Antitumor Effect by Hydroxyapatite Nanospheres: Activation of Mitochondria-Dependent Apoptosis and Negative Regulation of Phosphatidylinositol-3-Kinase/Protein Kinase B Pathway

Enhancing melanoma therapy by modulating the immunosuppressive microenvironment with an MMP-2 sensitive and nHA/GNE co-encapsulated hydrogel

The immunosuppressive tumor microenvironment, such as lactic acid and matrix metalloproteinases (MMPs) overexpression, has been well confirmed to be adverse for tumor therapy. In current study, a tumor microenvironment modulatory hydrogel was successfully developed to treat melanoma by taking advantage of the synergistic effects of nano-hydroxyapatite (nHA) with well-documented selective anti-tumor action, lactate dehydrogenase A inhibitor (R)-GNE-140 (GNE), and matrix metalloproteinase-2 (MMP-2) sensitive peptide. The hydrogel was acquired by the reaction of 4-arm-polyethylene glycol-maleic anhydride (4-arm-PEG-MAL) and MMP-2 sensitive peptide (CC-14), in which nHA and GNE were co-encapsulated physically. The in vitro degradation tests confirmed the accelerated release of nHA and GNE from the hydrogel under less-acidic (pH 6.8) and MMP-2 containing conditions compared to those neutral or without MMP-2 conditions, demonstrating the pH and MMP-2 responsive properties of as-prepared hydrogel. Findings from in vitro cell experiments revealed that the hydrogel could stop the proliferation of melanoma cells by stacking cell cycle via lactic acid metabolic dysregulation and boosting cell apoptosis via nHA direct killing effect. Moreover, after hydrogel treatment, the rate of migration and aggressiveness of melanoma cells both reduced significantly. An in vivo anti-melanoma study showed that the hydrogel could inhibit tumor growth significantly and result in more CD8+ T cells and antigen-presenting cells but less Treg cells infiltration, ultimately leading to an enhanced therapeutic efficacy. As thus, the fabricated hydrogel demonstrated great promise for treating melanoma and could be a new potent strategy for efficient melanoma therapy. STATEMENT OF SIGNIFICANCE: Nano-hydroxyapatite (nHA) has the capability of selectively killing cancer cells. The study reported a tumor microenvironment (TME) modulatory hydrogel with the goal of enhancing melanoma therapy efficacy by combining nHA administration with immunosuppressive microenvironment modulation. The hydrogel demonstrated pH and MMP-2 sensitivity. Hence, controlled release of nHA and lactate dehydrogenase A inhibitor (GNE) could be observed, and in situ MMP-2 consumption at the tumor site occurred. The hydrogel effectively inhibited the growth of melanoma cells. Furthermore, hydrogel increased the production of CD8+ T cells and antigen-presenting cells while decreasing the infiltration of Treg cells at the tumor site. This could transform the initial "cold" tumor into a "hot" tumor, ultimately resulting in an enhanced therapeutic effect.

In vitro/In vivo Evaluations of Hydroxyapatite Nanoparticles with Different Geometry

Purpose

Hydroxyapatite-based nanoparticles have found diverse applications in drug delivery, gene carriers, diagnostics, bioimaging and tissue engineering, owing to their ability to easily enter the bloodstream and target specific sites. However, there is limited understanding of the potential adverse effects and molecular mechanisms of these nanoparticles with varying geometries upon their entry into the bloodstream. Here, we used two commercially available hydroxyapatite nanoparticles (HANPs) with different geometries (less than 100 nm in size each) to investigate this issue.

Methods

First, the particle size, Zeta potential, and surface morphology of nano-hydroxyapatite were characterized. Subsequently, the effects of 2~2000 μM nano-hydroxyapatite on the proliferation, migration, cell cycle distribution, and apoptosis levels of umbilical vein endothelial cells were evaluated. Additionally, the impact of nanoparticles of various shapes on the differential expression of genes was investigated using transcriptome sequencing. Additionally, we investigated the in vivo biocompatibility of HANPs through gavage administration of nanohydroxyapatite in mice.

Results

Our results demonstrate that while rod-shaped HANPs promote proliferation in Human Umbilical Vein Endothelial Cell (HUVEC) monolayers at 200 μM, sphere-shaped HANPs exhibit significant toxicity to these monolayers at the same concentration, inducing apoptosis/necrosis and S-phase cell cycle arrest through inflammation. Additionally, sphere-shaped HANPs enhance SULT1A3 levels relative to rod-shaped HANPs, facilitating chemical carcinogenesis-DNA adduct signaling pathways in HUVEC monolayers. In vivo experiments have shown that while HANPs can influence the number of blood cells and comprehensive metabolic indicators in blood, they do not exhibit significant toxicity.

Conclusion

In conclusion, this study has demonstrated that the geometry and surface area of HANPs significantly affect VEC survival status and proliferation. These findings hold significant implications for the optimization of biomaterials in cell engineering applications.

Calcium Hexacyanoferrate (III) Nanocatalyst Enables Redox Homeostasis for Autism Spectrum Disorder Treatment

Autism spectrum disorder (ASD) is a multifaced neurodevelopmental disorder with considerable heterogeneity, in which over-generated reactive oxygen species (ROS) induce a cascade of pathological changes, including cellular apoptosis and inflammatory responses. Given the complex etiology of ASD, no effective treatment is available for ASD. In this work, a specific catalytic nanoenzyme, calcium hexacyanoferrate (III) nanocatalysts (CaH NCs), is designed and engineered for efficient ASD treatment. CaH NCs can mimic the activities of natural enzymes including superoxide dismutase, peroxidase, catalase, and glutathione peroxidase, which mitigates intracellular excessive ROS and regulates redox equilibrium. These CaH NCs modulate mitochondrial membrane potential, elevate B-cell lymphoma-2 levels, and suppress pro-apoptotic proteins, including Caspase-3 and B-cell lymphoma-2-associated X, thus effectively reducing cellular apoptosis. Importantly, CaH NCs alleviate inflammation by upregulating anti-inflammatory cytokine interleukin-10 and downregulating pro-inflammatory factors, resulting in attenuated activation of microglial and astrocytic and subsequent reduction in neuroinflammation. Subsequently, CaH NCs enhance social abilities, decrease anxiety levels, ameliorate repetitive behaviors, and improve learning and memory in ASD animal models through inflammation regulation and apoptosis inhibition. The CaH NCs in managing and preventing ASD represents a paradigm shift in autism treatment, paving the alternative but efficient way for clinical interventions in neurological conditions.

Hyaluronated nanohydroxyapatite responsively released from injectable hydrogels for targeted therapy of melanoma

Nanohydroxyapatite (nHAp) has attracted significant attention for its tumor suppression and tumor microenvironment modulation capabilities. However, a strong tendency to aggregate greatly affects its anti-tumor efficiency. To address this issue, a hydrogel platform consisting of thiolated hyaluronic acid (HA-SH) modified nanohydroxyapatite (nHAp-HA) and HA-SH was developed for sustained delivery of nHAp for melanoma therapy. The hydrophilic and negatively charged HA-SH significantly improved the size dispersion and stability of nHAp in aqueous media while conferring nHAp targeting effects. Covalent sulfhydryl self-cross-linking between HA-SH and nHAp-HA groups ensured homogeneous dispersion of nHAp in the matrix material. Meanwhile, the modification of HA-SH conferred the targeting properties of nHAp and enhanced cellular uptake through the HA/CD44 receptor. The hydrogel platform could effectively reduce the aggregation of nHAp and release nHAp in a sustained and orderly manner. Antitumor experiments showed that the modified nHAp-HA retained the tumor cytotoxicity of nHAp in vitro and inhibited the growth of highly malignant melanomas up to 78.6% while being able to induce the differentiation of macrophages to the M1 pro-inflammatory and antitumor phenotype. This study will broaden the application of nanohydroxyapatite in tumor therapy.

Biocompatibility and Osteogenic Activity of Samarium-Doped Hydroxyapatite-Biomimetic Nanoceramics for Bone Regeneration Applications

In this study, we report on the development of hydroxyapatite (HAp) and samarium-doped hydroxyapatite (SmHAp) nanoparticles using a cost-effective method and their biological effects on a bone-derived cell line MC3T3-E1. The physicochemical and biological features of HAp and SmHAp nanoparticles are explored. The X-ray diffraction (XRD) studies revealed that no additional peaks were observed after the integration of samarium (Sm) ions into the HAp structure. Valuable information regarding the molecular structure and morphological features of nanoparticles were obtained by using Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The elemental composition obtained by using energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of the HAp constituent elements, Ca, O, and P, as well as the presence and uniform distribution of Sm3+ ions. Both HAp and SmHAp nanoparticles demonstrated biocompatibility at concentrations below 25 μg/mL and 50 μg/mL, respectively, for up to 72 h of exposure. Cell membrane integrity was preserved following treatment with concentrations up to 100 μg/mL HAp and 400 μg/mL SmHAp, confirming the role of Sm3+ ions in enhancing the cytocompatibility of HAp. Furthermore, our findings reveal a positive, albeit limited, effect of SmHAp nanoparticles on the actin dynamics, osteogenesis, and cell migration compared to HAp nanoparticles. Importantly, the biological results highlight the potential role of Sm3+ ions in maintaining cellular balance by mitigating disruptions in Ca2+ homeostasis induced by HAp nanoparticles. Therefore, our study represents a significant contribution to the safety assessment of both HAp and SmHAp nanoparticles for biomedical applications focused on bone regeneration.

