Interactions between osteopontin and vascular endothelial growth factor: Implications for skeletal disorders

Enhancing osteoblast proliferation and bone regeneration by poly (amino acid)/selenium-doped hydroxyapatite

Among various biomaterials employed for bone repair, composites with good biocompatibility and osteogenic ability had received increasing attention from biomedical applications. In this study, we doped selenium (Se) into hydroxyapatite (Se-HA) by the precipitation method, and prepared different amounts of Se-HA-loaded poly (amino acid)/Se-HA (PAA/Se-HA) composites (0, 10 wt%, 20 wt%, 30 wt%) byin-situmelting polycondensation. The physical and chemical properties of PAA/Se-HA composites were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and their mechanical properties. XRD and FT-IR results showed that PAA/Se-HA composites contained characteristic peaks of PAA and Se-HA with amide linkage and HA structures. DSC and TGA results specified the PAA/Se-HA30 composite crystallization, melting, and maximum weight loss temperatures at 203.33 °C, 162.54 °C, and 468.92 °C, respectively, which implied good thermal stability. SEM results showed that Se-HA was uniformly dispersed in PAA. The mechanical properties of PAA/Se-HA30 composites included bending, compressive, and yield strengths at 83.07 ± 0.57, 106.56 ± 0.46, and 99.17 ± 1.11 MPa, respectively. The cellular responses of PAA/Se-HA compositesin vitrowere studied using bone marrow mesenchymal stem cells (BMSCs) by cell counting kit-8 assay, and results showed that PAA/Se-HA30 composites significantly promoted the proliferation of BMSCs at the concentration of 2 mg ml-1. The alkaline phosphatase activity (ALP) and alizarin red staining results showed that the introduction of Se-HA into PAA enhanced ALP activity and formation of calcium nodule. Western blotting and Real-time polymerase chain reaction results showed that the introduction of Se-HA into PAA could promoted the expression of osteogenic-related proteins and mRNA (integrin-binding sialoprotein, osteopontin, runt-related transcription factor 2 and Osterix) in BMSCs. A muscle defect at the back and a bone defect at the femoral condyle of New Zealand white rabbits were introduced for evaluating the enhancement of bone regeneration of PAA and PAA/Se-HA30 composites. The implantation of muscle tissue revealed good biocompatibility of PAA and PAA/Se-HA30 composites. The implantation of bone defect showed that PAA/Se-HA30 composites enhanced bone formation at the defect site (8 weeks), exhibiting good bone conductivity. Therefore, the PAA-based composite was a promising candidate material for bone tissue regeneration.

Vascular calcification inhibitors and cardiovascular events in peritoneal dialysis patients

The prevalence of cardiovascular diseases is high among patients with chronic kidney disease (CKD) and peritoneal dialysis (PD) patients, which increases morbidity and mortality in this population and represents a significant financial burden for both the patients and the healthcare systems. Vascular calcification (VC) is associated with increased morbidity and mortality and VC risk is higher in patients with CKD than in healthy individuals. Calcification inhibitors, compounds that inhibit VC, were discovered as a result of efforts to explain why some patients are spared. It was found that certain proteins (e.g., fetuin-A, osteopontin, osteoprotegerin, bone morphogenetic protein-7) inhibit calcification in dialysis patients. In this narrative review, we provide an overview of known calcification inhibitors, describe the relevant regulatory mechanisms, and discuss their relation to VC development in PD patients.

Molecular Signature of Biological Aggressiveness in Clear Cell Sarcoma of the Kidney (CCSK)

Clear cell sarcoma of the kidney (CCSK) is a rare pediatric renal tumor with a worse prognosis than Wilms' tumor. Although recently, BCOR internal tandem duplication (ITD) has been found as a driver mutation in more than 80% of cases, a deep molecular characterization of this tumor is still lacking, as well as its correlation with the clinical course. The aim of this study was to investigate the differential molecular signature between metastatic and localized BCOR-ITD-positive CCSK at diagnosis. Whole-exome sequencing (WES) and whole-transcriptome sequencing (WTS) were performed on six localized and three metastatic BCOR-ITD-positive CCSKs, confirming that this tumor carries a low mutational burden. No significant recurrences of somatic or germline mutations other than BCOR-ITD were identified among the evaluated samples. Supervised analysis of gene expression data showed enrichment of hundreds of genes, with a significant overrepresentation of the MAPK signaling pathway in metastatic cases (p < 0.0001). Within the molecular signature of metastatic CCSK, five genes were highly and significantly over-expressed: FGF3, VEGFA, SPP1, ADM, and JUND. The role of FGF3 in the acquisition of a more aggressive phenotype was investigated in a cell model system obtained by introducing the ITD into the last exon of BCOR by Crispr/Cas9 gene editing of the HEK-293 cell line. Treatment with FGF3 of BCOR-ITD HEK-293 cell line induced a significant increase in cell migration versus both untreated and scramble cell clone. The identification of over-expressed genes in metastatic CCSKs, with a particular focus on FGF3, could offer new prognostic and therapeutic targets in more aggressive cases.

