The organization of the osteocyte network mirrors the extracellular matrix orientation in bone

Kerschnitzki, Michael; Wagermaier, Wolfgang; Roschger, Paul; Seto, Jong; Shahar, Ron; Duda, Georg N.; Mundlos, Stefan; Fratzl, Peter

doi:10.1016/j.jsb.2010.11.014

Cited by 198 publications

(214 citation statements)

References 45 publications

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“…[4][5][6] Although effectively trapped within lacunae in the mineralized matrix, osteocytes maintain a complex networking system, communicating with their neighbors and with cells on bone surfaces via long cellular processes, which extend from their lacunar cell bodies via microscopic canals (canaliculi) that perforate the bone matrix. [7][8][9][10] The extensiveness of the lacunar-canalicular network provides support for the hypothesis that osteocytes function primarily as local sensors, triggering processes that allow bone to respond to surrounding environmental mechanical conditions or to hormonal signals during changing ion homeostasis demands. As the mechanosensors of bone, osteocytes detect local changes in strain in their vicinity, [11][12][13] and in response express membranebound proteins and release soluble factors that regulate and coordinate the function of bone surface cells (bone-forming osteoblasts and bone-resorbing osteoclasts 3,[14][15][16][17] ).…”

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confidence: 87%

The enigmas of bone without osteocytes

Shahar¹,

Dean²

2013

BoneKEy Reports

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One of the hallmarks of tetrapod bone is the presence of numerous cells (osteocytes) within the matrix. Osteocytes are vital components of tetrapod bone, orchestrating the processes of bone building, reshaping and repairing (modeling and remodeling), and probably also participating in calcium-phosphorus homeostasis via both the local process of osteocytic osteolysis, and systemic effect on the kidneys. Given these critical roles of osteocytes, it is thought-provoking that the entire skeleton of many fishes consists of bone material that does not contain osteocytes. This raises the intriguing question of how the skeleton of these animals accomplishes the various essential functions attributed to osteocytes in other vertebrates, and raises the possibility that in acellular bone some of these functions are either accomplished by non-osteocytic routes or not necessary at all. In this review, we outline evidence for and against the fact that primary functions normally ascribed to osteocytes, such as mechanosensation, regulation of osteoblast/clast activity and mineral metabolism, also occur in fish bone devoid of these cells, and therefore must be carried out through alternative and perhaps ancient pathways. To enable meaningful comparisons with mammalian bone, we suggest thorough, phylogenetic examinations of regulatory pathways, studies of structure and mechanical properties and surveys of the presence/absence of bone cells in fishes. Insights gained into the micro-/nanolevel structure and architecture of fish bone, its mechanical properties and its physiology in health and disease will contribute to the discipline of fish skeletal biology, but may also help answer questions of basic bone biology.

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confidence: 87%

The enigmas of bone without osteocytes

Shahar¹,

Dean²

2013

BoneKEy Reports

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“…18 In another study, ECM fiber alignment was shown to impact cell length order at lengths greater than a few hundred microns; in addition, it also indicated that the extent of cell order can correspond to bone type and quality. 19 These studies underscore the importance of the material morphology on cell arrangement and interconnectivity within native and 3D scaffolds. Properly engineered 3D fibrous scaffolds can potentially facilitate cell-cell interactions that extend in both horizontal and vertical directions to form native tissue-like formation.…”

Section: Introductionmentioning

confidence: 95%

Airbrushed Composite Polymer Zr-ACP Nanofiber Scaffolds with Improved Cell Penetration for Bone Tissue Regeneration

Hoffman

Škrtić²,

Sun³

et al. 2015

Tissue Engineering Part C: Methods

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Electrospun polymer nanofibers have multiple applications in the tissue engineering field despite limited cell penetration within the scaffolds and slow synthesis rates. Airbrushing, a proposed alternative to traditional electrospinning, is a technique capable of synthesizing open structure nanofiber scaffolds at high rates. In this study, three biocompatible polymers-poly-D,L-lactic acid (P-DL-LA), polycaprolactone (PCL), and poly (methyl methacrylate) (PMMA), were airbrushed to form networks for bone tissue regeneration. All three polymers were loaded with up to 20% (w/w) zirconium-modified amorphous calcium phosphate (Zr-ACP). A simple one-step mix and straightforward material deposition yielded open structure networks with welldistributed Zr-ACP. Cell penetration within the airbrushed scaffolds was found to be more than twice the cell penetration within conventional electrospun networks. The airbrushed polymer network supported cell growth and differentiation. Cells grown on the Zr-ACP in P-DL-LA fibers exhibited improved levels of osteocalcin protein with an increase in the Zr-ACP content by day 16. This airbrushing method promises to be a viable and attractive alternative to currently used electrospinning techniques in the formation of composite 3D nanofiber scaffolds for tissue engineering applications.

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“…5b shows the magnification of a typical plexiform microstructure with predominantly circumferential canals with radial anastomosis (branching network). Plexiform bone is primarily found in large rapidly growing animals such as bovine or ovine [28]. Mineral buds grow first perpendicular and then parallel to the outer bone surface, which produces the brick like structure characteristic of plexiform bone.…”

Section: Microstructurementioning

confidence: 99%