Development and characterization of an injectable dextrin-based hydrogel for bone regeneration

Bone is a dynamic, highly vascularized tissue that remodels itself continuously over an individual ́s lifetime. It plays several important roles in maintaining homeostasis of the body systems [ 1 , 2 ] . However, this regenerative capac ity is limited and, as in the case of large bone defects, where the template for an orchestrated regeneration is absent, surgical proce dures are needed [ 2 ] . In this respect , bone tissue engineering is a very challe nging and promising field given the need to mimic bone mechanical and biological functions and also due to the failure of current orthoped ic implants. The general concept consists in the development of three - dimensional scaffolds, from biocompatible materials (natu ral or synthetic), which confer temporary support for the regeneration of bone tissue, while the scaffold itself will be resorbed and replaced by new ly formed tissue [ 2 , 3 ] . Hydrogels are cross - linked networks made of natural or synthetic polymers, which are able to support high water contents [ 4 ] . These materials are usua lly biocompatible, have the ability to mimic physiological conditions, promote an environment that can protect cells or unstable drugs, their physical characteristics can be controlled to some extent and some can be injected in vivo . These features make th em attractive materials in the biomedical field for cell encapsulation, drug or gene delivery or to act as an interfa ce between tissue and materials [ 4 - 7 ] . Natural polymers are advantageous for this kind of applications since they are cheap raw materials, bear a great biocompatibility and are usually biodegradable [ 8 ] . Dextrin is low molecular weight carbohydrate, generally regarded as safe (GRAS), obtained from partial hydrolysis of starch or glycogen [ 9 ] . It is a glucose polymer linked by α - 1,4 glycosidic linkages with some degree of branching due to the presence of α - 1,6 bonds [ 10 ] . I t is biocompatible and non - immunogenic, degradable by α - amylases and can undergo renal clearance avoiding tissue accumulation [ 11 , 12 ] . This work describes the preparation and characterization of an injectable dextrin - bas ed hydrogel (oDex) able to incorporate nanoparticles , cells, biomolecules or Bonelike ® granules [ 13 ] . Bonelike ® is a Biosckin - molecular and cell therapies S.A. proprietary synthetic bone graft, and the outcome of the project will result in a novel injectable presentation of this product. The hydrogel was produced by dextrin oxidation with sodium periodate followed by cross - linking with a dihydrazide [ 14 ] . In vitro characterization of oDex hydrogel has shown acceptable m echanical properties, overall good biocompatibility and the ability to be combined with other materials such as a nanogel and urinary bladder matrix, without affecting its structure. The cytotoxicity of the free dihydrazide was evaluated and only a mild in hibitory effect on cell proliferation was observed for the concentration used in the hydrogel crosslinking. The biocompatibilit y of oDex hydrogels was confirmed through the encapsulation of cells, which were able to endure the gelation process. Subcutaneou s implants were performed in Sasco Sprague Dawley rats in order to evaluate the inflammatory response and systemic effects of oDex hydrogels and their combination with Bonelike ® and human mesenchymal stem cells isolated from umbilical cord’s Wharton jelly. After 3 and 15 days post - implantation, a quantitative evaluation of both responses was performed according to ISO 10993 by a scoring system leading to a classification of the implanted material as s light irritant even when associated to Bonelike ® or to the cellular system. The performance of oDex hydrogel combined with Bonelike granules and/or UBM in bone defects was investigated in New Zealand rabbits. Bone defects in several anatomical locations (t ibiae and cranium) of non - critical and critical size were filled with those materials. Histological analysis showed that oDex does not constitute a barrier for cellular colonization and proliferation since the defects that were filled with these materials presented a higher degree of regeneration and a higher amount of collagen fibers with higher organization degrees, when compared with the empty defects. Even though oDex hydrogels purpose is to act as an injectable carrier for osteoconductive materials, li ke Bonelike ® granules, the hydrogel itself seems to assists the regenerative pro cess when compared with the empty defects. This is due to the 3D supp ort conferred by hydrogels that facilitates cell migration to the defect site. Moreover, the presence of UB M strongly stimulates the bone regeneration, for levels comparable with the Bonelike ® conditions, since an increase in cellular colonization and organization in the defect site can be denoted. A sterilization protocol for oDex hydrogels by gamma and beta r adiation was investigated through irradiation of oxidized dextrin solutions. Despite b oth kinds of radiation induced slight differences in the storage modulus of the hydrogels, indicating the occurrence of chain scission/cross - linking effects on the dextri n cha in, all materials were gelable after the irradiation treatments . These effects seem to not be dose or temperature dependent and the irradiation process in liquid or solid state also does not induce major differences in the rheology of the final hydrog els. Due to its known advantages, gamma radiation seems to be a suitable sterilization method for oxidized dextrin solutions. The stability of gamma irradiated dextrin solutions was evaluated up to 8 months. Despite the increase of storage modulus of the h ydrogels over the time, this effect does not constitute a disadvantage since it improves elastic behavior of the hydrogels. oDex hydrogels provides a system that can carry and stabilize cells, nanogels, Bonelike ® granules and other biomolecules. It is a pr omising biomaterial due to its biocompatibility, and potential to promote an adequate environment for bone regeneration. Its injectability allows a minimal invasive surgical procedure with decreased patient morbidity, lower risk of infection and reduced sc ar formation. This work has been developed in the scope of an European project that allowed collaborations with research groups, which have complementary expertise. The tight collaboration between University of Minho and Bioskin S.A. company, envisioning t echnology transfer and product valorization, has resulted in a published international patent of the product ( WO2011070529A2 ) [ 15 ] . Currently, a new set of pre - clinical trials in sheep model s are being planned as well as the submission of a request for the authorization for the clinical trialsGrant SFRH/BD/64571/2009 from Fundação para a Ciência e Tecnologia (FCT), Portugal. We thank FCT funding through EuroNanoMed ENMED/0002/2

