GPNMB enhances bone regeneration by promoting angiogenesis and osteogenesis: potential role for tissue engineering bone

Endogenous dual-responsive and self-adaptive silk fibroin-based scaffold with enhancement of immunomodulation for skull regeneration

Despite the current biomaterials (e.g. titanium mesh and polyether ether ketone) have been applied to clinical skull repair, the limitations on mechanical match, shape adaptability, bioactivity and osteointegration have greatly limited their clinical application. In this work, we constructed a water and inflammatory microenvironment dual-responsive self-adaptive silk fibroin-magnesium oxide-based scaffold with the matrix metalloproteinase-2-responsive gelatin-methacryloyl-interleukin-4 (IL-4) coating, which presented good mechanical compliance, quickly shape matching and intraoperative reprocessability. With the capability of responding to an acute inflammation microenvironment followed by a triggered on-demand release of the IL-4, the combination of immunoactive IL-4 and Mg2+ co-ordinately facilitated metabolic reprogramming by suppressing glycolysis, promoting mitochondrial oxidative phosphorylation and modulating adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathways in macrophages, resulting in significantly facilitating M2 macrophage activation. During the stage of tissue remodelling, the sustained release of Mg2+ further promoted macrophage M2 polarization and the expression of anti-inflammatory cytokines, significantly reduced immune response and improved ectopic osteogenesis ability. Meanwhile, the cranial defect models of male rats demonstrated that this scaffold could significantly enhance biomineralized deposition and vascularisation, and achieve good bone regeneration of cranial defects. Overall, the bioactive scaffold provides a promising biomaterial and alternative repair strategy for critical-size skull defect repair.

GPNMB disrupts SNARE complex assembly to maintain bacterial proliferation within macrophages

Xenophagy plays a crucial role in restraining the growth of intracellular bacteria in macrophages. However, the machinery governing autophagosome‒lysosome fusion during bacterial infection remains incompletely understood. Here, we utilize leprosy, an ideal model for exploring the interactions between host defense mechanisms and bacterial infection. We highlight the glycoprotein nonmetastatic melanoma protein B (GPNMB), which is highly expressed in macrophages from lepromatous leprosy (L-Lep) patients and interferes with xenophagy during bacterial infection. Upon infection, GPNMB interacts with autophagosomal-localized STX17, leading to a reduced N-glycosylation level at N296 of GPNMB. This modification promotes the degradation of SNAP29, thus preventing the assembly of the STX17-SNAP29-VAMP8 SNARE complex. Consequently, the fusion of autophagosomes with lysosomes is disrupted, resulting in inhibited cellular autophagic flux. In addition to Mycobacterium leprae, GPNMB deficiency impairs the proliferation of various intracellular bacteria in human macrophages, suggesting a universal role of GPNMB in intracellular bacterial infection. Furthermore, compared with their counterparts, Gpnmbfl/fl Lyz2-Cre mice presented decreased Mycobacterium marinum amplification. Overall, our study reveals a previously unrecognized role of GPNMB in host antibacterial defense and provides insights into its regulatory mechanism in SNARE complex assembly.

Malignant mesothelioma-associated inflammatory microenvironment promotes tumor progression via GPNMB

BACKGROUND

Tumor-Associated Macrophages (TAMs) are the main immune component of the tumor stroma with heterogeneous functional activities, predominantly suppressing the immune response and promoting tumor progression, also via secretion of different factors. Among these, GPNMB (Glycoprotein non-metastatic B) is usually associated with disease progression in several tumor types. Malignant pleural mesothelioma (MPM) a severe neoplasia with poor prognosis, is characterized by an abundancy of TAMs, testifying the presence of a long-lasting inflammation which is pathogenetic of the disease. However, the role of GPNMB in MPM is unclear.

METHODS

Clinical samples from patients with MPM were used to measure RNA and protein levels of GPNMB. The functional role of GPNMB in vivo was studied in an orthotopic mouse model of mesothelioma using the murine cell lines AB1 and AB22. Experiments included in vivo tumor growth in wild type and in GPNMB-deficient mice and blocking of GPNMB-induced signaling with anti-CD44 antibodies.

RESULTS

We show that in human and murine MPM tissues the protein GPNMB is mainly produced by infiltrating TAMs. Gpnmb RNA levels in MPM patients from TCGA are significantly associated with lower survival. Using an orthotopic mouse model of mesothelioma we observed that in GPNMB-defective mice (DBA2/J mice) unable to produce the protein, tumors formed by AB1 and AB22 mesothelioma cells grow significantly less than in GPNMB-proficient mice (DBA2/J-Gpnmb+ mice), indicating that host GPNMB is involved in tumor progression. Likewise, the ectopic expression of GPNMB in AB1 and AB22 cells causes an acceleration of tumor growth in vivo, significantly different compared to mock-transduced cells. Treatment of tumor-bearing mice with blocking anti-CD44 (a major receptor for GPNMB) results in a significant reduction of tumor growth.

CONCLUSIONS

Overall, these results indicate that the protein GPNMB, a product and marker gene of TAMs, is a driver of mesothelioma progression and may constitute a promising therapeutic target.

Mechanically robust and personalized silk fibroin-magnesium composite scaffolds with water-responsive shape-memory for irregular bone regeneration

The regeneration of critical-size bone defects, especially those with irregular shapes, remains a clinical challenge. Various biomaterials have been developed to enhance bone regeneration, but the limitations on the shape-adaptive capacity, the complexity of clinical operation, and the unsatisfied osteogenic bioactivity have greatly restricted their clinical application. In this work, we construct a mechanically robust, tailorable and water-responsive shape-memory silk fibroin/magnesium (SF/MgO) composite scaffold, which is able to quickly match irregular defects by simple trimming, thus leading to good interface integration. We demonstrate that the SF/MgO scaffold exhibits excellent mechanical stability and structure retention during the degradative process with the potential for supporting ability in defective areas. This scaffold further promotes the proliferation, adhesion and migration of osteoblasts and the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. With suitable MgO content, the scaffold exhibits good histocompatibility, low foreign-body reactions (FBRs), significant ectopic mineralisation and angiogenesis. Skull defect experiments on male rats demonstrate that the cell-free SF/MgO scaffold markedly enhances bone regeneration of cranial defects. Taken together, the mechanically robust, personalised and bioactive scaffold with water-responsive shape-memory may be a promising biomaterial for clinical-size and irregular bone defect regeneration.

Ethnic Variations in the Levels of Bone Biomarkers (Osteoprostegerin, Receptor Activator of Nuclear Factor Kappa-Β Ligand and Glycoprotein Non-Metastatic Melanoma Protein B) in People with Type 2 Diabetes

The global incidence of Type 2 diabetes (T2D) is on the rise, fueled by factors such as obesity, sedentary lifestyles, socio-economic factors, and ethnic backgrounds. T2D is a multifaceted condition often associated with various health complications, including adverse effects on bone health. This study aims to assess key biomarkers linked to bone health and remodeling-Osteoprotegerin (OPG), Receptor Activator of Nuclear Factor Kappa-Β Ligand (RANKL), and Glycoprotein Non-Metastatic Melanoma Protein B (GPNMB)-among individuals with diabetes while exploring the impact of ethnicity on these biomarkers. A cross-sectional analysis was conducted on a cohort of 2083 individuals from diverse ethnic backgrounds residing in Kuwait. The results indicate significantly elevated levels of these markers in individuals with T2D compared to non-diabetic counterparts, with OPG at 826.47 (405.8) pg/mL, RANKL at 9.25 (17.3) pg/mL, and GPNMB at 21.44 (7) ng/mL versus 653.75 (231.7) pg/mL, 0.21 (9.94) pg/mL, and 18.65 (5) ng/mL in non-diabetic individuals, respectively. Notably, this elevation was consistent across Arab and Asian populations, except for lower levels of RANKL observed in Arabs with T2D. Furthermore, a positive and significant correlation between OPG and GPNMB was observed regardless of ethnicity or diabetes status, with the strongest correlation (r = 0.473, p < 0.001) found among Arab individuals with T2D. Similarly, a positive and significant correlation between GPNMB and RANKL was noted among Asian individuals with T2D (r = 0.401, p = 0.001). Interestingly, a significant inverse correlation was detected between OPG and RANKL in non-diabetic Arab individuals. These findings highlight dysregulation in bone remodeling markers among individuals with T2D and emphasize the importance of considering ethnic variations in T2D-related complications. The performance of further studies is warranted to understand the underlying mechanisms and develop interventions based on ethnicity for personalized treatment approaches.

Recent progress in bone-repair strategies in diabetic conditions

Bone regeneration following trauma, tumor resection, infection, or congenital disease is challenging. Diabetes mellitus (DM) is a metabolic disease characterized by hyperglycemia. It can result in complications affecting multiple systems including the musculoskeletal system. The increased number of diabetes-related fractures poses a great challenge to clinical specialties, particularly orthopedics and dentistry. Various pathological factors underlying DM may directly impair the process of bone regeneration, leading to delayed or even non-union of fractures. This review summarizes the mechanisms by which DM hampers bone regeneration, including immune abnormalities, inflammation, reactive oxygen species (ROS) accumulation, vascular system damage, insulin/insulin-like growth factor (IGF) deficiency, hyperglycemia, and the production of advanced glycation end products (AGEs). Based on published data, it also summarizes bone repair strategies in diabetic conditions, which include immune regulation, inhibition of inflammation, reduction of oxidative stress, promotion of angiogenesis, restoration of stem cell mobilization, and promotion of osteogenic differentiation, in addition to the challenges and future prospects of such approaches.