Beyond the promise: Exploring the complex interactions of nanoparticles within biological systems

The exploration of nanoparticle applications is filled with promise, but their impact on the environment and human health raises growing concerns. These tiny environmental particles can enter the human body through various routes, such as the respiratory system, digestive tract, skin absorption, intravenous injection, and implantation. Once inside, they can travel to distant organs via the bloodstream and lymphatic system. This journey often results in nanoparticles adhering to cell surfaces and being internalized. Upon entering cells, nanoparticles can provoke significant structural and functional changes. They can potentially disrupt critical cellular processes, including damaging cell membranes and cytoskeletons, impairing mitochondrial function, altering nuclear structures, and inhibiting ion channels. These disruptions can lead to widespread alterations by interfering with complex cellular signaling pathways, potentially causing cellular, organ, and systemic impairments. This article delves into the factors influencing how nanoparticles behave in biological systems. These factors include the nanoparticles' size, shape, charge, and chemical composition, as well as the characteristics of the cells and their surrounding environment. It also provides an overview of the impact of nanoparticles on cells, organs, and physiological systems and discusses possible mechanisms behind these adverse effects. Understanding the toxic effects of nanoparticles on physiological systems is crucial for developing safer, more effective nanoparticle-based technologies.

Oroxylin A ameliorates ultraviolet radiation-induced premature skin aging by regulating oxidative stress via the Sirt1 pathway

Skin is susceptible to premature aging in response to ultraviolet (UV) radiation-induced oxidative stress, which can ultimately result in aberrant aging or age-related disorders. Accordingly, strategies that can be adopted to mitigate oxidative stress may contribute to protecting skin from induced aging-related damage, thereby offering promising approaches for the treatment of skin diseases and disorders. In this regard, oroxylin A (OA), a natural flavonoid isolated from certain plants used in traditional Chinese medicine, is considered to have notable antioxidant, anti-inflammatory, and anti-apoptotic properties, and is often used to treat certain inflammatory diseases. To date, however, there has been comparatively little research on the effects of OA with respect skin aging. In this study, we utilized UV radiation-induced mouse and cellular models of aging to assess the efficacy of OA in protecting against skin aging. Subsequently, to elucidate the potential mechanisms underlying the protective effect of OA on skin aging, we performed molecular docking analysis to investigate the involvement of the anti-aging gene Sirt1, which was further confirmed on the basis of Sirt1 gene silencing. We accordingly demonstrated that by promoting an increase in the expression of Sirt1, OA can contribute to suppressing UV-induced skin photo-aging in cells/mice by reducing oxidative stress. Furthermore, we established that by activating Sirt1, OA can also promote the dissociation of Nrf2 from Keap1 and its subsequent nuclear translocation. Collectively, our findings in this study reveal OA to be an effective natural compound that can be administered to delay the aging of skin triggered by UV, both in vivo and in vitro, by binding to Sirt1 to promote the deacetylation and nuclear translocation of Nrf2, thereby contributing to a reduction in oxidative stress. These findings may this provide a therapeutic target for the prevention of skin aging or aging-induced skin diseases.

3D-printed tri-element-doped hydroxyapatite/ polycaprolactone composite scaffolds with antibacterial potential for osteosarcoma therapy and bone regeneration

The resection of malignant osteosarcoma often results in large segmental bone defects, and the residual cells can facilitate recurrence. Consequently, the treatment of osteosarcoma is a major challenge in clinical practice. The ideal goal of treatment for osteosarcoma is to eliminate it thoroughly, and repair the resultant bone defects as well as avoid bacterial infections. Herein, we fabricated a selenium/strontium/zinc-doped hydroxyapatite (Se/Sr/Zn-HA) powder by hydrothermal method, and then employed it with polycaprolactone (PCL) as ink to construct composite scaffolds through 3D printing, and finally introduced them in bone defect repair induced by malignant osteosarcoma. The resultant composite scaffolds integrated multiple functions involving anti-tumor, osteogenic, and antibacterial potentials, mainly attributed to the anti-tumor effects of SeO32-, osteogenic effects of Sr2+ and Zn2+, and antibacterial effects of SeO32- and Zn2+. In vitro studies confirmed that Se/Sr/Zn-HA leaching solution could induce apoptosis of osteosarcoma cells, differentiation of MSCs, and proliferation of MC3T3-E1 while showing excellent antibacterial properties. In vivo tests demonstrated that Se/Sr/Zn-HA could significantly suppress tumors after 8 days of injection, and the Se/Sr/Zn-HA-PCLs scaffold repaired femoral defects effectively after 3 months of implantation. Summarily, the Se/Sr/Zn-HA-PCLs composite scaffolds developed in this study were effective for tumor treatment, bone defect repair, and post-operative anti-infection, which provided a great potential to be a facile therapeutic material for osteosarcoma resection.

A multifunctional nano-hydroxyapatite/MXene scaffold for the photothermal/dynamic treatment of bone tumours and simultaneous tissue regeneration

After resection of bone tumour, the risk of cancer recurrence and numerous bone defects continues to threaten the health of patients. To overcome the challenge, we developed a novel multifunctional scaffold material consisting mainly of nano-hydroxyapatite particles (n-HA), MXene nanosheets and g-C3N4 to prevent tumour recurrence and promote bone formation. N-HA has the potential to restrict the growth of osteosarcoma cells, and the combination of MXene and g-C3N4 enables the scaffolds to produce photodynamic and photothermal effects simultaneously under near infrared (NIR) irradiation. Surprisingly, n-HA can further enhance the synergistic anti-tumour function of photodynamic and photothermal, and the scaffolds can eradicate osteosarcoma cells in only 10 min at a mild temperature of 45 ℃. Moreover, the scaffold exhibit exceptional cytocompatibility and possesses the capacity to induce osteogenic differentiation of bone marrow mesenchymal stem cells. Therefore, this multifunctional scaffold can not only inhibits the proliferation of bone tumour cells and rapidly eradicate bone tumour through NIR irradiation, but also enhances osteogenic activity. This promising measure can be used to treat tissue damage after bone tumour resection.

Aspect ratio-dependent dual-regulation of the tumor immune microenvironment against osteosarcoma by hydroxyapatite nanoparticles

Accumulating studies demonstrated that hydroxyapatite nanoparticles (HANPs) showed a selective anti-tumor effect, making them a good candidate for osteosarcoma (OS) treatment. However, the capacity of HANPs with different aspect ratios to regulate tumor immune microenvironment (TIM) was scarcely reported before. To explore it, the three HANPs with aspect ratios from 1.86 to 6.25 were prepared by wet chemical method. After a 24 or 72 h-exposure of OS UMR106 cells or macrophages to the nanoparticles, the tumor cells exhibited immunogenic cell death (ICD) indicated by the increased production of calreticulin (CRT), adenosine triphosphate (ATP) and high mobility group box 1 (HMGB1), and macrophages were activated with the release of pro-inflammatory cytokines. Next, the beneficial crosstalk between tumor cells and macrophages generated in the presence of HANPs for improved anti-tumor immunity activation. In the OS-bearing cognate rat model, HANPs inhibited OS growth, which was positively correlated with CRT and HMGB1 expression, and macrophage polarization in the tumor tissues. Additionally, HANPs promoted CD8+ T cell infiltration into the tumor and systemic dendritic cell maturation. Particularly, HANPs bearing the highest aspect ratio exhibited the strongest immunomodulatory and anti-tumor function. This study suggested the potential of HANPs to be a safe and effective drug-free nanomaterial to control the TIM for OS therapy. STATEMENT OF SIGNIFICANCE: Emerging studies demonstrated that hydroxyapatite nanoparticles (HANPs) inhibited tumor cell proliferation and tumor growth. However, the underlying anti-tumor mechanism still remains unclear, and the capacity of HANPs without any other additive to regulate tumor immune microenvironment (TIM) was scarcely reported before. Herein, we demonstrated that HANPs, in an aspect ratio-dependent manner, showed the potential to delay the growth of osteosarcoma (OS) and to regulate TIM by promoting the invasion of CD8+ T cells and F4/80+ macrophages, and inducing immunogenic cell death (ICD) in tumors. This work revealed the new molecular mechanism for HANPs against OS, and suggested HANPs might be a novel ICD inducer for OS treatment.

Hydroxyapatite nanoparticles induced calcium overload-initiated cancer cell-specific apoptosis through inhibition of PMCA and activation of calpain

Hydroxyapatite nanoparticles (HAPNs) have been reported to specifically induce apoptosis and sustained elevation of intracellular Ca2+ concentration ([Ca2+]i) in cancer cells. However, it remains unclear whether calcium overload, the abnormal intracellular accumulation of Ca2+, is the intrinsic cause of cell apoptosis, how HAPNs specifically evoke calcium overload in cancer cells, and which potential pathways were involved in apoptosis initiation in response to calcium overload. In this study, using various cancer and normal cells, we observed a positive correlation between the degree of increased [Ca2+]i and the specific toxicity of HAPNs. Moreover, chelating intracellular Ca2+ with BAPTA-AM inhibited HAPN-induced calcium overload and apoptosis, thus demonstrating that calcium overload was the main cause of HAPN-induced cytotoxicity in cancer cells. Notably, the dissolution of particles outside the cells did not affect cell viability or [Ca2+]i. In contrast, internalized HAPNs dissolved more readily in cancer cells than in normal cells and inhibited the activity of plasma membrane calcium-ATPase solely in cancer cells to prevent extrusion of excessive Ca2+, hence leading to calcium overload in tumor cells. Upon exposure to HAPNs, the Ca2+-sensitive cysteine protease calpain was activated and then cleaved the BH3-only protein Bid. Consequently, cytochrome c was released, and caspase-9 and -3 were activated, leading to mitochondrial apoptosis. However, these effects were alleviated by the calpain inhibitor calpeptin, confirming the involvement of calpain in HANP-induced apoptosis. Therefore, our results demonstrated that calcium overload induced by HAPNs caused cancer cell-specific apoptosis by inhibiting PMCA and activating calpain in tumor cells and thus may contribute to a more comprehensive understanding of biological effects of this nanomaterial and facilitate the development of calcium overload cancer therapy.

