Bioactive Glass Scaffolds with Hierarchical Structure and their 3D Characterization

2010 ◽  
Vol 441 ◽  
pp. 123-137 ◽  
Author(s):  
Julian R. Jones ◽  
Peter D. Lee
Keyword(s):  
Bioactive Glass ◽  
Hierarchical Structure ◽  
Bone Growth ◽  
Bone Cells ◽  
Sol Gel ◽  
Three Dimensional ◽  
The Body ◽  
Native Bone ◽  
Degradation Rates ◽  
Hierarchical Porous

Bone tissue has evolved into hierarchical three-dimensional structures with dimensions ranging from nanometres to metres. The structure varies depending on the site in the body, which is dictated by the loading environment. Medically, bone is one of the most replaced body parts (second only to blood) but replicating these complex living hierarchical structures for the purpose of regenerating defective bone is a challenge that has yet to be overcome. A temporary template (scaffold) is needed that matches the hierarchical structure of native bone as closely as possible that is available ‘off the shelf’ for surgeons to use. After implantation the scaffold must bond to bone and stimulate not only three dimensional (3D) bone growth, but also vascularisation to feed the new bone. There are many engineering design criteria for a successful bone scaffold and bioactive glass foam scaffolds have been developed that can fulfil most of them, as they have a hierarchical porous structure, they can bond to bone, and they release soluble silica species and calcium ions that have been found to up-regulate seven families of genes in osteogenic cells. Other ions have also been incorporated to combat infection and to counteract osteoporosis. Their tailorable hierarchical structure consists of highly interconnected open spherical macropores, further, because the glass is sol-gel derived, the entire structure is nanoporous. The macropores are critical for bone and blood vessel growth, the nanopores for tailoring degradation rates and protein adsorption and for cell attachment. This chapter describes the optimised sol-gel foaming process and how bone cells respond to them. Whatever type of scaffold is used for bone regeneration, it is critically important to be able to quantify the hierarchial pore structure. The nanopore size can be quantified using gas sorption, but to obtain full information of the macropore structure, imaging must be done using X-ray microtomography and the resulting images must be quantified via 3D image analysis. These techniques are reviewed.

Bone Regulation of Insulin Secretion and Glucose Homeostasis

Endocrinology ◽  
2020 ◽  
Vol 161 (10) ◽  
Author(s):  
Patricia Ducy
Keyword(s):  
Cell Biology ◽  
Regulatory Networks ◽  
Bone Growth ◽  
Bone Cells ◽  
Protective Role ◽  
Brain Cell ◽  
Mouse Genetics ◽  
The Body ◽  
Lipocalin 2 ◽  
Inner Organs

Abstract For centuries our image of the skeleton has been one of an inert structure playing a supporting role for muscles and a protective role for inner organs like the brain. Cell biology and physiology modified this view in the 20st century by defining the constant interplay between bone-forming and bone resorbing cells that take place during bone growth and remodeling, therefore demonstrating that bone is as alive as any other tissues in the body. During the past 40 years human and, most important, mouse genetics, have allowed not only the refinement of this notion by identifying the many genes and regulatory networks responsible for the crosstalk existing between bone cells, but have redefined the role of bone by showing that its influence goes way beyond its own physiology. Among its newly identified functions is the regulation of energy metabolism by 2 bone-derived hormones, osteocalcin and lipocalin-2. Their biology and respective roles in this process are the topic of this review.

scholarly journals A Comparison of Bioactive Glass Scaffolds Fabricated ‎by Robocasting from Powders Made by Sol–Gel and Melt-Quenching Methods

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 615
Author(s):  
Basam A. E. Ben-Arfa ◽  
Robert C. Pullar
Keyword(s):  
Mechanical Properties ◽  
Bioactive Glass ◽  
Bone Growth ◽  
Sol Gel ◽  
Glass Network ◽  
Silica Content ◽  
Bioactive Glasses ◽  
Phosphorous Content ◽  
High Silica ◽  
45S5 Bioglass