Spatiotemporal Immunomodulation and Biphasic Osteo-Vascular Aligned Electrospun Membrane for Diabetic Periosteum Regeneration

Under diabetic conditions, blood glucose fluctuations and exacerbated immunopathological inflammatory environments pose significant challenges to periosteal regenerative repair strategies. Responsive immune regulation in damaged tissues is critical for the immune microenvironment, osteogenesis, and angiogenesis stabilization. Considering the high-glucose microenvironment of such acute injury sites, a functional glucose-responsive immunomodulation-assisted periosteal regeneration composite material-PLA（Polylactic Acid）/COLI(Collagen I）/Lipo(Liposome）-APY29 (PCLA)-is constructed. Aside from stimulating osteogenic differentiation, owing to the presence of surface self-assembled type I collagen in the scaffolds, PCLA can directly respond to focal area high-glucose microenvironments. The PCLA scaffolds trigger the release of APY29-loaded liposomes, shifting the macrophages toward the M2 phenotype, inhibiting the release of inflammatory cytokines, improving the bone immune microenvironment, and promoting osteogenic differentiation and angiogenesis. Bioinformatics analyses show that PCLA enhances bone repair by inhibiting the inflammatory signal pathway regulating the polarization direction and promoting osteogenic and angiogenic gene expression. In the calvarial periosteal defect model of diabetic rats, PCLA scaffolds induce M2 macrophage polarization and improve the inflammatory microenvironment, significantly accelerating periosteal repair. Overall, the PCLA scaffold material regulates immunity in fluctuating high-glucose inflammatory microenvironments, achieves relatively stable and favorable osteogenic microenvironments, and facilitates the effective design of functionalized biomaterials for bone regeneration therapy in patients with diabetes.

Polysaccharide-Based Composite Hydrogel with Hierarchical Microstructure for Enhanced Vascularization and Skull Regeneration

Critical-size skull defects caused by trauma, infection, and tumor resection raise great demands for efficient bone substitutes. Herein, a hybrid cross-linked hierarchical microporous hydrogel scaffold (PHCLS) was successfully assembled by a multistep procedure, which involved (i) the preparation of poly(lactic-co-glycolic)/nanohydroxyapatite (PLGA-HAP) porous microspheres, (ii) embedding the spheres in a solution of dopamine-modified hyaluronic acid and collagen I (Col I) and cross-linking via dopamine polyphenols binding to (i) Col I amino groups (via Michael addition) and (ii) PLGA-HAP (via calcium ion chelation). The introduction of PLGA-HAP not only improved the diversity of pore size and pore communication inside the matrix but also greatly enhanced the compressive strength (5.24-fold, 77.5 kPa) and degradation properties to construct a more stable mechanical structure. In particular, the PHCLS (200 mg, nHAP) promoted the proliferation, infiltration, and angiogenic differentiation of bone marrow mesenchymal stem cells in vitro, as well as significant ectopic angiogenesis and mineralization with a storage modulus enhancement of 2.5-fold after 30 days. Meanwhile, the appropriate matrix microenvironment initiated angiogenesis and early osteogenesis by accelerating endogenous stem cell recruitment in situ. Together, the PHCLS allowed substantial skull reconstruction in the rabbit cranial defect model, achieving 85.2% breaking load strength and 84.5% bone volume fractions in comparison to the natural cranium, 12 weeks after implantation. Overall, this study reveals that the hierarchical microporous hydrogel scaffold provides a promising strategy for skull defect treatment.

Hollow Hydroxyapatite Microspheres Loaded with rhCXCL13 to Recruit BMSC for Osteogenesis and Synergetic Angiogenesis to Promote Bone Regeneration in Bone Defects

Introduction

Bone tissue engineering is a promising method to treat bone defects. However, the current methods of preparing composite materials that mimic the complex structure and biological activity of natural bone are challenging for recruitment of bone marrow mesenchymal stem cells (BMSCs), which affects the application of these materials in situ bone regeneration. Hollow hydroxyapatite microspheres (HHMs) possess a natural porous bone structure, good adsorption, and slow release of chemokines, but have low ability to recruit BMSCs and induce osteogenesis. In this study, The HHM/chitosan (CS) and recombinant human C-X-C motif chemokine ligand 13 (rhCXCL13)-HHM/CS biomimetic scaffolds that optimize bone regeneration and investigated their mechanism of BMSC recruitment and osteogenesis through cell and animal experiments and transcriptomic sequencing.

Methods

Evaluate the physical characteristics of the HHM/CS and rhCXCL13-HHM/CS biomimetic scaffolds through Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and the cumulative release curve of rhCXCL13. Transwell migration experiments and co-culture with BMSCs were conducted to study the recruitment ability and osteogenic differentiation of the scaffolds. Transcriptomic sequencing was performed to analyze the osteogenic differentiation mechanism. The osteogenesis and bone healing performance were evaluated using a rabbit radial defect model.

Results

SEM demonstrated that the rhCXCL13-HHM/CS scaffold comprised hydroxyapatite microspheres in a porous three-dimensional network. The rhCXCL13 showed excellent sustained release capability. The rhCXCL13-HHM/CS scaffold could recruit BMSCs and induce bone regeneration. Transcriptome sequencing and experimental results showed that the osteogenesis mechanism of rhCXCL13-HHM/CS was through the PI3K-AKT pathway. In vivo, the rhCXCL13-HHM/CS scaffold significantly promoted osteogenesis and angiogenesis at 12 weeks after surgery.

Conclusion

The rhCXCL13-HHM/CS scaffold demonstrates excellent potential for BMSC recruitment, osteogenesis, vascularized tissue-engineered bone reconstruction, and drug delivery, providing a theoretical basis for material osteogenesis mechanism study and promising clinical applications for treating large bone defects.

Current concepts of microRNA-mediated regulatory mechanisms in human pulp tissue-derived stem cells: a snapshot in the regenerative dentistry

One of the most studied class of non-coding RNAs is microRNAs (miRNAs) which regulate more than 60% of human genes. A network of miRNA gene interactions participates in stem cell self-renewal, proliferation, migration, apoptosis, immunomodulation, and differentiation. Human pulp tissue-derived stem cells (PSCs) are an attractive source of dental mesenchymal stem cells (MSCs) which comprise human dental pulp stem cells (hDPSCs) obtained from the dental pulp of permanent teeth and stem cells isolated from exfoliated deciduous teeth (SHEDs) that would be a therapeutic opportunity in stomatognathic system reconstruction and repair of other damaged tissues. The regenerative capacity of hDPSCs and SHEDs is mediated by osteogenic, odontogenic, myogenic, neurogenic, angiogenic differentiation, and immunomodulatory function. Multi-lineage differentiation of PSCs can be induced or inhibited by the interaction of miRNAs with their target genes. Manipulating the expression of functional miRNAs in PSCs by mimicking miRNAs or inhibiting miRNAs emerged as a therapeutic tool in the clinical translation. However, the effectiveness and safety of miRNA-based therapeutics, besides higher stability, biocompatibility, less off-target effects, and immunologic reactions, have received particular attention. This review aimed to comprehensively overview the molecular mechanisms underlying miRNA-modified PSCs as a futuristic therapeutic option in regenerative dentistry.

Preclinical Study of Human Bone Marrow-Derived Mesenchymal Stem Cells Using a 3-Dimensional Manufacturing Setting for Enhancing Spinal Fusion

Spinal fusion surgery is a surgical technique that connects one or more vertebrae at the same time to prevent movement between the vertebrae. Although synthetic bone substitutes or osteogenesis-inducing recombinant proteins were introduced to promote bone union, the rate of revision surgery is still high due to pseudarthrosis. To promote successful fusion after surgery, stem cells with or without biomaterials were introduced; however, conventional 2D-culture environments have resulted in a considerable loss of the innate therapeutic properties of stem cells. Therefore, we conducted a preclinical study applying 3D-spheroids of human bone marrow-dewrived mesenchymal stem cells (MSCs) to a mouse spinal fusion model. First, we built a large-scale manufacturing platform for MSC spheroids, which is applicable to good manufacturing practice (GMP). Comprehensive biomolecular examinations, which include liquid chromatography-mass spectrometry and bioinformatics could suggest a framework of quality control (QC) standards for the MSC spheroid product regarding the identity, purity, viability, and potency. In our animal study, the mass-produced and quality-controlled MSC spheroids, either undifferentiated or osteogenically differentiated were well-integrated into decorticated bone of the lumbar spine, and efficiently improved angiogenesis, bone regeneration, and mechanical stability with statistical significance compared to 2D-cultured MSCs. This study proposes a GMP-applicable bioprocessing platform and QC directions of MSC spheroids aiming for their clinical application in spinal fusion surgery as a new bone graft substitute.

