Cellular Bone Research Articles

Detection of defects in cellular solids using highly nonlinear solitary waves: a numerical study of the proximal femur.

This study investigates the suitability of a relatively new non-destructive evaluation (NDE) technique for the detection of non-visible defects in cellular solids using highly nonlinear solitary waves (HNSWs) in a one-dimensional granular chain. Specifically, the HNSW-based NDE approach is employed to identify the existence of micro-fractures in trabecular bone within the femoral neck (FN) and the intertrochanteric (IT) region of the proximal femur which are fracture-prone sites due to their relatively low bone density, particularly in osteoporosis patients. The availability of a HNSW-based bone quality assessment tool could not only help in early diagnosis of osteoporosis but also affect surgical decisions and improve clinical outcomes in joint replacement surgeries which motivated this study. To obtain a realistic representation of the trabecular microstructure, high-resolution finite-element (FE) models of the FN and the IT region are first constructed using a topology optimization-based bone reconstruction scheme. Then, artificial defects in the form of fractured ligaments are generated in the FN and IT models by selectively disconnecting various struts within the trabecular network. Using the FE models as the inspection medium, hybrid discrete-element/finite-element (DE/FE) simulations are performed to examine the interaction of the HNSWs with the cellular bone samples through two different inspection modes, i.e., inspection via direct contact with the sample and indirect contact through an adequately chosen face sheet inserted between the cellular sample and the granular chain. The delays and amplitudes of the HNSWs are used to estimate the effective elastic moduli of the cellular samples and these estimates were found to be reasonably accurate only in case the face sheet was applied. For the latter case, it was shown that the HNSW-based modulus estimates can be used as indicators for defect detection, allowing to discern between pristine and damaged cellular solids. These results suggest that HNSW-based NDE is a reliable and cost-effective technique for the identification of defects in cellular solids, and is expected to find applications in various fields, such as non-invasive screening of bone diseases and fractures, or damage detection in additively manufactured cellular structures.

Nanomaterials-Incorporated Chemically Modified Gelatin Methacryloyl-Based Biomedical Composites: A Novel Approach for Bone Tissue Engineering.

Gelatin methacryloyl (GelMA)-based composites are evolving three-dimensional (3D) networking hydrophilic protein composite scaffolds with high water content. These protein composites have been devoted to biomedical applications due to their unique abilities, such as flexibility, soft structure, versatility, stimuli-responsiveness, biocompatibility, biodegradability, and others. They resemble the native extracellular matrix (ECM) thanks to their remarkable cell-adhesion and matrix-metalloproteinase (MMP)-responsive amino acid motifs. These favorable properties promote cells to proliferate and inflate within GelMA-protein scaffolds. The performance of GelMA composites has been enriched using cell-amenable components, including peptides and proteins with a high affinity to harmonize cellular activities and tissue morphologies. Due to their inimitable merits, GelMA systems have been used in various fields such as drug delivery, biosensor, the food industry, biomedical, and other health sectors. The current knowledge and the role of GelMA scaffolds in bone tissue engineering are limited. The rational design and development of novel nanomaterials-incorporated GelMA-based composites with unique physicochemical and biological advantages would be used to regulate cellular functionality and bone regeneration. Substantial challenges remain. This review focuses on recent progress in mitigating those disputes. The study opens with a brief introduction to bone tissue engineering and GelMA-based composites, followed by their potential applications in bone tissue engineering. The future perspectives and current challenges of GelMA composites are demonstrated. This review would guide the researchers to design and fabricate more efficient multifunctional GelMA-based composites with improved characteristics for their practical applications in bone tissue engineering and biomedical segments.

Characterization of an advanced viable bone allograft with preserved native bone-forming cells