The effect of different irrigation solutions on fracture healing in a rat femur fracture model

Objectives

This study aims to evaluate and compare radiological, biomechanical, histopathological, histomorphometric and immunohistochemical effects of povidone iodine (PVP-I), hydrogen peroxide (HPO) and chlorhexidine gluconate (CHG) on fracture healing in their minimum cytotoxic and most efficient concentrations.

Materials and methods

This experimental animal study, conducted between April 2018 and January 2019, included 48 male Sprague Dawley® rats (weighing 356 g; aging 9 weeks) which were randomly divided into four groups: control (saline), HPO, PVP-I and CHG. Rat model of femoral fracture was established and intramedullary fixation was applied. Solutions were applied to fracture region in determined concentration and time, and all subjects were sacrificed on Day 28. Extracted femurs were investigated radiologically by micro-computed tomography. Then, all groups were divided into two random groups to be evaluated biomechanically, histopathologically, histomorphometrically and immunohistochemically.

Results

In histopathological evaluation, inflammation score of CHG group was significantly lower than other groups, and inflammation score of PVP-I group was significantly lower than control and HPO groups (p<0.05). Biomechanically, flexural strength (σbend) (megapascal) values of CHG and control groups showed similar results, but there was no significant difference between all groups (p>0.05). In immunohistochemical localization of bone morphogenic protein (BMP)-4, osteoblast and chondroblast histoscores (H-scores) of HPO group were significantly lower than other groups, and chondroblast H-score in CHG group was lower than control and PVP-I groups (p<0.05). In immunohistochemical localization of BMP-7, osteoblast H-score was significantly higher in CHG group than other groups (p<0.05).

Conclusion

We determined that CHG 0.05% solution had no negative effect on the fourth week of fracture healing histopathologically, immunohistochemically and biomechanically, and is an alternative irrigative to normal saline.

Alterations of bone material properties in adult patients with X-linked hypophosphatemia (XLH)

X-linked hypophosphatemia (XLH) caused by PHEX mutations results in elevated serum FGF23 levels, renal phosphate wasting and low 1,25-dihydroxyvitamin D. The glycophosphoprotein osteopontin, a potent inhibitor of mineralization normally degraded by PHEX, accumulates within the bone matrix. Conventional therapy consisting of supplementation with phosphate and vitamin D analogs is burdensome and the effects on bone material poorly characterized. We analyzed transiliac bone biopsies from four adult patients, two of them severely affected due to no diagnosis and no treatment until adulthood. We used light microscopy, qBEI and FTIRI to study histology, histomorphometry, bone mineralization density distribution, properties of the organic matrix and size of hypomineralized periosteocytic lesions. Non-treatment resulted in severe osteomalacia, twice the amount of mineralized trabecular volume, multiple osteon-like perforations, continuity of lamellae from mineralized to unmineralized areas and distinctive patches of woven bone. Periosteocytic lesions were larger than in treated patients. The latter had nearly normal osteoid thicknesses, although surface was still elevated. The median calcium content of the matrix was always within normal range, although the percentage of lowly mineralized bone areas was highly increased in non-treated patients, resulting in a marked heterogeneity in mineralization. Divalent collagen cross-links were evident independently of the mineral content of the matrix. Broad osteoid seams lacked measurable pyridinoline, a mature trivalent cross-link and exhibited considerable acidic lipid content, typically found in matrix vesicles. Based on our results, we propose a model that possibly integrates the relationship between the observed mineralization disturbances, FGF23 secretion and the known osteopontin accumulation in XLH.

Low-dose cadmium exposure acts on rat mesenchymal stem cells via RANKL/OPG and downregulate osteogenic differentiation genes