GPNMB: a potent inducer of immunosuppression in cancer

The immune system is comprised of both innate and adaptive immune cells, which, in the context of cancer, collectively function to eliminate tumor cells. However, tumors can actively sculpt the immune landscape to favor the establishment of an immunosuppressive microenvironment, which promotes tumor growth and progression to metastatic disease. Glycoprotein-NMB (GPNMB) is a transmembrane glycoprotein that is overexpressed in a variety of cancers. It can promote primary tumor growth and metastasis, and GPNMB expression correlates with poor prognosis and shorter recurrence-free survival in patients. There is growing evidence supporting an immunosuppressive role for GPNMB in the context of malignancy. This review provides a description of the emerging roles of GPNMB as an inducer of immunosuppression, with a particular focus on its role in mediating cancer progression by restraining pro-inflammatory innate and adaptive immune responses.

Downregulation of glycoprotein non-metastatic melanoma protein B prevents high glucose-induced angiogenesis in diabetic retinopathy

Diabetic retinopathy (DR), a microvascular complication characterized by abnormal angiogenesis, is the most common reason for irreversible blindness. Glycoprotein non-metastatic melanoma protein B (GPNMB), as a transmembrane protein, was found to be associated with angiogenesis. This study aims to investigate the role of GPNMB in DR. The levels of GPNMB and Integrin β1 were detected by real-time PCR and western blot and were found to be increased in human retinal microvascular endothelial cells (HRMECs) with high glucose (HG, 25 mmol/L) treatment. Knockdown of GPNMB was mediated by lentivirus carrying shRNA targeting GPNMB in vivo and in vitro. Functional experiments, including cell counting kit-8 (CCK-8), scratch, and tube formation assays, showed the anti-proliferative, anti-migrative, and anti-angiogenic roles of GPNMB knockdown in HRMECs using the lentivirus system following HG challenge. Additionally, increased GPNMB levels were detected in the retina of DR rats induced by a single intraperitoneal injection of streptozotocin (60 mg/kg) using real-time PCR, western blot, and immunofluorescence assays. Downregulation of GPNMB inhibited the angiogenesis and vascular endothelial growth factor production in the retina of rats with DR. Furthermore, overexpression of Integrin β1 led to increased angiogenesis in DR. Integrin β1 was indicated as a target protein of GPNMB. Upregulated-Integrin β1 restored GPNMB knockdown-induced inhibition of cell viability, migration, and tube formation in HRMECs. In conclusion, we provide evidence for the angiogenic role of GPNMB and demonstrate that silencing GPNMB may represent a therapeutic potential in the treatment of DR.

An instantly fixable and self-adaptive scaffold for skull regeneration by autologous stem cell recruitment and angiogenesis

Limited stem cells, poor stretchability and mismatched interface fusion have plagued the reconstruction of cranial defects by cell-free scaffolds. Here, we designed an instantly fixable and self-adaptive scaffold by dopamine-modified hyaluronic acid chelating Ca²⁺ of the microhydroxyapatite surface and bonding type I collagen to highly simulate the natural bony matrix. It presents a good mechanical match and interface integration by appropriate calcium chelation, and responds to external stress by flexible deformation. Meanwhile, the appropriate matrix microenvironment regulates macrophage M2 polarization and recruits endogenous stem cells. This scaffold promotes the proliferation and osteogenic differentiation of BMSCs in vitro, as well as significant ectopic mineralization and angiogenesis. Transcriptome analysis confirmed the upregulation of relevant genes and signalling pathways was associated with M2 macrophage activation, endogenous stem cell recruitment, angiogenesis and osteogenesis. Together, the scaffold realized 97 and 72% bone cover areas after 12 weeks in cranial defect models of rabbit (Φ = 9 mm) and beagle dog (Φ = 15 mm), respectively.

Limited stem cells and mismatched interface fusion have plagued biomaterial-mediated cranial reconstruction. Here, the authors engineer an instantly fixable and self-adaptive scaffold to promote calcium chelation and interface integration, regulate macrophage M2 polarization, and recruit endogenous stem cells.

GPNMB Extracellular Fragment Protects Melanocytes from Oxidative Stress by Inhibiting AKT Phosphorylation Independent of CD44

Glycoprotein non-metastatic melanoma protein B (GPNMB) is a type I transmembrane glycoprotein that plays an important role in cancer metastasis and osteoblast differentiation. In the skin epidermis, GPNMB is mainly expressed in melanocytes and plays a critical role in melanosome formation. In our previous study, GPNMB was also found to be expressed in skin epidermal keratinocytes. In addition, decreased GPNMB expression was observed in the epidermis of lesional skin of patients with vitiligo. However, the exact role of keratinocyte-derived GPNMB and its effect on vitiligo is still unknown. In this study, we demonstrated that GPNMB expression was also decreased in rhododendrol-induced leukoderma, as seen in vitiligo. The extracellular soluble form of GPNMB (sGPNMB) was found to protect melanocytes from cytotoxicity and the impairment of melanogenesis induced by oxidative stress. Furthermore, the effect of rGPNMB was not altered by the knockdown of CD44, which is a well-known receptor of GPNMB, but accompanied by the suppressed phosphorylation of AKT but not ERK, p38, or JNK. In addition, we found that oxidative stress decreased both transcriptional GPNMB expression and sGPNMB protein expression in human keratinocytes. Our results suggest that GPNMB might provide novel insights into the mechanisms related to the pathogenesis of vitiligo and leukoderma.

SARS-CoV-2 Infects Endothelial Cells In Vivo and In Vitro

SARS-CoV-2 infection can cause fatal inflammatory lung pathology, including thrombosis and increased pulmonary vascular permeability leading to edema and hemorrhage. In addition to the lung, cytokine storm-induced inflammatory cascade also affects other organs. SARS-CoV-2 infection-related vascular inflammation is characterized by endotheliopathy in the lung and other organs. Whether SARS-CoV-2 causes endotheliopathy by directly infecting endothelial cells is not known and is the focus of the present study. We observed 1) the co-localization of SARS-CoV-2 with the endothelial cell marker CD31 in the lungs of SARS-CoV-2-infected mice expressing hACE2 in the lung by intranasal delivery of adenovirus 5-hACE2 (Ad5-hACE2 mice) and non-human primates at both the protein and RNA levels, and 2) SARS-CoV-2 proteins in endothelial cells by immunogold labeling and electron microscopic analysis. We also detected the co-localization of SARS-CoV-2 with CD31 in autopsied lung tissue obtained from patients who died from severe COVID-19. Comparative analysis of RNA sequencing data of the lungs of infected Ad5-hACE2 and Ad5-empty (control) mice revealed upregulated KRAS signaling pathway, a well-known pathway for cellular activation and dysfunction. Further, we showed that SARS-CoV-2 directly infects mature mouse aortic endothelial cells (AoECs) that were activated by performing an aortic sprouting assay prior to exposure to SARS-CoV-2. This was demonstrated by co-localization of SARS-CoV-2 and CD34 by immunostaining and detection of viral particles in electron microscopic studies. Moreover, the activated AoECs became positive for ACE-2 but not quiescent AoECs. Together, our results indicate that in addition to pneumocytes, SARS-CoV-2 also directly infects mature vascular endothelial cells in vivo and ex vivo, which may contribute to cardiovascular complications in SARS-CoV-2 infection, including multipleorgan failure.

Endothelial cell infection and dysfunction, immune activation in severe COVID-19

Rationale: Pulmonary vascular endotheliitis, perivascular inflammation, and immune activation are observed in COVID-19 patients. While the initial SARS-CoV-2 infection mainly infects lung epithelial cells, whether it also infects endothelial cells (ECs) and to what extent SARS-CoV-2-mediated pulmonary vascular endotheliitis is associated with immune activation remain to be determined. Methods: To address these questions, we studied SARS-CoV-2-infected K18-hACE2 (K18) mice, a severe COVID-19 mouse model, as well as lung samples from SARS-CoV-2-infected nonhuman primates (NHP) and patient deceased from COVID-19. We used immunostaining, RNAscope, and electron microscopy to analyze the organs collected from animals and patient. We conducted bulk and single cell (sc) RNA-seq analyses, and cytokine profiling of lungs or serum of the severe COVID-19 mice. Results: We show that SARS-CoV-2-infected K18 mice develop severe COVID-19, including progressive body weight loss and fatality at 7 days, severe lung interstitial inflammation, edema, hemorrhage, perivascular inflammation, systemic lymphocytopenia, and eosinopenia. Body weight loss in K18 mice correlated with the severity of pneumonia, but not with brain infection. We also observed endothelial activation and dysfunction in pulmonary vessels evidenced by the up-regulation of VCAM1 and ICAM1 and the downregulation of VE-cadherin. We detected SARS-CoV-2 in capillary ECs, activation and adhesion of platelets and immune cells to the vascular wall of the alveolar septa, and increased complement deposition in the lungs, in both COVID-19-murine and NHP models. We also revealed that pathways of coagulation, complement, K-ras signaling, and genes of ICAM1 and VCAM1 related to EC dysfunction and injury were upregulated, and were associated with massive immune activation in the lung and circulation. Conclusion: Together, our results indicate that SARS-CoV-2 causes endotheliitis via both infection and infection-mediated immune activation, which may contribute to the pathogenesis of severe COVID-19 disease.

