pH-Sensitive, Long-Circulating Liposomes as an Alternative Tool to Deliver Doxorubicin into Tumors: a Feasibility Animal Study

Theoretical and Experimental Analyses of the Interfacial Mechanism of Dendrimer-Doxorubicin Complexes Formation

The work presents correlations between the physicochemical properties of the carrier and the active substance and optimization of the conditions for creating an active system based on PAMAM dendrimers and doxorubicin. The study monitored the influence of the ionized form of the doxorubicin molecule on the efficiency of complex formation. The deprotonated form of doxorubicin occurs under basic conditions in the pH range of 9.0-10.0. In the presence of doxorubicin, changes in the zeta potential of the complex concerning the initial system are observed. These changes result from electrostatic interactions between the drug molecules and external functional groups. Based on changes in the absorbance intensity of UV-vis spectra, the binding of the drug in the polymer structure is observed depending on the pH of the environment and the molar ratio. Optimal conditions for forming complexes occur under alkaline conditions. UV-vis, Fourier transform infrared spectroscopy, and circular dichroism spectroscopy confirmed the stability of the formed dendrimer-DOX complex. Molecular dynamics simulations were conducted to gain a deeper insight into the molecular mechanism of DOX adsorption on and within the G4.0 PAMAM dendrimers. It was observed that the protonation state of both the dendrimer and DOX significantly influences the adsorption stability. The system exhibited high stability at high pH values (∼9-10), with DOX molecules strongly adsorbed on the dendrimer surface and partially within its bulk. However, under lower pH conditions, a reduction in adsorption strength was observed, leading to the detachment of DOX clusters from the dendrimer structure.

Evaluation of acute toxicity and in vitro antitumor activity of a novel doxorubicin-loaded folate-coated pH-sensitive liposome

Doxorubicin (DOX) loaded liposomes have been used and studied in the last decades due to the significant decrease in DOX induced cardiac and systemic toxicity relative to administration of free drug. Therefore, new strategies are sought to improve DOX delivery and antitumor activity, while avoiding side effects. Recently, folate-coated pH-sensitive liposomes (SpHL-Fol) have been studied as a tool to enhance cellular uptake and antitumor activity of paclitaxel and DOX in breast cancer cells expressing folate receptor (FR+). However, the elucidation of folate functionalization relevance in DOX-loaded SpHL (SpHL-DOX-Fol) in different cell types (MDA-MB-231, MCF-7, and A549), as well as, the complete safety evaluation, is necessary. To achieve these objectives, SpHL-DOX-Fol was prepared and characterized as previously described. Antitumor activity and acute toxicity were evaluated in vivo through direct comparison of free DOX verses SpHL-DOX, a well-known formulation to reduce DOX cardiotoxicity. The obtained data are crucial to support future translational research. Liposomes showed long-term stability, suitable for biological use. Cellular uptake, cytotoxicity, and percentage of migration inhibition were significantly higher for MDA-MB-231 (FR+) treated with SpHL-DOX-Fol. In addition, SpHL-DOX-Fol demonstrated a decrease in the systemic toxic effects of DOX, mainly in renal and cardiac parameters evaluation, even using a higher dose (20 mg/kg). Collectively these data build the foundation of support demonstrating that SpHL-DOX-Fol could be considered a promising drug delivery strategy for the treatment of FR+ breast tumors.

Sorafenib-Loaded PLGA Carriers for Enhanced Drug Delivery and Cellular Uptake in Liver Cancer Cells

Introduction

Currently, conventional treatments of hepatocellular carcinoma (HCC) are not selective enough for tumor tissue and lead to multidrug resistance and drug toxicity. Although sorafenib (SOR) is the standard first-line systemic therapy approved for the clinical treatment of HCC, its poor aqueous solubility and rapid clearance result in low absorption efficiency and severely limit its use for local treatment.

Methods

Herein, we present the synthesis of biodegradable polymeric Poly (D, L-Lactide-co-glycolide) (PLGA) particles loaded with SOR (PS) by emulsion-solvent evaporation process. The particles are carefully characterized focusing on particle size, surface charge, morphology, drug loading content, encapsulation efficiency, in vitro stability, drug release behaviour and tested on HepG2 cells. Additionally, PLGA particles have been coupled on side emitting optical fibers (seOF) integrated in a microfluidic device for light-triggered local release.