Bone grafts are widely used to successfully restore structure and function to patients with a broad range of musculoskeletal ailments and bone defects. Autogenous bone grafts are historically preferred because they theoretically contain the three essential components of bone healing (ie, osteoconductivity, osteoinductivity, and osteogenicity), but they have inherent limitations. Allograft bone derived from deceased human donors is one alternative that is also capable of providing both an osteoconductive scaffold and osteoinductive potential but, until recently, lacked the osteogenic component of bone healing. Relatively new, cellular bone allografts (CBAs) were designed to address this need by preserving viable cells. Although most commercially-available CBAs feature mesenchymal stem cells (MSCs), osteogenic differentiation is time-consuming and complex. A more advanced graft, a viable bone allograft (VBA), was thus developed to preserve lineage-committed bone-forming cells, which may be more suitable than MSCs to promote bone fusion. The purpose of this paper was to present the results of preclinical research characterizing VBA. Through a comprehensive series of in vitro and in vivo assays, the present results demonstrate that VBA in its final form is capable of providing all three essential bone remodeling properties and contains viable lineage-committed bone-forming cells, which do not elicit an immune response. The results are discussed in the context of clinical evidence published to date that further supports VBA as a potential alternative to autograft without the associated drawbacks.

Poly (Butylene Succinate)/Silicon Nitride Nanocomposite with Optimized Physicochemical Properties, Biocompatibility, Degradability, and Osteogenesis for Cranial Bone Repair.

Congenital disease, tumors, infections, and trauma are the main reasons for cranial bone defects. Herein, poly (butylene succinate) (PB)/silicon nitride (Si3N4) nanocomposites (PSC) with Si3N4 content of 15 w% (PSC15) and 30 w% (PSC30) were fabricated for cranial bone repair. Compared with PB, the compressive strength, hydrophilicity, surface roughness, and protein absorption of nanocomposites were increased with the increase in Si3N4 content (from 15 w% to 30 w%). Furthermore, the cell adhesion, multiplication, and osteoblastic differentiation on PSC were significantly enhanced with the Si3N4 content increasing in vitro. PSC30 exhibited optimized physicochemical properties (compressive strength, surface roughness, hydrophilicity, and protein adsorption) and cytocompatibility. The m-CT and histological results displayed that the new bone formation for SPC30 obviously increased compared with PB, and PSC30 displayed proper degradability (75.3 w% at 12 weeks) and was gradually replaced by new bone tissue in vivo. The addition of Si3N4 into PB not only optimized the surface performances of PSC but also improved the degradability of PSC, which led to the release of Si ions and a weak alkaline environment that significantly promoted cell response and tissue regeneration. In short, the enhancements of cellular responses and bone regeneration of PSC30 were attributed to the synergism of the optimized surface performances and slow release of Si ion, and PSC30 were better than PB. Accordingly, PSC30, with good biocompatibility and degradability, displayed a promising and huge potential for cranial bone construction.

Tissue specific considerations in implementing high intensity focussed ultrasound under magnetic resonance imaging guidance.

High-intensity focused ultrasound can ablate a target permanently, leaving tissues through which it passes thermally unaffected. When delivered under magnetic resonance (MR) imaging guidance, the change in tissue relaxivity on heating is used to monitor the temperatures achieved. Different tissue types in the pre-focal beam path result in energy loss defined by their individual attenuation coefficients. Furthermore, at interfaces with different acoustic impedances the beam will be both reflected and refracted, changing the position of the focus. For complex interfaces this effect is exacerbated. Moreover, blood vessels proximal to the focal region can dissipate heat, altering the expected region of damage. In the target volume, the temperature distribution depends on the thermal conductivity (or diffusivity) of the tissue and its heat capacity. These are different for vascular tissues, water and fat containing tissues and bone. Therefore, documenting the characteristics of the pre-focal and target tissues is critical for effective delivery of HIFU. MR imaging provides excellent anatomic detail and characterization of soft tissue components. It is an ideal modality for real-time planning and monitoring of HIFU ablation, and provides non-invasive temperature maps. Clinical applications involve soft-tissue (abdomino-pelvic applications) or bone (brain applications) pre-focally and at the target (soft-tissue tumors and bone metastases respectively). This article addresses the technical difficulties of delivering HIFU effectively when vascular tissues, densely cellular tissues, fat or bone are traversed pre-focally, and the clinical applications that target these tissues. The strengths and limitations of MR techniques used for monitoring ablation in these tissues are also discussed.

Twelve-Month Results from a Prospective Clinical Study Evaluating the Efficacy and Safety of Cellular Bone Allograft in Subjects Undergoing Lumbar Spinal Fusion.