Development of a dextrin-based hydrogel for bone regeneration

[Excerpt] Bone tissue engineering is a very challenging and promising field, which handles with the limitations of bone regenerative capacity and the failure of current orthopedic implants [1]. This work describes the preparation and characterization of an injectable dextrin-based hydrogel (oDex) able to incorporate nanoparticles, cells, biomolecules or Bonelike~ granules [2]. (...

Origin of the large dispersion of magnetic properties in nanostructured oxides: FexO/Fe3O4 nanoparticles as a case study

The intimate relationship in transition-metal oxides between stoichiometry and physiochemical properties makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxide

Origin of the large dispersion of magnetic properties in nanostructured oxides: FexO/Fe3O4 nanoparticles as a case study

The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides

Spatial Organization and Molecular Correlation of Tumor-Infiltrating Lymphocytes Using Deep Learning on Pathology Images

Beyond sample curation and basic pathologic characterization, the digitized H&E-stained images of TCGA samples remain underutilized. To highlight this resource, we present mappings of tumorinfiltrating lymphocytes (TILs) based on H&E images from 13 TCGA tumor types. These TIL maps are derived through computational staining using a convolutional neural network trained to classify patches of images. Affinity propagation revealed local spatial structure in TIL patterns and correlation with overall survival. TIL map structural patterns were grouped using standard histopathological parameters. These patterns are enriched in particular T cell subpopulations derived from molecular measures. TIL densities and spatial structure were differentially enriched among tumor types, immune subtypes, and tumor molecular subtypes, implying that spatial infiltrate state could reflect particular tumor cell aberration states. Obtaining spatial lymphocytic patterns linked to the rich genomic characterization of TCGA samples demonstrates one use for the TCGA image archives with insights into the tumor-immune microenvironment

Sequestration of Highly Expressed mRNAs in Cytoplasmic Granules, P-Bodies, and Stress Granules Enhances Cell Viability

