In vivo study of doxorubicin-loaded cell-penetrating peptide-modified pH-sensitive liposomes: biocompatibility, bio-distribution, and pharmacodynamics in BALB/c nude mice bearing human breast tumors

Cancer immunotherapy and its facilitation by nanomedicine

Cancer immunotherapy has sparked a wave of cancer research, driven by recent successful proof-of-concept clinical trials. However, barriers are emerging during its rapid development, including broad adverse effects, a lack of reliable biomarkers, tumor relapses, and drug resistance. Integration of nanomedicine may ameliorate current cancer immunotherapy. Ultra-large surface-to-volume ratio, extremely small size, and easy modification surface of nanoparticles enable them to selectively detect cells and kill cancer cells in vivo. Exciting synergistic applications of the two approaches have emerged in treating various cancers at the intersection of cancer immunotherapy and cancer nanomedicine, indicating the potential that the combination of these two therapeutic modalities can lead to new paradigms in the treatment of cancer. This review discusses the status of current immunotherapy and explores the possible opportunities that the nanomedicine platform can make cancer immunotherapy more powerful and precise by synergizing the two approaches.

Surface modification strategies in translocating nano-vesicles across different barriers and the role of bio-vesicles in improving anticancer therapy

Nanovesicles and bio-vesicles (BVs) have emerged as promising tools to achieve targeted cancer therapy due to their ability to overcome many of the key challenges currently being faced with conventional chemotherapy. These challenges include the diverse and often complex pathophysiology involving the progression of cancer, as well as the various biological barriers that circumvent therapeutic molecules reaching their target site in optimum concentration. The scientific evidence suggests that surface-functionalized nanovesicles and BVs camouflaged nano-carriers (NCs) both can bypass the established biological barriers and facilitate fourth-generation targeting for the improved regimen of treatment. In this review, we intend to emphasize the role of surface-functionalized nanovesicles and BVs camouflaged NCs through various approaches that lead to an improved internalization to achieve improved and targeted oncotherapy. We have explored various strategies that have been employed to surface-functionalize and biologically modify these vesicles, including the use of biomolecule functionalized target ligands such as peptides, antibodies, and aptamers, as well as the targeting of specific receptors on cancer cells. Further, the utility of BVs, which are made from the membranes of cells such as mesenchymal stem cells (MSCs), white blood cells (WBCs), red blood cells (RBCs), platelets (PLTs) as well as cancer cells also been investigated. Lastly, we have discussed the translational challenges and limitations that these NCs can encounter and still need to be overcome in order to fully realize the potential of nanovesicles and BVs for targeted cancer therapy. The fundamental challenges that currently prevent successful cancer therapy and the necessity of novel delivery systems are in the offing.

Activity of Bacteriophage D29 Loaded on Nanoliposomes against Macrophages Infected with Mycobacterium tuberculosis

The search for new antimicrobial agents is a continuous struggle, mainly because more and more cases of resistant strains are being reported. Mycobacterium tuberculosis (MTB) is the main microorganism responsible for millions of deaths worldwide. The development of new antimicrobial agents is generally aimed at finding strong interactions with one or more bacterial receptors. It has been proven that bacteriophages have the ability to adhere to specific and selective regions. However, their transport and administration must be carefully evaluated as an excess could prevent a positive response and the bacteriophages may be eliminated during their journey. With this in mind, the mycobacteriophage D29 was encapsulated in nanoliposomes, which made it possible to determine its antimicrobial activity during transport and its stability in the treatment of active and latent Mycobacterium tuberculosis. The antimicrobial activity, the cytotoxicity in macrophages and fibroblasts, as well as their infection and time-kill were evaluated. Phage nanoencapsulation showed efficient cell internalization to induce MTB clearance with values greater than 90%. Therefore, it was shown that nanotechnology is capable of assisting in the activity of degradation-sensitive compounds to achieve better therapy and evade the immune response against phages during treatment.

