79 results found
Ferreira SA, Tallia F, Heyraud A, et al., 2024, 3D printed hybrid scaffolds do not induce adverse inflammation in mice and direct human BM-MSC chondrogenesis in vitro, Biomaterials and Biosystems, Vol: 13, ISSN: 2666-5344
Biomaterials that can improve the healing of articular cartilage lesions are needed. To address this unmet need, we developed novel 3D printed silica/poly(tetrahydrofuran)/poly(ε-caprolactone) (SiO2/PTHF/PCL-diCOOH) hybrid scaffolds. Our aim was to carry out essential studies to advance this medical device towards functional validation in pre-clinical trials. First, we show that the chemical composition, microarchitecture and mechanical properties of these scaffolds were not affected by sterilisation with gamma irradiation. To evaluate the systemic and local immunogenic reactivity of the sterilised 3D printed hybrid scaffolds, they were implanted subcutaneously into Balb/c mice. The scaffolds did not trigger a systemic inflammatory response over one week of implantation. The interaction between the host immune system and the implanted scaffold elicited a local physiological reaction with infiltration of mononuclear cells without any signs of a chronic inflammatory response. Then, we investigated how these 3D printed hybrid scaffolds direct chondrogenesis in vitro. Human bone marrow-derived mesenchymal stem/stromal cells (hBM-MSCs) seeded within the 3D printed hybrid scaffolds were cultured under normoxic or hypoxic conditions, with or without chondrogenic supplements. Chondrogenic differentiation assessed by both gene expression and protein production analyses showed that 3D printed hybrid scaffolds support hBM-MSC chondrogenesis. Articular cartilage-specific extracellular matrix deposition within these scaffolds was enhanced under hypoxic conditions (1.7 or 3.7 fold increase in the median of aggrecan production in basal or chondrogenic differentiation media). Our findings show that 3D printed SiO2/PTHF/PCL-diCOOH hybrid scaffolds have the potential to support the regeneration of cartilage tissue.
Taylor H, Zaghi A, Rankin S, 2023, Marginalising dyslexic researchers is bad for science., Elife, Vol: 12
Communication in the sciences is often based on text, which places researchers with dyslexia at a disadvantage. However, this means that science is missing out on the original insights and specific strengths in exploration that dyslexic researchers bring to their disciplines. Here we discuss how the scientific community can address the challenges that dyslexic researchers face, and how science stands to benefit as a result. We discuss this in the context of a new theoretical framework proposing the existence of complementary learning strategies that could play a key role in scientific progress, particularly with regard to accelerating innovation.
Heyraud A, Tallia F, Sory D, et al., 2023, 3D printed hybrid scaffolds for bone regeneration using calcium methoxyethoxide as a calcium source, Frontiers in Bioengineering and Biotechnology, Vol: 11, Pages: 1-18, ISSN: 2296-4185
Introduction: Hybrids consist of inorganic and organic co-networks that are indistinguishable above the nanoscale, which can lead to unprecedented combinations of properties, such as high toughness and controlled degradation.Methods: We present 3D printed bioactive hybrid scaffolds for bone regeneration, produced by incorporating calcium into our “Bouncy Bioglass”, using calcium methoxyethoxide (CME) as the calcium precursor. SiO2-CaOCME/PTHF/PCL-diCOOH hybrid “inks” for additive manufacturing (Direct Ink Writing) were optimised for synergy of mechanical properties and open interconnected pore channels.Results and Discussion: Adding calcium improved printability. Changing calcium content (5, 10, 20, 30, and 40 mol.%) of the SiO2-CaOCME/PTHF/PCL-diCOOH hybrids affected printability and mechanical properties of the lattice-like scaffolds. Hybrids containing 30 mol.% calcium in the inorganic network (70S30CCME-CL) printed with 500 µm channels and 100 µm strut size achieved the highest strength (0.90 ± 0.23 MPa) and modulus of toughness (0.22 ± 0.04 MPa). These values were higher than Ca-free SiO2/PTHF/PCL-diCOOH hybrids (0.36 ± 0.14 MPa strength and 0.06 ± 0.01 MPa toughness modulus). Over a period of 90 days of immersion in simulated body fluid (SBF), the 70S30CCME-CL hybrids also kept a stable strain to failure (∼30 %) and formed hydroxycarbonate apatite within three days. The extracts released by the 70S30CCME-CL hybrids in growth medium did not cause cytotoxic effects on human bone marrow stromal cells over 24 h of culture.