Results

PS have a size of 248 nm, tunable surface charge and a uniform and spherical shape without aggregation. PS shows encapsulation efficiency of 89.7% and the highest drug loading (8.9%) between the SOR-loaded PLGA formulations. Treating HepG2 cells with PS containing SOR at 7.5 µM their viability is dampened to 40%, 30% and 17% after 48, 129 and 168 hours of incubation, respectively.

Conclusion

The high PS stability, their sustained release profile and the rapid cellular uptake corroborate the enhanced cytotoxicity effect on HepG2. With the prospect of developing biomedical tools to control the spatial and temporal release of drugs, we successfully demonstrated the potentiality of seOF for light-triggered local release of the carriers. Our prototypical system paves the way to new devices integrating microfluidics, optical fibers, and advanced carriers capable to deliver minimally invasive locoregional cancer treatments.

A new theranostic pH-responsive niosome formulation for Doxorubicin delivery and bio-imaging against breast cancer

As one of the newest generations of nanoplatforms, smart nanotheranostics have attracted signifivant attentions for medical applications, especially in oncology and cancer treatment. Indeed, their capability to provide treatment and diagnosis simultaneously leads to reduce time and side effects along with improving the performance. This study aims to introduce a novel smart nano-platform composed of doxorubicin-loaded pH-responsive stealth niosomes containing CdSe/ZnS Quantum dots as an imaging agent. Drug loaded nano-platform was fabricated via thin-film hydration method and then evaluated using different physicochemical tests. The entrapment efficiency and release profile of doxorubicin were assessed at three different pH (4, 6.5, and 7.4). Biological features and imaging ability of the nanoparticles were also evaluated by MTT assay, apoptosis assay, and fluorescence microscopy. Results showed that the fabricated nanoparticles were round-shaped, with a mean size of about 100±10 nm, -2 mV surface charge, and about 87% entrapment efficiency. The drug release profile presented a pH-responsive behavior (80, 60, and 40% drug release in pH 4, 6.5, and 7.4, respectively). The bio-activity assessments showed nearly 55% cytotoxicity effects via inducing cell apoptosis. Besides, the uptake of samples by the cells was confirmed through fluorescence imaging. Based on the results, this new nanoformulation could be considered as a candidate for future cancer theranostic applications.

Recent Preclinical and Clinical Progress in Liposomal Doxorubicin

Doxorubicin (DOX) is a potent anti-cancer agent that has garnered great interest in research due to its high efficacy despite dose-limiting toxicities. Several strategies have been exploited to enhance the efficacy and safety profile of DOX. Liposomes are the most established approach. Despite the improvement in safety properties of liposomal encapsulated DOX (in Doxil and Myocet), the efficacy is not superior to conventional DOX. Functionalized (targeted) liposomes present a more effective system to deliver DOX to the tumor. Moreover, encapsulation of DOX in pH-sensitive liposomes (PSLs) or thermo-sensitive liposomes (TSLs) combined with local heating has improved DOX accumulation in the tumor. Lyso-thermosensitive liposomal DOX (LTLD), MM-302, and C225-immunoliposomal(IL)-DOX have reached clinical trials. Further functionalized PEGylated liposomal DOX (PLD), TSLs, and PSLs have been developed and evaluated in preclinical models. Most of these formulations improved the anti-tumor activity compared to the currently available liposomal DOX. However, the fast clearance, the optimization of ligand density, stability, and release rate need more investigations. Therefore, we reviewed the latest approaches applied to deliver DOX more efficiently to the tumor, preserving the benefits obtained from FDA-approved liposomes.

Radionuclide Delivery Strategies in Tumor Treatment: A Systematic Review

The aim of this review was to assess recent progress in targeted radionuclide tumor therapy, focusing on the best delivery strategies. A literature search was conducted in PubMed, Web of Science, and Scopus using the terms "radionuclides", "liposomes", "avidin-biotin interaction", "theranostic", and "molecular docking". The 10 year filter was applied, except for the avidin-biotin interaction. Data were retrieved from both preclinical and clinical settings. Three targeting strategies were considered: pretargeting, liposomes, and ligands. Pretargeting can be achieved by exploiting the avidin-biotin interaction. This strategy seems very promising, although it has been investigated mainly in resectable tumors. Radiolabeled liposomes have attracted new interest as probes to identify the most suitable patients for treatment with liposomal formulations of common chemotherapeutics. The use of ligands for the delivery of radiotherapeutics to a specific target is still the most appealing strategy for treating tumors. The most appropriate ligand can be identified by virtually simulating its interaction with the receptor. All strategies showed great potential for use in targeted radionuclide therapy, but they also have numerous drawbacks. The most promising option is probably the one based on the use of new ligands.

Biodistribution Study of Niosomes in Tumor-Implanted BALB/C Mice Using Scintigraphic Imaging

The purpose of this work was to study the biodistribution of niosomes in tumor-implanted BALB/c mice using gamma scintigraphy. Niosomes were first formulated and characterized, then radiolabeled with Technetium-99 m (^99mTc). The biodistribution of 99mTc-labeled niosomes was evaluated in tumor-bearing mice through intravenous injection and imaged with gamma scintigraphy. The labeled complexes possessed high radiolabeling efficiency (98.08%) and were stable in vitro (>80% after 8 h). Scintigraphic imaging showed negligible accumulation in the stomach and thyroid, indicating minimal leaching of the radiolabel in vivo. Radioactivity was found mainly in the liver, spleen and kidneys. Tumor-to-muscle ratio indicated a higher specificity of the formulation for the tumor area. Overall, the formulated niosomes are stable both in vitro and in vivo, and show preferential tumor accumulation.

pH-responsive and folate-coated liposomes encapsulating irinotecan as an alternative to improve efficacy of colorectal cancer treatment

Irinotecan (IRN) is a semisynthetic derivative of camptothecin that acts as a topoisomerase I inhibitor. IRN is used worldwide for the treatment of several types of cancer, including colorectal cancer, however its use can lead to serious adverse effects, as diarrhea and myelosuppression. Liposomes are widely used as drug delivery systems that can improve chemotherapeutic activity and decrease side effects. Liposomes can also be pH-sensitive to release its content preferentially in acidic environments, like tumors, and be surface-functionalized for targeting purposes. Herein, we developed a folate-coated pH-sensitive liposome as a drug delivery system for IRN to reach improved tumor therapy without potential adverse events. Liposomes were prepared containing IRN and characterized for particle size, polydispersity index, zeta potential, concentration, encapsulation, cellular uptake, and release profile. Antitumor activity was investigated in a murine model of colorectal cancer, and its toxicity was evaluated by hematological/biochemical tests and histological analysis of main organs. The results showed vesicles smaller than 200 nm with little dispersion, a surface charge close to neutral, and high encapsulation rate of over 90%. The system demonstrated prolonged and sustained release in pH-dependent manner with high intracellular drug delivery capacity. Importantly, the folate-coated pH-sensitive formulation had significantly better antitumor activity than the pH-dependent system only or the free drug. Tumor tissue of IRN-containing groups presented large areas of necrosis. Furthermore, no evidence of systemic toxicity was found for the groups investigated. Thus, our developed nanodrug IRN delivery system can potentially be an alternative to conventional colorectal cancer treatment.

A Dual pH-Responsive DOX-Encapsulated Liposome Combined with Glucose Administration Enhanced Therapeutic Efficacy of Chemotherapy for Cancer

BACKGROUND

The acidic microenvironment of cancer can promote tumor metastasis and drug resistance. Acidic tumor microenvironment-targeted therapy is currently an important means for treating tumors, inhibiting metastasis, and overcoming drug resistance. In this study, a dual pH-responsive DOX-encapsulated liposome (DOPE-DVar7-lip@DOX) was designed and fabricated for targeting the acidic tumor microenvironment. On the one hand, the response of acid-sensitive peptide (DVar7) to the acidic tumor microenvironment increased the uptake of liposomes in tumors and prolonged the retention time; on the other hand, the response of acid-sensitive phospholipid (DOPE) to the acidic tumor microenvironment improved the controlled release of DOX in tumors.

METHODS

The acid-sensitive peptide DVar7 modified liposomes can be obtained by simple incubation of DSPE-DVar7 with DOX-loaded DOPE liposomes (DOPE-lip@DOX). The tumor targeting of the dual pH-responsive liposome was investigated in vitro and in vivo by near-infrared fluorescence imaging. The tumor therapeutic efficacy of DOPE-DVar7-lip@DOX was evaluated in breast cancer mouse model using the traditional liposome as a control. Moreover, we regulated the tumor microenvironment acidity by injecting glucose to further enhance the therapeutic efficacy of cancer.