Flexible Mixture Model Approaches That Accommodate Footprint Size Variability for Robust Detection of Balancing Selection

Long-term balancing selection typically leaves narrow footprints of increased genetic diversity, and therefore most detection approaches only achieve optimal performances when sufficiently small genomic regions (i.e., windows) are examined. Such methods are sensitive to window sizes and suffer substantial losses in power when windows are large. Here, we employ mixture models to construct a set of five composite likelihood ratio test statistics, which we collectively term B statistics. These statistics are agnostic to window sizes and can operate on diverse forms of input data. Through simulations, we show that they exhibit comparable power to the best-performing current methods, and retain substantially high power regardless of window sizes. They also display considerable robustness to high mutation rates and uneven recombination landscapes, as well as an array of other common confounding scenarios. Moreover, we applied a specific version of the B statistics, termed B2, to a human population-genomic data set and recovered many top candidates from prior studies, including the then-uncharacterized STPG2 and CCDC169-SOHLH2, both of which are related to gamete functions. We further applied B2 on a bonobo population-genomic data set. In addition to the MHC-DQ genes, we uncovered several novel candidate genes, such as KLRD1, involved in viral defense, and SCN9A, associated with pain perception. Finally, we show that our methods can be extended to account for multiallelic balancing selection and integrated the set of statistics into open-source software named BalLeRMix for future applications by the scientific community.

Comparison of Serum Pharmacodynamic Biomarkers in Prednisone-Versus Deflazacort-Treated Duchenne Muscular Dystrophy Boys

Prednisone (Pred) and Deflazacort (Dfz) are commonly used glucocorticoids (GCs) for Duchenne muscular dystrophy (DMD) treatment and management. While GCs are known to delay the loss of ambulation and motor abilities, chronic use can result in onerous side effects, e.g., weight gain, growth stunting, loss of bone density, etc. Here, we use the CINRG Duchenne natural history study to gain insight into comparative safety of Pred versus Dfz treatment through GC-responsive pharmacodynamic (PD) biomarkers. Longitudinal trajectories of SOMAscan® protein data obtained on serum of DMD boys aged 4 to 10 (Pred: n = 7; Dfz: n = 8) were analyzed after accounting for age and time on treatment. Out of the pre-specified biomarkers, seventeen candidate proteins were differentially altered between the two drugs (p < 0.05). These include IGFBP-2 and AGER associated with diabetes complications, and MMP-3 associated with extracellular remodeling. As a follow-up, IGFBP-2, MMP-3, and IGF-I were quantified with an ELISA using a larger sample size of DMD biosamples (Dfz: n = 17, Pred: n = 12; up to 76 sera samples) over a longer treatment duration. MMP-3 and IGFBP-2 validated the SOMAscan® signal, however, IGF-I did not. This study identified GC-responsive biomarkers, some associated with safety, that highlight differential PD response between Dfz and Pred.

Cycloastragenol prevents age-related bone loss: Evidence in d-galactose-treated and aged rats

BACKGROUND AND AIMS

Aging-induced bone loss is a multifactorial, age-related, and progressive phenomenon among the general population and may further progress to osteoporosis and increase the risk of fractures. Cycloastragenol (CAG), currently the only compound reported that activates human telomerase, is thought to be able to alleviate or delay the symptoms of aging and chronic diseases. Previous research has suggested that CAG may have the potential to alleviate age-related bone loss. However, to date, no research has specifically focused on this aspect. In this study, we aimed to investigate whether CAG could prevent senile osteoporosis, and further reveal its underlying mechanism.

METHODS

CAG treatment was administrated into two bone loss rat models (D-galactose administration and aging) for 20 weeks and 33 weeks, respectively. Serum biomarkers analyses, bone biomechanical tests, micro-computed tomography assessment, and bone histomorphometry analyses were performed on the bone samples collected at the endpoint, to determine whether CAG could prevent or alleviate age-related bone loss. Proteomic analysis was performed to reveal the changes in protein profiles of the bones, and western blot was used to further verify the identity of the key proteins. The viability, osteoblastic differentiation, and mineralization of MC3T3-E1 cells were also evaluated after CAG treatment in vitro.

RESULTS

The results suggest that CAG treatment improves bone formation, reduces osteoclast number, alleviates the degradation of bone microstructure, and enhances bone biomechanical properties in both d-galactose- and aging-induced bone loss models. CAG treatment promotes viability, osteoblastic differentiation, and mineralization in MC3T3-E1 cells. Proteomic and western blot analyses revealed that CAG treatment increases osteoactivin (OA) expression to alleviate bone loss.

CONCLUSION

The results revealed that CAG alleviates age-related bone loss and improves bone microstructure and biomechanical properties. This may due to CAG-induced increase in OA expression. In addition, the results support preclinical investigations of CAG as a potential therapeutic medicine for the treatment of senile osteoporosis.

Glycoprotein nonmetastatic melanoma protein B: A key mediator and an emerging therapeutic target in autoimmune diseases

The glycoprotein nonmetastatic melanoma protein B (GPNMB, also known as osteoactivin) is highly expressed in many cell types and regulates the homeostasis in various tissues. In different physiological contexts, it functions as a melanosome-associated protein, membrane-bound surface receptor, soluble ligand, or adhesion molecule. Therefore, GPNMB is involved in cell differentiation, migration, inflammation, metabolism, and neuroprotection. Because of its various involvement in different physiological conditions, GPNMB has been implicated in many diseases, including cancer, neurological disorders, and more recently immune-mediated diseases. This review summarizes the regulation and function of GPNMB in normal physiology, and discusses the involvement of GPNMB in disease conditions with a particular focus on its potential role and therapeutic implications in autoimmunity.

Transgenic Overexpression of GPNMB Protects Against MPTP-Induced Neurodegeneration

Parkinson's disease (PD) is a progressive neurodegenerative disease highlighted by a marked loss of dopaminergic cell loss and motor disturbances. Currently, there are no drugs that slow the progression of the disease. A myriad of factors have been implicated in the pathogenesis and progression of PD including neuroinflammation. Although anti-inflammatory agents are being evaluated as potential disease-modifying therapies for PD, none has proven effective to date, suggesting that new and novel targets are needed. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a transmembrane glycoprotein that has recently been shown to reduce inflammation in astrocytes and to be increased in post-mortem PD brain samples. Here we show that transgenic overexpression of GPNMB protects against dopaminergic neurodegeneration in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropridine mouse model of Parkinson's disease. Furthermore, GPNMB overexpression reduces gliosis and prevented microglial morphological changes following MPTP treatment compared with wild-type MPTP-treated mice. Additionally, recombinant GPNMB attenuates LPS-induced inflammation in primary mouse microglia. These results suggest a neuroprotective and anti-inflammatory role for GPNMB and warrant further investigation for GPNMB as a novel therapy for PD.

3D Bioprinting for Vascularized Tissue-Engineered Bone Fabrication

Vascularization in bone tissues is essential for the distribution of nutrients and oxygen, as well as the removal of waste products. Fabrication of tissue-engineered bone constructs with functional vascular networks has great potential for biomimicking nature bone tissue in vitro and enhancing bone regeneration in vivo. Over the past decades, many approaches have been applied to fabricate biomimetic vascularized tissue-engineered bone constructs. However, traditional tissue-engineered methods based on seeding cells into scaffolds are unable to control the spatial architecture and the encapsulated cell distribution precisely, which posed a significant challenge in constructing complex vascularized bone tissues with precise biomimetic properties. In recent years, as a pioneering technology, three-dimensional (3D) bioprinting technology has been applied to fabricate multiscale, biomimetic, multi-cellular tissues with a highly complex tissue microenvironment through layer-by-layer printing. This review discussed the application of 3D bioprinting technology in the vascularized tissue-engineered bone fabrication, where the current status and unique challenges were critically reviewed. Furthermore, the mechanisms of vascular formation, the process of 3D bioprinting, and the current development of bioink properties were also discussed.

Altered expression of glycoprotein non‑metastatic melanoma protein B in the distal sciatic nerve following injury

Glycoprotein non‑metastatic melanoma protein B (GPNMB) exerts neuroprotective effects on amyotrophic lateral sclerosis and cerebral ischemia reperfusion injury in the central nervous system. However, the expression and function of GPNMB in the peripheral nervous system, particularly following peripheral nerve injury, remains unknown. In the present study, the mRNAs and long non‑coding RNAs of the distal sciatic nerve were profiled via microarray analysis at days 0, 1, 3, 7, 14, 21 and 28 following transection. The results revealed that the expression of GPNMB mRNA was similar to the proliferation tendency of distal acute denervated Schwann cells (SCs), the results of which were further validated by reverse transcription quantitative polymerase chain reaction, western blot analysis and immunohistochemistry. To investigate the function of GPNMB on SCs, recombinant human GPNMB (rhGPNMB) was added to cultured denervated SCs from the distal stumps of transected sciatic nerve. The proliferation, expression and secretion of neurotrophic factors (NTFs) and neural adhesion molecules (NAMs) were subsequently detected. The results demonstrated that GPNMB expression was increased in distal sciatic nerve following transection in vivo, while rhGPNMB promoted the proliferation of SCs as well as expression and secretion of NTFs and NAMs in vitro. Therefore, GPNMB could be a novel strategy for peripheral nerve regeneration.

