Enhanced antitumor efficacy of gemcitabine-loaded temperature-sensitive liposome by hyperthermia in tumor-bearing mice

Co-delivery of gemcitabine and salinomycin in PEGylated liposomes for enhanced anticancer efficacy against colorectal cancer

Colorectal cancer remains one of the major causes of morbidity and mortality in both developed and emerging countries. Cancer stem cells (CSCs) are a subpopulation of cells within the tumor mass harboring stem cell characteristics, considered responsible for tumor initiation, growth, relapse, and treatment failure. Lately, it has become clear that both CSCs and non-CSCs have to be eliminated for the successful eradication of cancer. Drug delivery systems have been extensively employed to enhance drug efficacy. In this study, salinomycin (SAL), a selective anti-CSC drug, and gemcitabine (GEM), a conventional anticancer drug, were co-loaded in liposomes and tested for optimal therapeutic efficacy. We employed the Design of Experiments approach to develop and optimize a liposomal delivery system for GEM and SAL. The antiproliferative effect of the liposomes was evaluated in SW-620 human colorectal cancer cells. The GEM and SAL-loaded liposomes exhibited adequate size, polydispersity, zeta potential, and drug content. The in vitro release study showed a sustained release of GEM and SAL from the liposomes over 72 h. Moreover, no sign of liposome aggregation was seen over 1 month and in a biological medium (FBS). The in vitro cytotoxic effects of the co-loaded liposomes were superior to that of single GEM either in free or liposomal form. The combination therapy using GEM and SAL co-loaded in liposomes could be a promising strategy for tackling colorectal cancer.

Hyperthermia Treatment as a Promising Anti-Cancer Strategy: Therapeutic Targets, Perspective Mechanisms and Synergistic Combinations in Experimental Approaches

Despite recent developments in diagnosis and treatment options, cancer remains one of the most critical threats to health. Several anti-cancer therapies have been identified, but further research is needed to provide more treatment options that are safe and effective for cancer. Hyperthermia (HT) is a promising treatment strategy for cancer because of its safety and cost-effectiveness. This review summarizes studies on the anti-cancer effects of HT and the detailed mechanisms. In addition, combination therapies with anti-cancer drugs or natural products that can effectively overcome the limitations of HT are reviewed because HT may trigger protective events, such as an increase of heat shock proteins (HSPs). In the 115 reports included, the mechanisms related to apoptosis, cell cycle, reactive oxygen species, mitochondrial membrane potential, DNA damage, transcription factors and HSPs were considered important. This review shows that HT is an effective inducer of apoptosis. Moreover, the limitations of HT may be overcome using combined therapy with anti-cancer drugs or natural products. Therefore, appropriate combinations of such agents with HT will exert maximal effects to treat cancer.

In Vivo Assessment of Thermosensitive Liposomes for the Treatment of Port Wine Stains by Antifibrinolytic Site-Specific Pharmaco-Laser Therapy

Antifibrinolytic site-specific pharmaco-laser therapy (SSPLT) is an experimental treatment modality for refractory port wine stains (PWS). Conceptually, antifibrinolytic drugs encapsulated in thermosensitive liposomes are delivered to thrombi that form in semi-photocoagulated PWS blood vessels after conventional laser treatment. Local release of antifibrinolytics is induced by mild hyperthermia, resulting in hyperthrombosis and complete occlusion of the target blood vessel (clinical endpoint). In this study, 20 thermosensitive liposomal formulations containing tranexamic acid (TA) were assayed for physicochemical properties, TA:lipid ratio, encapsulation efficiency, and endovesicular TA concentration. Two candidate formulations (DPPC:DSPE-PEG, DPPC:MPPC:DSPE-PEG) were selected based on optimal properties and analyzed for heat-induced TA release at body temperature (T), phase transition temperature (T_m), and at T > T_m. The effect of plasma on liposomal stability at 37 °C was determined, and the association of liposomes with platelets was examined by flow cytometry. The accumulation of PEGylated phosphocholine liposomes in laser-induced thrombi was investigated in a hamster dorsal skinfold model and intravital fluorescence microscopy. Both formulations did not release TA at 37 °C. Near-complete TA release was achieved at T_m within 2.0–2.5 min of heating, which was accelerated at T > T_m. Plasma exerted a stabilizing effect on both formulations. Liposomes showed mild association with platelets. Despite positive in vitro results, fluorescently labeled liposomes did not sufficiently accumulate in laser-induced thrombi in hamsters to warrant their use in antifibrinolytic SSPLT, which can be solved by coupling thrombus-targeting ligands to the liposomes.