Todorova VB, Baxan N, Delahaye M, et al., 2023, Drug-based mobilisation of mesenchymal stem/stromal cells improves cardiac function post myocardial infarction, Disease Models and Mechanisms, Vol: 16, Pages: 1-28, ISSN: 1754-8403
There is an unmet need for treatments that prevent the progressive cardiac dysfunction following myocardial infarction. Mesenchymal stem/stromal cells (MSCs) are under investigation for cardiac repair; however, culture expansion prior to transplantation is hindering their homing and reparative abilities. Pharmacological mobilisation could be an alternative to MSC transplantation. Here, we report that endogenous MSCs mobilise into the circulation at day 5 post myocardial infarction in male Lewis rats. This mobilisation can be significantly increased by using a combination of the FDA-approved drugs mirabegron (β3-adrenoceptor agonist) and AMD3100 (CXCR4 antagonist). Blinded cardiac magnetic resonance imaging analysis showed the treated group to have increased left ventricular ejection fraction and decreased end systolic volume at 5 weeks post myocardial infarction. The mobilised group had a significant decrease in plasma IL-6 and TNF-α levels, a decrease in interstitial fibrosis, and an increase in the border zone blood vessel density. Conditioned medium from blood-derived MSCs supported angiogenesis in vitro, as shown by tube formation and wound healing assays. Our data suggest a novel pharmacological strategy that enhances myocardial infarction-induced MSC mobilisation and improves cardiac function after myocardial infarction.
Young G, Tallia F, Clark J, et al., 2023, Hybrid materials with continuous mechanical property gradients that can be 3D printed, Materials Today Advances, Vol: 17, Pages: 1-9, ISSN: 2590-0498
Here, we show tough materials with continuous composition and stiffness gradients, without interfaces between regions, using inorganic/organic hybrid materials that can also be 3Dprinted. Sol-gel hybrid materials have interacting and interpenetrating organic and inorganic co-networks and can deliver a synergy of the properties of those constituents. Their mechanical behaviour can be tuned through inorganic/organic content and cross-linkingdensity. We describe hybrids of covalently linked silica-poly(tetrahydrofuran) (SiO 2 /PTHF) that show an unprecedented range of mechanical properties. SiO2 /PTHF hybrids were formed with different silica contents, producing materials ranging from elastomeric to glassy, with a compressive stiffness at 10% strain of between 2 and 200 MPa: at an SiO 2 content of 9 wt.%, hybrids show a failure stress in compression of 8 MPa, at 70% strain, and in tension of 2 MPa at 80% strain. Gradual sol-gel gelation was employed to generate monoliths with composition and stiffness gradients without visible joins or points of weakness, and for the development of ‘inks’ for additive manufacturing of 3D structures through direct ink writing. Monoliths with gradients were at least as strong, in tension and compression, as those made by casting a single sol. Cytocompatible materials with seamless stiffness gradients will have many applications: one is biomimicry of natural cartilaginous structures of the body, such as the intervertebral disc, which has a natural radial stiffness gradient.
Todorova V, Baxan N, Delahaye M, et al., 2022, Mechanism of improved cardiac function after pharmacological, 24th World Congress of the International-Society-for-Heart-Research, Publisher: ELSEVIER SCI LTD, Pages: S54-S56, ISSN: 0022-2828
Skandalis A, Selianitis D, Sory DR, et al., 2022, Poly(2-(dimethylamino) ethyl methacrylate)-b-poly(lauryl methacrylate)-b-poly(oligo ethylene glycol methacrylate) triblock terpolymer micelles as drug delivery carriers for curcumin, JOURNAL OF APPLIED POLYMER SCIENCE, Vol: 139, ISSN: 0021-8995
Naruphontjirakul P, Li S, Pinna A, et al., 2022, Interaction of monodispersed strontium containing bioactive glass nanoparticles with macrophages, Biomaterials Advances, Vol: 133, Pages: 1-12, ISSN: 2772-9508
The cellular response of murine primary macrophages to monodisperse strontium containing bioactive glass nanoparticles (SrBGNPs), with diameters of 90 ± 10 nm and a composition (mol%) of 88.8 SiO2–1.8CaO-9.4SrO (9.4% Sr-BGNPs) was investigated for the first time. Macrophage response is critical as applications of bioactive nanoparticles will involve the nanoparticles circulating in the blood stream and macrophages will be the first cells to encounter the particles, as part of inflammatory response mechanisms. Macrophage viability and total DNA measurements were not decreased by particle concentrations of up to 250 μg/mL. The Sr-BGNPs were actively internalised by the macrophages via formation of endosome/lysosome-like vesicles bordered by a membrane inside the cells. The Sr-BGNPs degraded inside the cells, with the Ca and Sr maintained inside the silica network. When RAW264.7 cells were incubated with Sr-BGNPs, the cells were polarised towards the pro-regenerative M2 population rather than the pro-inflammatory M1 population. Sr-BGNPs are potential biocompatible vehicles for therapeutic cation delivery for applications in bone regeneration.
