甘草次酸修饰姜黄素阳离子脂质体对肿瘤Walker256细胞的影响

目的：研究姜黄素及甘草次酸修饰姜黄素阳离子脂质体对Walker256细胞的影响。方法：不同浓度姜黄素与甘草次酸修饰姜黄素阳离子脂质体处理Walker256细胞后,采用CCK-8法检测细胞增殖抑制率;用流式细胞仪检测细胞吸收、细胞周期变化情况;Annexin V/PI双染法检测细胞凋亡;Western blot检测Wnt及β-catenin表达水平。结果：姜黄素和甘草次酸修饰姜黄素阳离子脂质体对肿瘤细胞Walker256均具有明显的抑制作用。与游离姜黄素相比,甘草次酸修饰姜黄素阳离子脂质体明显增强细胞对姜黄素的吸收,显著增强对Walker256细胞的增殖抑制、凋亡、细胞周期G2期的阻滞作用,明显下调Wnt及β-catenin的表达。结论：甘草次酸修饰姜黄素阳离子脂质体比游离姜黄素具有更强的抗肿瘤Walker256细胞的作用。     

Time Interval of Two Injections and First-Dose Dependent of Accelerated Blood Clearance Phenomenon Induced by PEGylated Liposomal Gambogenic Acid: The Contribution of PEG-Specific IgM

Repeated injection of PEGylated liposomes can cause the disappearance of long circulating property because of the induction of anti-PEG IgM antibody referred to as “accelerated blood clearance (ABC) phenomenon.” Although ABC phenomenon typically occurs when entrapped drugs are chemotherapeutic agent with low cytotoxic, there is little evidence of accelerated blood clearance of PEGylated herbal-derived compound on repeated injection. Herein, we investigated the blood concentration of PEGylated liposomal gambogenic acid (PEG-GEA-L), a model PEGylated liposomal herbal extract, on its repeated injection to rats. We found time interval between injections had considerable impact on the magnitude of ABC phenomenon induced by PEG-GEA-L. When time interval was prolonged from 3 days to 7 days, ABC phenomenon could be attenuated. Furthermore, its magnitude was enhanced accompanied by a marked rise in the accumulation of PEG-GEA-L in the liver and spleen in a first-dose–dependent manner. Consistently, the level of anti-PEG IgM significantly increased with the first dose of PEG-GEA-L and decreased with the extended time interval between injections, which implies anti-PEG IgM is a major contributor to the ABC phenomenon. Notably, the increased expression of liver anti-PEG IgM was accompanied by an increased expression of efflux transporters in the induction process of the ABC phenomenon.     

Codelivery of Adriamycin and P-gp Inhibitor Quercetin Using PEGylated Liposomes to Overcome Cancer Drug Resistance

Transmembrane protein P-gp's overexpression at the drug-resistant cell membrane is the most important characteristic of multidrug resistance (MDR). Quercetin (QUE) can effectively suppress the function of P-gp to reverse MDR. This study uses QUE as the P-gp inhibitor andfilm-ultrasound technique with ammonium sulfate transmembrane gradient method to prepare long-circulating liposomes simultaneously encapsulating QUE and Adriamycin (doxorubicin) (AMD/DOX). The optimal conditions for the preparation of AMD_QUE_long-circulating liposomes (SLs) are as follows: hydrogenated soybean phospholipids (HSPC):cholesterol:DSPE-PEG 2000 = 73.07:24.36:2.57 mol/mol, QUE:HSPC = 1:20 mol/mol, AMD:HSPC = 1:7.9 w/w (NH₄₎₂SO₄ 0.15 mol/L, drug loaded (AMD) at 55°C for 25 min). The average encapsulation efficiency of AMD and QUE was 97.49% and 95.50%, respectively. The average particle size is 85 nm (n = 3), and the average zeta potential is ?14.9 mV. First, the pharmacokinetic study proved that codelivery liposomes enveloping QUE and AMD (AMD_QUE_SL) can obviously increase the blood concentration of AMD (C_max: 140.50 ± 32.37 μg/mL) and extend the half-life period of AMD in plasma (t_1/2:14.02 ± 1.54 h). Second, AMD_QUE_SL can obviously enhance the cell toxicity to AMD-resistant cell strains (HL-6/ADR and MCF-7/ADR), and the reverse effects on the resistance of HL-6/ADR and MCF-7/ADR is increased to 4.81-fold and 3.21-fold, respectively. Third, according to the in vivo pharmacodynamic study, the relative tumor volume and relative tumor growth of the AMD_QUE_SL group were the lowest. The inhibition rate of tumor growth of this group was the highest. It can be concluded that AMD_QUE_SL can effectively reverse MDR, lower cardiac toxicity of AMD in clinical treatment, and improve the clinical treatment effect of AMD.     