Nacre-mimetic cerium-doped nano-hydroxyapatite/chitosan layered composite scaffolds regulate bone regeneration via OPG/RANKL signaling pathway

Autogenous bone grafting has long been considered the gold standard for treating critical bone defects. However, its use is plagued by numerous drawbacks, such as limited supply, donor site morbidity, and restricted use for giant-sized defects. For this reason, there is an increasing need for effective bone substitutes to treat these defects. Mollusk nacre is a natural structure with outstanding mechanical property due to its notable "brick-and-mortar" architecture. Inspired by the nacre architecture, our team designed and fabricated a nacre-mimetic cerium-doped layered nano-hydroxyapatite/chitosan layered composite scaffold (CeHA/CS). Hydroxyapatite can provide a certain strength to the material like a brick. And as a polymer material, chitosan can slow down the force when the material is impacted, like an adhesive. As seen in natural nacre, the combination of these inorganic and organic components results in remarkable tensile strength and fracture toughness. Cerium ions have been demonstrated exceptional anti-osteoclastogenesis capabilities. Our scaffold featured a distinct layered HA/CS composite structure with intervals ranging from 50 to 200 μm, which provided a conducive environment for human bone marrow mesenchymal stem cell (hBMSC) adhesion and proliferation, allowing for in situ growth of newly formed bone tissue. In vitro, Western-blot and qPCR analyses showed that the CeHA/CS layered composite scaffolds significantly promoted the osteogenic process by upregulating the expressions of osteogenic-related genes such as RUNX2, OCN, and COL1, while inhibiting osteoclast differentiation, as indicated by reduced TRAP-positive osteoclasts and decreased bone resorption. In vivo, calvarial defects in rats demonstrated that the layered CeHA/CS scaffolds significantly accelerated bone regeneration at the defect site, and immunofluorescence indicated a lowered RANKL/OPG ratio. Overall, our results demonstrate that CeHA/CS scaffolds offer a promising platform for bone regeneration in critical defect management, as they promote osteogenesis and inhibit osteoclast activation.

Macrophage fusion event as one prerequisite for inorganic nanoparticle-induced antitumor response

While most nanomaterials are designed to assist tumor therapy, some inorganic nanoparticles have been reported to impede cancer development. We assume that the immune response elicited by these foreign nanoparticles might be associated with the remodeling of immune landscape in the tumor microenvironment (TME). We studied representative inorganic nanoparticles widely used in the biomedical field and first demonstrated that needle-shaped hydroxyapatite (n-nHA), granule-shaped hydroxyapatite, and silicon dioxide can effectively impair tumor progression in vivo. Substantial multinucleated giant cells (MNGCs) were formed around these antitumor nanoparticles, while the ratio of monocytes and macrophages was decreased in the TME. We found that high expression of the STXBP6 protein induced by n-nHA-treated macrophages triggers autophagy, which markedly promotes macrophage fusion into MNGCs. In this way, extensive depletion of tumor-associated macrophages in the TME was achieved, which suppressed tumor growth and metastasis. This intrinsic antitumor immunity of inorganic nanoparticles should not be neglected when designing future nanomedicines to treat cancer.

Near-Infrared Fluorescent Hydroxyapatite Nanoparticles for Targeted Photothermal Cancer Therapy

Near-infrared (NIR) fluorophores have attracted great attention due to their excellent optical and photothermal properties. Among them, a bone-targeted NIR fluorophore (named P800SO3) contains two phosphonate groups, which play important roles in binding with hydroxyapatite (HAP) as the main mineral component of bones. In this study, biocompatible and NIR fluorescent HAP nanoparticles functionalized with P800SO3 and polyethylene glycol (PEG) were readily prepared for tumor-targeted imaging and photothermal therapy (PTT). The PEGylated HAP nanoparticle (HAP800-PEG) demonstrated improved tumor targetability with high tumor-to-background ratios (TBR). Moreover, the HAP800-PEG also showed excellent photothermal properties, and the temperature of tumor tissue reached 52.3 °C under NIR laser irradiation, which could completely ablate the tumor tissue without recurrence. Therefore, this new type of HAP nanoparticle has great potential as a biocompatible and effective phototheranostic material, which enables the use of P800SO3 for targeted photothermal cancer treatment.

Hydroxyapatite nanoparticles promote TLR4 agonist-mediated anti-tumor immunity through synergically enhanced macrophage polarization

Macrophages represent the most prevalent immune cells in the tumor micro-environment, making them an appealing target for tumor immunotherapy. One of our previous studies showed that hydroxyapatite nanoparticles (HANPs) enhanced Toll-like receptor 4 (TLR4) signal transduction in macrophages. This study was proposed to investigate how HANPs manipulated the phenotype and function of macrophage against 4T1 tumors in the presence or absence of MPLA, a low toxic Toll-like receptor 4 (TLR4) agonist. The results demonstrated that the addition of HANPs to MPLA significantly promoted cytokine secretion and macrophage polarization toward a tumoricidal M1 phenotype. Further, the resulting supernatant from HANPs/MPLA co-stimulated macrophages enhanced 4T1 tumor cells apoptosis compared to that from macrophages treated with a single component or PBS control. In particular, we found HANPs elicited immunogenic cell death (ICD) indicated by the increased expression of "danger signals", including HMGB1, CRT and ATP in 4T1 cells. Subsequently, the ICD derivatives-containing supernatant from HANPs-treated 4T1 cells activated macrophage and shifted the phenotype of the cells toward M1 type. Moreover, in a tumor-bearing mice model, HANPs and MPLA synergistically delayed tumor growth compared to PBS control, which was positively associated with the promoted macrophage polarization and ICD induction. Therefore, our findings demonstrated a potential platform to modulate the function of macrophages, and shed a new insight into the mechanism involving the immunomodulatory effect of HANPs for tumor therapy. STATEMENT OF SIGNIFICANCE: Polarizing macrophage toward tumoricidal phenotype by harnessing Toll-like receptor (TLR) agonists has been proven effective for tumor immunotherapy. However, the immunomodulatory potency of TLR agonists is limited due to immune suppression or tolerance associated with TLR activation in immune cells. Herein, we introduced hydroxyapatite nanoparticles (HANPs) to MPLA, a TLR4 agonist. The results demonstrated that the addition of HANPs to MPLA promoted macrophage shift toward tumoricidal M1 phenotype, supported a "hot" tumor transformation, and delayed 4T1 tumor growth. Moreover, we found that HANPs elicited immunogenic cell death that produced "danger" signals from cancer cells thereby further facilitated macrophage polarization. This work is significant to direct the rational design of HANPs coupled with or without TLR agonists for tumor immunotherapy.

Recent applications of phase-change materials in tumor therapy and theranostics

Phase-change materials (PCMs) are a type of special material which can store and release a large amount of thermal energy without any significant temperature change. They are emerging in recent years as a promising functional material in tumor therapy and theranostics due to their accurate responses to the temperature variations, biocompatibility and low toxicity. In this review, we will introduce the main types of PCMs and their desirable physiochemical properties for biomedical applications, and highlight the recent progress of PCM's applications in the modulated release of antitumor drugs, with special attentions paid to various ways to initiate temperature-dependent phase change, the concomitant thermal therapy and its combination with or activation of other therapies, particularly unconventional therapies. We will also summarize PCM's recent applications in tumor theranostics, where both drugs and imaging probes are delivered by PCMs for controlled drug release and imaging-guided therapy. Finally, the future perspectives and potential limitations of harnessing PCMs in tumor therapy will be discussed.

Metal-polyphenol network coated magnetic hydroxyapatite for pH-activated MR imaging and drug delivery

Engineered nanoparticles responsive to tumor microenvironment parameters such as pH have been developed as drug carriers and for magnetic resonance imaging (MRI) as contrast agents (CA). Nanoscale hydroxyapatite (HAP) has good biocompatibility and specific inhibition of tumor cells. However, the inherent tendency of nanoscale HAP to agglomerate and degrade under natural conditions has hindered its further application. To address this challenge, polyacrylic acid-coordinated Mn²⁺ and F^- co-doped nanoscale HAP (Mn_xFHA-PAA) were developed for MRI and doxorubicin (DOX) loading. Moreover, the metal-polyphenol network (MPN) formed by ligating tannic acid (TA) and Fe³⁺ was successfully functionalized onto the surface of Mn_xFHA-PAA-DOX. The pH-sensitive MPN improves biocompatibility and therapeutic efficacy while preventing the premature release of DOX in a neutral environment. It was demonstrated that the mesoporous structure of Mn_xFHA-PAA@TA-Fe nanoparticles with good dispersion, high specific surface area and large pore size, which can reach more than 90 % encapsulation efficiency (EE) for DOX. Mn_xFHA-PAA-DOX@TA-Fe degrades at low pH and releases Mn²⁺ and DOX that are confined in the nanoparticles. Binding of Mn²⁺ to proteins leads to increased relaxation and enhanced MRI contrast. Such nanoparticles with sensitive pH responsiveness have great potential for tumor diagnosis and therapeutic synergy.