Enhanced cytotoxic T lymphocytes recruitment targeting tumor vasculatures by endoglin aptamer and IP-10 plasmid presenting liposome-based nanocarriers

Background: Adequate recruitment of highly active tumor antigen-specific cytotoxic T lymphocytes (CTLs) remains a major challenge in cancer immunotherapy.

Objective: To construct liposome (LP)-based nanocapsules with surface endoglin aptamer (ENG-Apt) encapsulating mouse interferon-inducible protein-10 (mIP-10), with the ability to target mouse tumor vascular endothelial cells (mTECs) and enhance CTLs targeting and recruitment to the tumor vasculature.

Methods: ENG-Apt/mIP-10-LP nanocapsules were prepared by grafting DSPE-PEG₂₀₀₀-ENG-Apt on the surface of liposomes containing mIP-10 plasmids, characterized and assessed for the cell binding specificity in vitro. The tumor-targeting ability of ENG-Apt/mIP-10-LP nanocapsules was evaluated in vivo. The anti-tumor efficacy of ENG-Apt/mIP-10-LP nanocapsules treatment, as well as the combination treatment of ENG-Apt/mIP-10-LP nanocapsules and adoptive TRP2CD8⁺ T cells, were both tested in melanoma-bearing mice, by evaluation of the tumor volume and the mouse survival time. To discuss the anti-tumoral mechanism of ENG-Apt/mIP-10-LP nanocapsules-based therapies, IFN-γ secretion, proportion of TRP2CD8⁺ T cells among TILs, MDSCs in the tumor microenvironment and Tregs in the spleen, were determined after the treatments. Proliferation and apoptosis of tumor cells, and tumor angiogenesis were also assessed.

Results: The prepared ENG-Apt/mIP-10-LP nanocapsules possess an adequate nanometric size, good stability, high specificity to mTECs and tumor sites, along with the ability to induce mIP-10 expression in vitro and in vivo. Treatment of ENG-Apt/mIP-10-LP nanocapsules demonstrated CTLs enrichment into the tumor site, which inhibited tumor cell proliferation and angiogenesis, as well as promoted tumor-cell apoptosis, leading to a decrease in tumor progression and prolonged survival time in melanoma tumor-bearing mice. In addition, the proportion of MDSCs and Tregs was found to decrease. The combination of ENG-Apt/mIP-10-LP nanocapsules with adoptive TRP2CD8⁺ T cells, showed stronger abilities in inhibiting tumor growth and increasing animal survival time, thereby displayed an enhanced anti-melanoma tumor efficacy, due to the recruitment of both endogenous CD8⁺ T cells and exogenous TRP2CD8⁺ T cells in vivo.

Conclusion: ENG-Apt/mIP-10-LP nanocapsules could enhance the recruitment of both endogenous and exogenous CTLs specifically targeting melanoma tumor vasculatures and exert anti-tumoral effect, therefore provides a potentially novel strategy for tumor immunotherapy.

Novel Hyaluronic Acid Conjugates for Dual Nuclear Imaging and Therapy in CD44-Expressing Tumors in Mice In Vivo

Hyaluronic acid, a natural CD44 receptor ligand, has attracted attention in the past years as a macromolecular delivery of anticancer agents to cancer. At the same time, the clinical applications of Gemcitabine (Gem) have been hindered by its short biological half-life, high dose and development of drug resistance. This work reports the synthesis of a hyaluronic acid (HA) conjugate for nuclear imaging, and in vivo Gem delivery to CD44-expressing solid tumors in mice. HA was individually conjugated, via amide coupling, to Gem (HA-Gem), 4'-(aminomethyl)fluorescein hydrochloride (HA-4'-AMF) or tris(hydroxypyridinone) amine (HA-THP) for cancer therapy, in vitro tracking or single photon emission computed tomography/computed tomography (SPECT/CT) imaging, respectively. Gem conjugation to HA was directly confirmed by nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) and UV-visible spectrometry, or indirectly by a nucleoside transporter inhibition study. Gem conjugation to HA improved its plasma stability, reduced blood hemolysis and resulted in delayed cytotoxicity in vitro. Uptake inhibition studies in colon CT26 and pancreatic PANC-1 cells, by flow cytometry, revealed that uptake of fluorescent HA conjugate is CD44 receptor and macropinocytosis-dependent. Gamma scintigraphy and SPECT/CT imaging confirmed the relatively prolonged blood circulation profile and uptake in CT26 (1.5 % ID/gm) and PANC-1 (1 % ID/gm) subcutaneous tumors at 24 h after intravenous injection in mice. Four injections of HA-Gem at ~15 mg/kg, over a 28-day period, resulted in significant delay in CT26 tumor growth and prolonged mice survival compared to the free drug. This study reports for the first time dual nuclear imaging and drug delivery (Gem) of HA conjugates to solid tumors in mice. The conjugates show great potential in targeting, imaging and killing of CD44-over expressing cells in vivo. This work is likely to open new avenues for the application of HA-based macromolecules in the field of image-guided delivery in oncology.

