Inhalable Porous Microspheres Loaded with Metformin and Docosahexaenoic Acid Suppress Tumor Metastasis by Modulating Premetastatic Niche

Nanomaterial-Based Strategies for Preventing Tumor Metastasis by Interrupting the Metastatic Biological Processes

Tumor metastasis is the primary cause of cancer-related deaths. The prevention of tumor metastasis has garnered notable interest and interrupting metastatic biological processes is considered a potential strategy for preventing tumor metastasis. The tumor microenvironment (TME), circulating tumor cells (CTCs), and premetastatic niche (PMN) play crucial roles in metastatic biological processes. These processes can be interrupted using nanomaterials due to their excellent physicochemical properties. However, most studies have focused on only one aspect of tumor metastasis. Here, the hypothesis that nanomaterials can be used to target metastatic biological processes and explore strategies to prevent tumor metastasis is highlighted. First, the metastatic biological processes and strategies involving nanomaterials acting on the TME, CTCs, and PMN to prevent tumor metastasis are briefly summarized. Further, the current challenges and prospects of nanomaterials in preventing tumor metastasis by interrupting metastatic biological processes are discussed. Nanomaterial-and multifunctional nanomaterial-based strategies for preventing tumor metastasis are advantageous for the long-term fight against tumor metastasis and their continued exploration will facilitate rapid progress in the prevention, diagnosis, and treatment of tumor metastasis. Novel perspectives are outlined for developing more effective strategies to prevent tumor metastasis, thereby improving the outcomes of patients with cancer.

Development of a new inhaled swellable microsphere system for the dual delivery of naringenin-loaded solid lipid nanoparticles and doxofylline for the treatment of asthma

This study developed a new dual delivery system of naringenin (NRG), a polyphenol, and doxofylline (DOX), a xanthine derivative, as an inhaled microsphere system. In this system, NRG has been first loaded into glyceryl tristearate-based solid lipid nanoparticles (NRG SLN), which were further loaded with DOX into swellable chitosan-tripolyphosphate-based microspheres (NRG SLN DOX sMS). The system was characterized based on particle size, PDI, zeta potential, surface morphology (SEM, AFM, and TEM), solid-state and chemical properties (XRD, IR, and NMR), aerodynamic parameters, drug loading, entrapment efficiency and in vitro drug release study. The optimized NRG SLN DOX sMS exhibited particle size, zeta potential, and PDI of 2.1 µm, 31.2 mV, and 0.310, respectively; a drug entrapment efficiency > 79 %; a drug loading efficiency > 13 %; cumulative drug releases of about 78 % for DOX and 72 % for NRG after 6 and 12 h, respectively; good swelling and desirable aerodynamic properties. In addition, in vivo studies conducted in mice, a murine model of asthma showed significant reductions in serum bicarbonate and eosinophil counts and improvement in respiratory flow rate, tidal volume, and bronchial wall lining compared with the asthmatic control group. Overall, this novel inhalable dual-delivery system may represent a good alternative for the effective treatment of asthma.

Relaxin-Loaded Inhaled Porous Microspheres Inhibit Idiopathic Pulmonary Fibrosis and Improve Pulmonary Function Post-Bleomycin Challenges

Idiopathic pulmonary fibrosis (IPF) causes worsening pulmonary function, and no effective treatment for the disease etiology is available now. Recombinant Human Relaxin-2 (RLX), a peptide agent with anti-remodeling and anti-fibrotic effects, is a promising biotherapeutic candidate for musculoskeletal fibrosis. However, due to its short circulating half-life, optimal efficacy requires continuous infusion or repeated injections. Here, we developed the porous microspheres loading RLX (RLX@PMs) and evaluated their therapeutic potential on IPF by aerosol inhalation. RLX@PMs have a large geometric diameter as RLX reservoirs for a long-term drug release, but smaller aerodynamic diameter due to their porous structures, which were beneficial for higher deposition in the deeper lungs. The results showed a prolonged release over 24 days, and the released drug maintained its peptide structure and activity. RLX@PMs protected mice from excessive collagen deposition, architectural distortion, and decreased compliance after a single inhalation administration in the bleomycin-induced pulmonary fibrosis model. Moreover, RLX@PMs showed better safety than frequent gavage administration of pirfenidone. We also found RLX-ameliorated human myofibroblast-induced collagen gel contraction and suppressed macrophage polarization to the M2 type, which may be the reason for reversing fibrosis. Hence, RLX@PMs represent a novel strategy for the treatment of IPF and suggest clinical translational potential.

An injectable and pH-responsive hyaluronic acid hydrogel as metformin carrier for prevention of breast cancer recurrence

To achieve the pH-responsive release of metformin in tumor acidic microenvironment, we prepared OHA-Met by covalently grafting metformin (Met) onto oxidized hyaluronic acid (OHA) through imine bonds, and then prepared carboxymethyl chitosan (CMCS)/OHA-Met drug loaded hydrogels. The CMCS/OHA-Met hydrogels showed the in-situ injection performance. At pH = 7.4, the cumulative release rate of metformin from CMCS/OHA-Met20 hydrogel was 42.7 ± 2.6 % in 6 h, and the release tended to balance after 72 h. At pH = 5.5, the release kept constant and the cumulative release rate was 79.3 ± 4.7 % at 6 h, showing good pH-responsive behavior. Metformin induced apoptosis of MCF-7 cells through the caspase 3/PARP pathway. CMCS/OHA-Met20 hydrogel could effectively kill MCF-7 cells, while reducing the cytotoxicity of free metformin to L929 cells. In vivo breast cancer recurrence experiments showed CMCS/OHA-Met20 hydrogel could achieve local injection and pH-responsive smart drug delivery at the tumor resection site, inhibiting breast cancer recurrence. Compared with direct administration, CMCS/OHA-Met20 hydrogel reduced the metformin dosage, frequency of administration and systemic side effects.

AMPK activation by metformin protects against pulmonary hypertension in rats and relaxes isolated human pulmonary artery

Pulmonary hypertension (PH) is associated with pulmonary vasoconstriction and endothelial dysfunction leading to impaired nitric oxide (NO) and prostacyclin (PGI₂) pathways. Metformin, the first line treatment for type 2 diabetes and AMP-activated protein kinase (AMPK) activator, has been recently highlighted as a potential PH treatment. AMPK activation has been reported to improve endothelial function by enhancing endothelial NO synthase (eNOS) activity and to have relaxant effects in blood vessels. In this study, we examined the effect of metformin treatment on PH as well as on NO and PGI₂ pathways in monocrotaline (MCT)-injected rats with established PH. Moreover, we investigated the anti-contractile effects of AMPK activators on endothelium-denuded human pulmonary arteries (HPA) from Non-PH and Group 3 PH patients (due to lung diseases and/or hypoxia). Furthermore, we explored the interaction between treprostinil and the AMPK/eNOS pathway. Our results showed that metformin protected against PH progression in MCT rats where it reduced the mean pulmonary artery pressure, pulmonary vascular remodeling and right ventricular hypertrophy and fibrosis compared to vehicle-treated MCT rats. The protective effects on rat lungs were mediated in part by increasing eNOS activity and protein kinase G-1 expression but not through the PGI₂ pathway. In addition, incubation with AMPK activators reduced the phenylephrine-induced contraction of endothelium-denuded HPA from Non-PH and PH patients. Finally, treprostinil also augmented eNOS activity in HPA smooth muscle cells. In conclusion, we found that AMPK activation can enhance the NO pathway, attenuate vasoconstriction by direct effects on smooth muscles, and reverse established MCT-induced PH in rats.

Formulation, Statistical Optimization, and In Vivo Pharmacodynamics of Cydonia oblonga Mucilage/Alginate Mucoadhesive Microspheres for the Delivery of Metformin HCl

In recent years, attention has shifted toward the utilization of natural polymers for encapsulation and sustained release of health-hazardous drugs. The purpose of this work is to define and assess the sustained delivery potential and mucoadhesive potential of a Cydonia oblonga mucilage (COM) and sodium alginate (Na-Alg)-constituting polymeric delivery carrier of antidiabetic drugs with a specific end goal to retain metformin HCl in the stomach while expanding the drug's bioavailability. Metformin HCl was encapsulated in mucoadhesive microspheres by an ionic gelation method. Polymers with different combinations were tried, and the resulting mucoadhesive COM/Na-Alg microspheres were assessed for particle size (mm) PS/Y₁, drug encapsulation efficiency DEE (%)/Y₂, and in vitro percentage cumulative drug release R_12h/Y₃ using Drug Design Expert software version 10. The response surface methodology by a 3²-central composite design predicted optimal synthesis parameters for the microspheres to be 295 mg for COM and 219 mg for Na-Alg. An optimized formulation was prepared under these conditions and used to evaluate the micrometric properties, morphology and structural characteristics, swelling behavior, in vitro drug release, and kinetics. Acute toxicity studies were carried out on blank COM/Na-Alg microspheres to deem them safe for in vivo studies. The DEE (%) was calculated to be 85.8 ± 1.67, whereas scanning electron microscopy (SEM) showed a coarse surface with characteristic wrinkles and cracks with an optical microscopic particle size of 0.96 ± 2.45. The ex vivo tests showed great mucoadhesive properties and good swelling behavior with pH-responsive drug release and a significant reduction in in vivo blood glucose levels. The results advocated the use of optimized microspheres to enhance the bioactivity with a possible dose reduction, making it less symptomatic, reducing the expense of the treatment, and subsequently facilitating better patient compliance.

Inhalable microparticles as drug delivery systems to the lungs in a dry powder formulations

Inhalation-administrated drugs remain an interesting possibility of addressing pulmonary diseases. Direct drug delivery to the lungs allows one to obtain high concentration in the site of action with limited systemic distribution, leading to a more effective therapy with reduced required doses and side effects. On the other hand, there are several difficulties in obtaining a formulation that would meet all the criteria related to physicochemical, aerodynamic and biological properties, which is the reason why only very few of the investigated systems can reach the clinical trial phase and proceed to everyday use as a result. Therefore, we focused on powders consisting of polysaccharides, lipids, proteins or natural and synthetic polymers in the form of microparticles that are delivered by inhalation to the lungs as drug carriers. We summarized the most common trends in research today to provide the best dry powders in the right fraction for inhalation that would be able to release the drug before being removed by natural mechanisms. This review article addresses the most common manufacturing methods with novel modifications, pros and cons of different materials, drug loading capacities with release profiles, and biological properties such as cytocompatibility, bactericidal or anticancer properties.

Combination of DNA demethylation and chemotherapy to trigger cell pyroptosis for inhalation treatment of lung cancer

Pyroptosis is an inflammation-dependent and self-cascade amplifying type of programmed cell death, serving as an effective means for activating the local immune response and improving the anticancer efficacy. As the effector of pyroptosis, gasdermin-E (GSDME) is silenced in most tumor cells. The gene silencing can be reversed by DNA demethylation, but the systemic side effects and toxicity of chemotherapeutic agents are inevitable. In this work, inhaled poly(lactic-co-glycolic acid) (PLGA) porous microspheres loaded with Decitabine (DAC) and Doxorubicin (DOX) (denoted as CO-MPs) were prepared to induce cell pyroptosis for orthotopic lung cancer therapy with fewer systemic side effects. The CO-MPs showed a hollow and porous spherical morphology and exhibited an excellent aerodynamic property, lung distribution and a sustained release effect. The CO-MPs could reverse GSDME silencing and elevate the expression of cleaved-caspase 3 in tumor cells. The cleaved-caspase 3 protein cleaved the GSDEM protein to obtain GSDME-N protein, causing the rupture of cell plasma membranes, release of cell contents and activation of the immune system. The CO-MPs could lead to the suppression of lung tumors, the decrease of the lung metastatic nodules in tumor-bearing mice and the induction of immunological memory that provides continuous protection from the tumor rechallenge. The inhalable microspheres loaded with DAC and DOX could be an effective strategy for lung cancer treatment via the pyroptosis mechanism.