiology (Bethesda, Md.) Jan 2015Bone evolved to serve many mechanical and physiological functions. Osteocytes and bone remodeling first appeared in the dermal skeleton of fish, and subsequently adapted... (Review)
Review
Bone evolved to serve many mechanical and physiological functions. Osteocytes and bone remodeling first appeared in the dermal skeleton of fish, and subsequently adapted to various challenges in terrestrial animals occupying diverse environments. This review discusses the physiology of bone and its role in mechanical and calcium homeostases from an evolutionary perspective. We review how bone physiology responds to changing environments and the adaptations to unique and extreme physiological conditions.
Topics: Adaptation, Physiological; Animals; Biological Evolution; Bone and Bones; Environment; Humans; Osteocytes; Stress, Mechanical
PubMed: 25559152
DOI: 10.1152/physiol.00022.2014 -
Archives of Biochemistry and Biophysics Nov 2010The growing number of genetically modified mouse models available but also of the possibility to delete one or several genes at will in a defined time frame or in a... (Review)
Review
The growing number of genetically modified mouse models available but also of the possibility to delete one or several genes at will in a defined time frame or in a specific cell type or tissue(s) has open new possibilities for the study of whole animal physiology. This in vivo approach has been especially successful in uncovering a regulatory loop linking the control of energy metabolism and the regulation of bone remodeling. This review is intended to summarize the key events that led to the identification and the characterization of the different steps and molecules constituting this regulatory network.
Topics: Adipocytes; Animals; Bone Density; Bone and Bones; Energy Metabolism; Humans; Leptin; Osteocalcin
PubMed: 20515647
DOI: 10.1016/j.abb.2010.05.021