While autologous bone grafts remain the gold standard for spinal fusion procedures, harvesting autologous bone is associated with significant complications, including donor site infection, hematomas, increased operative time, and prolonged pain. Cellular bone allograft (CBA) presents an alternative to autologous bone harvesting, with a favorable efficacy and safety profile. The current study further investigates CBA as an adjunct to lumbar spinal fusion procedures. A prospective, multicenter, open-label clinical study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616). Radiographic fusion status was assessed by an independent review of dynamic radiographs and CT scans. Clinical outcome measures included the Oswestry Disability Index (ODI) and visual analogue scale (VAS) for back and leg pain. Adverse-event reporting was conducted throughout 12 months of follow-up. Available subject data at 12 months were analyzed. A total of 274 subjects were enrolled into the study, with available data from 201 subjects (73.3%) who completed 12 months of postoperative radiographic and clinical evaluation at the time of analysis. Subjects had a mean age of 60.2 ± 11.5 years. A higher number of women (n = 124, 61.7%) than men (n = 77, 38.3%) were enrolled, with a collective mean BMI of 30.6 + 6.5 kg/m² (range 18.0-51.4). At month 12, successful fusion was achieved in 90.5% of subjects. A significant (<i>p</i> &amp;lt; 0.001) improvement in ODI, VAS-back, and VAS-leg clinical outcomes was also observed compared to baseline scores. One adverse event related to CBA (postoperative radiculopathy) was reported, with surgical exploration demonstrating interbody extrusion of graft material. This subject reported successful fusion at month 12. CBA represents a viable substitute for harvesting of autograft alone with a high rate of successful fusion and significant improvements in subject-reported outcomes, such as pain and disability. Positive benefit was observed in subjects reporting single and multiple risk factors for pseudoarthrosis.

Fluid shear stress promotes osteogenesis of bone mesenchymal stem cells at early matrix maturity phase through Lamin A/ METTL3 signal axis

During the construction of tissue-engineered bone in vitro, bionic mechanical stimulation has been considered to be critical to cellular response and bone tissue formation. Bone mesenchymal stem cells (BMSCs) at different osteogenesis phases in the bone marrow cavity are subjected to fluid shear stress (FSS). However, the responses of BMSCs at different phases of osteogenic differentiation to FSS remain unknown. Therefore, FSS was applied to BMSCs at different osteogenesis phases in vitro by parallel plate flow chamber, and the osteogenic ability and relaed underlying mechanisms were explored. Our study showed that BMSCs underwent rapid proliferation, early matrix maturity and late mineralization phases at 1, 7 and 14 days of osteogenic induction, respectively. FSS significantly promoted the osteogenic differentiation of BMSCs at early matrix maturation phase. Applying FSS on BMSCs at early matrix maturity phase resulted in significant remodeling of F-actin, forming of stress fibers, and the transduction of mechanical signal by the cytoskeleton-Lamin A pathway. Through the interaction between Lamin A and Methyltransferase-like 3 (METTL3), the levels of METTL3 protein and the m6A methylation genes were increased, promoting the osteoblastic differentiation of BMSCs. The results provided a new insight into the construction of bone tissue in vitro and the treatment strategy for bone defects. Data AvailabilityThe data used to support the findings of this study are available from the corresponding author upon request.

Current use and outcomes of hematopoietic stem cell transplantation: Brazilian summary slides

The first HSCT program in Latin America started in 1979 at the Federal University Hospital (Curitiba, Paraná). Over the years, the number of centers performing transplants in the country increased, generating the need to know the results of this modality of treatment. Understanding the HSCT scenario in Brazil is still challenging since not all Brazilian centers report data to the Center for International Blood and Marrow Research (CIBMTR). Although it has been improving over the last years, infrastructure and trained data managers are still lacking. The partnership between the Brazilian Cellular Therapy and Bone Marrow Transplant Society (SBTMO) and the CIBMTR, allowed the return of Brazilian data registered in the CIBMTR, through the Data Back to Center (DBtC), in a standardized and organized way. With this database it was possible to know the demographic data and the outcomes of transplants performed in Brazil. Between 2012 and 2021, complete information of 7,982 transplants were reported to the CIBMTR from 31 Brazilian transplant centers. The consolidation of the Hematopoietic Stem Cell Transplantation Brazilian Registry (HSCTBR) using CIBMTR infrastructure, allowed the Brazilian Summary slides development and update. Despite the difference in the number of cases and of follow-up time, the results in this study were similar to those presented in the US Summary Slides.