Key components of engineering vascularized 3-dimensional bioprinted bone constructs

Vascularization has a pivotal role in engineering successful tissue constructs. However, it remains a major hurdle of bone tissue engineering, especially in clinical applications for the treatment of large bone defects. Development of vascularized and clinically-relevant engineered bone substitutes with sufficient blood supply capable of maintaining implant viability and supporting subsequent host tissue integration remains a major challenge. Since only cells that are 100-200 µm from blood vessels can receive oxygen through diffusion, engineered constructs that are thicker than 400 µm face a challenging oxygenation problem. Following implantation in vivo, spontaneous ingrowth of capillaries in thick engineered constructs is too slow. Thus, it is critical to provide optimal conditions to support vascularization in engineered bone constructs. To achieve this, an in-depth understanding of the mechanisms of angiogenesis and bone development is required. In addition, it is also important to mimic the physiological milieu of native bone to fabricate more successful vascularized bone constructs. Numerous applications of engineered vascularization with cell-and/or microfabrication-based approaches seek to meet these aims. Three-dimensional (3D) printing promises to create patient-specific bone constructs in the future. In this review, we discuss the major components of fabricating vascularized 3D bioprinted bone constructs, analyze their related challenges, and highlight promising future trends.

The suppressive effects of miR-508-5p on the odontogenic differentiation of human dental pulp stem cells by targeting glycoprotein non-metastatic melanomal protein B

BACKGROUND

Although the involvement of glycoprotein non-metastatic melanomal protein B (GPNMB) in regulating the odontogenic differentiation of human dental pulp stem cells (hDPCs) has been identified, the underlying mechanisms are largely unknown. The purpose of this study is to investigate the effects of miR-508-5p on the GPNMB expression and the odontogenic differentiation of hDPCs.

METHODS

In this study, hDPCs were isolated and identified by flow cytometric analysis. Based on bioinformatics analysis, dual luciferase reporter assay was performed to verify GPNMB acting as a target of miR-508-5p. The regulatory roles of miR-508-5p in odontogenetic differentiation of hDPCs were investigated through its inhibition or overexpression (miRNA mimics and miRNA inhibitors). qRT-PCR and Western blot analysis were used to detect the expression of odontogenetic marker genes and proteins. The assays of alkaline phosphatase (ALP) activity and Alizarin Red S staining were performed to evaluate the odontogenetic phenotype.

RESULTS

We first found that the levels of miR-508-5p expression decreased gradually during odontogenesis of hDPCs, while the expressions of GPNMB were upregulated obviously. The suppressive effects of miR-508-5p on GPNMB were determined by oligonucleotide transfection in hDPCs and dual luciferase reporter assay in 293T cells. Subsequently, the significant inhibition of hDPC odontogenesis after the overexpression of miR-508-5p was observed, which is consistent with the decreased expression levels of several odontoblast-specific genes, such as dentin matrix protein 1 (DMP-1), dentin sialophosphoprotein (DSPP), and osteocalcin (OCN), as well as the decreased activity of ALP and weakened Alizarin Red S staining. Furthermore, ectopic expression of GPNMB (lacking 3'-UTR) rescued the effects of miR-508-5p on odontogenic differentiation.

CONCLUSIONS

Our study demonstrated that miR-508-5p regulated the osteogenesis of hDPCs by targeting GPNMB and provided novel insight into the critical roles of microRNAs in hDPC differentiation.

Glycoprotein Non-Metastatic Protein B: An Emerging Biomarker for Lysosomal Dysfunction in Macrophages

Several diseases are caused by inherited defects in lysosomes, the so-called lysosomal storage disorders (LSDs). In some of these LSDs, tissue macrophages transform into prominent storage cells, as is the case in Gaucher disease. Here, macrophages become the characteristic Gaucher cells filled with lysosomes laden with glucosylceramide, because of their impaired enzymatic degradation. Biomarkers of Gaucher cells were actively searched, particularly after the development of costly therapies based on enzyme supplementation and substrate reduction. Proteins selectively expressed by storage macrophages and secreted into the circulation were identified, among which glycoprotein non-metastatic protein B (GPNMB). This review focusses on the emerging potential of GPNMB as a biomarker of stressed macrophages in LSDs as well as in acquired pathologies accompanied by an excessive lysosomal substrate load in macrophages.

Synergistic effect of extracellularly supplemented osteopontin and osteocalcin on stem cell proliferation, osteogenic differentiation, and angiogenic properties

A high demand for functional bone grafts is being observed worldwide, especially due to the increased life expectancy. Osteoinductive components should be incorporated into functional bone grafts, accelerating cell recruitment, cell proliferation, angiogenesis, and new bone formation at a defect site. Noncollagenous bone matrix proteins, especially osteopontin (OPN) and osteocalcin (OC), have been reported to regulate some physiological process, such as cell migration and bone mineralization. However, the effects of OPN and OC on cell proliferation, osteogenic differentiation, mineralization, and angiogenesis are still undefined. Therefore, we assessed the exogenous effect of OPN and OC supplementation on human bone marrow mesenchymal stem/stromal cells (hBM MSC) proliferation and osteogenic differentiation. OPN dose-dependently increased the proliferation of hBM MSC, as well as improved the angiogenic properties of human umbilical vein endothelial cells (HUVEC) by increasing the capillary-like tube formation in vitro. On the other hand, OC enhanced the differentiation of hBM MSC into osteoblasts and demonstrated an increase in extracellular calcium levels and alkaline phosphatase activity, as well as higher messenger RNA levels of mature osteogenic markers osteopontin and osteocalcin. In vivo assessment of OC/OPN-enhanced scaffolds in a critical-sized defect rabbit long-bone model revealed no infection, while new bone was being formed. Taken together, these results suggest that OC and OPN stimulate bone regeneration by inducing stem cell proliferation, osteogenesis and by enhancing angiogenic properties. The synergistic effect of OC and OPN observed in this study can be applied as an attractive strategy for bone regeneration therapeutics by targeting different vital cellular processes.

Embryonic-Like Mineralized Extracellular Matrix/Stem Cell Microspheroids as a Bone Graft Substitute

Native bone extracellular matrix (ECM) secreted by mesenchymal precursors provides an optimal biological framework, comprising structural collagen proteins and a microenvironment niche, which supports cell attachment and differentiation, and bone growth. Inspired by nature, the embryonic-like mineralized ECM/stem cell microspheroids (MECS) are developed, in which self-assembly of the stem cell microspheroids (CS) and mineralization of the self-produced ECM occur simultaneously. The uniform-sized MECS exhibit a solid spherical appearance with stem cells embedded inside, recapitulating the early stage of intramembranous ossification. Compared with pure CS, MECS show enhanced Young's modulus, cell viability, intercellular communication, and osteogenic differentiation. Additionally, the capability of MECS is explored without the use of exogenous scaffolds to substitute and repair lost bone in rat critical-sized defects. It is found that the MECS can achieve excellent bone regeneration outcomes with 97.99 ± 2.28% of the defect area filled with new bony structures and blood vessels, while nearly half or one-third of the defect area is repaired by CS (52.79 ± 4.63%) or β-tricalcium phosphate (38.09 ± 7.79%), respectively. The study demonstrates that embryonic-like MECS is a novel effective bone graft substitute for bone tissue regeneration.

Melanoma-Derived Soluble DC-HIL/GPNMB Promotes Metastasis by Excluding T-Lymphocytes from the Pre-Metastatic Niches

Soluble factors from the primary tumor induce recruitment of bone marrow-derived progenitors to form tumor-supportive microenvironments or pre-metastatic niches in distal organs before metastasis. How tumor-secreted factors condition the sites for tumor progression remains ambiguous. B16 melanoma produces the secreted form of T cell-inhibitory DC-HIL (sDC-HIL) that travels to distal organs and potentiates the metastatic capacity of tumor cells. We studied the molecular mechanisms and found that sDC-HIL binds to select endothelial cells that co-localize with the sites where bone marrow-derived progenitors and tumor cells migrate. sDC-HIL-bound endothelial cells exist at a similar frequency in mice with or without tumors, and they are strongly associated with survival of intravenously injected tumor cells in the lung. sDC-HIL binding conferred T-cell suppressor function on the ECs and awakened the angiogenic property by inducing vascular endothelial growth factor expression, resulting in enhanced transendothelial migration of bone marrow-derived progenitors and tumor cells, but not for T cells. This selectivity is achieved by the T-cell binding of sDC-HIL, which prevents formation of the leading edges required for chemotaxis. Finally, inducing tumor expression of sDC-HIL significantly reduced tumor-infiltrated T cells. Therefore, the highly metastatic attribute of B16 melanoma can be explained by the endothelial gatekeeper function of sDC-HIL that limits lymphocyte transmigration to pre-metastatic niches.