Synthetic biodegradable polymer materials in the repair of tumor-associated bone defects

The repair and reconstruction of bone defects and the inhibition of local tumor recurrence are two common problems in bone surgery. The rapid development of biomedicine, clinical medicine, and material science has promoted the research and development of synthetic degradable polymer anti-tumor bone repair materials. Compared with natural polymer materials, synthetic polymer materials have machinable mechanical properties, highly controllable degradation properties, and uniform structure, which has attracted more attention from researchers. In addition, adopting new technologies is an effective strategy for developing new bone repair materials. The application of nanotechnology, 3D printing technology, and genetic engineering technology is beneficial to modify the performance of materials. Photothermal therapy, magnetothermal therapy, and anti-tumor drug delivery may provide new directions for the research and development of anti-tumor bone repair materials. This review focuses on recent advances in synthetic biodegradable polymer bone repair materials and their antitumor properties.

Biomaterial-assisted tumor therapy: A brief review of hydroxyapatite nanoparticles and its composites used in bone tumors therapy

Malignant bone tumors can inflict significant damage to affected bones, leaving patients to contend with issues like residual tumor cells, bone defects, and bacterial infections post-surgery. However, hydroxyapatite nanoparticles (nHAp), the principal inorganic constituent of natural bone, possess numerous advantages such as high biocompatibility, bone conduction ability, and a large surface area. Moreover, nHAp's nanoscale particle size enables it to impede the growth of various tumor cells via diverse pathways. This article presents a comprehensive review of relevant literature spanning the past 2 decades concerning nHAp and bone tumors. The primary goal is to explore the mechanisms responsible for nHAp's ability to hinder tumor initiation and progression, as well as to investigate the potential of integrating other drugs and components for bone tumor diagnosis and treatment. Lastly, the article discusses future prospects for the development of hydroxyapatite materials as a promising modality for tumor therapy.

Nanohydroxyapatite Stimulates PD-L1 Expression to Boost Melanoma Combination Immunotherapy

Although checkpoint-inhibitor immunotherapy held tremendous advances, improving immune response during treatment has always been an urgent clinical issue. With the help of mRNA microarray technology, it was found that short rod-like nanohydroxyapatite (nHA) promoted the upregulation of CD274 and PD-L1 related gene transcription, which was confirmed by the significantly enhanced PD-L1 expression level in B16, B16F10, and 4T1 cells in vitro. Hence, an injectable in situ responsive hydrogel reservoir embed with nHA and PD-1/PD-L1 inhibitor was engineered for a combination immunotherapy by peritumoral administration. The results confirmed that the combinational strategy effectively suppressed tumorigenesis and tumor growth, recovered the abnormal lactate dehydrogenase, aspartate transaminase, and alanine aminotransferase indicators, and significantly elongated the life span of a tumor-bearing mouse. The substantive progress mainly derived from nHA-induced T cell infiltration reinforcement in a tumor site and CD8⁺ T cell polarization in spleen, implying that nHA might function as an immunomodulator for melanoma immunotherapy.

A Selective Reduction of Osteosarcoma by Mitochondrial Apoptosis Using Hydroxyapatite Nanoparticles

Background

In recent years, using hydroxyapatite nanoparticles (HANPs) for tumor therapy attracted increasing attention because HANPs were found to selectively suppress the growth of tumor cells but exhibit ignorable toxicity to normal cells.

Purpose

This study aimed to investigate the capacities of HANPs with different morphologies and particle sizes against two kinds of osteosarcoma (OS) cells, human OS 143B cells and rat OS UMR106 cells.

Methods

Six kinds of HANPs with different morphologies and particle sizes were prepared by wet chemical method. Then, the antitumor effect of these nanoparticles was characterized by means of in vitro cell experiments and in vivo tumor-bearing mice model. The underlying antitumor mechanism involving mitochondrial apoptosis was also investigated by analysis of intracellular calcium, expression of apoptosis-related genes, reactive oxygen species (ROS), and the endocytosis efficiency of the particles in tumor cells.

Results

Both in vitro cell experiments and in vivo mice model evaluation revealed the anti-OS performance of HANPs depended on the concentration, morphology, and particle size of the nanoparticles, as well as the OS cell lines. Among the six HANPs, rod-like HANPs (R-HANPs) showed the best inhibitory activity on 143B cells, while needle-like HANPs (N-HANPs) inhibited the growth of UMR106 cells most efficiently. We further demonstrated that HANPs induced mitochondrial apoptosis by selectively raising intracellular Ca²⁺ and the gene expression levels of mitochondrial apoptosis-related molecules, and depolarizing mitochondrial membrane potential in tumor cells but not in MC3T3-E1, a mouse pre-osteoblast line. Additionally, the anti-OS activity of HANPs also linked with the endocytosis efficiency of the particles in the tumor cells, and their ability to drive oxidative damage and immunogenic cell death (ICD).

Conclusion

The current study provides an effective strategy for OS therapy where the effectiveness was associated with the particle morphology and cell line.

The Nanostructured lipid carrier gel of Oroxylin A reduced UV-induced skin oxidative stress damage

Oxidative stress damage caused by sun exposure damages the appearance and function of the skin, which is one of the essential inducements of skin aging and even leads to skin cancer. Oroxylin A (OA) is a flavonoid with excellent antioxidant activity and has protective effects against photoaging induced by UV irradiation. However, the strong barrier function of the skin stratum corneum prevents transdermal absorption of the drug, which limits the application of OA in dermal drug delivery. Studies have shown that nanostructured lipid carriers (NLC) can promote not only transdermal absorption of drugs but also increase drug stability and control drug release efficiency, which has broad prospects for clinical applications. In this paper, NLC loaded with OA (OA-NLC) was prepared in order to improve the skin permeability and stability of OA. In vitro studies revealed that OA-NLC had better therapeutic effects than OA solution (OA-Sol) in the cellular model of UVB radiation. OA-Sol and OA-NLC were immobilized in a hydrogel matrix to facilitate application to the dorsal skin of mice. It was found that OA-NLC-gel showed significant antioxidant and anti-apoptotic activity compared to OA-Sol-gel, which was able to protect against skin damage in mice after UV radiation. These results suggest that OA-NLC can improve the deficiencies of OA in skin delivery and show better resistance to UV-induced oxidative damage. The application of OA-NLC to skin delivery systems has good prospects and deserves further development and investigation.

Anti-melanoma effect and action mechanism of a novel chitosan-based composite hydrogel containing hydroxyapatite nanoparticles

Hydroxyapatite nanoparticles (HANPs) have been increasingly regarded and reported due to their potential anti-tumor ability. Previously, we found that the rod-like HANPs had good application potential for cutaneous melanoma (CMM). To satisfy the actual requirements in repairing post-operative skin defects and inhibiting CMM recurrence after tumorectomy, we constructed a novel chitosan/alginate (CS/Alg) hydrogel containing the aforementioned HANPs. The in vitro cell experiments confirmed that activated mitochondrial-dependent apoptosis was tightly related to the anti-tumor ability of HANPs. Specifically, we further discovered several target proteins might be involved in abnormal activating Wnt, proteoglycans in cancer, oxidative phosphorylation and p53 signaling pathways. The in vivo animal experiments demonstrated that the HANPs-loaded CS/Alg hydrogel (CS/Alg/HANPs) had a similar effect on inhibiting tumor growth as HANPs, and CS/Alg hydrogel as well as phosphate buffered saline (PBS) group (control) not showed any effect, proving the key role of HANPs. The immunohistochemical staining demonstrated a tumor inhibition via the mitochondria-mediated apoptosis pathway, consistent with the in vitro evaluation. Moreover, CS/Alg/HANPs exhibited no additional biosafety risk to the functions of major organs. Overall, this CS/Alg/HANPs hydrogel has substantial application potential for treating CMM.

Hydroxyapatite nanoparticles drive the potency of Toll-like receptor 9 agonist for amplified innate and adaptive immune response

The potency of Toll-like receptor 9 (TLR9) agonist to drive innate immune response was limited due to immune suppression or tolerance during TLR9 signaling activation in immune cells. Herein we addressed this problem by introducing hydroxyapatite nanoparticles (HANPs) to CpG ODN (CpG), a TLR9 agonist. The study revealed that HANPs concentration and duration-dependently reprogramed the immune response by enhancing the secretion of immunostimulatory cytokines (tumor necrosis factor α (TNFα) or IL-6) while reducing the production of immunosuppressive cytokine (IL-10) in macrophages in response to CpG. Next, the enhanced immune response benefited from increased intracellular Ca²⁺ in macrophage by the addition of HANPs. Further, we found exposure to HANPs impacted the mitochondrial function of macrophages in support of the synthesis of adenosine triphosphate (ATP), the production of nicotinamide adenine dinucleotide (NAD), and reactive oxygen species (ROS) in the presence or absence of CpG. In vaccinated mice model, only one vaccination with a mixture of CpG, HANPs, and OVA, a model antigen, allowed the development of a long-lasting balanced humoral immunity in mice without any histopathological change in the local injection site. Therefore, this study revealed that HANPs could modulate the intracellular calcium level, mitochondrial function, and immune response in immune cells, and suggested a potential combination adjuvant of HANPs and TLR9 agonist for vaccine development.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (TEM image, LDH activity, the Ca²⁺ release in PBS, qRT-PCR analysis, H&E staining, and IL-6 level in the injection site and serum) is available in the online version of this article at 10.1007/s12274-022-4683-x.