RESULTS

DVar7 can allosterically insert into the tumor cell membrane in the acidic tumor microenvironment to enhance the tumor uptake of liposomes and prolong the retention time of liposomes in tumor. In addition, the therapeutic efficacy of pH-responsive liposomes can be further enhanced by glucose injection regulating the acidity of tumor microenvironment.

DISCUSSION

DVar7 modified acid-sensitive nanocarriers combined with acidity regulation have great potential to improve drug resistance in clinical practice, thus improving the response rate and therapeutic effect of chemotherapy.

Triggered Drug Release From Liposomes: Exploiting the Outer and Inner Tumor Environment

Since more than 40 years liposomes have being extensively studied for their potential as carriers of anticancer drugs. The basic principle behind their use for cancer treatment consists on the idea that they can take advantage of the leaky vasculature and poor lymphatic drainage present at the tumor tissue, passively accumulating in this region. Aiming to further improve their efficacy, different strategies have been employed such as PEGlation, which enables longer circulation times, or the attachment of ligands to liposomal surface for active targeting of cancer cells. A great challenge for drug delivery to cancer treatment now, is the possibility to trigger release from nanosystems at the tumor site, providing efficacious levels of drug in the tumor. Different strategies have been proposed to exploit the outer and inner tumor environment for triggering drug release from liposomes and are the focus of this review.

Mechanistic insights into the intracellular release of doxorubicin from pH-sensitive liposomes

pH-sensitive liposomes are interesting carriers for drug-delivery, undertaking rapid bilayer destabilization in response to pH changes, allied to tumor accumulation, a desirable behavior in the treatment of cancer cells. Previously, we have shown that pH-sensitive liposomes accumulate in tumor tissues of mice, in which an acidic environment accelerates drug delivery. Ultimately, these formulations can be internalized by tumor cells and take the endosome-lysosomal route. However, the mechanism of doxorubicin release and intracellular traffic of pH-sensitive liposomes remains unclear. To investigate the molecular mechanisms underlying the intracellular release of doxorubicin from pH-sensitive liposomes, we followed HeLa cells viability, internalization, intracellular trafficking, and doxorubicin's intracellular delivery mechanisms from pH-sensitive (SpHL-DOX) and non-pH-sensitive (nSpHL-DOX) formulations. We found that SpHL-DOX has faster internalization kinetics and intracellular release of doxorubicin, followed by strong nuclear accumulation compared to nSpHL-DOX. The increased nuclear accumulation led to the activation of cleaved caspase-3, which efficiently induced apoptosis. Remarkably, we found that chloroquine and E64d enhanced the cytotoxicity of SpHL-DOX. This knowledge is paramount to improve the efficiency of pH-sensitive liposomes or to be used as a rational strategy for developing new formulations to be applied in vivo.

Alpha-tocopheryl succinate improves encapsulation, pH-sensitivity, antitumor activity and reduces toxicity of doxorubicin-loaded liposomes

Doxorubicin (DOX) plays an important role in cancer treatment; however, high cardiotoxicity and low penetration in solid tumors are the main limitations of its use. Liposomal formulations have been developed to attenuate the DOX toxicity, but the technological enhancement of the liposomal formulation as well as the addition of another agent with antitumor properties, like alpha-tocopheryl succinate (TS), a semi-synthetic analog of vitamin E, could certainly bring benefits. Thus, in this study, it was proposed the development of liposomes composed of DOX and TS (pHSL-TS-DOX). A new DOX encapsulation method, without using the classic ammonium sulfate gradient with high encapsulation percentage was developed. Analysis of Small Angle X-ray Scattering (SAXS) and release study proved the pH-sensitivity of the developed formulation. It was observed stabilization of tumor growth using pHSL-TS-DOX when compared to free DOX. The toxicity tests showed the safety of this formulation since it allowed body weight initial recovery after the treatment and harmless to heart and liver, main target organs of DOX toxicity. The developed formulation also avoided the occurrence of myelosuppression, a typical adverse effect of DOX. Therefore, pHSL-TS-DOX is a promising alternative for the treatment of breast cancer since it has adequate antitumor activity and a safe toxicity profile.