The glycoprotein GPNMB attenuates astrocyte inflammatory responses through the CD44 receptor

BACKGROUND

Neuroinflammation is one of the hallmarks of neurodegenerative diseases, such as Parkinson's disease (PD). Activation of glial cells, including microglia and astrocytes, is a characteristic of the inflammatory response. Glycoprotein non-metastatic melanoma protein B (GPNMB) is a transmembrane glycoprotein that releases a soluble signaling peptide when cleaved by ADAM10 or other extracellular proteases. GPNMB has demonstrated a neuroprotective role in animal models of ALS and ischemia. However, the mechanism of this protection has not been well established. CD44 is a receptor expressed on astrocytes that can bind GPNMB, and CD44 activation has been demonstrated to reduce NFκB activation and subsequent inflammatory responses in macrophages. GPNMB signaling has not been investigated in models of PD or specifically in astrocytes. More recently, genetic studies have linked polymorphisms in GPNMB with risk for PD. Therefore, it is important to understand the role this signaling protein plays in PD.

METHODS

We used data mining techniques to evaluate mRNA expression of GPNMB and its receptor CD44 in the substantia nigra of PD and control brains. Immunofluorescence and qPCR techniques were used to assess GPNMB and CD44 levels in mice treated with MPTP. In vitro experiments utilized the immortalized mouse astrocyte cell line IMA2.1 and purified primary mouse astrocytes. The effects of recombinant GPNMB on cytokine-induced astrocyte activation was determined by qPCR, immunofluorescence, and measurement of nitric oxide and reactive oxygen production.

RESULTS

Increased GPNMB and CD44 expression was observed in the substantia nigra of human PD brains and in GFAP-positive astrocytes in an animal model of PD. GPNMB treatment attenuated cytokine-induced levels of inducible nitric oxide synthase, nitric oxide, reactive oxygen species, and the inflammatory cytokine IL-6 in an astrocyte cell line and primary mouse astrocytes. Using primary mouse astrocytes from CD44 knockout mice, we found that the anti-inflammatory effects of GPNMB are CD44-mediated.

CONCLUSIONS

These results demonstrate that GPNMB may exert its neuroprotective effect through reducing astrocyte-mediated neuroinflammation in a CD44-dependent manner, providing novel mechanistic insight into the neuroprotective properties of GPNMB.

Macrophage-Associated Osteoactivin/GPNMB Mediates Mesenchymal Stem Cell Survival, Proliferation, and Migration Via a CD44-Dependent Mechanism

Although MSCs have been widely recognized to have therapeutic potential in the repair of injured or diseased tissues, it remains unclear how functional activities of mesenchymal stem cells (MSCs) are influenced by the surrounding inflammatory milieu at the site of tissue injury. Macrophages constitute an essential component of innate immunity and have been shown to exhibit a phenotypic plasticity in response to various stimuli, which play a central role in both acute inflammation and wound repair. Osteoactivin (OA)/Glycoprotein non-metastatic melanoma protein B (GPNMB), a transmembrane glycoprotein that plays a role in cell differentiation, survival, and angiogenesis. The objective of this study was to investigate the potential role of OA/GPNMB in macrophage-induced MSC function. We found that reparative M2 macrophages express significantly greater levels of OA/GPNMB than pro-inflammatory M1 macrophages. Furthermore, using loss of function and rescue studies, we demonstrated that M2 macrophages-secreted OA/GPNMB positively regulates the viability, proliferation, and migration of MSCs. More importantly, we demonstrated that OA/GPNMB acts through ERK and AKT signaling pathways in MSCs via CD44, to induce these effects. Taken together, our results provide pivotal insight into the mechanism by which OA/GPNMB contributes to the tissue reparative phenotype of M2 macrophages and positively regulates functional activities of MSCs. J. Cell. Biochem. 117: 1511-1521, 2016. © 2015 Wiley Periodicals, Inc.

Glycoprotein Nonmelanoma Clone B Regulates the Crosstalk between Macrophages and Mesenchymal Stem Cells toward Wound Repair

The process of wound repair requires the coordinated participation of multiple types of cells, which are sequentially recruited during the healing process. In response to tissue injury, both macrophages and mesenchymal stem cells (MSCs) are recruited to the site of injury, where they participate in the repair process. Despite considerable understanding of the role of each cell type in the process of wound repair, the nature of the dynamic interplay between these two cell types and how this interaction influences the process of wound repair are not well understood. Here, using an in vivo model of cutaneous wound healing in mice, we provide evidence that GPNMB is functionally important in promoting the recruitment of MSCs to the site of skin injury, which in turn modulates inflammatory responses by directing the M2 polarization of macrophages in acute wound healing. Furthermore, we show that GPNMB activity is impaired in a diabetic wound environment, which is associated with impaired MSC recruitment that is reversed by the topical administration of recombinant GPNMB protein to the wounds of diabetic mice. Our study provides important insight into the crosstalk between macrophages and endogenous MSCs toward wound repair.

Visualizing Angiogenesis by Multiphoton Microscopy In Vivo in Genetically Modified 3D-PLGA/nHAp Scaffold for Calvarial Critical Bone Defect Repair

The reconstruction of critically sized bone defects remains a serious clinical problem because of poor angiogenesis within tissue-engineered scaffolds during repair, which gives rise to a lack of sufficient blood supply and causes necrosis of the new tissues. Rapid vascularization is a vital prerequisite for new tissue survival and integration with existing host tissue. The de novo generation of vasculature in scaffolds is one of the most important steps in making bone regeneration more efficient, allowing repairing tissue to grow into a scaffold. To tackle this problem, the genetic modification of a biomaterial scaffold is used to accelerate angiogenesis and osteogenesis. However, visualizing and tracking in vivo blood vessel formation in real-time and in three-dimensional (3D) scaffolds or new bone tissue is still an obstacle for bone tissue engineering. Multiphoton microscopy (MPM) is a novel bio-imaging modality that can acquire volumetric data from biological structures in a high-resolution and minimally-invasive manner. The objective of this study was to visualize angiogenesis with multiphoton microscopy in vivo in a genetically modified 3D-PLGA/nHAp scaffold for calvarial critical bone defect repair. PLGA/nHAp scaffolds were functionalized for the sustained delivery of a growth factor pdgf-b gene carrying lentiviral vectors (LV-pdgfb) in order to facilitate angiogenesis and to enhance bone regeneration. In a scaffold-implanted calvarial critical bone defect mouse model, the blood vessel areas (BVAs) in PHp scaffolds were significantly higher than in PH scaffolds. Additionally, the expression of pdgf-b and angiogenesis-related genes, vWF and VEGFR2, increased correspondingly. MicroCT analysis indicated that the new bone formation in the PHp group dramatically improved compared to the other groups. To our knowledge, this is the first time multiphoton microscopy was used in bone tissue-engineering to investigate angiogenesis in a 3D bio-degradable scaffold in vivo and in real-time.

Glycoprotein NMB: an Emerging Role in Neurodegenerative Disease

Neurodegeneration is characterized by severe neuronal loss leading to the cognitive and physical impairments that define various neurodegenerative diseases. Neuroinflammation is one hallmark of neurodegenerative diseases and can ultimately contribute to disease progression. Increased inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-1β (IL-1 β), and tumor necrosis factor-α (TNF-α) are associated with Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Unfortunately, current therapeutic options lack ability to stop or effectively slow progression of these diseases and are primarily aimed at alleviating symptoms. Thus, it is crucial to discover novel treatment candidates for neurodegenerative diseases. Glycoprotein nonmetastatic melanoma protein B (GPNMB) is a type-I transmembrane glycoprotein first identified in a melanoma cell line. GPNMB augments bone mineral deposition by stimulating osteoblast differentiation. Aside from its anabolic function in the bone, emerging evidence suggests that GPNMB has anti-inflammatory and reparative functions. GPNMB has also been demonstrated to be neuroprotective in an animal model of ALS, cerebral ischemia, and other disease models. Given these discoveries, GPNMB should be investigated as a potential therapeutic option for multiple neurodegenerative diseases.

High levels of FLT3-ligand in bone marrow and peripheral blood of patients with advanced multiple myeloma

Introduction

Multiple myeloma (MM) is still incurable due to resistance against various therapies. Thus, the identification of biomarkers predicting progression is urgently needed. Here, we evaluated four biomarkers in bone marrow and peripheral blood of MM patients for their prognostic significance.

Materials & methods

Bone marrow- and peripheral blood plasma levels of FLT3-L, soluble TIE2, endostatin, and osteoactivin were determined in patients with monoclonal gammopathy of undetermined significance (MGUS, n = 14/n = 4), patients with newly diagnosed MM (NDMM, n = 42/n = 31) and patients with relapsed/refractory MM (RRMM, n = 27/n = 16) by sandwich ELISA.

Results

Median FLT3-L expression increased from MGUS (58.77 pg/ml in bone marrow; 80.40 pg/ml in peripheral blood) to NDMM (63.15 pg/ml in bone marrow; 85.05 pg/ml in peripheral blood) and was maximal in RRMM (122 pg/ml in bone marrow; 160.47 pg/ml in peripheral blood; NDMM vs. RRMM p<0.001). A cut-off value of FLT3-L >92 pg/ml in bone marrow and >121 pg/ml in peripheral blood was associated with relapse or refractoriness in MM patients. FLT3-L was found to be a high predictive marker for discrimination between NDMM and RRMM as well in bone marrow as in peripheral blood (AUC 0.75 in bone marrow; vs 0.84 in peripheral blood).