Connecting Calcium-Based Nanomaterials and Cancer: From Diagnosis to Therapy

As the indispensable second cellular messenger, calcium signaling is involved in the regulation of almost all physiological processes by activating specific target proteins. The importance of calcium ions (Ca2+) makes its "Janus nature" strictly regulated by its concentration. Abnormal regulation of calcium signals may cause some diseases; however, artificial regulation of calcium homeostasis in local lesions may also play a therapeutic role. "Calcium overload," for example, is characterized by excessive enrichment of intracellular Ca2+, which irreversibly switches calcium signaling from "positive regulation" to "reverse destruction," leading to cell death. However, this undesirable death could be defined as "calcicoptosis" to offer a novel approach for cancer treatment. Indeed, Ca2+ is involved in various cancer diagnostic and therapeutic events, including calcium overload-induced calcium homeostasis disorder, calcium channels dysregulation, mitochondrial dysfunction, calcium-associated immunoregulation, cell/vascular/tumor calcification, and calcification-mediated CT imaging. In parallel, the development of multifunctional calcium-based nanomaterials (e.g., calcium phosphate, calcium carbonate, calcium peroxide, and hydroxyapatite) is becoming abundantly available. This review will highlight the latest insights of the calcium-based nanomaterials, explain their application, and provide novel perspective. Identifying and characterizing new patterns of calcium-dependent signaling and exploiting the disease element linkage offer additional translational opportunities for cancer theranostics.

Corylin from Psoralea fructus (Psoralea corylifolia L.) protects against UV-induced skin aging by activating Nrf2 defense mechanisms

Oxidative stress damage can lead to premature skin aging or age-related skin disorders. Therefore, strategies to improve oxidative stress-induced aging are needed to protect the skin and to treat skin diseases. This study aimed to determine whether the flavonoid corylin derived from Psoralea corylifolia can prevent UV-induced skin aging and if so, to explore the potential molecular mechanisms. We found that corylin potently blocked UV-induced skin photoaging in mice by reducing oxidative stress and increasing the nuclear expression of nuclear factor-erythroid factor 2-related factor 2 Nrf2. We also found that corylin stimulated Nrf2 translocation into the nucleus and increased the delivery of its target antioxidant genes together with Kelch-like ECH-associated protein 1 (Keap1) to dissociate Nrf2. These findings indicate that corylin could prevent skin aging by inhibiting oxidative stress via Keap1-Nrf2 in mouse cells. Thus, Nrf2 activation might be a therapeutic target for preventing skin aging or skin diseases caused by aging. Our findings also provided evidence that warrants the further investigation of plant ingredients to facilitate the discovery of novel therapies targeting skin aging.

Nano-hydroxyapatite-evoked immune response synchronized with controllable immune adjuvant release for strengthening melanoma-specific growth inhibition

Concerns about the potential systematic toxicity limit the extensive application of traditional therapeutic drugs for melanoma therapy, nano-hydroxyapatite (nHA) with good biocompatibility and anti-tumor ability could be an alternative choice. In this study, nHA was employed as an anti-tumor biomaterial due to its tumor-specific toxicity. Meanwhile, granulocyte-macrophage colony-stimulating factor (GM-CSF) served as the immune adjuvant to activate the immune response. The delivery platform was fabricated by co-encapsulation of both nHA and GM-CSF into a biocompatible thermosensitive PLGA-PEG-PLGA hydrogel. The results showed that the bio-activities of nHA and GM-CSF could be well-maintained within the hydrogel. Interestingly, the addition of nHA could attenuate the burst release of GM-CSF due to possible protein absorption capacity of nHA, which is beneficial for GM-CSF sustainable release at the tumor site, achieving boosted and prolonged anti-tumor immunity. The in vitro and in vivo data demonstrated that nHA/GM-CSF hydrogel exhibited greater potency to inhibit tumor growth via enhanced CD8⁺ T-cell response compared with hydrogel and nHA hydrogel groups, contributed by the synergistic effects of nHA and GM-CSF. Overall, the strategy combining nHA and immune adjuvant shows great promise, which largely broadens the choice of combinational therapies for melanoma. STATEMENT OF SIGNIFICANCE: Nano-hydroxyapatite (nHA) has been confirmed to specifically inhibit melanoma tumor growth and induce immune response. However, its antitumor efficiency and immunity-evoking capacity are limited. In this study, granulocyte-macrophage colony-stimulating factor (GM-CSF) was introduced to serve as the immune adjuvant. Both of them were encapsulated into a biocompatible thermosensitive PLGA-PEG-PLGA hydrogel. The addition of nHA could attenuate the burst release of GM-CSF due to the interaction with nHA, which is beneficial for GM-CSF sustainable release at tumor site, achieving boosted and prolonged anti-tumor immunity. Anti-tumor immune response could be activated due to the release of tumor-associated antigen and tumor debris induced by the specifically tumor inhibition effect of nHA and GM-CSF. The combination of nHA and GM-CSF could play synergistic inhibiting effect on tumor growth via boosting and prolonging anti-tumor immunity.

Bifunctional scaffolds for tumor therapy and bone regeneration: Synergistic effect and interplay between therapeutic agents and scaffold materials

Bone tumor patients often face the problems with cancer cell residues and bone defects after the operation. Therefore, researchers have developed many bifunctional scaffolds with both tumor treatment and bone repair functions. Therapeutic agents are usually combined with bioactive scaffolds to achieve the "bifunctional". However, the synergistic effect of bifunctional scaffolds on tumor therapy and bone repair, as well as the interplay between therapeutic agents and scaffold materials in bifunctional scaffolds, have not been emphasized and discussed. This review proposes a promising design scheme for bifunctional scaffolds: the synergistic effect and interplay between the therapeutic agents and scaffold materials. This review summarizes the latest research progress in bifunctional scaffolds for therapeutic applications and regeneration. In particular, it summarizes the role of tumor therapeutic agents in bone regeneration and the role of scaffold materials in tumor treatment. Finally, a perspective on the future development of bifunctional scaffolds for tumor therapy and bone regeneration is discussed.

Screening of immune cell activators from Astragali Radix using a comprehensive two-dimensional NK-92MI cell membrane chromatography/C18 column/time-of-flight mass spectrometry system

Astragali Radix (AR) is a clinically used herbal medicine with multiple immunomodulatory activities that can strengthen the activity and cytotoxicity of natural killer (NK) cells. However, owing to the complexity of its composition, the specific active ingredients in AR that act on NK cells are not clear yet. Cell membrane chromatography (CMC) is mainly used to screen the active ingredients in a complex system of herbal medicines. In this study, a new comprehensive two-dimensional (2D) NK-92MI CMC/C₁₈ column/time-of-flight mass spectrometry (TOFMS) system was established to screen for potential NK cell activators. To obtain a higher column efficiency, 3-mercaptopropyltrimethoxysilane-modified silica was synthesized to prepare the NK-92MI CMC column. In total, nine components in AR were screened from this system, which could be washed out from the NK-92MI/CMC column after 10 min, and they showed good affinity for NK-92MI/CMC column. Two representative active compounds of AR, isoastragaloside I and astragaloside IV, promoted the killing effect of NK cells on K562 cells in a dose-dependent manner. It can thus suggest that isoastragaloside I and astragaloside IV are the main immunomodulatory components of AR. This comprehensive 2D NK-92MI CMC analytical system is a practical method for screening immune cell activators from other herbal medicines with immunomodulatory effects.

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A comprehensive 2D NK-92MI/CMC system was developed to screen for immune cell activators.

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Nine components of Astragali Radix were screened as potential immune activators.

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Isoastragaloside I and astragaloside IV were first confirmed to have immunomodulatory effects.

Synthesis, Characterization and Anticancer Efficacy Evaluation of Benzoxanthone Compounds toward Gastric Cancer SGC-7901

Three benzoxanthone derivatives were synthesized through a new photochemical strategy. The in vitro cytotoxic activity of these compounds was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and their partition coefficients (logP) were measured by shake flask method. The pK_a values of the compounds were detected by potentionmetric titration. The interaction of the compounds with calf thymus DNA (CT-DNA) was investigated by electronic absorption, luminescence spectra and viscosity. A molecular docking analysis was performed. The antitumor efficacy of the compounds was evaluated by cell apoptosis, cell cycle arrest, intracellular Ca²⁺ concentrations and reactive oxygen species (ROS) levels. The mitochondrial membrane potential was assayed using JC-1 (5,5′,6,6′-tetrachloro-1,1,3′,3′-tetraethyl-imidacarbocyanine iodide) as the fluorescence probe. The expression of Bcl-2 family protein, caspase 3 and poly ADP-ribose polymerase (PARP) was explored by western blot. The results showed that the compounds induced apoptosis through a ROS-mediated mitochondrial dysfunction pathway. This work provides an efficient approach to synthesize benzoxanthone derivatives, and is helpful for understanding the apoptotic mechanism.