Bioactive glass scaffolds are used in bone and tissue biomedical implants, and there is great interest in their fabrication by additive manufacturing/3D printing techniques, such as robocasting. Scaffolds need to be macroporous with voids ≥100 m to allow cell growth and vascularization, biocompatible and bioactive, with mechanical properties matching the host tissue (cancellous bone for bone implants), and able to dissolve/resorb over time. Most bioactive glasses are based on silica to form the glass network, with calcium and phosphorous content for new bone growth, and a glass modifier such as sodium, the best known being 45S5 Bioglass®. 45S5 scaffolds were first robocast in 2013 from melt-quenched glass powder. Sol–gel-synthesized bioactive glasses have potential advantages over melt-produced glasses (e.g., greater porosity and bioactivity), but until recently were never robocast as scaffolds, due to inherent problems, until 2019 when high-silica-content sol–gel bioactive glasses (HSSGG) were robocast for the first time. In this review, we look at the sintering, porosity, bioactivity, biocompatibility, and mechanical properties of robocast sol–gel bioactive glass scaffolds and compare them to the reported results for robocast melt-quench-synthesized 45S5 Bioglass® scaffolds. The discussion includes formulation of the printing paste/ink and the effects of variations in scaffold morphology and inorganic additives/dopants.

Preparation and Properties of Porous Apatite-Wollastonite Bioactive Glass-Ceramic

2007 ◽  
Vol 330-332 ◽  
pp. 169-172 ◽  
Author(s):  
Ming Xue ◽  
Jun Ou ◽  
Da Li Zhou ◽  
Dange Feng ◽  
Wei Zhong Yang ◽  
...  
Keyword(s):  
Bioactive Glass ◽  
Stromal Cells ◽  
Glass Ceramic ◽  
Sol Gel ◽  
Three Dimensional ◽  
Chemical Properties ◽  
Polymer Foam ◽  
Physical Chemical ◽  
Sol Gel Process ◽  
Precursor Powders

The porous apatite-wollastonite bioactive glass-ceramic (AW-GG) was made from nano-precursor powders derived from sol-gel process, and shaped by dipping method with polymer foam. The physical-chemical properties, bioactivity and biocompatibility of the materials were studied by means of TG, XRD, SEM, TEM and so on. The bioactivity was investigated in simulated body fluid (SBF) and the biocompatibility was evaluated by co-culturing with marrow stromal cells (MSCs). The result shows that: the particle size of the AW precursor powders is 40~100nm; porous AW GC has three-dimensional pored structure with 300~500um macropores and 2~5um micropores; the materials possess high bioactivity and biocompatibility. Porous AW GC may therefore have great potential application as bone tissue engineering scaffold.

scholarly journals Characterizing the hierarchical structures of bioactive sol–gel silicate glass and hybrid scaffolds for bone regeneration

2012 ◽  
Vol 370 (1963) ◽  
pp. 1422-1443 ◽  
Author(s):  
R. A. Martin ◽  
S. Yue ◽  
J. V. Hanna ◽  
P. D. Lee ◽  
R. J. Newport ◽  
...  
Keyword(s):  
Cellular Response ◽  
Bone Growth ◽  
Sol Gel ◽  
Hierarchical Structures ◽  
Atomic Scale ◽  
Bioactive Glasses ◽  
Degradation Rates ◽  
Defect Sites ◽  
Gel Glasses ◽  
Hybrid Scaffolds

Bone is the second most widely transplanted tissue after blood. Synthetic alternatives are needed that can reduce the need for transplants and regenerate bone by acting as active temporary templates for bone growth. Bioactive glasses are one of the most promising bone replacement/regeneration materials because they bond to existing bone, are degradable and stimulate new bone growth by the action of their dissolution products on cells. Sol–gel-derived bioactive glasses can be foamed to produce interconnected macropores suitable for tissue ingrowth, particularly cell migration and vascularization and cell penetration. The scaffolds fulfil many of the criteria of an ideal synthetic bone graft, but are not suitable for all bone defect sites because they are brittle. One strategy for improving toughness of the scaffolds without losing their other beneficial properties is to synthesize inorganic/organic hybrids. These hybrids have polymers introduced into the sol–gel process so that the organic and inorganic components interact at the molecular level, providing control over mechanical properties and degradation rates. However, a full understanding of how each feature or property of the glass and hybrid scaffolds affects cellular response is needed to optimize the materials and ensure long-term success and clinical products. This review focuses on the techniques that have been developed for characterizing the hierarchical structures of sol–gel glasses and hybrids, from atomic-scale amorphous networks, through the covalent bonding between components in hybrids and nanoporosity, to quantifying open macroporous networks of the scaffolds. Methods for non-destructive in situ monitoring of degradation and bioactivity mechanisms of the materials are also included.