Conclusion

High levels of FLT3-L in bone marrow and peripheral blood of MM patients identify patients with progressive disease and are associated with relapse or refractoriness in MM patients. FLT3-L could be useful as a marker to identify RRMM patients and should be evaluated as target for future therapies.

[Research progress of correlation between traumatic brain injury and fracture healing]

Objective

To review the current status and advances of the correlation between traumatic brain injury (TBI) and fracture healing.

Methods

The related domestic and abroad literature about the correlation between TBI and fracture healing was extensively reviewed and analyzed.

Results

There are a variety of studies on the correlation between TBI and fracture healing, which can be divided into two major aspects: revascularization and osteogenesis; the local and systemic changes of the neuropeptide and hormone after TBI.

Conclusion

TBI facilitates callus formation, the further research is needed to clarify the exact mechanism.

Repair of bone defects with prefabricated vascularized bone grafts and double-labeled bone marrow-derived mesenchymal stem cells in a rat model

This study aims to investigate the repair of bone defects with prefabricated vascularized bone grafts and double-labeled bone marrow-derived mesenchymal stem cells (BMSCs) in a rat model. BMSCs were separated from rat bone marrow. LTR-CMVpro-RFP and LTR-CMVpro-GFP were transfected into the BMSCs for in vitro and in vivo tracking. BMSCs-RFP and BMSCs-GFP were induced into endothelial progenitor cells (EPCs) and osteoblasts (OBs). Rats were divided into five groups: Group A: in vitro prefabrication with EPCs-RFP + in vivo prefabrication with arteriovenous vascular bundle + secondary OBs-GFP implantation; Group B: in vitro prefabrication with EPCs-RFP + secondary OBs-GFP implantation; Group C: in vivo prefabrication with arteriovenous vascular bundle + secondary OBs-GFP implantation; Group D: implantation of EPCs-RFP + implantation of with arteriovenous vascular bundle + simultaneous OBs-GFP implantation; Group E: demineralized bone matrix (DBM) grafts (blank control). Among five groups, Group A had the fastest bone regeneration and repair, and the regenerated bone highly resembled normal bone tissues; Group D also had fast bone repair, but the repair was slightly slower than Group A. Therefore, in vitro prefabrication with EPCs-RFP plus in vivo prefabrication with arteriovenous vascular bundle and secondary OBs-GFP implantation could be the best treatment for bone defect.

GPNMB ameliorates mutant TDP-43-induced motor neuron cell death

Glycoprotein nonmetastatic melanoma protein B (GPNMB) aggregates are observed in the spinal cord of amyotrophic lateral sclerosis (ALS) patients, but the detailed localization is still unclear. Mutations of transactive response DNA binding protein 43kDa (TDP-43) are associated with neurodegenerative diseases including ALS. In this study, we evaluated the localization of GPNMB aggregates in the spinal cord of ALS patients and the effect of GPNMB against mutant TDP-43 induced motor neuron cell death. GPNMB aggregates were not localized in the glial fibrillary acidic protein (GFAP)-positive astrocyte and ionized calcium binding adaptor molecule-1 (Iba1)-positive microglia. GPNMB aggregates were localized in the microtubule-associated protein 2 (MAP-2)-positive neuron and neurofilament H non-phosphorylated (SMI-32)-positive neuron, and these were co-localized with TDP-43 aggregates in the spinal cord of ALS patients. Mock or TDP-43 (WT, M337V, and A315T) plasmids were transfected into mouse motor neuron cells (NSC34). The expression level of GPNMB was increased by transfection of mutant TDP-43 plasmids. Recombinant GPNMB ameliorated motor neuron cell death induced by transfection of mutant TDP-43 plasmids and serum-free stress. Furthermore, the expression of phosphorylated ERK1/2 and phosphorylated Akt were decreased by this stress, and these expressions were increased by recombinant GPNMB. These results indicate that GPNMB has protective effects against mutant TDP-43 stress via activating the ERK1/2 and Akt pathways, and GPNMB may be a therapeutic target for TDP-43 proteinopathy in familial and sporadic ALS. © 2016 Wiley Periodicals, Inc.

Investigation of angiogenesis in bioactive 3-dimensional poly(d,l-lactide-co-glycolide)/nano-hydroxyapatite scaffolds by in vivo multiphoton microscopy in murine calvarial critical bone defect

Reconstruction of critical size bone defects remains a major clinical challenge because of poor bone regeneration, which is usually due to poor angiogenesis during repair. Satisfactory vascularization is a prerequisite for the survival of grafts and the integration of new tissue with existing tissue. In this work, we investigated angiogenesis in 3D scaffolds by in vivo multiphoton microscopy during bone formation in a murine calvarial critical bone defect model and evaluated bone regeneration 8weeks post-implantation. The continuous release of bioactive lentiviral vectors (LV-pdgfb) from the scaffolds could be detected for 5days in vitro. In vivo, the released LV-pdgfb transfected adjacent cells and expressed PDGF-BB, facilitating angiogenesis and enhancing bone regeneration. The expression of both pdgfb and the angiogenesis-related genes vWF and VEGFR2 was significantly increased in the pdgfb gene-carrying scaffold (PHp) group. In addition, microCT scanning and histomorphology results proved that there was more new bone ingrowth in the PHp group than in the PLGA/nHA (PH) and control groups. MicroCT parameters, including BMD, BV/TV, Tb.Sp, and Tb.N indicated that there was significantly more new bone formation in the PHp group than in the other groups. With regard to neovascularization, 8weeks post-implantation, blood vessel areas (BVAs) were 9428±944μm(2), 4090±680.3μm(2), and none in the PHp, PH, and control groups, respectively. At each time point, BVAs in the PHp scaffolds were significantly higher than in the PH scaffolds. To our knowledge, this is the first use of multiphoton microscopy in bone tissue-engineering to investigate angiogenesis in scaffolds in vivo. This method represents a valuable tool for investigating neovascularization in bone scaffolds to determine if a certain scaffold is beneficial to neovascularization. We also proved that delivery of the pdgfb gene alone can improve both angiogenesis and bone regeneration Acronyms.

STATEMENT OF SIGNIFICANCE

Reconstruction of critical size bone defects remains a major clinical challenge because of poor bone regeneration, which is usually due to poor angiogenesis during repair. Satisfactory vascularization is a prerequisite for the survival of grafts and the integration of new tissue with existing tissue. In this work, we investigated angiogenesis in 3D scaffolds by in vivo multiphoton microscopy during bone formation in a murine calvarial critical bone defect model and evaluated bone regeneration 8weeks post-implantation. To verify that pdgfb-expressing vectors carried by the scaffolds can promote angiogenesis in 3D-printed scaffolds in vivo, we monitored angiogenesis within the implants by multiphoton microscopy. To our knowledge, this is the first study to dynamically investigate angiogenesis in bone tissue engineering scaffolds in vivo.

Osteoactivin inhibition of osteoclastogenesis is mediated through CD44-ERK signaling

Osteoactivin is a heavily glycosylated protein shown to have a role in bone remodeling. Previous studies from our lab have shown that mutation in Osteoactivin enhances osteoclast differentiation but inhibits their function. To date, a classical receptor and a signaling pathway for Osteoactivin-mediated osteoclast inhibition has not yet been characterized. In this study, we examined the role of Osteoactivin treatment on osteoclastogenesis using bone marrow-derived osteoclast progenitor cells and identify a signaling pathway relating to Osteoactivin function. We reveal that recombinant Osteoactivin treatment inhibited osteoclast differentiation in a dose-dependent manner shown by qPCR, TRAP staining, activity and count. Using several approaches, we show that Osteoactivin binds CD44 in osteoclasts. Furthermore, recombinant Osteoactivin treatment inhibited ERK phosphorylation in a CD44-dependent manner. Finally, we examined the role of Osteoactivin on receptor activator of nuclear factor-κ B ligand (RANKL)-induced osteolysis in vivo. Our data indicate that recombinant Osteoactivin inhibits RANKL-induced osteolysis in vivo and this effect is CD44-dependent. Overall, our data indicate that Osteoactivin is a negative regulator of osteoclastogenesis in vitro and in vivo and that this process is regulated through CD44 and ERK activation.

Prospects of osteoactivin in tissue regeneration

INTRODUCTION

Osteoactivin (OA) was first discovered in an osteopetrotic rat model using mRNA differential display a decade ago and has been studied recently. OA in bone tissue can directly or indirectly regulate the differentiation of osteoblasts by influencing cell behaviours, such as proliferation and adhesion, as well as inducing serial signal cascades, which would be of great importance in the field of tissue engineering. The results of recent studies have further demonstrated that OA plays a critical role in the differentiation and function of cells, especially in bone formation and fracture healing. Areas covered: The discovery, structure, and function of OA as well as its therapeutic potential in tissue regeneration of bone defects, kidney injury, liver damage, and muscle atrophy. Expert opinion: OA has great potential in promoting the regeneration of damaged tissues, particularly bone tissue, which is supported by a large body of data. Future studies should focus on exploring the underlying mechanism of OA as well as pursuing the ideal form of OA-related regenerative medicine.