Expression profile analysis of long noncoding RNA and messenger RNA during mouse cementoblast mineralization.

Emerging evidence has uncovered that long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) exert biofunctions on cellular mineralization and bone formation. In this study, we aimed to identify lncRNA-mRNA expression profiles and expression patterns, and explore their underlying biofunctions during cementoblast mineralization. Cementoblasts were cultured in mineralized medium for 0, 7, and 14 days. We used quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) to detect expression levels of osteocalcin (OCN), bone sialoprotein (BSP), and Osterix (Osx). Alkaline phosphatase (ALP) staining and alizarin red staining (ARS) were conducted to detect ALP activity and number of mineralized nodule. Total RNA was extracted from cells and used for high-throughput sequencing. EBSeq package was applied to analyze differentially expressed genes. Mfuzz R package was used to identify gene expression patterns. The weighted gene co-expression network analysis (WGCNA) was performed to explore co-expressed mRNAs of differentially expressed lncRNAs (DElncRNAs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were adopted by Clusterprofile R package. Cementoblasts were successfully induced by osteogenic medium. Compared with those on day 0, 384 DElncRNAs and 4255 differentially expressed mRNAs (DEmRNAs), respectively, were found on day 7. Meanwhile, 645 DElncRNAs and 4717 DEmRNAs were detected on day 14. Both DElncRNAs and DEmRNAs were classified into six clusters with different expression patterns. DEmRNAs and co-expressed mRNA of DElncRNAs were predominantly related to cell process, binding, phosphatidylinositol-3 kinase (PI3K)-Akt signaling pathway, hypoxia-inducible factor-1 (HIF-1) signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, and hippo signaling pathway. The results demonstrated that both noncoding and coding RNAs were involved in the process of mineralization in cementoblasts, which may provide a new database for further study.

The paleohistology of †Araripichthys castilhoi from the Lower Cretaceous of Araripe Basin, Northeastern Brazil: a typical case of basal teleost

ABSTRACT †Araripichthys castilhoi belongs to the paleo-ichthyofauna from the Aptian calcareous concretions of Romualdo Member, Santana Formation, Araripe Basin, northeast Brazil. It was originally placed within Beryciformes (Acanthomorphata) by a combination of plesiomorphic and apomorphic characters. Later, an anatomical review of †Araripichthys demonstrated the presence of several primitive characters (cf. presence of fin spines, orbitosphenoid, two supramaxillae, seven hypurals, autogenous hypurals 1 and 2, second ural centrum and first uroneural not fused, and cycloid scales) and aligned it with Clupeocephala. †Araripichthys was also considered closely related to †Acanthichthys (primitive Acanthomorphata), basically by the body shape resemblance. Other included †Araripichthys in †Protobramoidei (basal Clupeocephala) based on the absence of pelvic fins, presence of stout neural spines and scales partially covering the dorsal fin. The odd taxonomic history of †Araripichthys is directly related to its scarce number of available well-preserved specimens and concurrently its absence in a comprehensive phylogenetic analysis. Here we present a paleohistological study, an efficient tool to precise the taxonomic position of fossil fishes, especially in cases like that of †Araripichthys. Its paleohistology presents pseudolamellar bony tissues with stellate lacunae, filled by osteocytes with ramified cytoplasmic extensions. The star-shaped osteocytes of †Araripichthys are clearly characteristic of basal teleosts. Conversely, in the scarce Acanthopterygii taxa with cellular bone the osteocytes morphology is clearly distinct since their canaliculi are not regularly localized around these cells. The currently accepted synapomorphies for Elopomorpha, Clupeocephala, Acanthopterygii, and the already known anatomical data for †Araripichthys together with its paleohistology, corroborate its incertae sedis position within basal Teleostei.

Comparing Rates of Fusion and Time to Fusion in Viable Cellular Allograft and Autograft.