Jørgensen AS, Daugvilaite V, De Filippo K, et al., 2021, Biased action of the CXCR4-targeting drug plerixafor is essential for its superior hematopoietic stem cell mobilization., Communications Biology, Vol: 4, Pages: 569-569, ISSN: 2399-3642
Following the FDA-approval of the hematopoietic stem cell (HSC) mobilizer plerixafor, orally available and potent CXCR4 antagonists were pursued. One such proposition was AMD11070, which was orally active and had superior antagonism in vitro; however, it did not appear as effective for HSC mobilization in vivo. Here we show that while AMD11070 acts as a full antagonist, plerixafor acts biased by stimulating β-arrestin recruitment while fully antagonizing G protein. Consequently, while AMD11070 prevents the constitutive receptor internalization, plerixafor allows it and thereby decreases receptor expression. These findings are confirmed by the successful transfer of both ligands' binding sites and action to the related CXCR3 receptor. In vivo, plerixafor exhibits superior HSC mobilization associated with a dramatic reversal of the CXCL12 gradient across the bone marrow endothelium, which is not seen for AMD11070. We propose that the biased action of plerixafor is central for its superior therapeutic effect in HSC mobilization.
Juzenaite G, Secklehner J, Vuononvirta J, et al., 2021, Lung marginated and splenic murine resident neutrophils constitute pioneers in tissue-defense during systemic E. coli challenge, Frontiers in Immunology, Vol: 12, Pages: 1-15, ISSN: 1664-3224
The rapid response of neutrophils throughout the body to a systemic challenge is a critical first step in resolution of bacterial infection such as Escherichia coli (E. coli). Here we delineated the dynamics of this response, revealing novel insights into the molecular mechanisms using lung and spleen intravital microscopy and 3D ex vivo culture of living precision cut splenic slices in combination with fluorescent labelling of endogenous leukocytes. Within seconds after challenge, intravascular marginated neutrophils and lung endothelial cells (ECs) work cooperatively to capture pathogens. Neutrophils retained on lung ECs slow their velocity and aggregate in clusters that enlarge as circulating neutrophils carrying E. coli stop within the microvasculature. The absolute number of splenic neutrophils does not change following challenge; however, neutrophils increase their velocity, migrate to the marginal zone (MZ) and form clusters. Irrespective of their location all neutrophils capturing heat-inactivated E. coli take on an activated phenotype showing increasing surface CD11b. At a molecular level we show that neutralization of ICAM-1 results in splenic neutrophil redistribution to the MZ under homeostasis. Following challenge, splenic levels of CXCL12 and ICAM-1 are reduced allowing neutrophils to migrate to the MZ in a CD29-integrin dependent manner, where the enlargement of splenic neutrophil clusters is CXCR2-CXCL2 dependent. We show directly molecular mechanisms that allow tissue resident neutrophils to provide the first lines of antimicrobial defense by capturing circulating E. coli and forming clusters both in the microvessels of the lung and in the parenchyma of the spleen.