Folate-coated, long-circulating and pH-sensitive liposomes enhance doxorubicin antitumor effect in a breast cancer animal model

Long circulating pH-sensitive liposomes have been shown to effectively deliver doxorubicin (DOX) to tumors and reduce its toxic effects. Folic acid receptors are upregulated in a wide variety of solid, epithelial tumors, including breast cancer. In order to improve liposomal endocytosis and antitumor activity, folic acid has been added to nanoparticles surfaces to exploit overexpression of folate receptors in tumor cells. The purpose of this study was to evaluate the antitumor activity in vitro and in vivo of long circulating pH-sensitive folate-coated DOX-loaded liposomes (SpHL-DOX-Fol) in a 4T1 breast cancer model system in vitro and in vivo. Biodistribution studies were performed and in vivo electrocardiographic parameters were evaluated. A higher tumor uptake for radiolabeled SpHL-Fol (^99mTc-SpHL-Fol) 4 h after intravenous administration was observed in comparision with non-folate-coated liposomes (^99mTc-SpHL). Antitumor activity showed that SpHL-DOX-Fol treatment led to a 68% growth arrest and drastically reduce pulmonary metastasis foci. Additionally, eletrocardiographic parameters analysis revealed no dispersion in the QT and QTc interval was observed in liposomal treated mice. In summary, this novel multifunctional nanoplatform deomonstrated higher tumor uptake and antitumor activity. SpHL-DOX-Fol represents a drug delivery platform to improve DOX tumor delivery and reduce dose-limiting toxicity.

Influence of PEG coating on the biodistribution and tumor accumulation of pH-sensitive liposomes

Liposomes are lipid vesicles widely used as nanocarriers in targeted drug delivery systems for therapeutic and/or diagnostic purposes. A strategy to prolong the blood circulation time of the liposomes includes the addition of a hydrophilic polymer polyethylene glycol (PEG) moiety onto the surface of the vesicle. Several studies claim that liposome PEGylation by a single chain length or a combination of PEG with different chain lengths may alter the liposomes' pharmacokinetic properties. Therefore, the purpose of this study was to evaluate the influence of PEG on the biodistribution of pH-sensitive liposomes in a tumor-bearing animal model. Three liposomal formulations (PEGylated or not) were prepared and validated to have a similar mean diameter, monodisperse distribution, and neutral zeta potential. The pharmacokinetic properties of each liposome were evaluated in healthy animals, while the biodistribution and scintigraphic images were evaluated in tumor-bearing mice. High tumor-to-muscle ratios were not statistically different between the PEGylated and non-PEGylated liposomes. While PEGylation is a well-established strategy for increasing the blood circulation of nanostructures, in our study, the use of polymer coating did not result in a better in vivo profile. Further studies must be carried out to confirm the feasibility of the non-PEGylated pH-sensitive liposomes for tumor treatment.

PEGylated trimethylchitosan emulsomes conjugated to octreotide for targeted delivery of sorafenib to hepatocellular carcinoma cells of HepG2

The current study aimed to develop PEGylated trimethyl chitosan (TMC) coated emulsomes (EMs) conjugated with octreotide for targeted delivery of sorafenib to hepatocellular carcinoma cells (HCC) of HepG2. Sorafenib loaded TMC coated EMs were prepared by the emulsion evaporation method and characterized concerning particle size, zeta potential, drug encapsulation efficiency, and in vitro drug release. Synthesized EMs were then conjugated to octreotide. The cytotoxicity of the targeted and non-targeted EMs was determined by cellular uptake and MTT assay on HepG2 cell. Cell cycle assay was also studied using flow cytometry. The results showed the optimized EMs had the particle size of 127 nm, zeta potential of -5.41 mV, loading efficiency of 95%, and drug release efficiency of 62% within 52 h. Octreotide was attached efficiently to the surface of EMs as much as 71%. MTT assay and cellular uptake studies showed that targeted EMs had more cytotoxicity than free sorafenib and non-targeted EMs. Cell cycle analyses revealed that there was a significant more accumulation of targeted EMs treated HepG2 cells in the G1 phase than free sorafenib and non-targeted EMs. The results indicate that designed EMs may be promising for the treatment of hepatocellular carcinoma.