Glycoprotein non-metastaticmelanoma protein B promotes glioma motility and angiogenesis through the Wnt/β-catenin signaling pathway

Glioma is a common tumor with high mortality and poor overall survival. However, the regulatory mechanisms of glioma tumorigenesis and glioma cell motility are completely unknown. Here, we investigated the role of glycoprotein non-metastatic melanoma protein B in glioma. The expression of glycoprotein non-metastatic melanoma protein B is observed to be aberrantly regulated in glioma tissues and cells, and high levels of glycoprotein non-metastatic melanoma protein B present an inverse correlation with the survival of glioma patients. Compared with the control, glycoprotein non-metastatic melanoma protein B inhibition significantly retarded the proliferation and migration of human glioma cells. The tube formation ability of HBMECs induced by glioma cells was also remarkably reduced by glycoprotein non-metastatic melanoma protein B silencing. Increased levels of VEGF-C and TEM7 were down-regulated by the suppression of glycoprotein non-metastatic melanoma protein B in glioma cells. Additionally, the activity of MMP-2/3/9 was assessed in glioma cells using Western blotting and gelatin zymography assay; their activities were strongly decreased following the suppression of glycoprotein non-metastatic melanoma protein B. Further studies suggested that canonical Wnt/β-catenin pathway was activated, but was inactivated by glycoprotein non-metastatic melanoma protein B suppression in glioma cells. In conclusion, we demonstrate that glycoprotein non-metastatic melanoma protein B might be an inducer for glioma and could enhance matrix metalloproteinase activity through Wnt/β-catenin pathway to contribute to glioma tumorigenesis. This may represent a new understanding for malignant glioma.

Glycoprotein nonmetastatic melanoma protein B extracellular fragment shows neuroprotective effects and activates the PI3K/Akt and MEK/ERK pathways via the Na+/K+-ATPase

Glycoprotein nonmetastatic melanoma protein B (GPNMB) plays important roles in various types of cancer and amyotrophic lateral sclerosis (ALS). The details of GPNMB function and its interacting protein have not been clarified. Therefore, to identify GPNMB binding partners on the cell membrane, we used membrane protein library/BLOTCHIP-MS technology, which enables us to analyze all cell membrane proteins as binding partners of the GPNMB extracellular fragment. As a result of a comprehensive search, we identified the alpha subunits of Na(+)/K(+)-ATPase (NKA) as a possible binding partner. We confirmed the interaction between the GPNMB extracellular fragment and NKA by immunoprecipitation and immunostaining in NSC-34 cells. Indeed, endogenous GPNMB extracellular fragment bound to and colocalized with NKA alpha subunits. Furthermore, exogenous GPNMB extracellular fragment, i.e., human recombinant GPNMB, also bound to and colocalized with NKA alpha subunits. Additionally, we found that the GPNMB extracellular fragment had neuroprotective effects and activated the phosphoinositide 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK)-extracellular signal-regulated kinase (ERK) kinase (MEK)/ERK pathways via NKA. These findings indicated that NKA may act as a novel "receptor" for the GPNMB extracellular fragment, offering additional molecular targets for the treatment of GPNMB-related diseases, including various types of cancer and ALS.

Integrative systems analysis of diet-induced obesity identified a critical transition in the transcriptomes of the murine liver and epididymal white adipose tissue

BACKGROUND

It is well known that high-fat diet (HFD) can cause immune system-related pathological alterations after a significant body weight gain. The mechanisms of the delayed pathological alterations during the development of diet-induced obesity (DIO) are not fully understood.

METHODS

To elucidate the mechanisms underlying DIO development, we analyzed time-course microarray data obtained from a previous study. First, differentially expressed genes (DEGs) were identified at each time point by comparing the hepatic transcriptome of mice fed HFD with that of mice fed normal diet. Next, we clustered the union of DEGs and identified annotations related to each cluster. Finally, we constructed an 'integrated obesity-associated gene regulatory network (GRN) in murine liver'. We analyzed the epididymal white adipose tissue (eWAT) transcriptome usig the same procedure.

RESULTS

Based on time-course microarray data, we found that the genes associated with immune responses were upregulated with an oscillating expression pattern between weeks 2 and 8, relatively downregulated between weeks 12 and 16, and eventually upregulated after week 20 in the liver of the mice fed HFD. The genes associated with immune responses were also upregulated at late stage, in the eWAT of the mice fed HFD. These results suggested that a critical transition occurred in the immune system-related transcriptomes of the liver and eWAT around week 16 of the DIO development, and this may be associated with the delayed pathological alterations. The GRN analysis suggested that Maff may be a key transcription factor for the immune system-related critical transition thatoccurred at week 16. We found that transcription factors associated with immune responses were centrally located in the integrated obesity-associated GRN in the liver.

CONCLUSIONS

In this study, systems analysis identified regulatory network modules underlying the delayed immune system-related pathological changes during the development of DIO and could suggest possible therapeutic targets.

Glycoprotein nonmetastatic melanoma protein B ameliorates skeletal muscle lesions in a SOD1G93A mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motor neurons and subsequent muscular atrophy. The quality of life of patients with ALS is significantly improved by ameliorating muscular symptoms. We previously reported that glycoprotein nonmetastatic melanoma protein B (GPNMB; osteoactivin) might serve as a target for ALS therapy. In the present study, superoxide dismutase 1/glycine residue 93 changed to alanine (SOD1(G93A) ) transgenic mice were used as a model of ALS. Expression of the C-terminal fragment of GPNMB was increased in the skeletal muscles of SOD1(G93A) mice and patients with sporadic ALS. SOD1(G93A) /GPNMB transgenic mice were generated to determine whether GPNMB expression ameliorates muscular symptoms. The weight and cross-sectional area of the gastrocnemius muscle, number and cross-sectional area of myofibers, and denervation of neuromuscular junctions were ameliorated in SOD1(G93A) /GPNMB vs. SOD1(G93A) mice. Furthermore, direct injection of a GPNMB expression plasmid into the gastrocnemius muscle of SOD1(G93A) mice increased the numbers of myofibers and prevented myofiber atrophy. These findings suggest that GPNMB directly affects skeletal muscle and prevents muscular pathology in SOD1(G93A) mice and may therefore serve as a target for therapy of ALS.

Proteome-wide lysine acetylation in cortical astrocytes and alterations that occur during infection with brain parasite Toxoplasma gondii

Lysine acetylation is a reversible post-translational modification (PTM) that has been detected on thousands of proteins in nearly all cellular compartments. The role of this widespread PTM has yet to be fully elucidated, but can impact protein localization, interactions, activity, and stability. Here we present the first proteome-wide survey of lysine acetylation in cortical astrocytes, a subtype of glia that is a component of the blood-brain barrier and a key regulator of neuronal function and plasticity. We identified 529 lysine acetylation sites across 304 proteins found in multiple cellular compartments that largely function in RNA processing/transcription, metabolism, chromatin biology, and translation. Two hundred and seventy-seven of the acetylated lysines we identified on 186 proteins have not been reported previously in any other cell type. We also mapped an acetylome of astrocytes infected with the brain parasite, Toxoplasma gondii. It has been shown that infection with T. gondii modulates host cell gene expression, including several lysine acetyltransferase (KAT) and deacetylase (KDAC) genes, suggesting that the host acetylome may also be altered during infection. In the T. gondii-infected astrocytes, we identified 34 proteins exhibiting a level of acetylation >2-fold and 24 with a level of acetylation <2-fold relative to uninfected astrocytes. Our study documents the first acetylome map for cortical astrocytes, uncovers novel lysine acetylation sites, and demonstrates that T. gondii infection produces an altered acetylome.

Polyethylene glycol formulations show different soft tissue remodeling and angiogenesis features

BACKGROUND

Soft tissue regeneration and remodeling is fundamental in periodontal surgery, thus we investigated the angiogenic response elicited in the subcutaneous tissue of rats by a proprietary, polyethylene glycol hydrogel formulation (PEG) alone or conjugated with specific amelogenins (EMD) or nanobioglass particles (NBG).

METHODS

Discs with three different formulations (PEG, PEG-EMD, and PEG-NBG) were inserted into four unconnected subcutaneous pouches, produced on the back of Sprague-Dawley rats (n=56, divided into three groups), and used for blood flow evaluation by Laser Doppler analysis at 1, 2, 4, 8, and 16 weeks or for histological and immunohistochemical analysis at 1, 2, 4, 8, and 16 weeks.

RESULTS

All formulations showed tissue integration, absence of inflammatory reaction (as revealed by myeloperoxidase staining), and increased vascularization (by counting microvascular density following CD31 staining). Laser Doppler analysis revealed a statistically significant increase in blood flow after 1 week for PEG-EMD and after 2 weeks for PEG-NBG. The angiogenic response was significantly increased at 1, 2, and 8 weeks for PEG-EMD, but only at 4 weeks for PEG-NBG.

CONCLUSIONS

The studied biomaterials revealed equal biocompatibility and tissue integration properties. PEG-EMD showed the most pronounced and consistent angiogenic response in the early phases of wound healing, while the PEG-NBG formulation provided a slower and delayed, but relevant, response.