Development of doxorubicin-encapsulated magnetic liposome@PEG for treatment of breast cancer in BALB/c mice

The magnetic doxorubicin-encapsulated liposome/PEG/Fe3O4 (called as DOX@m-Lip/PEG) was synthesized and studied as a novel nanocarrier for the treatment of breast cancer in BALB/c mice. Nanocarrier was characterized by FT-IR, zeta-potential sizer, EDX elemental analysis, EDX mapping, TEM, and DLS techniques. The results showed that the size of the nanocarrier was determined around 128 nm by TEM. EDX study confirmed PEG-conjugation in the magnetic liposomes and was homogenously distributed in the nanosize range (100-200 nm) with a negative surface charge (-61.7 mV). The kinetic studies indicated that the release of doxorubicin from DOX@m-Lip/PEG follows the Korsmeyer-Peppas model. The n-value of the model was 0.315, indicating that doxorubicin release from the nanocarrier had a slow releasing rate and followed Fick's law. The DOX release from the nanocarrier lasted a long time (more than 300 h). In in vivo part, a mouse 4T1 breast tumor model was used. The in vivo results indicated that DOX@m-Lip/PEG caused much stronger tumor cell necrosis and less cardiotoxic effects than the other groups. In conclusion, we show that m-Lip/PEG is a promising nanocarrier for low dosage and slow release of doxorubicin in treating breast cancer, and treatment with encapsulated DOX (DOX@m-Lip/PEG) demonstrated higher efficacy with low cardiac toxicity. Besides, the magnetic property of m-Lip@PEG nanocarrier allows it to be a potent mater for hyperthermia and MRI studies.

Cell penetrating peptides: Highlighting points in cancer therapy

Cell-penetrating peptides (CPPs), first identified in HIV a few decades ago, deserved great attention in the last two decades; especially to support the penetration of anticancer drug means. In the drug delivery discipline, they have been involved in various approaches from mixing with hydrophobic drugs to the use of genetically conjugated proteins. The early classification as cationic and amphipathic CPPs has been extended to a few more classes such as hydrophobic and cyclic CPPs so far. Developing potential sequences utilized almost all methods of modern science: choosing high-efficiency peptides from natural protein sequences, sequence-based comparison, amino acid substitution, obtaining chemical and/or genetic conjugations, in silico approaches, in vitro analysis, animal experiments, etc. The bottleneck effect in this discipline reveals the complications that modern science faces in drug delivery research. Most CPP-based drug delivery systems (DDSs) efficiently inhibited tumor volume and weight in mice, but only in rare cases reduced their levels and continued further processes. The integration of chemical synthesis into the development of CPPs made a significant contribution and even reached the clinical stage as a diagnostic tool. But constrained efforts still face serious problems in overcoming biobarriers to reach further achievements. In this work, we reviewed the roles of CPPs in anticancer drug delivery, focusing on their amino acid composition and sequences. As the most suitable point, we relied on significant changes in tumor volume in mice resulting from CPPs. We provide a review of individual CPPs and/or their derivatives in a separate subsection.

Nanomedicine in therapeutic warfront against estrogen receptor-positive breast cancer

Breast cancer (BC) is the most frequently diagnosed malignancy in women worldwide. Almost 70-80% of cases of BC are curable at the early non-metastatic stage. BC is a heterogeneous disease with different molecular subtypes. Around 70% of breast tumors exhibit estrogen-receptor (ER) expression and endocrine therapy is used for the treatment of these patients. However, there are high chances of recurrence in the endocrine therapy regimen. Though chemotherapy and radiation therapy have substantially improved survival rates and treatment outcomes in BC patients, there is an increased possibility of the development of resistance and dose-limiting toxicities. Conventional treatment approaches often suffer from low bioavailability, adverse effects due to the non-specific action of chemotherapeutics, and low antitumor efficacy. Nanomedicine has emerged as a conspicuous strategy for delivering anticancer therapeutics in BC management. It has revolutionized the area of cancer therapy by increasing the bioavailability of the therapeutics and improving their anticancer efficacy with reduced toxicities on healthy tissues. In this article, we have highlighted various mechanisms and pathways involved in the progression of ER-positive BC. Further, different nanocarriers delivering drugs, genes, and natural therapeutic agents for surmounting BC are the spotlights of this article.

Stimuli-responsive liposomal nanoformulations in cancer therapy: Pre-clinical & clinical approaches

The site-specific delivery of antitumor agents is of importance for providing effective cancer suppression. Poor bioavailability of anticancer compounds and the presence of biological barriers prevent their accumulation in tumor sites. These obstacles can be overcome using liposomal nanostructures. The challenges in cancer chemotherapy and stimuli-responsive nanocarriers are first described in the current review. Then, stimuli-responsive liposomes including pH-, redox-, enzyme-, light-, thermo- and magneto-sensitive nanoparticles are discussed and their potential for delivery of anticancer drugs is emphasized. The pH- or redox-sensitive liposomes are based on internal stimulus and release drug in response to a mildly acidic pH and GSH, respectively. The pH-sensitive liposomes can mediate endosomal escape via proton sponge. The multifunctional liposomes responsive to both redox and pH have more capacity in drug release at tumor site compared to pH- or redox-sensitive alone. The magnetic field and NIR irradiation can be exploited for external stimulation of liposomes. The light-responsive liposomes release drugs when they are exposed to irradiation; thermosensitive-liposomes release drugs at a temperature of >40 °C when there is hyperthermia; magneto-responsive liposomes release drugs in presence of magnetic field. These smart nanoliposomes also mediate co-delivery of drugs and genes in synergistic cancer therapy. Due to lack of long-term toxicity of liposomes, they can be utilized in near future for treatment of cancer patients.

Opportunities in combinational chemo-immunotherapy for breast cancer using nanotechnology: an emerging landscape

INTRODUCTION

Breast carcinoma (BC) is one of the most frequent causes of cancer-related death among women, which is due to the poor response to conventional therapy. There are several complications associated with monotherapy for cancer, such as cytotoxicity to normal cells, multidrug resistance (MDR), side effects, and limited applications. To overcome these challenges, a combination of chemotherapy and immunotherapy (monoclonal antibodies, anticancer vaccines, checkpoint inhibitors, and cytokines) has been introduced. Drug delivery systems (DDSs) based on nanotechnology have more applications in BC treatment owing to their controlled and targeted drug release with lower toxicity and reduced adverse drug effects. Several nanocarriers, such as liposomes, nanoparticles, dendrimers, and micelles, have been used for the effective delivery of drugs.

AREAS COVERED

This article presents opportunities and challenges in BC treatment, the rationale for cancer immunotherapy, and several combinational approaches with their applications for BC treatment.

EXPERT OPINION

Nanotechnology can be used for the early prognosis and cure of BC. Several novel and targeted DDSs have been developed to enhance the efficacy of anticancer drugs. This article aims to understand new strategies for the treatment of BC and the appropriate design of nanocarriers used as a combinational DDS.

Nuclear Targeted Peptide Combined With Gambogic Acid for Synergistic Treatment of Breast Cancer

As a natural compound, gambogic acid (GA) emerged a shining multi-target antitumor activity in a variety of tumors. Whereas its poor solubility and non-specific effect to tumor blocked the clinical application of this drug. Herein, we reported a simple and effective strategy to construct liposome modified with nuclear targeted peptide CB5005N (VQRKRQKLMPC) via polyethylene glycol (PEG) linker to decrease the inherent limitations of GA and promote its anti-tumor activity. In this study, liposomes were prepared by thin film hydration method. The characterization of formulations contained particle size, Zeta potential, morphology and encapsulation efficiency. Further, in vitro cytotoxicity and uptake tests were investigated by 4T1 and MDA-MB-231 cells, and nuclear targeting capability was performed on MDA-MB-231 cells. In addition, the in vivo antitumor effect and biological distribution of formulations were tested in BALB/c female mice. The GA-loaded liposome modified by CB5005N showed small size, good uniformity, better targeting, higher anti-tumor efficiency, better tumor inhibition rate and lower toxicity to normal tissues than other groups. In vitro and in vivo research proved that CB5005N-GA-liposome exhibited excellent anti-tumor activity and significantly reduced toxicities. As a result, CB5005N-GA-liposome nano drug delivery system enhanced the tumor targeting and antitumor effects of GA, which provided a basis for its clinical application.