Ferreira SA, Young G, Jones JR, et al., 2021, Bioglass/carbonate apatite/collagen composite scaffold dissolution products promote human osteoblast differentiation, Materials Science and Engineering: C, Vol: 118, Pages: 1-13, ISSN: 0928-4931
OssiMend® Bioactive (Collagen Matrix Inc., NJ) is a three-component porous composite bone graft device of 45S5 Bioglass/carbonate apatite/collagen. Our in vitro studies showed that conditioned media of the dissolution products of OssiMend Bioactive stimulated primary human osteoblasts to form mineralized bone-like nodules in vitro in one week, in basal culture media (no osteogenic supplements). Osteoblast differentiation was followed by gene expression analysis and a mineralization assay. In contrast, the dissolution products from commercial OssiMend (Bioglass-free carbonate apatite/collagen scaffolds), or from 45S5 Bioglass particulate alone, did not induce the mineralization of the extracellular matrix, but did induce osteoblast differentiation to mature osteoblasts, evidenced by the strong upregulation of BGLAP and IBSP mRNA levels. The calcium ions and soluble silicon species released from 45S5 Bioglass particles and additional phosphorus release from OssiMend mediated the osteostimulatory effects. Medium conditioned with OssiMend Bioactive dissolution had a much higher concentration of phosphorus and silicon than media conditioned with OssiMend and 45S5 Bioglass alone. While OssiMend and OssiMend Bioactive led to calcium precipitation in cell culture media, OssiMend Bioactive produced a higher concentration of soluble silicon than 45S5 Bioglass and higher dissolution of phosphorus than OssiMend. These in vitro results suggest that adding 45S5 Bioglass to OssiMend produces a synergistic osteostimulation effect on primary human osteoblasts.
De Filippo K, Rankin SM, 2020, The secretive life of neutrophils revealed by intravital microscopy, Frontiers in Cell and Developmental Biology, Vol: 8, ISSN: 2296-634X
Neutrophils are the most abundant circulating leukocyte within the blood stream and for many years the dogma has been that these cells migrate rapidly into tissues in response to injury or infection, forming the first line of host defense. While it has previously been documented that neutrophils marginate within the vascular beds of the lung and liver and are present in large numbers within the parenchyma of tissues, such as spleen, lymph nodes, and bone marrow (BM), the function of these tissue resident neutrophils under homeostasis, in response to pathogen invasion or injury has only recently been explored, revealing the unexpected role of these cells as immunoregulators or immune helpers and also unraveling their heterogeneity and plasticity. Neutrophils are highly motile cells and the use of intravital microscopy (IVM) to image cells within their environment with little manipulation has dramatically increased our understanding of the function, migratory behavior, and interaction of these short-lived cells with other innate and adaptive immune cells. Contrary to previous dogma, these studies have shown that marginated and tissue resident neutrophils are the first responders to pathogens and injury, critical in limiting the spread of infection and contributing to the orchestration of the subsequent immune response. The interplay of neutrophils, with other neutrophils, leukocytes, and stroma cells can also modulate and tune their early and late response in order to eradicate pathogens, minimize tissue damage, and, in certain circumstances, contribute to tissue repair. In this review, we will follow the extraordinary journey of neutrophils from their origin in the BM to their death, exploring their role as tissue resident cells in the lung, spleen, lymph nodes, and skin and outlining the importance of neutrophil subsets, their functions under homeostasis, and in response to infection. Finally, we will comment on how understanding these processes in greater detail at
Sory DR, Amin HD, Chapman D, et al., 2020, Replicating landmine blast loading in cellular <i>in Vitro</i> models, Physical Biology, Vol: 17, ISSN: 1478-3967
Trauma arising from landmines and improvised explosive devices promotes heterotopic ossification, the formation of extra-skeletal bone in non-osseous tissue. To date, experimental platforms that can replicate the loading parameter space relevant to improvised explosive device and landmine blast wave exposure have not been available to study the effects of such non-physiological mechanical loading on cells. Here, we present the design and calibration of three distinct in vitro experimental loading platforms that allow us to replicate the spectrum of loading conditions recorded in near-field blast wave exposure. We subjected cells in suspension or in a three-dimensional hydrogel to strain rates up to 6000 s-1and pressure levels up to 45 MPa. Our results highlight that cellular activation is regulated in a non-linear fashion - not by a single mechanical parameter, it is the combined action of the applied mechanical pressure, rate of loading and loading impulse, along with the extracellular environment used to convey the pressure waves. Finally, our research indicates that PO MSCs are finely tuned to respond to mechanical stimuli that fall within defined ranges of loading.
