Evading Doxorubicin-Induced Systemic Immunosuppression Using Ultrasound-Responsive Liposomes Combined with Focused Ultrasound.

Doxorubicin (DOX) is a representative anticancer drug with a unique ability to induce immunogenic cell death of cancer cells. However, undesired toxicity on immune cells has remained a significant challenge, hindering the usage of DOX in cancer immunotherapy. Here, we report a combined therapy to avoid the off-target toxicity of DOX by adapting ultrasound-responsive liposomal doxorubicin and focused ultrasound exposure. Histological analysis demonstrated that the combined therapy induced less hemosiderosis of splenocytes and improved tumor infiltration of cytotoxic T lymphocytes. Additionally, in vivo therapeutic evaluation results indicate that the combined therapy achieved higher efficacy when combined with PD-1 immune-checkpoint blockade therapy by improving immunogenicity.

Dissolving microneedles for long-term storage and transdermal delivery of extracellular vesicles.

Extracellular vesicles (EVs) have shown great potential in disease diagnosis and treatment; however, their clinical applications remain challenging due to their unsatisfactory long-term stability and the lack of effective delivery strategies. In this study, we prepared human adipose stem cell-derived EV (hASC-EV)-loaded hyaluronic acid dissolving microneedles (EV@MN) to investigate the feasibility of EVs for their clinical applications. The biological activities of the EVs in this formulation were maintained for more than six months under mild storage conditions, especially at temperatures lower than 4 °C. Moreover, the EV@MN enabled precise and convenient intradermal delivery for sustained release of EVs in the dermis layer. Therefore, EV@MN significantly improved the biological functions of hASC-EVs on dermal fibroblasts by promoting syntheses of proteins for the extracellular matrix such as collagen and elastin, enhancing fibroblast proliferation, and regulating the phenotype of fibroblast, compared with other administration methods. This research revealed a possible and feasible formulation for the clinical application of EVs.

Chemiluminescence resonance energy transfer-based immunostimulatory nanoparticles for sonoimmunotherapy.

Sonodynamic therapy (SDT) has recently emerged as a promising alternative to photodynamic therapy because of its applicability in treating deeply located tumors accessible by ultrasound (US). However, the therapeutic potential of conventional sonosensitizers is limited by the low quantum yield of reactive oxygen species (ROS) and poor immune responses eliciting canonical apoptosis of cancer cells. Herein, we report chemiluminescence resonance energy transfer (CRET)-based immunostimulatory nanoparticles (iCRET NPs) for sonoimmunotherapy, which not only amplify the ROS quantum yield of sonosensitizers but also generate carbon dioxide (CO2) bubbles to induce immunogenic cell death in the tumor microenvironment (TME). Owing to their CRET phenomena responsive to H2O2 in the TME, iCRET NPs exhibit strong cytotoxicity to cancer cells by producing a large quantity of ROS. Additionally, iCRET NPs effectively induce CO2-mediated immunogenic cell death by rupturing the cancer cell membrane in the presence of US, leading to the release of bare damage-associated molecular patterns, such as HSP 70 and HMGB1. Consequently, when iCRET NPs are combined with anti-PD-1 antibodies, iCRET NPs exhibit synergistic effects in 4T1 tumor-bearing mice, in which antitumor immunity is remarkably amplified to inhibit tumor growth and metastasis.

Gold-installed hyaluronic acid hydrogel for ultrasound-triggered thermal elevation and on-demand cargo release.

The temporal and quantitative control of the cargo release is a challenging issue in the application of hydrogels for cancer therapy. Here, we report hyaluronic acid hydrogel-based depot that provides ultrasound-triggered thermal elevation and on-demand cargo release. The hyaluronic acid hydrogel was developed by employing the gold cluster as a sonothermal crosslinker which was grown on the cargo to prevent its undesired leakage until ultrasound-induced dissociation. The results demonstrated that, in the presence of ultrasound at 30 W, the hyaluronic acid hydrogel significantly increased the temperature to 53.7 °C, leading to dissociation of gold clusters and subsequent cargo release. In addition, the prepared hydrogel exhibited appropriate mechanical properties and superior biostability as an injectable hydrogel for in vivo applications.

Carboxymethyl dextran-based nanocomposites for enhanced chemo-sonodynamic therapy of cancer.

Glutathione (GSH), a tripeptide abundant in the cancer cells, inhibits the cytotoxic effect of reactive oxygen species (ROS) and is associated with anti-apoptosis, thus facilitating tumor growth. Here, we report GSH-depleting carboxymethyl dextran nanocomposites for chemo-sonodynamic therapy for cancer. The nanocomposite is composed of the TiO2-based core as the sonosensitizer, MnO2 coat as the GSH-consuming chemosensitizer, and carboxymethyl dextran as the hydrophilic shell. The in vitro cell experiments demonstrated that, when taken up by the cancer cells, the nanocomposites can deplete intracellular GSH by reducing MnO2 to Mn2+ which induces intracellular ROS production. Upon exposure to ultrasound, the nanocomposites effectively generated cytotoxic singlet oxygen at the intracellular level, remarkably enhancing the cytotoxicity to cancer cells. Notably, chemo-sonodynamic activity of the nanocomposites induced apoptosis as well as necrosis of cancer cells, implying their high potential as the anticancer therapeutics.

Engineering approaches for effective therapeutic applications based on extracellular vesicles.

The biological significance of extracellular vesicles (EVs) as intercellular communication mediators has been increasingly revealed in a wide range of normal physiological processes and disease pathogenesis. In particular, regenerative and immunomodulatory EVs hold potential as innate biotherapeutics, whereas pathological EVs are considered therapeutic targets for inhibiting their bioactivity. Given their ability to transport functional cargos originating from the source cells to target cells, EVs can also be used as a therapeutic means to deliver drug molecules. This review aims to provide an updated overview of the key engineering approaches for better exploiting EVs in disease intervention. The emphasis is lying on the preconditioning methods for therapeutic EVs, drug loading and targeting technologies for carrier EVs, and activity control strategies for pathological EVs.

Necroptosis-Inducible Polymeric Nanobubbles for Enhanced Cancer Sonoimmunotherapy.

Necroptosis, caspase-independent programmed necrosis, has emerged as a therapeutic target to make dying cancer cells stimulants for antitumor immune responses. The clinical translations exploiting necroptosis, however, have been limited since most cancer cells downregulate receptor-interacting protein kinase 3 (RIPK3) as a key enzyme for necroptosis. Herein, nanobubbles (NBs) that can trigger RIPK3-independent necroptosis, facilitating cell-membrane rupture via the acoustic cavitation effect are reported. The NBs, imbibing perfluoropentane as the gas precursor, are prepared using an amphiphilic polymer conjugate, composed of PEGylated carboxymethyl dextran as the hydrophilic backbone and chlorin e6 as the hydrophobic sonosensitizer. When exposed to ultrasound, the NBs efficiently promote the release of biologically active damage-associated molecular patterns by inducing burst-mediated cell-membrane disintegration. Consequently, the necroptosis-inducible NBs significantly improve antitumor immunity by maturation of dendritic cells and activation of CD8+ cytotoxic T cells both in vitro and in vivo. In addition, the combination of NBs and immune checkpoint blockade leads to complete regression of the primary tumor and beneficial therapeutic activity against metastatic tumors in an RIPK3-deficient CT26 tumor-bearing mouse model. Overall, the innovative NB that causes immunogenic cell death of cancer via RIPK3-independent necroptosis is a promising enhancer for cancer immunotherapy.

Preparation of gradient polyacrylate brushes in microchannels.

Gradient poly(2-hydroxyethyl methacrylate) brushes were synthesized by surface-initiated atom transfer radical polymerization (ATRP) confined within a microfluidic system on a silicon wafer. For ATRP, surface initiator, 11-((2-bromo, 2-methyl) propionyloxy) undecyltrichlorosilane (BUC), was synthesized, and allowed to self-assemble in a monolayer on the Si wafer, as analyzed by XPS to confirm the presence of an ester group of BUC. A solution containing 2-hydroxyethylmethacrylate, Cu catalyst, and bipyridin was allowed to flow in a microchannel and polymerize, resulting in the brushes with a gradient of thickness on the Si wafer. Using ellipsometry and ATR-IR, we verified the gradients of well established brushes on the Si wafer. AFM and contact angle data showed that wettability of the brushes did not exhibit a linear relationship with hydrophilicity.