Injectable and self-healing nanocomposite hydrogel loading needle-like nano-hydroxyapatite and graphene oxide for synergistic tumour proliferation inhibition and photothermal therapy

Non-chemotherapeutic tumour treatment has received extensive attention due to its having fewer side effects as compared to chemotherapy. However, nanomaterials-based non-chemotherapy still faces limitations such as poor targeting and low retention. Therefore, a Schiff base cross-linked hydrogel was designed and prepared using aldehyde-modified polyethylene glycol (PEG) and carboxymethyl chitosan (CMC). This hydrogel has good injectable and self-healing properties and can carry graphene oxide (GO) as a photothermal agent and needle-like nano-hydroxyapatite (HAP) as a tumour inhibitor. Combined with tumour proliferation inhibition therapy and photothermal therapy, the nanocomposite hydrogel system can avoid the side effects of chemotherapy and improve the accuracy of tumour treatment. The PEG-CMC/HAP/GO nanocomposite hydrogel system has a porous structure, good injectability and self-healing properties to meet the mechanical requirements. In vitro cell characterization showed that GO is phototoxic to tumour cells, HAP can inhibit the proliferation of tumour cells, the nanocomposite hydrogel remained in the tumour site, and the encapsulated GO and HAP did not transfer to the normal site and cause cell damage. In the in vivo investigation, the breast cancer tumour-bearing mice, the model animals for tumour treatment, were treated with an intratumoral injection of the PEG-CMC/HAP/GO nanocomposite hydrogel. This functional self-healing hydrogel loaded with GO and HAP effectively inhibited tumour cell proliferation and realized the synergistic effect of photothermal therapy, which is expected to become a new effective treatment approach for tumours.

MMP2-responsive dual-targeting drug delivery system for valence-controlled arsenic trioxide prodrug delivery against hepatic carcinoma

Arsenic trioxide (ATO) is the active ingredient in traditional Chinese medicine, i.e., Arsenic, which has shown excellent therapeutic effects on hepatocellular carcinoma. However, due to its poor tumor distribution and high toxicity, the mass adoption of ATO in clinical applications has been severely impeded. In this study, matrix metalloproteinase 2 (MMP2)-responsive cleaved cell-penetrating peptide (PF) and folate (FA) co-modified liposome coated calcium arsenate nanoparticles (FA/PF-LP-CaAs) were fabricated based on these two considerations: (1) The tumor microenvironment characterized by overexpressed MMP2 in extracellular matrix and folate receptor on the cell membrane can enhance drug accumulation and accelerate endocytosis; (2) leveraging different toxicity of arsenic in different valence states, i.e., AsV can be reduced to more toxic AsIII by glutathione in tumor cells. Furthermore, FA/PF-LP-CaAs could be responsively degraded by the mild acidic tumor environment, and the degraded product could escape from lysosomes after endocytosis. More importantly, in light of the in vivo biodistribution and pharmacodynamic studies, the vehicle was able to accumulate in the tumor efficiently. Also, it was able to exhibit excellent anti-tumor efficacy with minimized side effects when compared to single-modified counterparts. Thus, the novel strategy based on the tumor microenvironment proposed in this work can enhance the tumor-targeting efficiency and intratumor toxicity.

In vitro and in vitro toxicity study of diesel exhaust particles using BEAS-2B cell line and the nematode Caenorhabditis elegans as biological models

It is well accepted that diesel exhaust particles (DEPs) are highly associated with improper function of organ systems. In this study, DEP toxicity was performed by using in vitro human BEAS-2B cell line and in vivo animal model, namely, Caenorhabditis elegans (C. elegans). The potential toxicity of DEP was assessed by the apical endpoints of BEAS-2B cell line and reflections of C. elegans under exposure scenarios of 0~50 μg mL^-1 DEP. With the increase of DEP exposure concentration, microscopic accumulations in the cytoplasm of cell line and intestine of C. elegans were observed. Such invasion of DEP impaired the behaviors of C. elegans as well as its un-exposed offspring and caused significant impeded locomotion. Moreover, the disorders of dopaminergic function were observed simultaneously under DEP exposure, specifically manifested by the decreased transcriptional expression of dat-1. The stress responses instructed by the expression of hsp-16.2 were also increased sharply in TJ375 strain of C. elegans at DEP concentrations of 1 and 10 μg mL^-1. In the case of cellular reactions to DEP exposure, the injuries of membrane integrity and the decreased viability of cell line were simultaneously identified, and reactive oxygen species (ROS), damaged DNA fragment, and upregulated apoptosis were monotonically elevated in cell lines with the increase of DEP concentrations. This study provided a systematic insight into toxicity of DEP both in vivo and vitro, demonstrating that DEP exposure could disturb the stability of cell system and further threat the stability of organism.

Exposure to hydroxyapatite nanoparticles enhances Toll-like receptor 4 signal transduction and overcomes endotoxin tolerance in vitro and in vivo

Emerging studies indicate hydroxyapatite nanoparticles (HANPs) exhibit modest immunogenicity to elicit innate immune response which might involve Toll-like receptor 4 (TLR4) activation. This study was proposed to elucidate how HANPs direct over TLR4 signal activity in macrophage in response to TLR4 ligand, lipopolysaccharide (LPS). The present study for the first time reveals that HANPs themselves can induce TLR4 endocytosis and activate pathways both of nuclear factor-kappa B (NF-κB) and interferon regulatory factor 3 (IRF3), which potentially trigger the production of inflammatory cytokine by macrophage. Further, HANPs dose-dependently reprogram over LPS driven TLR4 signaling transduction in macrophage, leading to synergistically augmented innate immune response. In particular, HANPs synergize with LPS to promote macrophage polarization toward M1 phenotype. Moreover, HANPs abrogate the endotoxin tolerance in macrophages by restoring the production of inflammatory cytokines from macrophage in response to secondary LPS stimulation, and enhance the responsiveness of the body to LPS re-challenge in the endotoxin tolerance mice model. Therefore, this study sheds a new light on the mechanism by which HANPs drive the innate immune response, and offers a powerful strategy to potentiate LPS mediated TLR4 signaling activation in macrophage. STATEMENT OF SIGNIFICANCE: In recent years, increasing attention has been given to hydroxyapatite nanoparticles (HANPs) on how they interact with immune cells for achieving appropriate biological effect such as bone tissue repair, soft tissue filler, tumor treatment, vaccine delivery, et al. This study indicated HANPs can induce TLR4 signaling activation. In the further, HANPs dose-dependently synergize with LPS to program over LPS induced TLR4 signaling transduction in macrophage, to favor macrophage polarizing toward M1 phenotype, as well as to abrogate immune tolerance in macrophage in response to repeated LPS stimulation. This work opens a window for the intrinsic mechanism of HANPs to drive immune response and facilitate to direct the rational use or design of HANPs for their better biomedical application.

A Functionalized Octahedral Palladium Nanozyme as a Radical Scavenger for Ameliorating Alzheimer's Disease

Oxidative stress is always mentioned as a pathologic appearance of Alzheimer's disease (AD). It is attributed to mitochondrial dysfunction closely linked to Aβ deposition and neurofibrillary tangles (NFTs). Octahedral palladium nanoparticles (Pd NPs) exhibited excellent antioxidant enzyme-like activity and outstanding biocompatibility, but the poor blood-brain barrier (BBB) permeability limits their application in the treatment of Alzheimer's disease. Herein, we constructed a borneol (Bor)-modified octahedral palladium (Pd@PEG@Bor) nanozyme platform to eliminate intracellular reactive oxygen species (ROS) and elevate epithelial cell penetrability. Based on in vitro and in vivo studies, we demonstrate that the Pd@PEG@Bor could efficiently reduce ROS and Ca²⁺ contents, maintain the mitochondrial membrane potential, and further protect the mitochondria in SH-SY5Y cells. Furthermore, the nanozymes could quickly accumulate in the brain of AD mice and alleviate pathological characteristics such as Aβ plaque deposition, neuron loss, and neuroinflammation. The learning ability and memory function of AD mice are also significantly improved. Overall, this work indicates that the Pd@PEG@Bor nanozymes could delay the progression of AD by regulating ROS levels and also provides a new strategy for the treatment of AD.

Calcium Peroxide-Based Nanosystem with Cancer Microenvironment-Activated Capabilities for Imaging Guided Combination Therapy via Mitochondrial Ca2+ Overload and Chemotherapy

Mitochondria are the "power plant" of the cell, providing a constant source of energy, and are involved in a variety of intracellular signaling pathways. Among these pathways, Ca²⁺ homeostasis is closely related to the normal function of mitochondria. By destroying the Ca²⁺ steady state of mitochondria and disrupting their multiple cellular activities, tumor cell killing can be achieved. In addition, the presence of an intracellular oxidative stress state triggers the closure of cellular calcium channels, which leads to intracellular Ca²⁺ retention and enrichment. We designed a targeted and tumor microenvironment (TME)-responsive CaO₂-based nanosystem that can selectively target cancer cells for pH-controlled degradation and drug release, alter cellular physiological mechanisms by disrupting Ca²⁺ homeostasis in an artificial manner, and introduce mitochondrial Ca²⁺ excess-mediated apoptosis. Meanwhile, the production of Ca(OH)₂ will raise the pH of the microenvironment and subsequently promote the oxidation process of glutathione by H₂O₂ released from CaO₂ degradation, achieving the goal of remodeling TME. Moreover, calcium overload of tumor cells and calcification of tissues can both inhibit tumor growth and act as a contrast agent for computed tomography imaging.