Chen S, Greasley SL, Ong ZY, et al., 2020, Biodegradable zinc-containing mesoporous silica nanoparticles for cancer therapy, Materials Today, Vol: 6, Pages: 1-11, ISSN: 1369-7021
Triple-negative breast cancers are extremely aggressive with limited treatment options because of the reduced response of the cancerous cells to hormonal therapy. Here, monodispersed zinc-containing mesoporous silica nanoparticles (MSNPs-Zn) were produced as a tuneable biodegradable platform for delivery of therapeutic zinc ions into cells. We demonstrate that the nanoparticles were internalized by cells, and a therapeutic dose window was identified in which the MSNPs-Zn were toxic to breast cancer cells but not to healthy epithelial (MCF-10a) cells or to murine macrophages. A significant reduction in the viability of triple negative MDA-MB-231 and MCF-7 (ER+) breast cancer cells was seen following 24 h exposure to MSNPs-Zn. The more aggressive MDA-MB-231 cells, with higher metastatic potential, were more sensitive to MSNPs-Zn than the MCF-7 cells. MSNPs-Zn underwent biodegradation inside the cells, becoming hollow structures, as imaged by high-resolution transmission electron microscopy. The mesoporous silica nanoparticles provide a biodegradable vehicle for therapeutic ion release inside cells.
Pillay J, Tregay N, Juzenaite G, et al., 2020, Effect of the CXCR4 antagonist plerixafor on endogenous neutrophil dynamics in the bone marrow, lung and spleen, Journal of Leukocyte Biology, Vol: 107, Pages: 1175-1185, ISSN: 0741-5400
Treatment with the CXCR4 antagonist, plerixafor (AMD3100), has been proposed for clinical use in patients with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome and in pulmonary fibrosis. However, there is controversy with respect to the impact of plerixafor on neutrophil dynamics in the lung, which may affect its safety profile. In this study, we investigated the kinetics of endogenous neutrophils by direct imaging, using confocal intravital microscopy in mouse bone marrow, spleen, and lungs. Neutrophils are observed increasing their velocity and exiting the bone marrow following plerixafor administration, with a concomitant increase in neutrophil numbers in the blood and spleen, while the marginated pool of neutrophils in the lung microvasculature remained unchanged in terms of numbers and cell velocity. Use of autologous radiolabeled neutrophils and SPECT/CT imaging in healthy volunteers showed that plerixafor did not affect GM‐CSF‐primed neutrophil entrapment or release in the lungs. Taken together, these data suggest that plerixafor causes neutrophil mobilization from the bone marrow but does not impact on lung marginated neutrophil dynamics and thus is unlikely to compromise respiratory host defense both in humans and mice.
Fellous TG, Redpath AN, Fleischer MM, et al., 2020, Pharmacological tools to mobilise mesenchymal stromal cells into the blood promote bone formation after surgery, NPJ REGENERATIVE MEDICINE, Vol: 5
Fellous TG, Redpath AN, Fleischer MM, et al., 2020, Pharmacological tools to mobilise mesenchymal stromal cells into the blood promote bone formation after surgery., NPJ Regen Med, Vol: 5
Therapeutic approaches requiring the intravenous injection of autologous or allogeneic mesenchymal stromal cells (MSCs) are currently being evaluated for treatment of a range of diseases, including orthopaedic injuries. An alternative approach would be to mobilise endogenous MSCs into the blood, thereby reducing costs and obviating regulatory and technical hurdles associated with development of cell therapies. However, pharmacological tools for MSC mobilisation are currently lacking. Here we show that β3 adrenergic agonists (β3AR) in combination with a CXCR4 antagonist, AMD3100/Plerixafor, can mobilise MSCs into the blood in mice and rats. Mechanistically we show that reversal of the CXCL12 gradient across the bone marrow endothelium and local generation of endocannabinoids may both play a role in this process. Using a spine fusion model we provide evidence that this pharmacological strategy for MSC mobilisation enhances bone formation.