scholarly journals Strain amplification in bone mechanobiology: a computational investigation of the in vivo mechanics of osteocytes

2012 ◽  
Vol 9 (75) ◽  
pp. 2735-2744 ◽  
Author(s):  
Stefaan W. Verbruggen ◽  
Ted J. Vaughan ◽  
Laoise M. McNamara
Keyword(s):  
Computational Models ◽  
Bone Growth ◽  
Bone Cells ◽  
Physiological Activity ◽  
Three Dimensional ◽  
Mechanical Stimulus ◽  
Confocal Imaging ◽  
Mechanical Stimuli ◽  
Confocal Image

The osteocyte is believed to act as the main sensor of mechanical stimulus in bone, controlling signalling for bone growth and resorption in response to changes in the mechanical demands placed on our bones throughout life. However, the precise mechanical stimuli that bone cells experience in vivo are not yet fully understood. The objective of this study is to use computational methods to predict the loading conditions experienced by osteocytes during normal physiological activities. Confocal imaging of the lacunar–canalicular network was used to develop three-dimensional finite element models of osteocytes, including their cell body, and the surrounding pericellular matrix (PCM) and extracellular matrix (ECM). We investigated the role of the PCM and ECM projections for amplifying mechanical stimulation to the cells. At loading levels, representing vigorous physiological activity (3000 µ ɛ ), our results provide direct evidence that (i) confocal image-derived models predict 350–400% greater strain amplification experienced by osteocytes compared with an idealized cell, (ii) the PCM increases the cell volume stimulated more than 3500 µ ɛ by 4–10% and (iii) ECM projections amplify strain to the cell by approximately 50–420%. These are the first confocal image-derived computational models to predict osteocyte strain in vivo and provide an insight into the mechanobiology of the osteocyte.

Evaluation of Bioactive Glass (13-93) Scaffolds with an Oriented Microstructure for Regenerating Load-bearing Bones

2012 ◽  
Vol 1465 ◽  
Author(s):  
Xin Liu ◽  
Mohammed N. Rahaman
Keyword(s):  
Bioactive Glass ◽  
Bone Repair ◽  
Bone Cells ◽  
Three Dimensional ◽  
Bone Defects ◽  
Control Group ◽  
Bioactive Glasses ◽  
Low Load ◽  
Ability To Regenerate ◽  
Rat Calvarial Defect

ABSTRACTBioactive glass is an attractive scaffold material for use in filling bone defects because of its widely recognized ability to support the growth of bone cells and to bond firmly with hard and soft tissue. Use of bioactive glasses in the form of porous three-dimensional scaffolds for bone repair applications has been receiving considerable interest in recent years. However, bioactive glass scaffolds have been limited to the repair of low-load bone defects because of their low strength. In the present work, porous and strong bioactive glass scaffolds with an oriented microstructure were prepared by unidirectional freezing of camphene-based suspensions, and evaluated for their ability to regenerate bone in a non-healing rat calvarial defect model. Scaffolds of 13-93 glass (53SiO2, 6Na2O, 12K2O, 5MgO, 20CaO, 4P2O5; wt%) with a porosity of 50% and columnar pores of diameter 50–150 μm showed a compressive strength of 47 ± 5 MPa and an elastic modulus of 11 ± 3 GPa. Total bone regeneration in the oriented scaffolds, 18% after implantation for 12 weeks to 24% after 24 weeks, was not significantly different from that in 13-93 scaffolds with a microstructure similar to that of dry human trabecular bone (control group). The results indicated that these oriented bioactive glass (13-93) scaffolds could potentially be used in the regeneration of loaded bone.

Increasing the Potential of Bioactive Glass as a Scaffold for Bone Tissue Engineering

2009 ◽  
Vol 1236 ◽  
Author(s):  
Mohamed Ammar ◽  
Max Kaplan ◽  
Therese Quinn ◽  
Sabrina Jedlicka
Keyword(s):  
Tissue Engineering ◽  
Stem Cells ◽  
Bioactive Glass ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Bone Cells ◽  
Cell Model ◽  
Sol Gel ◽  
Material Surface ◽  
Differentiation Induction