Autograft or allograft frequently are used to enhance bone union in foot and ankle surgery. Viable cellular bone allograft uses viable cells and bone scaffolding in a gel base, but uncertainty remains around allograft's greater efficacy than autograft regarding rates of fusion (ROF) and time to fusion (TTF). Autograft, viable cellular allograft, and viable cellular allograft with autograft were compared in 199 forefoot, midfoot, and hindfoot arthrodeses performed over a 6-year period. Data collected from electronic medical records and radiographs were analyzed to determine ROF and TTF as well as rates of revision surgery for delayed or nonunion and compared among groups. Eighty-seven patients comprised the autograft group, 81 the allograft group, and 31 the combined group. No significant differences were noted in patient demographics among the groups. No statistically significant differences in ROF were noted among the 3 groups, with 86% (75 of 87) fusion in the autograft group, 93% (75 of 81) in the allograft group, and 84% (26 of 31) in the combined group (P = .20). After conducting a multivariate analysis, we found no statistically significant difference for allograft or combined graft on TTF (P = .1379 and .2311, respectively). No significant difference was found in rate of revision surgery for nonunion, which was 1.2% (1 of 81) in the allograft group, 3.4% (3 of 87) in the autograft group, and 6.5% (2 of 31) in the combined group (P = .3). No significant difference was found in ROF, TTF, or rate of revision surgery when comparing viable cellular allograft to autograft or combined allograft-autograft. Viable cellular allograft may be a reasonable alternative to the gold standard of autograft and should be considered an option in patients undergoing arthrodesis in foot and ankle surgery. Level III, therapeutic.

Actin nano-architecture of phagocytic podosomes

Podosomes are actin-enriched adhesion structures important for multiple cellular processes, including migration, bone remodeling, and phagocytosis. Here, we characterize the structure and organization of phagocytic podosomes using interferometric photoactivated localization microscopy, a super-resolution microscopy technique capable of 15–20 nm resolution, together with structured illumination microscopy and localization-based super-resolution microscopy. Phagocytic podosomes are observed during frustrated phagocytosis, a model in which cells attempt to engulf micropatterned IgG antibodies. For circular patterns, this results in regular arrays of podosomes with well-defined geometry. Using persistent homology, we develop a pipeline for semi-automatic identification and measurement of podosome features. These studies reveal an hourglass shape of the podosome actin core, a protruding knob at the bottom of the core, and two actin networks extending from the core. Additionally, the distributions of paxillin, talin, myosin II, α-actinin, cortactin, and microtubules relative to actin are characterized.

Protective Effect on Bone of Nacre Supplementation in Ovariectomized Rats

ABSTRACTNacre has emerged as a beneficial natural product for bone cells and tissues, but its effect was only studied by gavage in the ovariectomized mouse model. We sought to assess the antiosteoporotic effect of nacre through a nutritional supplementation in the ovariectomized rat model. Sixteen‐week‐old female Wistar rats were either Sham‐operated or bilateral ovariectomized (OVX) and then fed with standard diet (Sham and OVX groups) or standard diet supplemented with either 0.25% CaCO3 or nacre (OVX CaCO3 and OVX Nacre group, respectively) for 28 days (n = 10/group). The bone microarchitecture was assessed at appendicular and axial bones by micro‐computed tomography (μCT). Histomorphometric analysis was performed to determine cellular and dynamic bone parameters. Bone metabolism was also evaluated by biochemical markers and gene expression levels. Nacre‐based diet prevented the OVX‐induced bone loss better than that of the CaCO3 supplement, given the significant changes in trabecular bone volume fraction (BV/TV) both at the femoral distal metaphysis (difference, 35%; p = 0.004) and at the second lumbar spine (difference, 11%; p = 0.01). Trabecular osteoclast surfaces (Oc.S/BS) were also 1.5‐fold lower at the tibial proximal metaphysis in OVX Nacre group compared with OVX CaCO3 group (p = 0.02). By principal component analysis (PCA), OVX Nacre group formed a cluster away from OVX group and with a trend closest to Sham group. These data were consistent with biological measurements demonstrating a positive profile related to nacre supplementation, which blunted an increase in serum CTX level and enhanced serum P1NP secretion 14 days post‐OVX compared with CaCO3 supplementation. Bmp2 mRNA expression in OVX Nacre group was +1.76‐fold (p = 0.004) and +1.30‐fold (p = 0.20) compared with OVX and OVX CaCO3 groups, respectively. We conclude that supplementation with nacre could effectively limit bone loss induced by estrogen deficiency just after OVX in rats by modulating the negative imbalance of bone turnover. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Deep-scaled fish (Osteichthyes: Actinopterygii) from the lower Permian (Cisuralian) lacustrine deposits of the Parnaíba Basin, NE Brazil