Ternary supramolecular nanocomplexes for superior anticancer efficacy of natural medicines

The discovery of effective anticancer drug delivery systems and elucidation of the mechanism are enormous challenges. Using two drug administration-approved biomaterials, we constructed a natural medicine (NM)-loaded ternary supramolecular nanocomplex (TSN) suitable for large-scale production. The TSN has a better effect against cancer cells/stem cells than NM with differentially upregulated (27 versus 59) and downregulated (165 versus 66) proteins, respectively. Treatment with the TSN induced apoptosis and G2/M arrest, inhibited cell proliferation, metastasis and invasion, reduced colony/sphere formation, and decreased the frequency of side population cells and CD133⁺CD44⁺ABCG2⁺ cells. These results were revealed by multiple analyses (proteomic analysis, transwell migration and colony/sphere formation assays, biomarker profiling, etc.). We first reported the proteomic analysis of small lung cancer cells responding to a drug or its nanovesicles. We first conducted a proteomic evaluation of tumor cells responding to a drug supramolecular nanosystem. The supramolecular conformation of the TSN and the interactions of the TSN with albumin were verified by molecular docking experiments. The dominant binding forces in the TSN complexation process were electrostatic interactions, van der Waalsinteractions and bond stretching. The TSN binds to albumin more readily than NM does. The TSN has good in situ absorptive and in vitro/vivo kinetic properties. The relative bioavailability of the TSN to EA was 458.39%. The NM-loaded TSN is a supramolecular vesicle that can be produced at an industrial scale for efficient cancer therapy.

Glucose-Targeted Hydroxyapatite/Indocyanine Green Hybrid Nanoparticles for Collaborative Tumor Therapy

Nanoscale hydroxyapatite (nHA) is considered as a promising drug carrier or therapeutic agent against malignant tumors. But the strong agglomeration tendency and lack of active groups seriously hamper their usage in vivo. To address these issues, we fabricated an organic-inorganic hybrid nanosystem composed of poly(acrylic acid) (PAA), nHA, and indocyanine green (ICG), and further modified with glucose to give a targeting nanosystem (GA@HAP/ICG-NPs). These hybrid nanoparticles (∼90 nm) showed excellent storage and physiological stability assisted by PAA and had a sustained drug release in an acidic tumor environment. In vitro cell experiments confirmed that glucose-attached particles significantly promoted cellular uptake and increased intracellular ICG and Ca2+ concentrations by glucose transporter 1 (GLUT1)-mediated endocytosis. Subsequently, the excessive Ca2+ induced cell or organelle damage and ICG triggered photothermal and photodynamic effects (PTT/PDT) under laser irradiation, resulting in enhanced cell toxicity and apoptosis. In vivo tests revealed that the hybrid nanosystem possessed good hemocompatibility and biosafety, facilitating in vivo circulation and usage. NIR imaging further showed that tumor tissues had more drug accumulation, resulting in the highest tumor growth inhibition (87.89%). Overall, the glucose-targeted hybrid nanosystem was an effective platform for collaborative therapy and expected to be further used in clinical trials.

Development and evaluation studies of Corylin loaded nanostructured lipid carriers gel for topical treatment of UV-induced skin aging

We prepared nanostructured lipid carriers (NLC) to promote skin permeation of Corylin so that it can increase its effect on photoaging. Corylin-NLCs were prepared and characterized based on morphology, particle size, zeta potentials, FTIR and DSC. In vitro, we assess the cytotoxicity and lactate dehydrogenase (LDH) of HaCaT cells irradiated by UVB. Expression of antioxidant enzymes was evaluated by commercial kits. The effects of Corylin-NLC on apoptosis were confirmed by flow cytometry and western blotting. In vivo, we use UV irradiated mouse as the oxidative stress model to assess the therapeutic effect of Corylin loaded NLC gel. We identified the Corylin-NLCs can significantly suppress the LDH release, decrease MDA content, increase in CAT, SOD, GSH-Px activity, increase the expression of Bcl-2/Bax protein and reduce the expression of cleaved caspase-3/caspase-3 protein on UVB induced HaCaT cells. The histopathological lesions were significantly improved and observably decreased MDA level, increase in antioxidant enzymes activity in serum of mice by pretreatment of Corylin-NLCs gel. Overall, this study proposes a promising strategy for improving the therapeutic efficacy of photoaging.

Nano-Sized Hydroxyapatite Induces Apoptosis and Osteogenic Differentiation of Vascular Smooth Muscle Cells via JNK/c-JUN Pathway

Purpose

The deposition of hydroxyapatite (HAp) crystals plays an important role in the development of vascular calcification (VC). This study aimed to demonstrate the effects of nanosized HAp (nHAp) on vascular smooth muscle cells (VSMCs) and VC progression.

Methods

Transmission electron microscopy (TEM) was used to examine cellular uptake of nHAp. Cell viability was determined using CCK-8 assay kit. Mitochondrial impairment and reactive oxygen species were detected by TEM and fluorescence dye staining, respectively. Cell apoptosis was detected by Western blot analysis and Annexin V staining. Mouse model of VC was built via applying nHAp on the surface of abdominal aorta. Calcification was visualized by Alizarin red and von Kossa staining.

Results

We found that nHAp could promote osteogenic transformation of VSMCs by elevating expression of runt-related factor 2 (Runx2), osteopontin (OPN) and alkaline phosphatase (ALP), impairing function and morphology of mitochondria and inducing apoptosis of VSMCs. More phosphorylation of c-Jun N-terminal protein kinase/c-JUN (JNK/c-JUN) in VSMCs was detected after mixing nHAp with VSMCs. HAp-induced osteogenic transformation of VSMCs was blocked by JNK inhibitor SP600125, resulted in decreased ALP activity, less Runx2 and OPN expressions. SP600125 also inhibited apoptosis of VSMCs. Application of nHAp to outside of aorta induced osteogenic transformation and apoptosis of VSMCs, and significant deposition of calcium on the vessel walls of mice, which can be effectively attenuated by SP600125.

Conclusion

JNK/c-JUN signaling pathway is critical for nHAp-induced calcification, which could be a potential therapeutic target for controlling the progression of VC.

Quercetin-Loaded Luminescent Hydroxyapatite Nanoparticles for Theranostic Application in Monolayer and Spheroid Cultures of Cervical Cancer Cell Line In Vitro

Nanoscale materials have been explored as better alternatives to conventional therapeutic agents in cancer theranostics in the recent period due to efficacy in overcoming biological, biomedical, and biophysical barriers. Analysis on the ability of copper nanocluster (CuNC)-doped hydroxyapatite nanoparticles (Cu-HXNPs) as suitable nanocarriers for anticell proliferative application was carried out. Having high adsorption capacity, the Cu-HXNPs could be loaded with the anticancer drug quercetin, which is a polyphenolic flavonoid compound, and were used as nanocarriers to be applied on HeLa (cancer cells) and HEK-293 (normal cells). The drug release profile was found to be pH-dependent, where maximum release of quercetin from quercetin-loaded Cu-HXNPs was observed in acidic pH as compared to physiological pH. The Cu-HXNPs could release quercetin, which could effectively decline proliferation of cancer cells via generation of reactive oxygen species. Moreover, the released quercetin significantly altered the cell cycle pattern and triggered the cells to undergo apoptosis. Additionally, the efficacy of Cu-HXNPs as a nanocarrier to release quercetin on 3D spheroids of HeLa had been checked, which demonstrated significant reduction in the viability of 3D spheroids. The luminescent CuNCs used for doping HXNPs endowed the nanocarrier with the imaging property, which was an excellent feature in confirming their uptake by the cells. Thus, the study suggested Cu-HXNPs to be a beneficial nanocarrier for both bioimaging and therapeutic purpose in the field of cancer theranostics.

Synergistic Combination of Bioactive Hydroxyapatite Nanoparticles and the Chemotherapeutic Doxorubicin to Overcome Tumor Multidrug Resistance

Multidrug resistance (MDR) is one of the biggest obstacles in cancer chemotherapy. Here, a remarkable reversal of MDR in breast cancer through the synergistic effects of bioactive hydroxyapatite nanoparticles (HAPNs) and doxorubicin (DOX) is shown. DOX loaded HAPNs (DHAPNs) exhibit a 150-fold reduction in IC₅₀ compared with free DOX for human MDR breast cancer MCF-7/ADR cells, and lead to almost complete inhibition of tumor growth in vivo without obvious side effects of free DOX. This high efficacy and specificity could be attributed to multiple action mechanisms of HAPNs. In addition to acting as the conventional nanocarriers to facilitate the cellular uptake and retention of DOX in MCF-7/ADR cells, more importantly, drug-free HAPNs themselves are able to prevent drug being pumped out of MDR cells through targeting mitochondria to induce mitochondrial damage and inhibit ATP production and to trigger sustained mitochondrial calcium overload and apoptosis in MDR cancer cells while not affecting normal cells. The results demonstrate that this simple but versatile bioactive nanoparticle provides a practical approach to effectively overcome MDR.