AbstractBioactive glass is known for its potential as a bone scaffold due to its ability to stimulate osteogenesis and differentiation of stem cells into bone cells. In an attempt to investigate if we can increase these potentials, we decorated the structure of the bioactive glass made by the sol-gel technique with 3 peptides sequences from different proteins known for their potentials to stimulate the osteogensis process (fibronectin, BMP-2 and protein kinase CKI). This material was tested with Human Mesenchymal Stem Cells (hMSCs) and MC-3T3 preosteoblasts to see the difference in the effect on uncommitted and committed cells. The bioactive glass sol with and without the peptides was dip coated onto glass cover slips, leading to a film of the material, surface decorated with the peptides of choice. The two cell types were seeded onto the materials in standard proliferation medium without additives for differentiation induction. Cells were also grown on tissue culture treated cover slips with and without differentiation induction media as positive and negative controls, respectively. The cells were grown on the materials for a total of five weeks, and were tested at four time points (weekly from week two) by immunocytochemical assays to investigate the levels of different osteogenic markers (osteopontin, osteocalcin and osteonectin) and by qRT-PCR to investigate the mRNA potential of the same proteins. On the native bioactive glass samples, the hMSCs and the MC-3T3s adhered poorly. On peptide-decorated samples, the hMSC adhered poorly, however, the MC-3T3 cells appear to differentiate at a rate that is equal to or faster than the positive control, indicating that the peptide effect is similar to that achieved by traditional BMP-2 soluble protein techniques. This supports our hypothesis that adding specific peptide sequences known for their effects in cells adhesion, proliferation and differentiation can increase the potential of the bioactive glass as a scaffold for bone tissue engineering. The data, however, leads to some questions regarding the MC-3T3 cell model for use in further studies.

Scanning electron microscopy of freeze-fractured prescapular lymph node of caprine

1984 ◽  
Vol 42 ◽  
pp. 244-245
Author(s):  
O. Faroon ◽  
F. Al-Bagdadi ◽  
T. G. Snider ◽  
C. Titkemeyer
Keyword(s):  
Lymph Node ◽  
Lymph Nodes ◽  
Lymphatic System ◽  
Three Dimensional ◽  
Meat Products ◽  
The Body ◽  
Morphological Data ◽  
The World ◽  
Cellular Constituent ◽  
Scanning Electron

The lymphatic system is very important in the immunological activities of the body. Clinicians confirm the diagnosis of infectious diseases by palpating the involved cutaneous lymph node for changes in size, heat, and consistency. Clinical pathologists diagnose systemic diseases through biopsies of superficial lymph nodes. In many parts of the world the goat is considered as an important source of milk and meat products.The lymphatic system has been studied extensively. These studies lack precise information on the natural morphology of the lymph nodes and their vascular and cellular constituent. This is due to using improper technique for such studies. A few studies used the SEM, conducted by cutting the lymph node with a blade. The morphological data collected by this method are artificial and do not reflect the normal three dimensional surface of the examined area of the lymph node. SEM has been used to study the lymph vessels and lymph nodes of different animals. No information on the cutaneous lymph nodes of the goat has ever been collected using the scanning electron microscope.

HYDROXYAPATITE, ALGINATE, AND CHITOSAN FOR BONE SCAFFOLDS: SPECTROSCOPY STUDY

2016 ◽  
Vol 19 (2) ◽  
pp. 93-100
Author(s):  
Lalita El Milla
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Functional Groups ◽  
Bone Growth ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Tissue Engineering Scaffolds ◽  
Hydroxyapatite Powder ◽  
Materials Used

Scaffolds is three dimensional structure that serves as a framework for bone growth. Natural materials are often used in synthesis of bone tissue engineering scaffolds with respect to compliance with the content of the human body. Among the materials used to make scafffold was hydroxyapatite, alginate and chitosan. Hydroxyapatite powder obtained by mixing phosphoric acid and calcium hydroxide, alginate powders extracted from brown algae and chitosan powder acetylated from crab. The purpose of this study was to examine the functional groups of hydroxyapatite, alginate and chitosan. The method used in this study was laboratory experimental using Fourier Transform Infrared (FTIR) spectroscopy for hydroxyapatite, alginate and chitosan powders. The results indicated the presence of functional groups PO43-, O-H and CO32- in hydroxyapatite. In alginate there were O-H, C=O, COOH and C-O-C functional groups, whereas in chitosan there were O-H, N-H, C=O, C-N, and C-O-C. It was concluded that the third material containing functional groups as found in humans that correspond to the scaffolds material in bone tissue engineering.

Sign in / Sign up

Export Citation Format

Share Document