The richly fossiliferous deposits of the Brazilian Pedra de Fogo Formation originated in an extensive aquatic system in tropical Pangaea, and grade from marginal lacustrine into marine deposits at the depocenter in the western part of the Parnaíba Basin. In addition to the well-known tetrapod and macrofloral records from these deposits, the Pedra de Fogo Formation yields extensive fish fossils indicating a diverse and abundant ichthyofauna. Among the actinopterygians, deep-bodied morphotypes are represented by whole fish as well as disarticulated dermal scales found at various localities in the states of Maranhão and Piauí. The gross morphology, ornamentation, and histology of some of these scales is highly distinctive, indicating the presence of a novel taxon (Piratata rogersmithii gen. et sp. nov.). The external surface of a Piratata scale is covered in multiple round-to-slightly elongated tubercles. The scale lacks a ganoin cover and is made up of cellular bone and odontocomplexes of orthodentine composing the tuberculated scale surface. The scale morphology and ornamentation most closely resemble that of Cleithrolepis granulatus from the Triassic of Australia and Cleithrolepis extoni from the Triassic Stormberg Beds of South Africa, but the new taxon differs from previously described species in several diagnostic morphological features. The use of scale characters in the taxonomy of ray-finned fishes and the palaeogeographic, palaeoenvironmental, and geochronological implications of the new taxon are discussed.

Global Proteomics Analysis of Bone Marrow: Establishing Talin-1 and Centrosomal Protein of 55 kDa as Potential Molecular Signatures for Myelodysplastic Syndromes.

Myelodysplastic syndrome (MDS) is a hematological disorder characterized by abnormal stem cell differentiation and a high risk of acute myeloid leukemia transformation. Treatment options for MDS are still limited, making the identification of molecular signatures for MDS progression a vital task. Thus, we evaluated the proteome of bone marrow plasma from patients (n = 28) diagnosed with MDS with ring sideroblasts (MDS-RS) and MDS with blasts in the bone marrow (MDS-EB) using label-free mass spectrometry. This strategy allowed the identification of 1,194 proteins in the bone marrow plasma samples. Polyubiquitin-C (UBC), moesin (MSN), and Talin-1 (TLN1) showed the highest abundances in MDS-EB, and centrosomal protein of 55 kDa (CEP55) showed the highest relative abundance in the bone marrow plasma of MDS-RS patients. In a follow-up, in the second phase of the study, expressions of UBC, MSN, TLN1, and CEP55 genes were evaluated in bone marrow mononuclear cells from 45 patients by using qPCR. This second cohort included only seven patients from the first study. CEP55, MSN, and UBC expressions were similar in mononuclear cells from MDS-RS and MDS-EB individuals. However, TLN1 gene expression was greater in mononuclear cells from MDS-RS (p = 0.049) as compared to MDS-EB patients. Irrespective of the MDS subtype, CEP55 expression was higher (p = 0.045) in MDS patients with abnormal karyotypes, while MSN, UBC, and TALIN1 transcripts were similar in MDS with normal vs. abnormal karyotypes. In conclusion, proteomic and gene expression approaches brought evidence of altered TLN1 and CEP55 expressions in cellular and non-cellular bone marrow compartments of patients with low-risk (MDS-RS) and high-risk (MDS-EB) MDSs and with normal vs. abnormal karyotypes. As MDS is characterized by disrupted apoptosis and chromosomal alterations, leading to mitotic slippage, TLN1 and CEP55 represent potential markers for MDS prognosis and/or targeted therapy.