Three widely used pesticides and their mixtures induced cytotoxicity and apoptosis through the ROS-related caspase pathway in HepG2 cells

Difenoconazole, cypermethrin and triazophos are widely used pesticides in agricultural production and frequently detected in foods. The aim of this study was to determine the effect of these pesticides and their mixtures on cell viability, reactive oxygen species (ROS), lactate dehydrogenase (LDH) content, apoptosis rate and DNA fragmentation and synthesis in human hepatocellular carcinoma cells (HepG2). The order of inhibitory effects for the individual pesticides was ranked as difenoconazole > cypermethrin > triazophos. The enhanced expression of caspase-3, caspase-7 and PARP activity was observed in HepG2 cells, which was 1.7, 1.3 and 1.6-fold higher than the control, respectively, along with significant protein cleavage; and induced apoptosis in a concentration-dependent manner. Further, the pesticide mixtures significantly increased ROS level (up to 1.3-fold), induced DNA fragmentation (up to 1.8-fold), inhibited DNA synthesis (up to 53%), and damaged the cells by destroying the cell membrane and producing a large amount of LDH at concentration range of 10-30 μM. Specifically, mixtures containing difenoconazole showed stronger toxicities than individual pesticides, implying higher health risks associated with mixtures. Our results show that three widely used pesticides exhibited cytotoxicity and apoptosis through the ROS-related caspase pathway, providing a basis for evaluation of health risks from pesticide mixtures via food consumption.

Nanocellulose-Reinforced Hydroxyapatite Nanobelt Membrane as a Stem Cell Multi-Lineage Differentiation Platform for Biomimetic Construction of Bioactive 3D Osteoid Tissue In Vitro

Severe bone defects, especially accompanied by vascular and peripheral nerve injuries, remain a massive challenge. Most studies related to bone tissue engineering have focused on osteogenic differentiation of mesenchymal stem cells (MSCs), and ignored the formation of blood vessels and nerves in the newly generated bone owing to the lack of proper materials and methodology for tuning stem cells differentiated into osteogenic, neuronal, and endothelial cells (ECs) in the same scaffold system. Herein, a nanocellulose-reinforced hybrid membrane with good mechanical properties and control over biodegradation by assembling ultralong hydroxyapatite nanobelts in a bacterial nanocellulose hydrogel is designed and synthesized. Osteogenic, neuronal cells are successfully differentiated on this hybrid membrane. Based on the multi-lineage differentiation property of the membrane, a bioactive 3D osteoid tissue (osteogenic, neural, and ECs) is mimetically constructed in vitro using layer-by-layer culture and integration. The bone regeneration ability of the as-prepared bioactive osteoid tissue is assessed in vivo via heterotopic osteogenesis experiments for eight weeks. The rapid new bone growth and formation of blood capillaries and nerve fibers prove that the hybrid membrane can be universally applied as a stem cell multi-lineage differentiation platform, which has significant applications in bone tissue engineering.

A novel strategy for tumor therapy: targeted, PAA-functionalized nano-hydroxyapatite nanomedicine

The rapid development of nanotechnology has provided new strategies for the treatment of tumors. Nano-scale hydroxyapatite (HAP), as the main component of hard tissues in humans and vertebrates, have been found to specifically inhibit tumor cells. However, achieving controllable synthesis of HAP and endowing it with cancer cell-targeting properties remain enormous challenges. To solve this problem, we developed polyacrylic acid-coordinated hydroxyapatite nanoparticles (HAP-PAA) and further chemically grafted them with folic acid (HAP-PAA-FA) for cancer treatment in this study. The nucleation sites and steric hindrance provided by the PAA greatly inhibited the agglomeration of the nanoparticles, and at the same time, the excess functional groups further modified the surface of nanoparticles to achieve targeting efficiency. The spherical, low-crystallinity HAP-PAA nanoparticles exhibited good tumor cell lethality. After grafting the nanoparticles with folic acid for molecular targeting, their cellular uptake and specific killing ability of tumor cells were further enhanced. The HAP-PAA-FA nanoparticle system exerted a regulatory effect on the tumor microenvironment and had good biological safety. All the above results indicate that this research will broaden the application of hydroxyapatite in tumor treatment.

Ameliorating quercetin constraints in cancer therapy with pH-responsive agarose-polyvinylpyrrolidone -hydroxyapatite nanocomposite encapsulated in double nanoemulsion

Despite quercetin (QC) promising features for cancer therapy, low solubility, poor permeability, and short biological half-life time significantly confine its application in cancer therapy. In this study, a novel approach is developed to improve loading efficiency and attain quercetin sustained-release concurrently. In this direction, hydrogel nanocomposite of agarose (AG)-polyvinylpyrrolidone (PVP)-hydroxyapatite (HAp) was loaded with QC. Incorporating HAp nanoparticles in the AG-PVP hydrogel improved the loading efficiency up to 61%. Also, the interactions between nanoparticle, drug, and hydrogel polymers rendered the nanocomposite pH-responsive at acidic conditions and controlled the burst release at neutral conditions. Then, QC-loaded hydrogel was encapsulated into the water in oil in water nanoemulsions to further sustain the drug release. As a result, the pH-responsive release of QC with prolonged-release over 96 h was observed. In more detail, according to the Korsmeyer-Peppas mathematical model, the mechanism of release was anomalous (diffusion-controlled) at pH 7.4 and anomalous transport (dissolution-controlled) at pH 5.4. The presence of all nanocomposite components was confirmed with FTIR analysis, and XRD results approved the incorporation of QC in the fabricated nanocomposite. The homogeneous surface of the nanocomposite in FESEM images showed good compatibility between components. The zeta potential analysis confirmed the good stability of the nanocarriers. Besides, the fabricated AG-PVP-HAp-QC platform showed significant cytotoxicity on MCF-7 cells compared to QC as a free drug (p < 0.001) and to quercetin-loaded AG-PVP (AG-PVP-QC) (p < 0.001) with enhanced apoptosis induction after the addition of HAp. Accordingly, this delivery platform ameliorated loading and sustained-release of QC, as well as its anticancer activity by releasing the drug at an effective therapeutic level over a long period to induce apoptosis. Thus, turning this drug delivery system into a potential candidate for further biomedical applications.

High-Performance Self-Cascade Pyrite Nanozymes for Apoptosis-Ferroptosis Synergistic Tumor Therapy

As next-generation artificial enzymes, nanozymes have shown great promise for tumor catalytic therapy. In particular, their peroxidase-like activity has been employed to catalyze hydrogen peroxide (H₂O₂) to produce highly toxic hydroxyl radicals (^•OH) to kill tumor cells. However, limited by the low affinity between nanozymes with H₂O₂ and the low level of H₂O₂ in the tumor microenvironment, peroxidase nanozymes usually produced insufficient ^•OH to kill tumor cells for therapeutic purposes. Herein, we present a pyrite peroxidase nanozyme with ultrahigh H₂O₂ affinity, resulting in a 4144- and 3086-fold increase of catalytic activity compared with that of classical Fe₃O₄ nanozyme and natural horseradish peroxidase, respectively. We found that the pyrite nanozyme also possesses intrinsic glutathione oxidase-like activity, which catalyzes the oxidation of reduced glutathione accompanied by H₂O₂ generation. Thus, the dual-activity pyrite nanozyme constitutes a self-cascade platform to generate abundant ^•OH and deplete reduced glutathione, which induces apoptosis as well as ferroptosis of tumor cells. Consequently, it killed apoptosis-resistant tumor cells harboring KRAS mutation by inducing ferroptosis. The pyrite nanozyme also exhibited favorable tumor-specific cytotoxicity and biodegradability to ensure its biosafety. These results indicate that the high-performance pyrite nanozyme is an effective therapeutic reagent and may aid the development of nanozyme-based tumor catalytic therapy.

Constructing a biomimetic nanocomposite with the in situ deposition of spherical hydroxyapatite nanoparticles to induce bone regeneration

Inspired by the nanostructure of bone, biomimetic nanocomposites comprising natural polymers and inorganic nanoparticles have gained much attention for bone regenerative applications. However, the mechanical and biological performances of nanocomposites are largely limited by the inhomogeneous distribution, uncontrolled size and irregular morphology of inorganic nanoparticles at present. In this work, an innovative in situ precipitation method has been developed to construct a biomimetic nanocomposite which consists of spherical hydroxyapatite (HA) nanoparticles and gelatin (Gel). The homogeneous dispersion of HA nanoparticles in nHA-Gel endowed it with a low swelling ratio, enhanced mechanical properties and slow degradation. Moreover, strontium (Sr) was incorporated into HA nanoparticles to further enhance the bioactivity of nanocomposites. In vitro experiments suggested that nHA-Gel and Sr-nHA-Gel facilitated cell spreading and promoted osteogenic differentiation of bone-marrow-derived mesenchymal stem cells (BMSCs) as compared to pure Gel and mHA-Gel conventional composites developed by mechanical mixing. In vivo rat critical-sized calvarial defect repair further confirmed that nHA-Gel and Sr-nHA-Gel possessed relatively effective bone regenerative abilities among the four groups. Collectively, the biomimetic nanocomposites of nHA-Gel and Sr-nHA-Gel have good efficacy in inducing bone regeneration and would be a promising alternative to bone grafts for clinical applications.