Clark J, Garbout A, Rodrigues Mendes Ferreira S, et al., 2020, Propagation phase-contrast micro-computed tomography allows laboratory-based three-dimensional imaging of articular cartilage down to the cellular level, Osteoarthritis and Cartilage, Vol: 28, Pages: 102-111, ISSN: 1063-4584
ObjectiveHigh-resolution non-invasive three-dimensional (3D) imaging of chondrocytes in articular cartilage remains elusive. The aim of this study was to explore whether laboratory micro-computed tomography (micro-CT) permits imaging cells within articular cartilage.DesignBovine osteochondral plugs were prepared four ways: in phosphate-buffered saline (PBS) or 70% ethanol (EtOH), both with or without phosphotungstic acid (PTA) staining. Specimens were imaged with micro-CT following two protocols: 1) absorption contrast (AC) imaging 2) propagation phase-contrast (PPC) imaging. All samples were scanned in liquid. The contrast to noise ratio (C/N) of cellular features quantified scan quality and were statistically analysed. Cellular features resolved by micro-CT were validated by standard histology.ResultsThe highest quality images were obtained using propagation phase-contrast imaging and PTA-staining in 70% EtOH. Cellular features were also visualised when stained in PBS and unstained in EtOH. Under all conditions PPC resulted in greater contrast than AC (p < 0.0001 to p = 0.038). Simultaneous imaging of cartilage and subchondral bone did not impede image quality. Corresponding features were located in both histology and micro-CT and followed the same distribution with similar density and roundness values.ConclusionsThree-dimensional visualisation and quantification of the chondrocyte population within articular cartilage can be achieved across a field of view of several millimetres using laboratory-based micro-CT. The ability to map chondrocytes in 3D opens possibilities for research in fields from skeletal development through to medical device design and treatment of cartilage degeneration.
De Filippo K, Rankin SM, 2018, CXCR4, the master regulator of neutrophil trafficking in homoeostasis and disease., European Journal of Clinical Investigation, Vol: 48, ISSN: 0014-2972
BACKGROUND: Chemokines play a critical role in orchestrating the distribution and trafficking of neutrophils in homoeostasis and disease. RESULTS: The CXCR4/CXCL12 chemokine axis has been identified as a central regulator of these processes. CONCLUSION: In this review, we focus on the role of CXCR4/CXCL12 chemokine axis in regulating neutrophil release from the bone marrow and the trafficking of senescent neutrophils back to the bone marrow for clearance under homoeostasis and disease. We also discuss the role of CXCR4 in fine-tuning neutrophil responses in the context of inflammation.
Sory DR, Amin HD, Rankin SM, et al., 2018, Osteogenic Differentiation of Periosteum-Derived Stromal Cells in Blast-Associated Traumatic Loading, 20th Biennial Conference of the Topical-Group of the American-Physical-Society (APS) on Shock Compression of Condensed Matter (SCCM), Publisher: AMER INST PHYSICS, ISSN: 0094-243X
Nguyen TN, Sory DR, Rankin SM, et al., 2018, Platform development for primary blast injury studies, Trauma (United Kingdom), ISSN: 1460-4086
© 2018, The Author(s) 2018. Explosion-related injuries are currently the most commonly occurring wounds in modern conflicts. They are observed in both military and civilian theatres, with complex injury pathophysiologies. Primary blast injuries are the most frequently encountered critical injuries experienced by victims close to the explosion. They are caused by large and rapid pressure changes of the blast waves which produce a wide range of loading patterns resulting in varied injuries. Well-characterised experimental loading devices which can reproduce the real mechanical characteristics of blast loadings on biological specimens in in vivo, ex vivo, and in vitro models are essential in determining the injury mechanisms. This paper discusses the performance and application of platforms, including shock tubes, mechanical testing machines, drop-weight rigs, and split-Hopkinson pressure bar, with regards to the replication of primary blast.
Iordachescu A, Amin HD, Rankin SM, et al., 2018, An In vitro model for the development of mature bone containing an osteocyte network, Advanced Biosystems, Vol: 2, ISSN: 2366-7478
Bone is a dynamic tissue that remodels continuously in response to local mechanical and chemical stimuli. This process can also result in maladaptive ectopic bone in response to injury, yet pathological differences at the molecular and structural levels are poorly understood. A number of in vivo models exist but can often be too complex to allow isolation of factors which may stimulate disease progression. A self‐structuring model of bone formation is presented using a fibrin gel cast between two calcium phosphate ceramic anchors. Femoral periosteal cells, seeded into these structures, deposit an ordered matrix that closely resembles mature bone in terms of chemistry (collagen:mineral ratio) and structure, which is adapted over a period of one year in culture. Raman spectroscopy and X‐ray diffraction confirm that the mineral is hydroxyapatite associated with collagen. Second‐harmonic imaging demonstrates that collagen is organized similarly to mature mouse femora. Remarkably, cells differentiated to the osteocyte phase are linked by canaliculi (as demonstrated with nano‐computed tomography) and remained viable over the full year of culture. It is demonstrated that novel drugs can prevent ossification in constructs. This model can be employed to study bone formation in an effort to encourage or prevent ossification in a range of pathologies.