Peek dental implants coated with boron-doped nano-hydroxyapatites: Investigation of in-vitro osteogenic activity

BackgroundPEEK is a high-performance thermoplastic that has many potential uses in orthopaedics and dentistry, and it has been shown to be a substitute for titanium (Ti) implants. However, PEEK is an inherently inert material, and that characteristic limits its cellular adhesion and bone integration. The aim of this study is to determine a suitable surface modification method for increasing the osteogenic potential of polyetheretherketone (PEEK) implants used in periodontal applications. MethodsIn this work, a nanostructured porous surface is created on PEEK material by sulfonation, in sulfuric acid at room temperature for 20 min, and thus SPEEK samples were obtained. Then, PEEK and SPEEK samples were coated with boron (B) doped hydroxyapatite (HAp) nanoparticles (B-nHAp) precipitated from concentrated synthetic body fluid (10xSBF) by a microwave-assisted method conducted at 600 W. In vitro cell culture studies were carried out with periodontal ligament cells (PDL) on the samples. Osteogenic differentiation of PDL cells on PEEK, SPEEK and SPEEK-B-nHAp was evaluated using ALP activity assay, hydroxyproline assay, and RT-qPCR. ResultsIn vitro cell culture studies disclosed improved adhesion and proliferation of PDL cells on the SPEEK and B-nHAp coated SPEEK surfaces (SPEEK-B-nHAp). Results of these assays confirmed that treated PEEK surfaces, especially SPEEK-B-nHAp, significantly enhanced osteogenic differentiation of PDL cells in vitro compared with untreated PEEK surfaces. ConclusionHere a simple, easy to-use, and efficient modification method based on the properties of boron is proposed for increasing osteogenic potential of PEEK implants.

Experimental Validation and Evaluation of the Bending Properties of Additively Manufactured Metallic Cellular Scaffold Structures for Bone Tissue Engineering.

The availability of additive manufacturing enables the fabrication of cellular bone tissue engineering scaffolds with a wide range of structural and architectural possibilities. The purpose of bone tissue engineering scaffolds is to repair critical size bone defects due to extreme traumas, tumors, or infections. This research study presented the experimental validation and evaluation of the bending properties of optimized bone scaffolds with an elastic modulus that is equivalent to the young’s modulus of the cortical bone. The specimens were manufactured using laser powder bed fusion technology. The morphological properties of the manufactured specimens were evaluated using both dry weighing and Archimedes techniques, and minor variations in the relative densities were observed in comparison with the computer-aided design files. The bending modulus of the cubic and diagonal scaffolds were experimentally investigated using a three-point bending test, and the results were found to agree with the numerical findings. A higher bending modulus was observed in the diagonal scaffold design. The diagonal scaffold was substantially tougher, with considerably higher energy absorption before fracture. The shear modulus of the diagonal scaffold was observed to be significantly higher than the cubic scaffold. Due to bending, the pores at the top side of the diagonal scaffold were heavily compressed compared to the cubic scaffold due to the extensive plastic deformation occurring in diagonal scaffolds and the rapid fracture of struts in the tension side of the cubic scaffold. The failure in struts in tension showed signs of ductility as necking was observed in fractured struts. Moreover, the fractured surface was observed to be rough and dull as opposed to being smooth and bright like in brittle fractures. Dimple fracture was observed using scanning electron microscopy as a result of microvoids emerging in places of high localized plastic deformation. Finally, a comparison of the mechanical properties of the studied BTE scaffolds with the cortical bone properties under longitudinal and transverse loading was investigated. In conclusion, we showed the capabilities of finite element analysis and additive manufacturing in designing and manufacturing promising scaffold designs that can replace bone segments in the human body.

TIM3/CEACAM1 pathway involves in myeloid-derived suppressor cells induced CD8+ T cells exhaustion and bone marrow inflammatory microenvironment in myelodysplastic syndrome.

Myeloid-derived suppressor cells (MDSC) induced cellular immune deficiency and bone marrow inflammatory microenvironment play an important role in the pathogenesis and progression of myelodysplastic syndrome (MDS), but the underlying mechanism remains unclear. Here, we revealed that immune checkpoint protein TIM3 and CEACAM1 were highly demonstrated on MDSC and CD8+ T cells in MDS patients. CD8+ T cells were reduced in number and function and presented a exhaustion state. The levels of pro-inflammatory cytokines (IL-1β, IL-18) and CEACAM1 were raised in bone marrow supernatants and MDSC culture supernatants. Blocking or neutralizing TIM3/CEACAM1 and IL-1β/IL-18 partially reversed exhaustion of CD8+ T cells. Moreover, TIM3 correlated with NF-κB /NLRP3 inflammatory pathway. The levels of NF-κB/NLRP3/Caspase-1/IL-1β and IL-18 were all increased in MDSC of MDS. Co-culturing MDSC from MDS patients with rhCEACAM1 enhanced NF-κB/NLRP3/Caspase-1/IL-1β and IL-18 levels, whereas blocking TIM3 could partially reverse the above manifestations. These results indicated that TIM3/CEACAM1 pathway involved in CD8+ T cells exhaustion and might activate the NF-κB/NLRP3/Caspase-1 pathway in MDSC, increasing pro-inflammatory cytokines secretion in MDS bone marrow microenvironment. This study provided a basis for applying immune checkpoint inhibitors that could simultaneously modulate pro-inflammatory cytokine secretion and enhance anti-tumour immune function in the treatment of MDS.