Chronic cadmium (Cd) toxicity is a significant health concern, and the mechanism of long-term low-dose Cd exposure on bone has not been fully elucidated till date. This study aimed to assess the association between rat mesenchymal stem cells (MSCs) and long-term Cd exposure through 38-week intake of CdCl₂ at 1 and 2 mg/kg body weight (bw). Increased gene expression of receptor activator of NF-κB ligand (RANKL) and decreased gene expression of osteoprotegerin (OPG) were observed. Fold change of RANKL gene expression (fold change = 1.97) and OPG gene expression (fold change = 1.72) showed statistically significant differences at dose 2 mg/kg bw. Decreased expression of key genes was observed during the early osteogenic differentiation of MSCs. The gene expression of Osterix in 1 mg/kg bw group was decreased by 3.70-fold, and the gene expressions of Osterix, Osteopontin, collagen type I alpha 2 chain (COL1a2) and runt-related transcription factor 2 (RUNX2) in 2 mg/kg bw group were decreased by 1.79, 1.67, 1.45 and 1.35-folds, respectively. Exposure to CdCl₂ induced an increase in the renal Cd load, but only an adaptive response was observed, including increased expression of autophagy-related proteins LC3B and Beclin-1, autophagy receptor p62, and heme oxygenase 1 (HO-1), which is an inducible isoform that releases in response to stress. There were no significant changes in the urinary low molecular weight proteins including N-acetyl-b-D-glucosaminidase (NAG), β₂-microglobulin and albumin (U-Alb). Urinary calcium (Ca) excretion showed no increase, and no obvious renal histological changes. Taken together, these results indicated that the chronic CdCl₂ exposure directly act on MSCs through RANKL/OPG pathway and downregulate the key genes involved in osteogenic differentiation of MSCs. The toxic effect of Cd on bone may occur in parallel to nephrotoxicity.

Developmental characteristics of pearl oyster Pinctada fucata martensii: insight into key molecular events related to shell formation, settlement and metamorphosis

Background

Marine bivalves undergo complex development processes, such as shell morphology conversion and changes of anatomy and life habits. In this study, the transcriptomes of pearl oyster Pinctada fucata martensii and Pacific oyster Crassostrea gigas at different development stages were analyzed to determine the key molecular events related to shell formation, settlement and metamorphosis.

Result

According to the shell matrix proteome, biomineralization-related genes exhibited a consensus expression model with the critical stages of shell formation. Differential expression analysis of P. f. martensii, revealed the negative regulation and feedback of extracellular matrixs as well as growth factor pathways involved in shell formation of larvae, similar to that in C. gigas. Furthermore, neuroendocrine pathways in hormone receptors, neurotransmitters and neuropeptide receptors were involved in shell formation, settlement and metamorphosis.

Conclusion

Our research demonstrated the main clusters of regulation elements related to shell formation, settlement and metamorphosis. The regulation of shell formation and metamorphosis could be coupled forming the neuroendocrine-biomineralization crosstalk in metamorphosis. These findings could provide new insights into the regulation in bivalve development.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5505-8) contains supplementary material, which is available to authorized users.

Inflammatory mediators in the vitreal reflux of patients with diabetic macular edema

PURPOSE

To quantify inflammatory, growth/angiogenic, and tissue remodeling mediators in vitreal reflux (VR) in patients with diabetic macular edema (DME), as collected at first and third intravitreal anti-vascular endothelial growth factor (anti-VEGF, ranibizumab) injection.

METHODS

Thirty (30) consecutive patients (type-2 diabetes mellitus) with visual impairments due to DME and undergoing the first (untreated DME) or the third (treated DME) intravitreal injection of anti-VEGF were included in the study. At the time of surgery, patients were subjected to clinical assessment and spectral domain-optical coherence tomography (SD-OCT), including central retinal thickness (CRT), macular volume, and outer nuclear layer/retinal pigment epithelial (ONL/RPE) measurements. VR sampling was performed at the time of needle removal and subjected to customized protein-array, Western blotting (WB), Ella™ microfluidic, and/or enzyme-linked immunosorbent assay (ELISA) analysis. Biostrumental and biochemical data were collected just prior to the surgery and are representative of disease state. Clinical, biostrumental, and numerous biomarkers and cytokines were statistically compared.

RESULTS

Decreased CRT values were detected in treated DME retinas, as compared to untreated ones (p ≤ 0.05). Differences in VEGF and other mediator expressions between treated and untreated DME were detected in VR samples. Particularly, osteopontin (p ≤ 0.05), interleukin 6 (IL6) (p ≤ 0.05), and VEGF (p ≤ 0.1) values were decreased after treatment. Significant changes were validated by WB, ELISA, and Ella™ analysis.

CONCLUSION

Overall, the biostrumental and biochemical data suggest the presence of a specific pattern of inflammation in VR after treatment. The data would suggest the presence of other mechanisms and mediators, in addition to VEGF, accountable for DME progression.

Osteopontin levels in plasma, muscles, and bone in patient with non-healing diabetic foot ulcers: A new player in wound healing process?

BACKGROUND

The present study was designed to investigate the impact of osteopontin (OPN) in different tissue (e.g., plasma, muscles and bone) on amputation rate (in-hospital and during one year follow-up) for non-healing diabetic foot ulcers (DFUs).