Transcriptome analyses indicate that a core 10%–15% of the yeast genome is modulated by a variety of different stresses. However, not all the induced genes undergo translation, and null mutants of many induced genes do not show elevated sensitivity to the particular stress. Elucidation of the RNA lifecycle reveals accumulation of non-translating mRNAs in cytoplasmic granules, P-bodies, and stress granules for future regulation. P-bodies contain enzymes for mRNA degradation; under stress conditions mRNAs may be transferred to stress granules for storage and return to translation. Protein degradation by the ubiquitin-proteasome system is elevated by stress; and here we analyzed the steady state levels, decay, and subcellular localization of the mRNA of the gene encoding the F-box protein, UFO1, that is induced by stress. Using the MS2L mRNA reporter system UFO1 mRNA was observed in granules that colocalized with P-bodies and stress granules. These P-bodies stored diverse mRNAs. Granules of two mRNAs transported prior to translation, ASH1-MS2L and OXA1-MS2L, docked with P-bodies. HSP12 mRNA that gave rise to highly elevated protein levels was not observed in granules under these stress conditions. ecd3, pat1 double mutants that are defective in P-body formation were sensitive to mRNAs expressed ectopically from strong promoters. These highly expressed mRNAs showed elevated translation compared with wild-type cells, and the viability of the mutants was strongly reduced. ecd3, pat1 mutants also exhibited increased sensitivity to different stresses. Our interpretation is that sequestration of highly expressed mRNAs in P-bodies is essential for viability. Storage of mRNAs for future regulation may contribute to the discrepancy between the steady state levels of many stress-induced mRNAs and their proteins. Sorting of mRNAs for future translation or decay by individual cells could generate potentially different phenotypes in a genetically identical population and enhance its ability to withstand stress

Variant rs9939609 in the FTO gene is associated with body mass index among Chinese children

<p>Abstract</p> <p>Background</p> <p>Fat-mass and obesity-associated (<it>FTO</it>) gene is a gene located in chromosome region 16q12.2. Genetic variants in <it>FTO </it>are associated with the obesity phenotype in European and Hispanic populations. However, this association still remains controversial in Asian population. We aimed to test the association of <it>FTO </it>genetic variants with obesity and obesity-related metabolic traits among children living in Beijing, China.</p> <p>Methods</p> <p>We genotyped <it>FTO </it>variants rs9939609 in 670 children (332 girls and 338 boys) aged 8-11 years living in Beijing, and analyzed its association with obesity and obesity-related metabolic traits. Overweight and obesity were defined by age- and sex-specific BMI reference for Chinese children. Obesity-related metabolic traits included fasting plasma glucose, lipid profiles, leptin, ghrelin, adiponectin and blood pressures.</p> <p>Results</p> <p>The frequency of rs9939609 A allele was 12.2%, which was 21.9% for the heterozygote and 1.2% for the homozygote of the A allele. The obesity prevalence among the carriers of AA/AT genotypes was significantly higher than that among those with TT genotype (36.4% <it>vs</it>. 22.6%, <it>P </it>= 0.004). Compared to the carrier of TT genotype, the likelihood of obesity was 1.79 (95% confidence interval (95% CI) 1.20-2.67, <it>P </it>= 0.004) for the carrier of AA/AT genotype, after adjustment of sex, age and puberty stages. The BMI Z-score of children with AA/AT genotype were significantly higher than that of their counterparts with the TT genotype (1.1 ± 0.1 <it>vs</it>. 0.8 ± 0.1, <it>P </it>= 0.02). The concentration of triglyceride was 1.03 ± 0.52 mmol/L among TT carrier and 1.13 ± 0.68 mmol/L among AA/AT carrier (<it>P </it>= 0.045). While, the concentrations of adiponectin were 18.0 ± 0.4 μg/ml among carriers of TT and 16.2 ± 0.7 μg/ml among subjects with AA/AT genotype (<it>P </it>= 0.03). The level of glucose marginally increased in the AA/AT genotype subjects (4.67 ± 0.40 mmol/L <it>vs</it>. 4.60 ± 0.35 mmol/L, <it>P </it>= 0.08). The evidence of association was reduced after adjustment for BMI (<it>P </it>= 0.38 for triglyceride, <it>P </it>= 0.20 for adiponectin and glucose). There was weak evidence of association between rs9939609 and other obesity-related metabolic traits including total cholesterol (3.92 ± 0.03 mmol/L <it>vs</it>. 4.02 ± 0.05 mmol/L, <it>P </it>= 0.10), insulin (2.69 ± 1.77 ng/ml <it>vs</it>. 3.12 ± 2.91 ng/ml, <it>P </it>= 0.14), and insulin resistance (HOMA-IR 0.56 ± 0.03 <it>vs</it>. 0.66 ± 0.05, <it>P </it>= 0.10).</p> <p>Conclusions</p> <p>Genetic variation in the <it>FTO </it>gene associates with obesity in Chinese children.</p

Global Retinoblastoma Presentation and Analysis by National Income Level.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe