Exposure of the murine RAW 264.7 macrophage cell line to dicalcium silicate coating: assessment of cytotoxicity and pro-inflammatory effects

Nanoemulsions and nanocapsules loaded with Melaleuca alternifolia essential oil for sepsis treatment

Sepsis represents a complex clinical syndrome that results from a harmful host response to infection. The infections most associated with sepsis are pneumonia, intra-abdominal infection, and urinary tract infection. Tea tree oil (TTO) has shown high antibacterial activity; however, it exhibits low aqueous solubility and high volatility, which have motivated its nanoencapsulation. In this study, the performance of nanoemulsions (NE) and nanocapsules (NC) loaded with TTO was compared. These systems were prepared by spontaneous emulsification and nanoprecipitation methods, respectively. Poly-ε-caprolactone or Eudragit® RS100 were tested as polymers for NCs whereas Tween® 80 or Pluronic® F68 as surfactants in NE preparation. Pluronic® F68 and Eudragit® RS100 resulted in more homogeneous and stable nanoparticles. In accelerated stability studies at 4 and 25 °C, both colloidal suspensions (NC and NE) were kinetically stable. NCs showed to be more stable to photodegradation and less cytotoxic than NEs. After sepsis induction by the cecal ligation and puncture (CLP) model, both NE and NC reduced neutrophil infiltration into peritoneal lavage (PL) and kidneys. Moreover, the systems increased group thiols in the kidney and lung tissue and reduced bacterial growth in PL. Taken together, both systems showed to be effective against injury induced by sepsis; however, NCs should be prioritized due to advantages in terms of cytotoxicity and physicochemical stability.

Toxicity study of pro-angiogenic casein manganese oxide nanoparticles: an in vitro and in vivo approach

Recently, we have demonstrated casein manganese oxide nanoparticles (CMnNP) that exhibit pro-angiogenic property established through different in vitro and in vivo experiments. The CMnNP was explored for therapeutic angiogenesis for treatment of wounds and recovery of hindlimb ischemia in pre-clinical mouse prototypical. It is well known that to translate any therapeutic nanoparticle for future clinical applications, their biosafety evaluation in small and large animals is essential. Herein, in the current study, the biosafety and bioavailability of the CMnNP have been explored by a systematic toxicity profiling study in C57BL/6J mice model. Initially, the in vitro cytotoxic effects of CMnNP were validated in RAW 264.7 cells. Later, the CMnNP was administered intraperitoneally with different doses (50, 300, and 2000 mg/kg b.wt./day) at different time points of exposure (acute: 2 weeks, sub-chronic: 4 weeks as well as chronic exposure: 8 and 20 weeks) with reference to the maximum tolerable dose (MTD) of CMnNP as per the OECD guidelines. The blood hematological and serum biochemical parameters of CMnNP treatment groups indicate negligible changes similar to untreated group. The histopathological examination of CMnNP-treated vital organs (lung, spleen, liver, brain, kidney, and heart) illustrates no major changes even at higher doses. Further, the biodistribution and excretion study depicts normal clearance of CMnNP. Additionally, the serum cytokine levels were normal in the therapeutic dose of CMnNP. The results altogether indicate that the non-toxic nature of CMnNP makes them useful as future therapeutic angiogenic agent for the treatment of various diseases where angiogenesis plays an important role.

Nickel (II) and Cobalt (II) Alginate Biopolymers as a “Carry and Release” Platform for Polyhistidine-Tagged Proteins

Protein immobilization using biopolymer scaffolds generally involves undesired protein loss of function due to denaturation, steric hindrance or improper orientation. Moreover, most methods for protein immobilization require expensive reagents and laborious procedures. This work presents the synthesis and proof of concept application of two alginate hydrogels that are able to bind proteins with polyhistidine tags by means of interaction with the crosslinking cations. Nickel (II) and cobalt (II) alginate hydrogels were prepared using a simple ionic gelation method. Hydrogels were characterized by optical microscopy and AFM, and evaluated for potential cytotoxicity. In addition, binding capacity was tested towards proteins with or without HisTAG. Hydrogels had moderate cytotoxicity and were able to exclusively bind polyhistidine-tagged proteins with a binding capacity of approximately 300 µg EGFP (enhanced green fluorescent protein) per 1 mL of hydrogel. A lyophilized hydrogel-protein complex dissolved upon the addition of PBS and allowed the protein release and regain of biological activity. In conclusion, the nickel (II) and cobalt (II) alginate biopolymers provided an excellent platform for the “carry and release” of polyhistidine-tagged proteins.

Dicalcium silicate-induced mitochondrial dysfunction and autophagy-mediated macrophagic inflammation promotes osteogenic differentiation of BMSCs

Dicalcium silicate (Ca2SiO4, C2S) has osteogenic potential but induces macrophagic inflammation. Mitochondrial function plays a vital role in macrophage polarization and macrophagic inflammation. The mitochondrial function of C2S-treated macrophages is still unclear. This study hypothesized: (i) the C2S modulates mitochondrial function and autophagy in macrophages to regulate macrophagic inflammation, and (ii) C2S-induced macrophagic inflammation regulates osteogenesis. We used RAW264.7 cells as a model of macrophage. The C2S (75-150 μg/ml) extract was used to analyze the macrophagic mitochondrial function and macrophage-mediated effect on osteogenic differentiation of mouse bone marrow-derived mesenchymal stem cells (BMSCs). The results showed that C2S extract (150 μg/ml) induced TNF-α, IL-1β and IL-6 production in macrophages. C2S extract (150 μg/ml) enhanced reactive oxygen species level and intracellular calcium level but reduced mitochondrial membrane potential and ATP production. TEM images showed reduced mitochondrial abundance and altered the mitochondrial morphology in C2S (150 μg/ml)-treated macrophages. Protein level expression of PINK1, Parkin, Beclin1 and LC3 was upregulated but TOMM20 was downregulated. mRNA sequencing and KEGG analysis showed that C2S-induced differentially expressed mRNAs in macrophages were mainly distributed in the essential signaling pathways involved in mitochondrial function and autophagy. The conditioned medium from C2S-treated macrophage robustly promoted osteogenic differentiation in BMSCs. In conclusion, our results indicate mitochondrial dysfunction and autophagy as the possible mechanism of C2S-induced macrophagic inflammation. The promotion of osteogenic differentiation of BMSCs by the C2S-induced macrophagic inflammation suggests the potential application of C2S in developing immunomodulatory bone grafts.

Immunomodulatory bioactive glasses for tissue regeneration

The regulatory functions of the immune response in tissue healing, repair, and regeneration have been evidenced in the last decade. Immune cells play central roles in immune responses toward inducing favorable tissue regenerative processes. Modulating and controlling the immune cell responses (particularly macrophages) is an emerging approach to enhance tissue regeneration. Bioactive glasses (BGs) are multifunctional materials exhibiting osteogenic, angiogenic, and antibacterial properties, being increasingly investigated for various tissue regeneration scenarios, including bone regeneration and wound healing. On the other hand, the immunomodulatory effects of BGs in relation to regenerating tissues have started to be understood, and key knowledge is emerging. This is the first review article summarizing the immunomodulatory effects of BGs for tissue repair and regeneration. The immune response to BGs is firstly introduced, discussing potential mechanisms regarding the immunomodulation effects induced by BGs. Moreover, the interactions between the immune cells involved in the immunomodulation process and BGs (dissolution products) are summarized in detail. Particularly, a well-regulated and timely switch of macrophage phenotype from pro-inflammatory to anti-inflammatory is crucial to constructive tissue regeneration through modulating osteogenesis, osteoclastogenesis, and angiogenesis. The influence of BG characteristics on macrophage responses is discussed. We highlight the strategies employed to harness macrophage responses for enhanced tissue regeneration, including the incorporation of active ions, surface functionalization, and controlled release of immunomodulatory molecules. Finally, we conclude with our perspectives on future research challenges and directions in the emerging field of immunomodulatory BGs for tissue regeneration. STATEMENT OF SIGNIFICANCE: Immunomodulatory effects of bioactive glasses (BGs) in relation to bone regeneration and wound healing have started to be understood. We summarize those studies which have focused on immunomodulatory BGs for tissue regeneration. We first introduce the potential mechanisms of the immunomodulation effects induced by BGs. Interactions between the cells involved in immunomodulation processes and BGs (and their dissolution products, biologically active ions) are elaborated. We highlight the strategies employed to modulate macrophage responses for enhancing tissue regeneration, including incorporation of active ions, surface functionalization, and controlled release of immunomodulatory agents. This is the first review article summarizing and outlining the immunomodulatory effects of BGs for tissue regeneration. We anticipate that increasing research efforts will start to emerge in the area of immunomodulatory BGs.

The mTOR/ULK1 signaling pathway mediates the autophagy-promoting and osteogenic effects of dicalcium silicate nanoparticles

A novel bioactive inorganic material containing silicon, calcium and oxygen, calcium silicate (Ca₂SiO₄, C₂S) with a CaO-SiO₂ ingredient, has been identified as a potential candidate for artificial bone. Autophagy has an essential function in adult tissue homoeostasis and tumorigenesis. However, little is known about whether silicate nanoparticles (C₂S NPs) promote osteoblastic differentiation by inducing autophagy. Here we investigated the effects of C₂S NPs on bone marrow mesenchymal stem cell differentiation (BMSCs) in osteoblasts. Furthermore, we identified the osteogenic gene and protein expression in BMSCs treated with C₂S NPs. We found that autophagy is important for the ability of C₂S NPs to induce osteoblastic differentiation of BMSCs. Our results showed that treatment with C₂S NPs upregulated the expression of BMP2, UNX2, and OSX in BMSCs, and significantly promoted the expression of LC3 and Beclin, while P62 (an autophagy substrate) was downregulated. C₂S NP treatment could also enhance Alizarin red S dye (ARS), although alkaline phosphatase (ALP) activity was not significantly changed. However, all these effects could be partially reversed by 3-MA. We then detected potential signaling pathways involved in this biological effect and found that C₂S NPs could activate autophagy by suppressing mTOR and facilitating ULK1 expression. Autophagy further activated β-catenin expression and promoted osteogenic differentiation. In conclusion, C₂S NPs promote bone formation and osteogenic differentiation in BMSCs by activating autophagy. They achieve this effect by activating mTOR/ULK1, inducing autophagy, and subsequently triggering the WNT/β-catenin pathway to boost the differentiation and biomineralization of osteoblasts.

Antifungal and Antivirulence Activities of Hydroalcoholic Extract and Fractions of Platonia insignis Leaves against Vaginal Isolates of Candida Species

Vulvovaginal candidiasis is a common fungal infection in women. In this study, Platonia insignis hydroalcoholic extract (PiHE) and its fractions were evaluated for antifungal and antivirulence activities against vaginal Candida species. Dichloromethane (DCMF) and ethyl acetate fractions (EAF) obtained from PiHE effectively inhibited the pathogen. Electrospray ionization mass spectrometry was used for identifying the main compounds in extracts. Minimal inhibitory and fungicidal concentrations (MIC and MFC, respectively) were determined by a broth microdilution assay. Furthermore, we evaluated the effect of the extract and fractions on the virulence properties of Candida albicans, and their cytotoxicity effect was determined on RAW 264.7 cells. Compounds found in extracts were flavonoid glycosides, mainly derivatives of quercetin and myricetin. Extracts showed antifungal potential, with the lowest MIC value for EAF (1.3 mg/mL) and inhibited Candida adherence and biofilm formation. EAF disrupted 48 h biofilms with an inhibition rate of more than 90%. The extract and its fractions exhibited no cytotoxicity. The antifungal effects were attributed to the ability of these extracts to alter the mitochondrial membrane potential for the release of pro-apoptotic factors in the cytosol. In conclusion, our data suggest that PiHE and EAF could act as novel candidates for the development of new therapeutic treatments against fungal infections.

Dicalcium silicate microparticles modulate the differential expression of circRNAs and mRNAs in BMSCs and promote osteogenesis via circ_1983–miR-6931–Gas7 interaction

Among C₂S-induced differentially expressed circRNAs, circ_1983 is involved in osteogenesis via circ_1983–miR-6931–Gas7 ceRNA interaction-mediated Runx2 upregulation.

Dicalcium Silicate Induced Proinflammatory Responses through TLR2-Mediated NF-κB and JNK Pathways in the Murine RAW 264.7 Macrophage Cell Line

Proinflammatory responses are important aspects of the immune response to biomaterials, which may cause peri-implantitis and implant shedding. The purpose of this study was to test the cytotoxicity and proinflammatory effects of dicalcium silicate particles on RAW 264.7 macrophages and to investigate the proinflammatory response mechanism induced by C₂S and tricalcium phosphate (TCP). C₂S and TCP particles were characterized using scanning electron microscopy (SEM), energy spectrum analysis (EDS) and X-ray diffraction (XRD). Cytotoxicity and apoptosis assays with C₂S and TCP in the murine RAW 264.7 cell line were tested using the cell counting kit-8 (CCK-8) assay and flow cytometry (FCM). The detection results showed that C₂S and TCP particles had no obvious toxicity in RAW 264.7 cells and did not cause obvious apoptosis, although they both caused an oxidative stress response by producing ROS when the concentrations were at 100 μg/mL. C₂S particles are likely to induce a proinflammatory response by inducing high TLR2, TNF-α mRNA, TNF-α proinflammatory cytokine, p-IκB, and p-JNK1 + JNK2 + JNK3 expression levels. When we added siRNA-TLR2-1, a significant reduction was observed. These findings support the theory that C₂S particles induce proinflammatory responses through the TLR2-mediated NF-κB and JNK pathways in the murine RAW 264.7 macrophage cell line.

The Effects of Cerium Oxide Incorporation in Calcium Silicate Coating on Bone Mesenchymal Stem Cell and Macrophage Responses

Ideal coatings for orthopedic implants should be able to induce excellent osseointegration with host bone tissue, which requires good osteogenic responses and limited inflammatory reactions. Cerium oxide (CeO₂) ceramics have anti-oxidative properties and can be used to decrease mediators of inflammation, making them attractive for biomedical application. In this study, two kinds of CeO₂ incorporated calcium silicate coatings (CS-10Ce and CS-30Ce) were prepared via plasma spraying technique, and the effects of CeO₂ addition on the responses of bone mesenchymal stem cells (BMSCs) and RAW264.7 macrophages were evaluated. The CS-10Ce and CS-30Ce coatings were characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. An increase in CeO₂ content in the coatings resulted in enhanced chemical stability and better BMSCs osteogenic behaviors in terms of cell adhesion, proliferation, ALP activity, and mineralized nodule formation. With respect to either ZrO₂-added or unmodified CS coating, the CS-30Ce coating elicited higher effects on the macrophages, suppressing the gene expressions of pro-inflammatory (M1) markers (CCR7, IL-6, and TNF-α), while upregulating the expressions of anti-inflammatory (M2) markers (CD206, IL-1ra, and IL-10); moreover, it could also increase the expression of osteoinductive molecules (BMP2 and TGF-β1) by the macrophages. The results suggested that the regulation of BMSCs behaviors and macrophage-mediated responses at the coating's surface was related to CeO₂ incorporation. The incorporation of CeO₂ in CS coatings can be a valuable strategy to promote osteogenic responses and mitigate inflammatory reactions.

Comparative Study on the Antivirus Activity of Shuang-Huang-Lian Injectable Powder and Its Bioactive Compound Mixture against Human Adenovirus III In Vitro

Shuang-Huang-Lian injectable powder (SHL)-a classical purified herbal preparation extracted from Scutellaria baicalensis, Lonicera japonica, and Forsythia suspense-has been used against human adenovirus III (HAdV₃) for many years. The combination herb and its major bioactive compounds, including chlorogenic acid, baicalin, and forsythia glycosides A, are effective inhibitors of the virus. However, no comprehensive studies are available on the antiviral effects of SHL against HAdV₃. Moreover, it remains unclear whether the mixture of chlorogenic acid, baicalin, and forsythia glycosides A (CBF) has enhanced antiviral activity compared with SHL. Therefore, a comparative study was performed to investigate the combination which is promising for further antiviral drug development. To evaluate their antivirus activity in parallel, the combination ratio and dose of CBF were controlled and consistent with SHL. First, the fingerprint and the ratio of CBF in SHL were determined by high performance liquid chromatography. Then, a plaque reduction assay, reverse transcription polymerase chain reaction (PCR), real-time polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay (ELISA) were used to explore its therapeutic effects on viral infection and replication, respectively. The results showed that SHL and CBF inhibited dose- and time-dependently HAdV₃-induced plaque formation in A549 and HEp-2 cells. SHL was more effective than CBF when supplemented prior to and after viral inoculation. SHL prevented viral attachment, internalization, and replication at high concentration and decreased viral levels within and out of cells at non-toxic concentrations in both cell types. Moreover, the expression of tumor necrosis factor alpha (TNF)-α, interleukin (IL)-1ß, and IL-6 was lower and the expression of interferon (IFN)-γ was higher in both cell types treated with SHL than with CBF. In conclusion, SHL is much more effective and slightly less toxic than CBF.

3D-printed porous titanium changed femoral head repair growth patterns: osteogenesis and vascularisation in porous titanium

Osteonecrosis of the femoral head (ONFH) is a major cause of morbidity, and total hip arthroplasty is both traumatic and expensive. Here, we created a gelatine scaffold embedded in uniquely shaped, 3D-printed porous titanium parts, which could attract and promote the proliferation of osteoblasts as well as bone regeneration, as the extracellular matrix (ECM) does in vivo. Interestingly, after hybridisation with platelets, the scaffold exhibited a low yet considerable rate of stable, safe and long-term growth factor release. Additionally, a novel ONFH model was constructed and verified. Scaffolds implanted in this model were found to accelerate bone repair. In conclusion, our scaffold successfully simulates the ECM and considerably accelerates bone regeneration, in which platelets play an indispensable role. We believe that platelets should be emphasised as carriers that may be employed to transport drugs, cytokines and other small molecules to target locations in vivo. In addition, this novel scaffold is a useful material for treating ONFH. An overview of the novel scaffold mimicking the extracellular environment in bone repair. a and b: A gelatine scaffold was cross-linked and freeze-dried within 3D-printed porous titanium. c: Platelets were coated onto the gelatine microscaffold after freeze-drying platelet-rich plasma. d: The microscaffold supported the migration of cells into the titanium pores and their subsequent growth, while the platelets slowly released cell factors, exerting bioactivity.