Redpath AN, Francois M, Wong S-P, et al., 2017, Two distinct CXCR4 antagonists mobilize progenitor cells in mice by different mechanisms, BLOOD ADVANCES, Vol: 1, Pages: 1934-1943, ISSN: 2473-9529
Pharmacological mobilization of hematopoietic progenitor cells (HPCs) is used clinically to harvest HPCs for bone marrow transplants. It is now widely accepted that the CXCR4:CXCL12 chemokine axis plays a critical role in the retention of HPCs in the bone marrow, and CXCR4 antagonists have been developed for their mobilization. The first of this class of drugs to be US Food and Drug Administration-approved was the bicyclam AMD3100. In addition to mobilizing HPCs and leukocytes in naïve mice, AMD3100 has been shown to mobilize mesenchymal progenitor cells (MPCs) in vascular endothelial growth factor (VEGF-A) pretreated mice. AMD3100 binds to the transmembrane region of CXCR4 and is thought to mobilize HPCs by reversing the gradient of CXCL12 across the bone marrow endothelium. Consistent with this hypothesis, our data show that selective neutralization of CXCL12, with chalcone 4-phosphate (C4P), inhibited AMD3100-stimulated mobilization of HPCs and leukocytes in naïve mice and MPCs in VEGF-A pretreated mice. In contrast it is shown here that the CXCR4 antagonist KRH3955 that binds to the extracellular loop of CXCR4 does not reverse the CXCL12 chemokine gradient. However, this drug efficiently mobilizes HPCs, a response that is not inhibited by C4P. In contrast, KRH3955 does not mobilize MPCs in VEGF-A pretreated mice. These data suggest that CXCR4 antagonists that bind to distinct regions of the receptor mobilize progenitor cells by distinct molecular mechanisms.
Barnett-Vanes A, Sharrock A, Eftaxiopoulou T, et al., 2016, CD43Lo classical monocytes participate in the cellular immune response to isolated primary blast lung injury, Journal of Trauma and Acute Care Surgery, Vol: 81, Pages: 500-511, ISSN: 2163-0763
BACKGROUND: Understanding of the cellular immune response to primary blast lung injury (PBLI) is limited, with only the neutrophil response well documented. Moreover, its impact on the immune response in distal organs remains poorly understood. In this study, a rodent model of isolated primary blast injury was used to investigate the acute cellular immune response to isolated PBLI in the circulation and lung; including the monocyte response, and investigate distal sub-acute immune effects in the spleen and liver 6hr after injury. METHODS: Rats were subjected to a shock wave (~135kPa overpressure, 2ms duration) inducing PBLI or sham procedure. Rat physiology was monitored and at 1, 3 and 6 hr thereafter blood, lung, and Broncho-alveolar lavage fluid (BALF) were collected and analysed by flow cytometry (FCM), ELISA and Histology. In addition, at 6hr spleen and liver were collected and analysed by FCM. RESULTS: Lung histology confirmed pulmonary barotrauma and inflammation. This was associated with rises in CXCL-1, IL-6, TNF-α and albumin protein in the BALF. Significant acute increases in blood and lung neutrophils and CD43Lo/His48Hi (classical) monocytes/macrophages were detected. No significant changes were seen in blood or lung 'non-classical' monocyte, NK, B or T Cells. In the BALF, significant increases were seen in neutrophils, CD43Lo monocyte-macrophages and MCP-1. Significant increases in CD43Lo and Hi monocyte-macrophages were detected in the spleen at 6hr. CONCLUSIONS: This study reveals a robust and selective response of CD43Lo/His48Hi (classical) monocytes - in addition to neutrophils - in blood and lung tissue following PBLI. An increase in monocyte-macrophages was also observed in the spleen at 6hr. This profile of immune cells in the blood and BALF could present a new research tool for translational studies seeking to monitor, assess or attenuate the immune response in blast injured patients. EVIDENCE: Experimental laboratory study.WC- 300.