Central ossifying fibroma of mandible arising in association with cemento-osseous dysplasia. An unusual case presentation

<h3>Introduction</h3> Cemento-osseous dysplasia (COD) is known to develop complications including infection, necrosis, and traumatic bone cysts [1]. Neoplastic occurrence with COD has been reported, but is rare [2,3]. We report an unusual case of central ossifying fibroma (COF) of the mandibular symphysis in association with COD in a 46-yearold black female. <h3>Case Description</h3> The patient presented with a mandibular symphysis mass that was associated with difficulty of eating, speaking and paresthesia. The radiographic images showed a predominantly radiopaque mass in the symphysis region, measuring 7 × 6 × 5cm. There were discrete, minimally expansile mixed radiolucentopaque lesions in the posterior mandible and maxilla. The patient underwent mandibular resection due to the symptoms of eating and speaking difficulties as well as paresthesia. Before resection, three incisional biopsies including bilateral posterior regions of mandible and the central mass. Histopathologic examination of posterior specimens revealed similar findings of fragments consisting of cellular fibroblastic tissue intermixed with short bone spicules and cementum-like and hemorrhagic deposits associated with traumatic bone cysts. However, the central specimen showed solid tumor consisting of fibroblastic proliferation supporting spindled fibroblast-like cells. It supported cellular bone trabeculae as well as spherical cementum-like calcified deposits. This framework is interspersed with spaces lined by fibrovascular tissue supporting eosinophilic osteoid, consistent with traumatic bone cysts. <h3>Discussion</h3> COD lacks genetic abnormalities noted in fibrous dysplasia or neoplastic fibro-osseous lesions. We present an unusual association of COF with florid COD. This association has been previously reported in a patient who developed COF with COD and odontoma, and in another who developed peripheral osteoma, odontoma, COF and COD [2,3]. To the best of our knowledge, this presentation describes only the third case report of the association of COF and COD. The co-existence of COF and COD in these cases is unclear, but seems to be very rare.

Impact of the Endocannabinoid System on Bone Formation and Remodeling in p62 KO Mice.

Several studies have shown that the G-protein coupled cannabinoid receptor CB2 and its interaction partner p62 are molecularly involved in bone remodeling processes. Pharmacological activation of the CB2 receptor enhanced bone volume in postmenopausal osteoporosis and arthritis models in rodents, whereas knockout or mutation of the p62 protein in aged mice led to Paget’s disease of bone-like conditions. Studies of pharmacological CB2 agonist effects on bone metabolism in p62 KO mice have not been performed to date. Here, we assessed the effect of the CB2-specific agonist JWH133 after a short-term (5 days in 3-month-old mice) or long-term (4 weeks in 6-month-old mice) treatment on structural, dynamic, and cellular bone morphometry obtained by μCT of the femur and histomorphometry of the vertebral bodies in p62 KO mice and their WT littermates in vivo. A genotype-independent stimulatory effect of CB2 on bone formation, trabecular number, and trabecular thickness after short-term treatment and on tissue mineral density after long-term treatment was detected, indicating a weak osteoanabolic function of this CB2 agonist. Moreover, after short-term systemic CB2 receptor activation, we found significant differences at the cellular level in the number of osteoblasts and osteoclasts only in p62 KO mice, together with a weak increase in trabecular number and a decrease in trabecular separation. Long-term treatment showed an opposite JWH133 effect on osteoclasts in WT versus p62 KO animals and decreased cortical thickness only in treated p62 KO mice. Our results provide new insights into CB2 receptor signaling in vivo and suggest that CB2 agonist activity may be regulated by the presence of its macromolecular binding partner p62.