Enhanced pyroptosis induction with pore-forming gene delivery for osteosarcoma microenvironment reshaping.

Osteosarcoma is the most common malignant bone tumor without efficient management for improving 5-year event-free survival. Immunotherapy is also limited due to its highly immunosuppressive tumor microenvironment (TME). Pore-forming gasdermins (GSDMs)-mediated pyroptosis has gained increasing concern in reshaping TME, however, the expressions and relationships of GSDMs with osteosarcoma remain unclear. Herein, gasdermin E (GSDME) expression is found to be positively correlated with the prognosis and immune infiltration of osteosarcoma patients, and low GSDME expression was observed. A vector termed as LPAD contains abundant hydroxyl groups for hydrating layer formation was then prepared to deliver the GSDME gene to upregulate protein expression in osteosarcoma for efficient TME reshaping via enhanced pyroptosis induction. Atomistic molecular dynamics simulations analysis proved that the hydroxyl groups increased LPAD hydration abilities by enhancing coulombic interaction. The upregulated GSDME expression together with cleaved caspase-3 provided impressive pyroptosis induction. The pyroptosis further initiated proinflammatory cytokines release, increased immune cell infiltration, activated adaptive immune responses and create a favorable immunogenic hot TME. The study not only confirms the role of GSDME in the immune infiltration and prognosis of osteosarcoma, but also provides a promising strategy for the inhibition of osteosarcoma by pore-forming GSDME gene delivery induced enhanced pyroptosis to reshape the TME of osteosarcoma.

Reference Values for Paravertebral Muscle Size and Myosteatosis in Chinese Adults, a Nationwide Multicenter Study.

RATIONALE AND OBJECTIVES: The paravertebral muscles, characterized by their susceptibility to severe size loss and fat infiltration in old age, lack established reference values for age-related variations in muscle parameters. This study aims to fill this gap by establishing reference values for paravertebral muscles in a Chinese adult population. MATERIALS AND METHODS: This cross-sectional study utilized the baseline data from the prospective cohort China Action on Spine and Hip (CASH). A total of 4305 community-dwelling participants aged 21-80 years in China were recruited between 2013 and 2017. Pregnant women, individuals with metal implants, limited mobility or diseases/conditions (spinal tumor, infection, etc.) affecting lumbar vertebra were excluded from the study. Psoas and paraspinal muscles were measured in quantitative computed tomography (QCT) images at the L3 and L5 levels using Osirix software. Age-related reference values for muscle area, density, and fat fraction were constructed as percentile charts using the lambda-mu-sigma (LMS) method. RESULTS: The paravertebral muscles exhibited an age-related decline in muscle area and density, coupled with an increase in muscle fat fraction. Between the ages of 25 and 75, the reductions in psoas and paraspinal muscle cross-sectional area at the L3 level were - 0.47%/yr and - 0.53%/yr in men, and - 0.19%/yr and - 0.23%/yr in women, respectively. Notably, accelerated muscle loss was observed during menopause and postmenopause in women (45-75 years) and intermittently during middle and old age in men (35-55 and 60-75 years). Besides, the age-related decreases in PSMA, PMA, and PSMD and the increases in PSMFF were more pronounced in L5 than in L3 CONCLUSION: This study shows distinct patterns of accelerated muscle loss were identified in menopausal and postmenopausal women and in middle-aged and old men. The findings contribute valuable information for future investigations on paravertebral muscle loss and myosteatosis.

Two-Dimensional Biodegradable Black Phosphorus Nanosheets Promote Large Full-Thickness Wound Healing through In Situ Regeneration Therapy.