Eftaxiopoulou T, Barnett-Vanes A, Arora H, et al., 2016, Prolonged but not short duration blast waves elicit acute inflammation in a rodent model of primary blast limb trauma, Injury, Vol: 47, Pages: 625-632, ISSN: 0020-1383
BackgroundBlast injuries from conventional and improvised explosive devices account for 75% of injuries from current conflicts; of these over 70% involve the limbs. Variable duration and magnitude of blast wave loading occurs in real-life explosions and is hypothesised to cause different injuries. While a number of in-vivo models report the inflammatory response to blast injuries, the extent of this response has not been investigated with respect to the duration of the primary blast wave. The relevance is that explosions in open air are of short duration compared to those in confined spaces. MethodsHind limbs of adult Sprauge-Dawley rats were subjected to focal isolated primary blast waves of varying overpressure (1.8-3.65kPa) and duration (3.0-11.5ms), utilising a shock tube and purpose built experimental rig. Rats were monitored during and after blast. At 6 and 24hrs after exposure blood, lungs, liver and muscle tissue were collected and prepared for histology and flow cytometry.ResultsAt 6hrs increases in circulating neutrophils and CD43Lo/His48Hi monocytes were observed in rats subjected to longer duration blast waves. This was accompanied by increases in circulating pro-inflammatory chemo/cytokines KC and IL-6. No changes were observed with shorter duration blast waves irrespective of overpressure. In all cases, no histological damage was observed in muscle, lung or liver. By 24hrs post-blast all inflammatory parameters had normalised. ConclusionsWe report the development of a rodent model of primary blast limb trauma that is the first to highlight an important role played by blast wave duration and magnitude in initiating acute inflammatory response following limb injury in the absence of limb fracture or penetrating trauma. The combined biological and mechanical method developed can be used to further understand the complex effects of blast waves in a range of different tissues and organs in-vivo.
Barnett-Vanes A, Sharrock A, Birrell MA, et al., 2016, A single 9-colour flow cytometric method to characterise major leukocyte populations in the rat: validation in a model of LPS-induced pulmonary inflammation, PLOS One, Vol: 11, ISSN: 1932-6203
Chan JK, Glass GE, Ersek A, et al., 2015, Low-dose TNF augments fracture healing in normal and osteoporotic bone by up-regulating the innate immune response, EMBO Molecular Medicine, Vol: 7, Pages: 547-561, ISSN: 1757-4676
The mechanism by which trauma initiates healing remains unclear. Precise understanding of these events may define interventions for accelerating healing that could be translated to the clinical arena. We previously reported that addition of low‐dose recombinant human TNF (rhTNF) at the fracture site augmented fracture repair in a murine tibial fracture model. Here, we show that local rhTNF treatment is only effective when administered within 24 h of injury, when neutrophils are the major inflammatory cell infiltrate. Systemic administration of anti‐TNF impaired fracture healing. Addition of rhTNF enhanced neutrophil recruitment and promoted recruitment of monocytes through CCL2 production. Conversely, depletion of neutrophils or inhibition of the chemokine receptor CCR2 resulted in significantly impaired fracture healing. Fragility, or osteoporotic, fractures represent a major medical problem as they are associated with permanent disability and premature death. Using a murine model of fragility fractures, we found that local rhTNF treatment improved fracture healing during the early phase of repair. If translated clinically, this promotion of fracture healing would reduce the morbidity and mortality associated with delayed patient mobilization.
Johnson JR, Folestad E, Rowley JE, et al., 2015, Pericytes contribute to airway remodeling in a mouse model of chronic allergic asthma, AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY, Vol: 308, Pages: L658-L671, ISSN: 1040-0605
Singh RK, Furze RC, Birrell MA, et al., 2014, A role for Rab27 in neutrophil chemotaxis and lung recruitment, BMC CELL BIOLOGY, Vol: 15, ISSN: 1471-2121
Santo AIE, Chan JK, Glass GE, et al., 2014, Enhancement of fracture repair by upregulation of the innate immune response, EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Vol: 44, Pages: 30-31, ISSN: 0014-2972
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