Preparation, Characterization, and In Vitro pH-sensitivity Evaluation of Superparamagnetic Iron Oxide Nanoparticle- Misonidazole pH-sensitive Liposomes

Background:

The use of Misonidazole (MISO), the first and a potential hypoxic tumor cell radiosensitizer, has been limited by peripheral neurotoxicity, thus discouraging phase III clinical trials.

Objective:

To develop a targeted drug delivery and tracing System with pH-sensitive liposomes (SpHLs) and Superparamagnetic Iron Oxide Nanoparticles (SPIONs) to counter MISO-related adverse effects and to enable tracing under magnetic resonance.

Methods:

SPION-MISO-SpHLs were prepared by a reverse evaporation and freeze-thawing method. HPLC and phenanthroline spectrophotometry were established for MISO and Fe determination. The characterization and in vitro pH-sensitivity of SPION-MISO-SpHLs were evaluated.

Results:

The maximal entrapment efficiencies of MISO and SPIONs in SPION-MISO-SpHLs were 30.2% and 23.7%, respectively. The cumulative release rates of MISO and SPIONs were respectively 2.49 and 2.47 times higher in pH 5.5 than in pH 7.4 buffer. The mean particle size of SPION-MISOSpHLs was 950 nm. The zeta potential was -58.9 mV in pH 7.4 buffer and 36.3 mV in pH 5.5 buffer. SEM imaging showed that SPION-MISO-SpHLs had similar spherical morphologies. SPIONs were packed in the center of liposomes and were well dispersed in a TEM graph. Magnetization curve showed that SPION-MISO-SpHLs retained superparamagnetic properties. SPION-MISO-SpHLs were compared with MISO+SPION+blank liposome in hypoxia and control groups of A549 cells. MISO and SPION concentrations in culture medium showed significant differences between the same concentration groups (P < 0.0001) and at different times (P < 0.0001).

Conclusion:

SPION-MISO-SpHLs possess pH-dependent release ability and superparamagnetism, and thus provides a system for targeted delivery and tracing under magnetic resonance.

Affibody-functionalized Ag2S quantum dots for photoacoustic imaging of epidermal growth factor receptor overexpressed tumors

Photoacoustic imaging (PAI) is a new and attractive imaging modality, and it has strong potential for application in the early detection of tumors through the use of optically absorbing targeted contrast agents. Ag2S quantum dots (QD) are a promising bionanomaterial and have attracted significant attention in the field of bioimaging. In this study, water-soluble and carboxylic acid group-coated Ag2S QDs with an ultrasmall size (∼8 nm) were synthesized via a one-step method. Their surface plasmon resonance wavelength was determined to be ∼800 nm, which is ideal for PAI. Ag2S QDs were then modified with the epidermal growth factor receptor 1 (EGFR) targeted small protein affibody ZEGFR:1907. The resulted nanoprobe, ZEGFR:1907-Ag2S QDs, was then used for targeted PAI of EGFR-overexpressed tumors. The biodistribution of the nanoprobe was further measured by ex vivo near infrared fluorescence (NIRF) imaging of the dissected tissues. The PAI results showed that ZEGFR:1907-Ag2S QDs specifically image EGFR positive tumors. The biodistribution study revealed that the nanoprobe mainly accumulated in the liver, spleen and tumors; tissue H&E staining studies indicated that the probe has good biocompatibility. Overall, the affibody-functionalized Ag2S QDs are a novel targeted nanoprobe that can be used for specific PAI of tumors.

pH sensitive liposomes delivering tariquidar and doxorubicin to overcome multidrug resistance of resistant ovarian cancer cells

Multidrug resistance of tumour cells is one of the most important hurdles in tumour chemotherapy. To overcome the multidrug resistance, we constructed a pH-sensitive liposome formulation (pHSL) by loading tariquidar (TQR) and DOX simultaneously in this work. The formulation showed high stability at pH 7.4 and excellent sensitivity at acidic pH, which facilitated the delivery of TQR and DOX into cells. Cellular experiments demonstrated that the pHSL/TQR/DOX 0.05 could almost restore the drug sensitivity of OVCAR8/ADR cells. Therefore, the pH sensitive liposome formulation pHSL/TQR/DOX 0.05 was very promising in treating resistant tumours.