Large full-thickness skin lesions have been one of the most challenging clinical problems in plastic surgery repair and reconstruction. To achieve in situ skin regeneration and perfect clinical outcomes, we must address two significant obstacles: angiogenesis deficiency and inflammatory dysfunction. Recently, black phosphorus has shown great promise in wound healing. However, few studies have explored the bio-effects of BP to promote in situ skin regeneration based on its nanoproperties. Here, to investigate whether black phosphorus nanosheets have positive bio-effects on in situ skin repair, we verified black phosphorus nanosheets' positive effects on angiogenic and anti-inflammatory abilities in vitro. Next, the in vivo evaluation performed on the rat large full-thickness excisional wound splinting model more comprehensively showed that the positive bio-effects of black phosphorus nanosheets are multilevel in wound healing, which can effectively enhance anti-inflammatory ability, angiogenesis, collagen deposition, and skin re-epithelialization. Then, multiomics analysis was performed to explore further the mechanism of black phosphorus nanosheets' regulation of endothelial cells in depth. Molecular mechanistically, black phosphorus nanosheets activated the JAK-STAT-OAS signaling pathway to promote cellular function and mitochondrial energy metabolism in endothelial cells. This study can provide a theoretical basis for applying two-dimensional black phosphorus nanosheets as nanomedicine to achieve in situ tissue regeneration in complex human pathological microenvironments, guiding the subsequent optimization of black phosphorus.

Piezo-enhanced near infrared photocatalytic nanoheterojunction integrated injectable biopolymer hydrogel for anti-osteosarcoma and osteogenesis combination therapy.

Preventing local tumor recurrence while promoting bone tissue regeneration is an urgent need for osteosarcoma treatment. However, the therapeutic efficacy of traditional photosensitizers is limited, and they lack the ability to regenerate bone. Here, a piezo-photo nanoheterostructure is developed based on ultrasmall bismuth/strontium titanate nanocubes (denoted as Bi/SrTiO3), which achieve piezoelectric field-driven fast charge separation coupling with surface plasmon resonance to efficiently generate reactive oxygen species. These hybrid nanotherapeutics are integrated into injectable biopolymer hydrogels, which exhibit outstanding anticancer effects under the combined irradiation of NIR and ultrasound. In vivo studies using patient-derived xenograft models and tibial osteosarcoma models demonstrate that the hydrogels achieve tumor suppression with efficacy rates of 98.6 % and 67.6 % in the respective models. Furthermore, the hydrogel had good filling and retention capabilities in the bone defect region, which exerted bone repair therapeutic efficacy by polarizing and conveying electrical stimuli to the cells under mild ultrasound radiation. This study provides a comprehensive and clinically feasible strategy for the overall treatment and tissue regeneration of osteosarcoma.

Caulis Spatholobi extracts inhibit osteosarcoma growth and metastasis through suppression of CXCR4/PI3K/AKT signaling.

BACKGROUND: The therapeutic potential of Caulis Spatholobi (CS) extracts against various cancers has been well documented, yet its impact and mechanism in osteosarcoma (OS) remain unexplored. This study aims to elucidate the effects of CS extracts on the growth and metastasis of OS, along with its underlying molecular mechanism. METHODS: The impact of CS extracts on the proliferative potential of two OS cell lines (Saos-2 and U2OS) was assessed using MTT and colony-formation assays. Additionally, the migratory and invasive capacities of OS cells were investigated through Transwell assays. The modulation of CXCR4 expression by CS extracts was evaluated using qRT-PCR and Western blotting. Furthermore, the influence of CS extracts on the activation of PI3K/Akt signaling was determined through Western blotting. RESULTS: CS extracts exhibited a dose- and time-dependent inhibition of proliferation and colony formation in OS cells. Notably, CXCR4 expression was prominently observed in Saos-2 and U2OS, and treatment with CS extracts led to a dose-dependently reduction in CXCR4 levels. Silencing CXCR4 or inhibiting its function diminished the migratory and invasive capacities of OS cells. Conversely, the CS extracts induced suppression of OS cell migration and invasion was counteracted by CXCR4 overexpression. Mechanistically, CS extracts repressed PI3K/AKT signaling in OS cells by downregulating CXCR4 expression. CONCLUSIONS: CS extracts mitigate the CXCR4/PI3K/AKT signaling-mediated growth and metastasis capacities of OS cells, thus might play an anti-tumor role in OS.

Carboxypeptidase E is a prognostic biomarker co-expressed with osteoblastic genes in osteosarcoma.

Osteosarcoma (OS) is a rare primary malignant bone tumor in adolescents and children with a poor prognosis. The identification of prognostic genes lags far behind advancements in treatment. In this study, we identified differential genes using mRNA microarray analysis of five paired OS tissues. Hub genes, gene set enrichment analysis, and pathway analysis were performed to gain insight into the pathway alterations of OS. Prognostic genes were screened using the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) dataset, then overlapped with the differential gene dataset. The carboxypeptidase E (CPE) gene, found to be an independent risk factor, was further validated using RT-PCR and Gene Expression Omnibus (GEO) datasets. Additionally, we explored the specific expression of CPE in OS tissues by reanalyzing single-cell genomics. Interestingly, CPE was found to be co-expressed with osteoblast lineage cell clusters that expressed RUNX2, SP7, SPP1, and IBSP marker genes in OS. These results suggest that CPE could serve as a prognostic factor in osteoblastic OS and should be further investigated as a potential therapeutic target.

Reduction-responsive nucleic acid nanocarrier-mediated miR-22 inhibition of PI3K/AKT pathway for the treatment of patient-derived tumor xenograft osteosarcoma.

miRNAs are important regulators of gene expression and play key roles in the development of cancer, including osteosarcoma. During the development of osteosarcoma, the expression of miR-22 is significantly downregulated, making miR-22 as a promising therapeutic target against osteosarcoma. To design and fabricate efficient delivery carriers of miR-22 into osteosarcoma cells, a hydroxyl-rich reduction-responsive cationic polymeric nanoparticle, TGIC-CA (TC), was developed in this work, which also enhanced the therapeutic effects of Volasertib on osteosarcoma. TC was prepared by the ring-opening reaction between amino and epoxy groups by one-pot method, which had the good complexing ability with nucleic acids, reduction-responsive degradability and gene transfection performance. TC/miR-22 combined with volasertib could inhibit proliferation, migration and promote apoptosis of osteosarcoma cells in vitro. The anti-tumor mechanisms were revealed as TC/miR-22 and volasertib could inhibit the PI3K/Akt signaling pathway synergistically. Furthermore, this strategy showed outstanding tumor suppression performance in animal models of orthotopic osteosarcoma, especially in patient-derived chemo-resistant and chemo-intolerant patient-derived xenograft (PDX) models, which reduced the risk of tumor lung metastasis and overcame drug resistance. Therefore, it has great potential for efficient treatment of metastasis and drug resistance of osteosarcoma by the strategy of localized, sustained delivery of miR-22 using the cationic nanocarriers combined with non-traditional chemotherapy drugs.

Kinome-wide CRISPR-Cas9 knockout screens revealed PLK1 as a therapeutic target for osteosarcoma.

Osteosarcoma is the most common malignant bone tumor, tending to be aggressive and recurrent. The therapeutic development for treating osteosarcoma has been largely hampered by the lack of effective and specific targets. Using kinome-wide CRISPR-Cas9 knockout screens, we systematically revealed a cohort of kinases essential for the survival and growth of human osteosarcoma cells, in which Polo-like kinase 1 (PLK1) appeared as a specific prominent hit. PLK1 knockout substantially inhibited proliferation of osteosarcoma cells in vitro and the tumor growth of osteosarcoma xenograft in vivo. Volasertib, a potent experimental PLK1 inhibitor, can effectively inhibit the growth of the osteosarcoma cell lines in vitro. It can also disrupt the development of tumors in the patient-derived xenograft (PDX) models in vivo. Furthermore, we confirmed that the mode of action (MoA) of volasertib is primarily mediated by the cell-cycle arrest and apoptosis triggered by DNA damage. As PLK1 inhibitors are entering phase III clinical trials, our findings provide important insights into the efficacy and MoA of the relevant therapeutic approach for combating osteosarcoma.

[Corrigendum] Hsp90 inhibitor 17­AAG inhibits stem cell­like properties and chemoresistance in osteosarcoma cells via the Hedgehog signaling pathway.

Following the publication of the article, a concerned reader drew to the authors' attention that, in Fig. 1B and C on p. 316, two pairs of the data panels showing the results from invasion and migration assay experiments appeared to be overlapping, such that they would have been derived from the same original sources where they were intended to show the results from different experiments; moreover, on p. 1698, the '17­AAG / MG­63' data panels in Fig. 3B and C were also overlapping, albeit the images were presented at a different scale and in a slightly different orientation. After having examined their original data, the authors have realized that these figures were inadvertently assembled incorrectly. The corrected versions of Figs. 1 and 3, now showing the correct data in Fig. 1C (where the errors made in compiling the figure had occurred) and the correct data for the '17­AAG / MG­63' data panel in Fig. 3C, are shown on the next two pages. These corrections do not grossly affect either the results or the conclusions reported in this work. The authors all agree to the publication of this Corrigendum, and are grateful to the Editor of Oncology Reports for granting them the opportunity to correct the errors that were made during the assembly of these figures. Lastly, the authors apologize to the readership for any inconvenience these errors may have caused. [Oncology Reports 44: 313­324, 2020; DOI: 10.3892/or.2020.7597].

Zinc oxide nanoparticles inhibit osteosarcoma metastasis by downregulating ß-catenin via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway.

Osteosarcoma (OS) therapy faces many challenges, especially the poor survival rate once metastasis occurs. Therefore, it is crucial to explore new OS treatment strategies that can efficiently inhibit OS metastasis. Bioactive nanoparticles such as zinc oxide nanoparticles (ZnO NPs) can efficiently inhibit OS growth, however, the effect and mechanisms of them on tumor metastasis are still not clear. In this study, we firstly prepared well-dispersed ZnO NPs and proved that ZnO NPs can inhibit OS metastasis-related malignant behaviors including migration, invasion, and epithelial-mesenchymal transition (EMT). RNA-Seqs found that differentially expressed genes (DEGs) in ZnO NP-treated OS cells were enriched in wingless/integrated (Wnt) and hypoxia-inducible factor-1 (HIF-1) signaling pathway. We further proved that Zn2+ released from ZnO NPs induced downregulation of ß-catenin expression via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway. ZnO NPs combined with ICG-001, a ß-catenin inhibitor, showed a synergistic inhibitory effect on OS lung metastasis and a longer survival time. In addition, tissue microarray (TMA) of OS patients also detected much higher ß-catenin expression which indicated the role of ß-catenin in OS development. In summary, our current study not only proved that ZnO NPs can inhibit OS metastasis by degrading ß-catenin in HIF-1α/BNIP3/LC3B-mediated mitophagy pathway, but also provided a far-reaching potential of ZnO NPs in clinical OS treatment with metastasis.

IL-11Rα-targeted nanostrategy empowers chemotherapy of relapsed and patient-derived osteosarcoma.

Osteosarcoma (OS) is a rare but frequently lethal bone malignancy in children and adolescents. The adjuvant chemotherapy with doxorubicin (Dox) and cisplatin remains a mainstream clinical practice though it affords only limited clinical benefits due to low tumor deposition, dose-limiting toxicity and high rate of relapse/metastasis. Here, taking advantage of high IL-11Rα expression in the OS patients, we installed IL-11Rα specific peptide (sequence: cyclic CGRRAGGSC) onto redox-responsive polymersomes encapsulating Dox (IL11-PDox) to boost the specificity and anti-OS efficacy of chemotherapy. Of note, IL-11Rα peptide at a density of 20% greatly augmented the internalization, apoptotic activity, and migration inhibition of Dox in IL-11Rα-overexpressing 143B OS cells. The active targeting effect of IL11-PDox was supported in orthotopic and relapsed 143B OS models, as shown by striking repression of tumor growth and lung metastasis, and substantial survival benefits over free Dox control. We further verified that IL11-PDox could effectively inhibit patient-derived OS xenografts. IL-11Rα-targeted nanodelivery of chemotherapeutics provides a potential therapeutic strategy for advanced osteosarcoma.

Preparation of polycation with hydroxyls for enhanced delivery of miRNA in osteosarcoma therapy.

Osteosarcoma, a malignant bone tumor that usually occurs in children and adolescents, has a high rate of death and disability, bringing great pains to society and families. Improving treatment approaches for osteosarcoma patients remains a constant and major goal for researchers and clinical groups due to the limited therapeutic efficiency and survival rate. MiRNAs have been reported to play a crucial role in osteosarcoma occurrence, progression, and metastasis, which provides a new insight for osteosarcoma therapy. In other words, the intervention of the involved miRNA may be a promising way for osteosarcoma. In this study, we developed ethanolamine (EA)-decorated poly(glycidyl methacrylate) (PGMA) polycations (termed as PGEAs) to deliver miR-223 for osteosarcoma inhibition. The introduced hydroxyl groups via EA modification in the PGEA vector can form a hydration shell, hinder protein adsorption, and help the PGEA-based delivery system escape from the in vivo clearance, which further benefits the accumulation of the delivery system in the tumor area. A series of in vitro anti-tumor assays illustrate that the PGEA-2 vector can efficiently deliver miR-223 into osteosarcoma cells for impressive anti-tumor effects via inhibiting malignant behavior of osteosarcoma cells, including proliferation, migration, and invasion. Osteosarcoma inhibition assays in vivo further confirmed the anti-tumor efficiency of PGEA-2/miR-223 complexes without inducing evident toxicity. This work will help develop miRNA for osteosarcoma therapy, and the proposed PGEA based delivery system also provides a promising and safe strategy for gene therapy of osteosarcoma.

Correction: Anti-osteosarcoma effect of hydroxyapatite nanoparticles both in vitro and in vivo by downregulating the FAK/PI3K/Akt signaling pathway.

Correction for 'Anti-osteosarcoma effect of hydroxyapatite nanoparticles both in vitro and in vivo by downregulating the FAK/PI3K/Akt signaling pathway' by Renxian Wang et al., Biomater. Sci., 2020, 8, 4426-4437, DOI: 10.1039/D0BM00898B.

Whole-exome sequencing in osteosarcoma with distinct prognosis reveals disparate genetic heterogeneity.

The genomic profiles of osteosarcoma (OS) patients have been extensively investigated; however, the genetic prognostic biomarkers still remain unclear. In the present study, we analyzed the mutational profiles of pre-treatment primary tumor samples from 33 OS patients using whole exome sequencing (WES). These 33 OS patients were divided into two groups according to clinical outcomes: a good prognosis group involving 21 patients with tumor free survival, and a poor prognosis group involving the remaining12 patients who had lung metastases at initial diagnosis. Overall we found that the MAPK signaling pathway may play an important role in determining a good prognosis, while the PI3K-Akt signaling pathway may be an important factor leading to a poor prognosis. Significant differences were observed in the number of somatic copy number alterations, including del (3p), amp (4q), del (7p) and amp (8q), between the two groups. Moreover, significant differences were observed in mutation sites and frequencies between these two groups. The good prognosis group exhibited a significantly higher mutation frequency in somatic JAK-STAT and germline base excision repair pathways than the poor prognosis group. Furthermore, significant difference was also observed in the frequency of potentially actionable alterations between the two groups, suggesting that patients with a poor prognosis potentially have access to a larger number of treatment options. These findings highlight the importance of evaluating genomic disparities in OS, and provide a novel insight into the potential prognostic biomarkers.

Analysis of Immune Gene Expression Subtypes Reveals Osteosarcoma Immune Heterogeneity.

BACKGROUND: Osteosarcoma (OS) patients have a poor response to immunotherapy due to the sheer complexity of the immune system and the nuances of the tumor-immune microenvironment. Methodology. To gain insights into the immune heterogeneity of OS, we identified robust clusters of patients based on the immune gene expression profiles of OS patients in the TARGET database and assessed their reproducibility in an independent cohort collected from the GEO database. The association of comprehensive molecular characterization with reproducible immune subtypes was accessed with ANOVA. Furthermore, we visualized the distribution of individual patients in a tree structure by the graph structure learning-based dimensionality reduction algorithm. RESULTS: We found that 87 OS samples can be divided into 5 immune subtypes, and each of them was associated with distinct clinical outcomes. The immune subtypes also demonstrated widely different patterns in tumor genetic aberrations, tumor-infiltrating, immune cell composition, and cytokine profiles. The immune landscape of OS uncovered the significant intracluster heterogeneity within each subtype and depicted a continuous immune spectrum across patients. CONCLUSION: The established five immune subtypes in our study suggested immune heterogeneity in OS patients and may provide optimal individual immunotherapy for patients exhibiting OS.

Anti-osteosarcoma effect of hydroxyapatite nanoparticles both in vitro and in vivo by downregulating the FAK/PI3K/Akt signaling pathway.

Numerous studies have reported that hydroxyapatite nanoparticles (nano-HAPs) can inhibit the proliferation of a variety of tumor cells and this effect is different in different carcinoma cells. However, the effect of nano-HAPs on osteosarcoma cell proliferation has not been well understood thus far. In this study, we first showed that our synthesized nano-HAPs reduced cell viability and inhibited migration and invasion of OS-732 cells in a concentration-dependent manner. Using a BALB/c nude mouse tumor model, we demonstrated that nano-HAPs could effectively suppress tumor growth in vivo. We also performed RNA-seq analysis to investigate the underlying mechanism of these effects and discovered that treatment of OS-732 cells with nano-HAPs significantly downregulated the FAK/PI3K/Akt signaling pathway. Collectively, our study suggests that treatment with nano-HAPs can inhibit osteosarcoma cell growth, migration and invasion in vitro and suppress osteosarcoma in vivo.

Therapeutic Potential of Circular RNAs in Osteosarcoma.

Osteosarcoma is the most common malignant bone tumor in children and adolescents. Multiagent chemotherapy, together with surgical removal of all detectable lesions, has improved the long-term survival rate to 65-70% in patients with localized osteosarcoma and to 25-30% in patients with metastatic osteosarcoma since the 1970s. However, the conventional strategy has not improved in recent decades. With accumulating knowledge of the natural circular RNA (circRNA) pathogenesis of osteosarcoma, the diagnostic and therapeutic potential of some circRNAs has been explored. Meanwhile, artificial circular RNAs have been designed as onco-microRNA inhibitors to exert antitumor functions. Therefore, natural and artificial circular RNAs, like other RNA counterparts, are attractive new classes of therapeutic molecules for the treatment of osteosarcoma. This review summarizes the latest progress in the relationship between circRNAs and the malignant phenotype of osteosarcoma and sheds light on the therapeutic potential of the two types of circular RNA in the clinic.

Hsp90 inhibitor 17­AAG inhibits stem cell­like properties and chemoresistance in osteosarcoma cells via the Hedgehog signaling pathway.

Multiple drug resistance is a major obstacle to the successful treatment of osteosarcoma (OS). Recent studies have demonstrated that a subset of cells, referred to as OS stem cells (OSCs), play a crucial role in the acquisition of multiple drug resistance. Therefore, an improved understanding of OS biology and pathogenesis is required to advance the development of targeted therapies aimed at eradicating this particular subset of cells in order to reverse acquired chemoresistance in OS. The aim of the present study was to assess the anti­OSC effects of 17­AAG and determine the underlying molecular mechanism. Heat shock protein 90 expression was found to be increased in sarcosphere cells and was positively associated with cancer stem cell characteristics. In addition, 17­AAG was able to suppress the stem cell­like phenotype of OS cells. Mechanistically, 17­AAG inhibited OSC­like properties and chemoresistance through glycogen synthase kinase (GSK) 3ß inactivation­mediated repression of the Hedgehog signaling pathway. The findings of the present study provided comprehensive evidence for the inhibition of OSC properties and chemoresistance by 17­AAG through repression of the GSK3ß/Hedgehog signaling pathway, suggesting that 17­AAG may be a promising therapeutic agent for targeting OSCs.

Promoting osteogenic differentiation of BMSCs via mineralization of polylactide/gelatin composite fibers in cell culture medium.

Mineralization capability is an important issue in developing bone repairing biomaterials, while it is not quite clear how this feature would act in the presence of cells and influence cell osteogenic differentiation without adding extra osteoinductive factors such as ß­sodium glycerophosphate and dexamethasone. Poly(l­lactide) (PLLA) and gelatin composite fibers (PG, 1:1 in weight) were electrospun, treated with CaCl2 solution (PG-Ca), and used for mineralization studies by using cell culture media (αMEM, and αMEM + serum). Bone mesenchymal stromal cells (BMSCs) were then seeded and cultured on both PG and PG-Ca fibrous mats for 28 days by only using αMEM + serum. Interestingly, mineral depositions on both PG and PG-Ca fibers were detected in the environment of αMEM or αMEM + serum, in which, PG-Ca fibers demonstrated stronger ability in inducing hydroxyapatite formation than PG fibers, especially in the presence of fetal bovine serum. When BMSCs were cultured on the two kinds of fibrous mats, apatite depositions were still clearly detected, while the depositing amounts decreased in comparison with corresponding cell-free cases. It was ascribed to the consumption of ions by the continuously proliferating BMSCs, whose osteogenic differentiation was significantly promoted even without extra osteoinductive factors, especially on PG-Ca fibrous mats, in comparison with the control group. Therefore, it was confirmed the capability of scaffolding materials in enriching ions like calcium and phosphate around cells was an efficient way to promote bone regeneration.

Promoting in vivo early angiogenesis with sub-micrometer strontium-contained bioactive microspheres through modulating macrophage phenotypes.

Early vascularization capacity of biomaterials plays an essential role in efficient wound healing and tissue regeneration, especially in large tissue tension implanting position such as bone augmentation. Strontium-contained silica-based bioactive materials have shown the role of promoting angiogenesis by stimulating osteoblasts to secrete angiogenesis related cytokines. However, osteoblasts have little effect on early angiogenesis due to the inflammatory reaction of implantation site. Here, for the first time, we found that the monodispersed strontium-contained bioactive glasses microspheres (SrBGM) could significantly promote the early angiogenesis through regulating macrophage phenotypes. After being stimulated with SrBGM in vitro, RAW cells (macrophages) presented a trend towards to M2 phenotype and expressed high level of platelet-derived growth factor-BB (PDGF-BB). Moreover, the RAW conditioned medium of SrBGM significantly enhanced the angiogenic capacity of HUVECs. The in vivo early vascularization studies showed that significant new vessels were observed at the center of SrBGM-based scaffolds after implantation for 1 week in a bone defect model of rats, suggesting their enhanced early vascularization. Due to the efficient vascularization, the in vivo new bone formation was promoted significantly. Our study may provide a novel strategy to promote the early vascularization of biomaterials through modulating the microphage phenotypes, which has wide applications in various tissue regeneration and wound healing.