Blocked Autophagy is Involved in Layered Double Hydroxide-Induced Repolarization and Immune Activation in Tumor-Associated Macrophages.

Tumor-associated macrophages (TAMs) are important immune cells in the tumor microenvironment (TME). The polar plasticity of TAMs makes them important targets for improving the immunosuppressive microenvironment of tumors. The previous study reveals that layered double hydroxides (LDHs) can effectively promote the polarization of TAMs from the anti-inflammatory M2 type to the pro-inflammatory M1 type. However, their mechanisms of action remain unexplored. This study reveals that LDHs composed of different cations exhibit distinct abilities to regulate the polarity of TAMs. Compared to Mg-Fe LDH, Mg-Al LDH has a stronger ability to promote the repolarization of TAMs from M2 to M1 and inhibit the formation of myeloid-derived suppressor cells (MDSCs). In addition, Mg-Al LDH restrains the growth of tumors in vivo and promotes the infiltration of activated immune cells into the TME more effectively. Interestingly, Mg-Al LDH influences the autophagy of TAMs; this negatively correlates with the pro-inflammatory ability of TAMs. Therefore, LDHs exert their polarization ability by inhibiting the autophagy of TAMs, and this mechanism might be related to the ionic composition of LDHs. This study lays the foundation for optimizing the performance of LDH-based immune adjuvants, which display excellent application prospects for tumor immunotherapy.

A mitochondria-anchored supramolecular photosensitizer as a pyroptosis inducer for potent photodynamic therapy and enhanced antitumor immunity.

BACKGROUND: The discovery of a potent photosensitizer with desirable immunogenic cell death (ICD) ability can prominently enhance antitumor immunity in photodynamic therapy (PDT). However, majority of commercially-available photosensitizers suffer from serious aggregation and fail to elicit sufficient ICD. Pyroptosis as a newly identified pattern for potent ICD generation is rarely disclosed in reported photosensitizers. In addition, the photosensitizer with excellent mitochondria-anchored ability evokes prominent mitochondria oxidative stress, and consequently induces ICD. RESULTS: Herein, a novel supramolecular photosensitizer LDH@ZnPc is reported, without complicated preparation, but reveals desirable pyroptosis-triggered ability with mitochondria anchoring feature. LDH@ZnPc is obtained through isolation of ZnPc using positive charged layered double hydroxides (LDH), and excellent mitochondria-anchored ability is achieved. More importantly, LDH@ZnPc-mediated PDT can effectively initiate gasdermin D (GSDMD)-dependent pyroptosis of tumor cells. In vitro and in vivo results verify robust ICD ability and potent tumor inhibition efficacy, and antitumor immunity towards distant tumor inhibition. CONCLUSIONS: This study reveals that LDH@ZnPc can act as an excellent pyroptosis inducer with simultaneous mitochondria anchoring ability for enhancing photodynamic therapy and boosting antitumor immunity.

Interference of layered double hydroxide nanoparticles with pathways for biomedical applications.

Recent decades have witnessed a surge of explorations into the application of multifarious materials, especially biomedical applications. Among them, layered double hydroxides (LDHs) have been widely developed as typical inorganic layer materials to achieve remarkable advancements. Multiple physicochemical properties endow LDHs with excellent merits in biomedical applications. Moreover, LDH nanoplatforms could serve as "molecular switches", which are capable of the controlled release of payloads under specific physiological pH conditions but are stable during circulation in the bloodstream. In addition, LDHs themselves are composed of several specific cations and possess favorable biological effects or regulatory roles in various cellular functions. These advantages have caused LDHs to become increasingly of interest in the area of nanomedicine. Recent efforts have been devoted to revealing the potential factors that interfere with the biological pathways of LDH-based nanoparticles, such as their applications in shaping the functions of immune cells and in determining the fate of stem cells and tumor treatments, which are comprehensively described herein. In addition, several intracellular signaling pathways interfering with by LDHs in the above applications were also systematically expatiated. Finally, the future development and challenges of LDH-based nanomedicine are discussed in the context of the ultimate goal of practical clinical application.

Multifunctional silica nanocomposites prime tumoricidal immunity for efficient cancer immunotherapy.

The tumor immune microenvironment (TIME) has been demonstrated to be the main cause of cancer immunotherapy failure in various malignant tumors, due to poor immunogenicity and existence of immunosuppressive factors. Thus, establishing effective treatments for hostile TIME remodeling has considerable potential to enhance immune response rates for durable tumor growth retardation. This study aims to develop a novel nanocomposite, polyethyleneimine-modified dendritic mesoporous silica nanoparticles loaded with microRNA-125a (DMSN-PEI@125a) to synergistically enhance immune response and immunosuppression reversion, ultimately generating a tumoricidal environment. Our results showed that DMSN-PEI@125a exhibited excellent ability in cellular uptake by murine macrophages and the cervical cancer cell line TC-1, repolarization of tumor associated macrophages (TAMs) to M1 type in a synergistic manner, and promotion of TC-1 immunogenic death. Intratumor injection of DMSN-PEI@125a facilitated the release of more damage-related molecular patterns and enhanced the infiltration of natural killer and CD8+ T cells. Meanwhile, repolarized TAMs could function as a helper to promote antitumor immunity, thus inhibiting tumor growth in TC-1 mouse models in a collaborative manner. Collectively, this work highlights the multifunctional roles of DMSN-PEI@125a in generating an inflammatory TIME and provoking antitumor immunity, which may serve as a potential agent for cancer immunotherapy.

Layered Double Hydroxide Nanoparticles with Osteogenic Effects as miRNA Carriers to Synergistically Promote Osteogenesis of MSCs.

Inefficient differentiation and poor engraftment hinder the clinical applications of mesenchymal stem cell (MSC)-based cell therapies in regenerative medicine. Layered double hydroxide (LDH) nanoparticles are sheet-like materials with desirable biocompatibility and anion-exchange properties and have been widely applied as drug and nucleotide carriers in the field of tissue repair. However, few studies have focused on the biological effects of LDH itself. In this study, we demonstrated the novel function of LDH in stimulating osteogenic differentiation of bone marrow-derived MSCs (BMSCs). The expression of osteogenic-related genes, alkaline phosphatase (ALP) activity, and calcium deposits were significantly increased after LDH treatment. Mechanistic analysis performed with RNA sequencing revealed that LDH promoted osteogenesis by targeting the LGR5/ß-catenin axis. LDH also inactivated IKK/NF-κB signaling under LPS-triggered inflamed conditions, suggesting the dual benefits of LDH in enhancing bone regeneration and alleviating the inflammatory response. Furthermore, we utilized LDH as the transport vehicle of the osteoinductive miRNA let-7d to synergistically regulate BMSCs toward the osteoblastic lineage. The LDH/let-7d complex resulted in a better induction of osteogenesis than LDH alone. For cell transplantation, BMSCs were seeded in LDH/let-7d-incorporated fibrin scaffolds, which proved enhanced osteoinduction capability in the subcutaneous ectopic osteogenesis model in nude mice. Taken together, this study provides a novel strategy for effective and synergistic improvement of osteogenesis via LDH-mediated delivery of miRNA let-7d, thus shedding light on the future application of LDH in regenerative medicine.

Layer-Number-Dependent Effects of Graphene Oxide on the Pluripotency of Mouse Embryonic Stem Cells Through the Regulation of the Interaction Between the Extracellular Matrix and Integrins.

INTRODUCTION: Embryonic stem cells (ESCs) possess great application prospects in biological research and regenerative medicine, so it is important to obtain ESCs with excellent and stable cellular states during in vitro expansion. The feeder layer culture system with the addition of leukemia inhibitory factor (LIF) is currently applied in ESC cultures, but it has a series of disadvantages that could influence the culture efficiency and quality of the ESCs. With the development of nanotechnology, many studies have applied nanomaterials to optimize the stem cell culture system and regulate the fate of stem cells. In this study, we investigated the layer-number-dependent biofunction of graphene oxide (GO) on the pluripotency of ESCs from mice (mESCs). METHODS: Single-layer GO (SGO) and multi-layer GO (MGO) were characterized and their effects on the cytotoxicity and self-renewal of mESCs were detected in vitro. The differentiation potentials of mESCs were identified through the formation of embryoid bodies and teratomas. The regulatory mechanism of GO was verified by blocking the target receptors on the surface of mESCs using antibodies. RESULTS: Both SGO and MGO were biocompatible with mESCs, but only MGO effectively sustained their self-renewal and differentiation potential. In addition, GO influenced the cellular activities of mESCs by regulating the interactions between extracellular matrix proteins and integrins. CONCLUSION: This work demonstrates the layer-number-dependent effects of GO on regulating the cell behavior of mESCs and reveals the extracellular regulatory mechanism of this process.

Trifunctional Graphene Quantum Dot@LDH Integrated Nanoprobes for Visualization Therapy of Gastric Cancer.

Visualization technology has become a trend in tumor therapy in recent years. The superior optical properties of graphene quantum dots (GQDs) make them suitable candidates for tumor diagnosis, but their tumor targeting and drug-carrying capacities are still not ideal for treatment. Sulfur-doped graphene quantum dots (SGQDs) with stable fluorescence are prepared in a previous study. A reliable strategy by associating layered double hydroxides (LDHs) and etoposide (VP16) is designed for precise visualization therapy. Trifunctional LDH@SGQD-VP16 integrated nanoprobes can simultaneously achieve targeted aggregation, fluorescence visualization, and chemotherapy. LDH@SGQD-VP16 can accumulate in the tumor microenvironment, owing to pH-sensitive properties and long-term photostability in vivo, which can provide a basis for cancer targeting, real-time imaging, and effect tracking. The enhanced therapeutic and attenuated side effects of VP16 are demonstrated, and the apoptosis caused by LDH@SGQD-VP16 is ≈2.7 times higher than that of VP16 alone, in HGC-27 cells. This work provides a theoretical and experimental basis for LDH@SGQD-VP16 as a potential multifunctional agent for visualization therapy of gastric cancer.

Layered double hydroxide eliminate embryotoxicity of chemotherapeutic drug through BMP-SMAD signaling pathway.

Recent studies indicate that exogenous chemotherapy agents can cross the placenta barrier and cause fetal toxicity, while there exists barely alternative therapy for pregnant cancer patients. Here, we show a robust protective effect of layered double hydroxide (LDH) against etoposide (VP16) induced in vitro mouse embryonic stem cells (mESCs) toxicity and in vivo embryo developmental disorders. The nano-composite system (L-V) abrogated the original VP16 generated mitochondrial mediated mESCs toxicity totally, surprisingly maintained the pluripotency without leukemia inhibitory factor (LIF) and prevented the down-regulation of ectoderm marker expression during spontaneous embryoid bodies differentiation. Fetal growth retardation, the related placenta and skeletal structural abnormalities and long-term toxicity in the offspring were generated when pregnant mice exposed to VP16, while these detrimental effects were abolished when substituted with L-V. The different uterine drug accumulation of VP16 and L-V contributed to partly cause for the functional variation. And further transcriptome analysis confirmed developmental related BMP4-SMAD6 signaling pathway is of crucial importance. Our study revealed the devastating effects of VP16 on embryonic development and the toxicity-relieve method using nano-carrier system, which will provide important guidance for clinical application of LDH as alternative therapeutic system with minimal side effects for pregnant women diagnosed with cancer.