The Hypotonic Environmental Changes Affect Liposomal Formulations for Nose-to-Brain Targeted Drug Delivery

Systemic administration of drugs is ineffective in the treatment of central nervous system disorders because of the blood-brain barrier. Nasal administration has been suggested as an alternative administration route as drugs absorbed in the olfactory epithelium bypass the blood-brain barrier and reach the brain within minutes. However, the nasal mucosa properties (e.g., tonicity, pH) are not constant because of physiological and environmental factors, and this might limit the therapeutic outcome of nanocarrier-based formulations. To shine light on the impact of environmental ionic strength on nanocarrier-based formulations, we have studied how liposomal formulations respond to the change of tonicity of the external environment. Large unilamellar vesicles loaded with 6 different drugs were exposed to different hypotonic environments, creating an osmotic gradient within the inner core and external environment of the liposomes up to 650 mOsm/kg. Both size and polydispersity of liposomes were significantly affected by tonicity changes. Moreover, the release kinetics of hydrophilic and lipophilic drugs were largely enhanced by hypotonic environments. These results clearly demonstrate that the environmental ionic strength has an impact on liposomal formulation stability and drug release kinetics and it should be considered when liposomal formulations for nose-to-brain targeted drug delivery are designed.     

Tumor-targeting dual peptides-modified cationic liposomes for delivery of siRNA and docetaxel to gliomas

Combinations of drugs promoting anti-angiogenesis and apoptosis effects are meaningful for cancer therapy. In the present study, dual peptides-modified liposomes were designed by attaching two receptor-specific peptides, specifically low-density lipoprotein receptor-related protein receptor (Angiopep-2) and neuropilin-1 receptor (tLyP-1) for brain tumor targeting and tumor penetration. Vascular endothelial growth factor (VEGF) siRNA and chemotherapeutic docetaxel (DTX) were chosen as the two payloads because VEGF is closely associated with angiogenesis, and DTX can kill tumor cells efficiently. Binding to glioma cells, co-delivery of siRNA and DTX in human glioblastoma cells (U87 MG) and murine brain microvascular endothelial cells (BMVEC), VEGF gene silencing, antiproliferation and anti-tumor effects of the dual peptides-modified liposomes were evaluated in vitro and in vivo. The dual peptides-modified liposomes persisted the binding ability to glioma cells, enhanced the internalization via specific receptor mediated endocytosis and tissue penetration, thus the dual peptides-modified liposomes loading VEGF siRNA and DTX possessed stimulative gene silencing and antiproliferation activity compared with non-modified and single peptide-modified liposomes. The co-delivery research revealed different intracellular behavior of hydrophilic large molecular and lipophilic small molecule, the former involves endocytosis and subsequent escape of endosome/lysosomes, while the latter experiences passive diffusion of lipophilic small drugs after its release. Furthermore, the dual peptides-modified liposomes showed superiority in anti-tumor efficacy, combination of anti-angiogenesis by VEGF siRNA and apoptosis effects by DTX, after both intratumor and system application against mice with U87 MG tumors, and the treatment did not activate system-associated toxicity or the innate immune response. Combination with the dual peptides-guided tumor homing and penetration, the dual peptides-modified liposomes provide a strategy for effective targeting delivery of siRNA and DTX into the glioma cell and inhibition of tumor growth in a synergistic manner.     

Targeted drug delivery strategies to treat lung metastasis

Background: Most cancer patients die of metastatic disease, and in a high proportion of cases, from lung metastasis. Methods to target therapy to metastatic disease in general and specifically to lung metastasis are required. Objective: To describe the current and potential tools for the treatment of lung metastasis. Methods: Literature search tools were used with no predefined limitations to encompass the main tumor targeting methods. Methods in standard clinical use, in clinical trials and in preclinical development are reviewed. Data about treatment of lung metastasis and solid tumors are emphasized. Results: Physically targeting therapies to lung metastasis is feasible by aerosol-carried agents, magnetic targeting and intravascular devices. Biological targeting includes methods such as polymers and liposomes, which are based on the principle of enhanced permeability and retention of large molecules in tumor vascular field. Ligand-targeted treatments depend on cancer-specific antibodies or receptors. Few of these methods are in clinical trials or in standard clinical use. However, promising techniques are in advanced preclinical or early clinical studies. The authors believe that targeted treatments will be one the major anticancer tools in the near future.     

Coadministration of liposomal methylglyoxal increases the activity of amphotericin B against Candida albicans in leukopoenic mice

Abstract

In this study, we investigated the therapeutic efficacy of a combination of liposomal amphotericin B (Lip-Amp B) and Methylglyoxal (Lip-MG) against Candida albicans in the leukopoenic mice. The antifungal efficacy of Lip-Amp B or Lip-MG or a combination of Lip-Amp B and Lip-MG was evaluated by the analysis of the survival rate and the fungal load in the treated mice. The immune-stimulatory effect of Lip-MG on macrophages was evaluated by analysing the secretion of proinflammatory cytokines. C. albicans infected mice treated at the doses of 1 and 2?mg/kg of Lip-Amp B showed 20% and 50% survival rates, respectively. Whereas the mice treated with free Amp B at the same doses died within 40?days of treatment. Interestingly, C. albicans infected mice treated with a combination of Lip-Amp B and Lip-MG had 70% survival rate on day 40 postinfection. Moreover, treatment of macrophages with Lip-MG increased their fungicidal activity and the secretion of proinflammatory cytokines, including TNF-α and IL-1β. These findings suggested that co-treatment with Lip-Amp B and Lip-MG had a synergistic effect and could be effective against C. albicans in immunocompromised subjects.     

Prolonged duration local anesthesia with minimal toxicity

Injectable local anesthetics that would last for many days could have a marked impact on periprocedural care and pain management. Formulations have often been limited in duration of action, or by systemic toxicity, local tissue toxicity from local anesthetics, and inflammation. To address those issues, we developed liposomal formulations of saxitoxin (STX), a compound with ultrapotent local anesthetic properties but little or no cytotoxicity. In vitro, the release of bupivacaine and STX from liposomes depended on the lipid composition and on whether dexamethasone was incorporated. In cell culture, bupivacaine, but not STX, was myotoxic (to C2C12 cells) and neurotoxic (to PC12 cells) in a concentration- and time-dependent manner. Liposomal formulations containing combinations of the above compounds produced sciatic nerve blockade lasting up to 7.5 days (with STX + dexamethasone liposomes) in male Sprague–Dawley rats. Systemic toxicity only occurred where high loadings of dexamethasone increased the release of liposomal STX. Mild myotoxicity was only seen in formulations containing bupivacaine. There was no nerve injury on Epon-embedded sections, and these liposomes did not up-regulate the expression of 4 genes associated with nerve injury in the dorsal root ganglia. These results suggest that controlled release of STX and similar compounds can provide very prolonged nerve blocks with minimal systemic and local toxicity.     

Human VIP-α: an emerging biologic response modifier to treat primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare life-threatening disorder of unknown etiology manifested by chronic elevation of pulmonary arterial pressure. Given that pulmonary vasoconstriction, endothelial and vascular smooth muscle cell proliferation and in situ thrombosis contribute appreciably to the evolution of PPH, treatment with vasodilators, antiproliferative drugs and anticoagulants, alone or in combination, constitute the pharmacologic standard of care. To this end, long-term administration of oral calcium channel blockers, prostacyclin analogs by various routes and oral endothelin-1 receptor antagonists, alone or in combination, is efficacious in treating patients with PPH. Unfortunately, efficacy is hampered by poor stability, delivery and bioavailability, and by systemic toxicity. Hence, there is an ongoing need to develop and test new drugs to treat patients with PPH. To address this issue, a novel, targeted, long-acting, biocompatible and safe sterically stabilized liposomal and micellar formulation of human vasoactive intestinal peptide (VIP) was developed and tested for human use: the 28-amino acid pleiotropic biologic response modifier, human VIP-α. The long-lasting salutary effects of phospholipid-associated VIP on vasomotor tone and arterial pressure were expressed at low concentrations solely in diseased animals and were independent of its route of administration. Thus, the author proposes that human VIP-α could be developed as a safe long-acting drug to treat patients with PPH.