Sorafenib-loaded polymeric micelles as passive targeting therapeutic agents for hepatocellular carcinoma therapy

AIM

The clinical application of sorafenib is limited because of its hydrophobicity, low bioavailability and unsatisfying treatment effect. Therefore, sorafenib-loaded PEG-poly (ε-caprolactone) micelles (SF micelles) were fabricated for sorafenib delivery.

MATERIALS & METHODS

In vitro assays investigated the solubility, dispersity, stability, cytotoxicity and uptake capacity of SF micelles. In vivo biodistribution and therapeutic effects were studied using HepG2-Luc tumor-bearing mice.

RESULTS

SF micelles had a regular spherical structure with good water solubility. In vivo imaging results showed PEG-poly (ε-caprolactone) micelles could elevate the sorafenib concentration in tumor tissues. Meanwhile, SF micelles exhibited higher tumor growth inhibition in vivo.

CONCLUSION

SF micelles might be a potential drug delivery system, which could enhance the therapeutic effects of sorafenib.

Technetium-99m radiolabeled paclitaxel as an imaging probe for breast cancer in vivo

The high incidence and mortality of breast cancer supports efforts to develop innovative imaging probes to effectively diagnose, evaluate the extent of the tumor, and predict the efficacy of tumor treatments while concurrently and selectively delivering anticancer agents to the cancer tissue. In the present study we described the preparation of technetium-99m (99mTc)-labeled paclitaxel (PTX) and evaluated its feasibility as a radiotracer for breast tumors (4T1) in BALB/c mice. Thin Layer Chromatography (TLC) was used to determine the radiochemical purity and in vitro stability of 99mTc-PTX. PTX micelles showed a unimodal distribution with mean diameter of 13.46±0.06nm. High radiochemical purity (95.8±0.3%) and in vitro stability (over than 95%), up to 24h, were observed. Blood circulation time of 99mTc-PTX was determined in healthy BALB/c mice. 99mTc-PTX decays in a one-phase manner with a half-life of 464.3 minutes. Scintigraphic images and biodistribution were evaluated at 4, 8 and 24h after administration of 99mTc-PTX in 4T1 tumor-bearing mice. The data showed a significant uptake in the liver, spleen and kidneys, due to the importance of these routes for excretion. Moreover, high tumor uptake was achieved, indicated by high tumor-to-muscle ratios. These findings indicate the usefulness of 99mTc-PTX as a radiotracer to identify 4T1 tumor in animal models. In addition, 99mTc-PTX might be used to follow-up treatment protocols in research, being able to provide information about tumor progression after therapy.

Doxorubicin-loaded nanocarriers: A comparative study of liposome and nanostructured lipid carrier as alternatives for cancer therapy

Nowadays cancer is one of the most common causes of deaths worldwide. Conventional antitumor agents still present various problems related to specificity for tumor cells often leading to therapeutic failure. Nanoscale particles are considered potential alternative to direct access of drugs into tumor cells, therefore increasing the drug accumulation and performance. The aim of this study was to evaluate the antitumor activity of doxorubicin (DOX)-loaded nanostructured lipid carriers (NLC) versus liposomes against a breast cancer animal experimental model. NLC-DOX and liposomes-DOX were successfully prepared and characterized. Tumor-bearing mice were divided into five groups (blank-NLC, blank-liposome, DOX, NLC-DOX, liposome-DOX). Each animal received by the tail vein four doses of antitumoral drugs (total dose, 16mg/kg), every 3 days. Antitumor efficacy was assessed by measuring 1) tumor volume, calculating the inhibitory ratio (TV-IR, see after) and 2) acquiring scintigraphic images of the tumor using doxorubicin radiolabeled with technetium-99m as an imaging tumor probe. Liposome-DOX and free DOX did not showed differences in the tumor mean volume, whereas NLC-DOX proved to be the best treatments in controlling the tumor growth. NLC-DOX showed an inhibition ration (TV-IR) of 73.5% while free DOX and liposome-DOX decreased TV-RI of 48.8% and 68.0%, respectively. Tumor was clearly visualized in controls, DOX, and liposome-DOX groups. Yet, regarding the NLC-DOX group, tumor was barely identified by the image, indicating antitumor efficacy. Moreover, both NLC and liposomes proved to be able to delay the occurrence of lung metastasis. In conclusion, results of this study indicated that NLC-DOX might be an alternative strategy to achieve an efficient antitumor activity.