METHODS

This pilot study consisted of 30 diabetic patients, hospitalized due to non-healing DFUs. Patients were divided into two groups: Group 1 included 14 patients who underwent limb-preserved debridement procedure without amputation; Group 2 included 16 subjects who underwent amputation. Additionally, recurrent amputation rate during 1 year follow-up was investigated.

RESULTS

Plasma OPN was higher and bone OPN was lower in Group 2 compared to Group 1 (p = 0.016 and p = 0.004, respectively). In the logistic regression analysis, bone OPN emerged as a significant independent predictor of amputation (OR = 0.042, 95% CI 0.003-0.699, p = 0.027). Plasma OPN was also associated with amputation such that each unit increase in plasma OPN was associated with an increase in odds of amputation of 17.7% (95% CI 0.997-1.388, p = 0.045). During 1 year follow-up 11 patients underwent recurrent amputation. Plasma OPN were higher and bone osteopontin was lower in patients who underwent amputation compared to patients who did not need amputation at one year follow-up. However, in GLM analysis bone OPN was only marginally associated with one year amputation (OR 0.001, 95% CI 0.000-2.0, p = 0.076).

CONCLUSIONS

Decreased levels of OPN in bone and increased plasma OPN are independently associated with in-hospital amputation. Consequently, plasma OPN may be relevant in the routine assessment of amputation risk in this patient population.

Effects of polyvinylpyrrolidone-iodine on tendon-bone healing in a rabbit extra-articular model

Polyvinylpyrrolidone-iodine (PVP-I) is a broad-spectrum antimicrobial agent, but its effects on tendon-bone healing are unclear. The purpose of this study was to investigate the effects of PVP-I on bone marrow mesenchymal stem cells (BMSCs) in vitro and on tendon-bone healing in vivo. In this study, following investigation of the concentration-dependent effects of PVP-I on the viability and osteogenic differentiation of BMSCs, the appropriate concentration of PVP-I was selected for animal experiments. New Zealand white rabbits received autologous tendon transplantation with and without PVP-I treatment of the graft tendon. Subsequently, histological examination, biomechanical testing and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analyses were conducted. At 6 weeks post-surgery, connective tissue and osteogenesis was observed at the tendon-bone interface in the PVP-I group. At 12 weeks post-surgery, the interface width in the PVP-I group was much narrower compared with that of the control group. Furthermore, the biomechanical properties of the PVP-I group were significantly stronger than those in the control group (P<0.05). RT-qPCR examination revealed that the mRNA levels of bone morphogenetic protein-2 and osteopontin in the PVP-I group were higher than those in the control group at 6 weeks (P<0.05). In conclusion, these results indicated that PVP-I promoted tendon-bone healing via osteogenesis.

Matricellular proteins in drug delivery: Therapeutic targets, active agents, and therapeutic localization

Extracellular matrix is composed of a complex array of molecules that together provide structural and functional support to cells. These properties are mainly mediated by the activity of collagenous and elastic fibers, proteoglycans, and proteins such as fibronectin and laminin. ECM composition is tissue-specific and could include matricellular proteins whose primary role is to modulate cell-matrix interactions. In adults, matricellular proteins are primarily expressed during injury, inflammation and disease. Particularly, they are closely associated with the progression and prognosis of cardiovascular and fibrotic diseases, and cancer. This review aims to provide an overview of the potential use of matricellular proteins in drug delivery including the generation of therapeutic agents based on the properties and structures of these proteins as well as their utility as biomarkers for specific diseases.

Interactions between osteopontin and vascular endothelial growth factor: Implications for cancer

For this comprehensive review, 257 publications with the keywords "osteopontin" or "OPN" and "vascular endothelial growth factor" or "VEGF" in PubMed were screened (time frame from year 1996 to year 2014). 37 articles were excluded because they were not focused on the interactions between these molecules, and papers relevant for transformation-related phenomena were selected. Osteopontin (OPN) and vascular endothelial growth factor (VEGF) are characterized by a convergence in function for regulating cell motility and angiogenesis, the response to hypoxia, and apoptosis. Often, they are co-expressed or one molecule induces the other, however, in some settings OPN-associated pathways and VEGF-associated pathways are distinct. Their relationships affect the pathogenesis in cancer, where they contribute to progression and angiogenesis and serve as markers for poor prognosis. The inhibition of OPN may reduce VEGF levels and suppress tumor progression. In vascular pathologies, these two cytokines mediate remodeling, but may also perpetuate inflammation and narrowing of the arteries. OPN and VEGF are elevated and contribute to vascularization in inflammatory diseases.