Multidrug resistance (MDR) resulting from the overexpression of drug transporters such as P‐glycoprotein (Pgp) increases the efflux of drugs and thereby limits the effectiveness of chemotherapy. To ...address this issue, this work develops an injectable hollow microsphere (HM) system that carries the anticancer agent irinotecan (CPT‐11) and a NO‐releasing donor (NONOate). Upon injection of this system into acidic tumor tissue, environmental protons infiltrate the shell of the HMs and react with their encapsulated NONOate to form NO bubbles that trigger localized drug release and serve as a Pgp‐mediated MDR reversal agent. The site‐specific drug release and the NO‐reduced Pgp‐mediated transport can cause the intracellular accumulation of the drug at a concentration that exceeds the cell‐killing threshold, eventually inducing its antitumor activity. These results reveal that this pH‐responsive HM carrier system provides a potentially effective method for treating cancers that develop MDR.
Two is better than one: A carrier system is developed that can generate NO bubbles in the acidic environment of tumor tissues to trigger localized drug release (specifically irinotecan, denoted CPT‐11) and to reverse Pgp‐mediated multidrug resistance (Pgp=P‐glycoprotein). The combined system enhances intracellular drug accumulation in cancer cells so that the concentration exceeds the therapeutic threshold, eventually leading to antitumor activity.
Inflammation is involved in many human pathologies, including osteoarthritis (OA). Hydrogen (H2) is known to have anti‐inflammatory effects; however, the bioavailability of directly administered H2 ...gas is typically poor. Herein, a local delivery system that can provide a high therapeutic concentration of gaseous H2 at inflamed tissues is proposed. The delivery system comprises poly(lactic‐co‐glycolic acid) microparticles that contain magnesium powder (Mg@PLGA MPs). Mg@PLGA MPs that are intra‐muscularly injected close to the OA knee in a mouse model can act as an in situ depot that can evolve gaseous H2 continuously, mediated by the cycle of passivation/activation of Mg in body fluids, at a concentration that exceeds its therapeutic threshold. The analytical data that are obtained in the biochemical and histological studies indicate that the proposed Mg@PLGA MPs can effectively mitigate tissue inflammation and prevent cartilage from destruction, arresting the progression of OA changes.
Upon intramuscular administration, water infiltrates the PLGA microparticles to react with their encapsulated Mg powders, evolving H2 bubbles and producing Mg(OH)2 on their surfaces, making them unreactive. The passivated Mg can then be activated by the chloride (Cl−) ions in body fluids. The cycle of passivation/activation of Mg can thus evolve gaseous H2 continuously to the inflamed cartilage, arresting progression of osteoarthritis (OA).
Inflammation is associated with many diseases, in which activated inflammatory cells produce various reactive oxygen species (ROS), including H2O2. This work proposes an ultrasensitive ROS-responsive ...hollow microsphere (HM) carrier that contains an anti-inflammatory drug, an acid precursor consisting of ethanol and FeCl2, and sodium bicarbonate (SBC) as a bubble-generating agent. In cases of inflamed osteoarthritis, the H2O2 at low concentration diffuses through the HMs to oxidize their encapsulated ethanol in the presence of Fe2+ by the Fenton reaction, establishing an acidic milieu. In acid, SBC decomposes to form CO2 bubbles, disrupting the shell wall of the HMs and releasing the anti-inflammatory drug to the problematic site, eventually protecting against joint destruction. These results reveal that the proposed HMs may uniquely exploit biologically relevant concentrations of H2O2 and thus be used for the site-specific delivery of therapeutics in inflamed tissues.
Significant health risks are posed by meningitis due to its rapid progression, and challenges are encountered in intravenous antibiotic administration, especially in crossing the blood‐brain barrier. ...To address this, an inflammation‐activated, endogenous macrophage (MΦ)‐mediated oral prodrug delivery system is developed for targeted therapeutic interventions in bacterial meningitis treatment. This system is guided by inflammation‐derived chemoattractants and triggers drug release through inflammation‐induced reactive oxygen species (ROS). Comprised of naturally derived β‐glucans conjugated with the antibiotic cefotaxime (CTX) using a ROS‐responsive linker, nanoparticles (βGlus–CTX NPs) are formed in aqueous solutions. In a mouse model of Klebsiella pneumoniae‐induced meningitis, orally administered βGlus–CTX NPs are traversed by intestinal microfold cells, surpassing the intestine‐epithelial barrier, and are absorbed by resident endogenous MΦ. These MΦ‐mediated drug delivery vehicles are then traveled through the lymphatic and circulatory systems, crossing the compromised blood‐brain barrier, ultimately reaching inflamed brain tissues, guided by their derived chemoattractants. In ROS‐rich inflamed tissue environments, the linkers in the βGlus–CTX NPs are cleaved, releasing therapeutic CTX for localized treatment. Targeted antibiotic treatment for bacterial meningitis is offered by this oral, endogenous MΦ‐mediated prodrug delivery system, overcoming the robust gut‐to‐brain biological barriers and potentially enhancing effectiveness for comfortable home‐based treatment.
Guided by chemoattractants released from inflamed tissues, the prodrug nanoparticles, transported by endogenous MΦ, traverse the lymphatic and circulatory systems, ultimately reaching the infected brain. This inflammation‐activated MΦ‐mediated delivery system not only overcomes substantial biological barriers between the gut and the brain but also responds to elevated ROS levels in inflamed tissues, triggering the release of the therapeutic drug.
Bacteria‐mediated tumor therapy (BMTT) has been known for decades; however, its clinical use is inhibited by its association with infections. To address this issue, a spiky, bacterium‐like ...metal–organic framework (MOF), which can replicate the functional responses of BMTT without its adverse side‐effects, is proposed. MOFs are synthesized in a solvothermal reaction of aluminum sulfate, ruthenium chloride hydrate, and 2‐aminoterephthalic acid; they have a spherical morphology or many nanospikes on their surfaces, depending on the reaction temperature. Both spherical and spiky MOFs can function as photothermal agents, converting absorbed optical energy into local heat. Owing to their higher surface area of interaction, spiky MOFs are more easily phagocytosed by macrophages than are spherical MOFs, strengthening their immune responses. Moreover, when injected intratumorally, spiky MOFs reside significantly longer than spherical ones, enabling their use in repeated photothermal treatments. The combination of in situ vaccination with intratumorally injected bacterium‐like MOFs under exposure to an near‐infrared laser and the immune checkpoint blockade of systemically administered αPD‐1 is evaluated in tumor‐bearing mice. The results indicate that the checkpoint blockade acts synergistically with in situ vaccination to provide diverse antitumor functions of BMTT, destroying a primary tumor and suppressing tumor recurrence and metastasis.
The combination of in situ vaccination by intratumorally injected bacterium‐like MOFs under NIR exposure and the checkpoint blockade of systemically administered αPD‐1 is used to enable the diverse antitumor functions of bacteria‐mediated tumor therapy. The results indicate that the checkpoint blockade acts synergistically with in situ vaccination to strengthen immune memory responses, yielding remarkable antitumor efficacy.
In the absence of adequate oxygen, cancer cells that are grown in hypoxic solid tumors resist treatment using antitumor drugs (such as doxorubicin, DOX), owing to their attenuated intracellular ...production of reactive oxygen species (ROS). Hyperbaric oxygen (HBO) therapy favorably improves oxygen transport to the hypoxic tumor tissues, thereby increasing the sensitivity of tumor cells to DOX. However, the use of HBO with DOX potentiates the ROS-mediated cytotoxicity of the drug toward normal tissues. In this work, we hypothesize that regional oxygen treatment by an implanted oxygen-generating depot may enhance the cytotoxicity of DOX against malignant tissues in a highly site-specific manner, without raising systemic oxygen levels. Upon implantation close to the tumor, the oxygen-generating depot reacts with the interstitial medium to produce oxygen in situ, effectively shrinking the hypoxic regions in the tumor tissues. Increasing the local availability of oxygen causes the cytotoxicity of DOX that is accumulated in the tumors to be significantly enhanced by the elevated production of ROS, ultimately allaying the hypoxia-induced DOX resistance in solid malignancies. Importantly, this enhancement of cytotoxicity is limited to the site of the tumors, and this feature of the system that is proposed herein is unique.
Most cancer vaccines under development are associated with defined tumor antigens rather than with all antigens of whole tumor cells, limiting the anti-tumor immune responses that they elicit. This ...work proposes an immunomodulator (R848)-loaded nanoparticle system (R848@NPs) that can absorb near-infrared light (+NIR) to cause low-temperature hyperthermia that interacts synergistically with its loaded R848 to relieve the tumor-mediated immunosuppressive microenvironment, generating robust anti-tumor memory immunity. In vitro results reveal that the R848@NPs could be effectively internalized by dendritic cells, causing their maturation and the subsequent regulation of their anti-tumor immune responses. Post-treatment observations in mice in which tumors were heat-treated at high temperatures reveal that tumor growth was significantly inhibited initially but not in the longer term, while low-temperature hyperthermia or immunotherapy alone simply delayed tumor growth. In contrast, a combined therapy that involved low-temperature hyperthermia and immunotherapy using R848@NPs/+NIR induced a long-lasting immunologic memory and consequently inhibited tumor growth and prevented cancer recurrence and metastasis. These results suggest that the method that is proposed herein is promising for generating cancer vaccines in situ, by using the tumor itself as the antigen source and the introduced R848@NPs/+NIR to generate a long-term anti-tumor immunity, for personalized immunotherapy.
Bubbling over: After endocytosis and intracellular trafficking to lysosomes, liposomes containing ammonium bicarbonate can be thermally triggered to generate CO2 bubbles (see scheme). These bubbles ...grow rapidly and collapse violently to induce transient cavitation, a process that can disrupt the lysosomal membrane and release lysosomal proteases, thus leading to cell necrosis.