Curcumin-polymeric nanoparticles against colon-26 tumor-bearing mice: cytotoxicity, pharmacokinetic and anticancer efficacy studies

CONTEXT

Curcumin (CUR), can inhibit proliferation and induce apoptosis of tumor cells, its extreme insolubility and limited bioavailability restricted its clinical application.

OBJECTIVE

An innovative polymeric nanoparticle of CUR has been developed to enhance the bioavailability and anti-cancer efficacy of CUR, in vitro and in vivo.

MATERIALS AND METHODS

Cationic copolymer Eudragit E 100 was selected as carrier, which can enhance properties of poor bioavailable chemotherapeutic drugs (CUR). The CUR-loaded Eudragit E 100 nanoparticles (CENPs) were prepared by emulsification-diffusion-evaporation method. The in vitro cytotoxicity study of CENPs was carried out using sulphorhodamine B assay. Pharmacokinetic and anti-cancer efficacy of CENPs was investigated in Wister rats as well as colon-26 tumor-bearing mice after oral administration.

RESULTS

CENPs showed acceptable particle size and percent entrapment efficiency. In vitro cytotoxicity studies in terms of 50% cell growth inhibition values demonstrated ∼19-fold reduction when treated with CENPs as compared to pure CUR. ∼91-fold increase in Cmax and ∼95-fold increase in AUC0-12h were observed indicating a significant enhancement in the oral bioavailability of CUR when orally administered as CENPs compared to pure CUR. The in vivo anti-cancer study performed with CENPs showed a significant increase in efficacy compared with pure CUR, as observed by tumor volume, body weight and survival rate.

CONCLUSIONS

The results clearly indicate that the developed polymeric nanoparticles offer a great potential to improve bioavailability and anticancer efficacy of hydrophobic chemotherapeutic drug.

Tumor vascular permeabilization using localized mild hyperthermia to improve macromolecule transport

The abnormal tumor vasculature presents a major challenge to the adequate delivery of chemotherapeutics, often limiting efficacy. We developed a nanoparticle-based technique to deliver localized mild hyperthermia (MHT) used to transiently alter tumor vascular transport properties and enhance transport of macromolecules into tumor interstitium. The strategy involved administering and localizing accumulation of stealth gold nanorods (GNRs, 103 μg of GNRs/g of tumor), and irradiating tumor with a low-photon laser flux (1 W/cm(2)) to generate MHT. The treatment increased vascular permeability within 24 h after treatment, allowing enhanced transport of macromolecules up to 54 nm in size. A mathematical model is used to describe changes in tumor mass transport properties where the rate of macromolecular exchange between interstitial and vascular region (R) and maximum dye enhancement (Ymax) of 23-nm dextran dye is analytically solved. During enhanced permeability, R increased by 200% while Ymax increased by 30% relative to untreated group in pancreatic CAPAN-1 tumors. MHT treatment also enhanced transport of larger dextran dye (54 nm) as assessed by intravital microscopy, without causing occlusive cellular damage. Enhanced vascular transport was prolonged for up to 24 h after treatment, but reversible with transport parameters returning to basal levels after 36 h. This study indicates that localized mild hyperthermia treatment opens a transient time-window with which to enable and augment macromolecule transport and potentially improve therapeutic efficacy. From the clinical editor: In this study, local intra-tumor mild hyperthermia is induced using a nanoparticle-based approach utilizing stealth gold nanorods and irradiating the tumor with low-photon laser flux, resulting in locally increased vascular permeability enabling enhanced delivery of therapeutics, including macromolecules up to 54 nm in size. Similar approaches would be very helpful in addressing treatment-resistant malignancies in clinical practice.