Multifunctional CuO/Cu2O Truncated Nanocubes as Trimodal Image-Guided Near-Infrared-III Photothermal Agents to Combat Multi-Drug-Resistant Lung Carcinoma

Despite the development of various therapeutic modalities to tackle cancer, multidrug resistance (MDR) and incomplete destruction of deep tissue-buried tumors remain as long-standing challenges responsible for tumor recurrence and low survival rates. In addition to the MDR and deep tissue photoactivation problems, most primary tumors metastasize to the lungs and lymph nodes to form secondary tumors. Therefore, it leaves a great challenge to develop theranostic approaches to combat both MDR and deep tissue photoactivation problems. Herein, we develop a versatile plasmonic CuO/Cu₂O truncated nanocube-based theranostic nanomedicine to act as a triple modal near-infrared fluorescence (NIRF) imaging agent in the biological window II (1000-1500 nm)/photoacoustic imaging (PAI)/T₁-weighted magnetic resonance (MR) imaging agents, sensitize the formation of singlet oxygen (¹O₂) to exert nanomaterial-mediated photodynamic therapeutic (NIR-II NmPDT), and absorb long NIR light (i.e., 1550 nm) in the biological window III (1500-1700 nm) to exert nanomaterial-mediated photothermal therapeutic (NIR-III NmPTT) effects for the effective destruction of multi-drug-resistant lung tumors. We found that H69AR lung cancer cells do not create drug resistance toward plasmonic CuO/Cu₂O TNCs-based nanomedicines.

Lipidated Peptidomimetic Ligand-Functionalized HER2 Targeted Liposome as Nano-Carrier Designed for Doxorubicin Delivery in Cancer Therapy

The therapeutic index of chemotherapeutic agents can be improved by the use of nano-carrier-mediated chemotherapeutic delivery. Ligand-targeted drug delivery can be used to achieve selective and specific delivery of chemotherapeutic agents to cancer cells. In this study, we prepared a peptidomimetic conjugate (SA-5)-tagged doxorubicin (Dox) incorporated liposome (LP) formulation (SA-5-Dox-LP) to evaluate the targeted delivery potential of SA-5 in human epidermal growth factor receptor-2 (HER2) overexpressed non-small-cell lung cancer (NSCLC) and breast cancer cell lines. The liposome was prepared using thin lipid film hydration and was characterized for particle size, encapsulation efficiency, cell viability, and targeted cellular uptake. In vivo evaluation of the liposomal formulation was performed in a mice model of NSCLC. The cell viability studies revealed that targeted SA-5-Dox-LP showed better antiproliferative activity than non-targeted Dox liposomes (Dox-LP). HER2-targeted liposome delivery showed selective cellular uptake compared to non-targeted liposomes on cancer cells. In vitro drug release studies indicated that Dox was released slowly from the formulations over 24 h, and there was no difference in Dox release between Dox-LP formulation and SA-5-Dox-LP formulation. In vivo studies in an NSCLC model of mice indicated that SA-5-Dox-LP could reduce the lung tumors significantly compared to vehicle control and Dox. In conclusion, this study demonstrated that the SA-5-Dox-LP liposome has the potential to increase therapeutic efficiency and targeted delivery of Dox in HER2 overexpressing cancer.

Integrin αvβ3-targeted liposomal drug delivery system for enhanced lung cancer therapy

Conventional chemotherapy for tumor treatment remains flawed because it fails to limit cytotoxicity to a small set of selectable tissues. Active targeting techniques for the delivery of drugs to specific sites are increasingly used to enhance drug accumulation at tumor sites with the aim of reducing side effects in vivo. Liposomes, modified with different targeting ligands, are considered to be one of the most promising targeted drug carriers. Herein, novel linear and cyclic arginine-glycine-aspartate (RGD) peptide-based lipids were synthesized to develop modified liposomal drug delivery systems with active targeting and pH-sensitivity. The RGD-modified liposomes showed excellent active targeting ability for integrin α_vβ₃ receptors, resulting in improved cellular uptake. The modified liposomes also enhanced intracellular doxorubicin (DOX) release because of their degradation in an acidic environment. Consequently, the RGD-modified, DOX-loaded liposomes exhibited significant antitumor efficacy and low toxicity in vitro and in vivo. In particular, 5% cRGD-lipid modified DOX-loaded liposome showed the greatest inhibition of tumor growth in mice among the tested formulations, and much less toxicity than free DOX. In conclusion, the DOX-loaded pH-sensitive liposome modified with 5% cRGD-lipid developed in the current study provides a potential approach for improved tumor therapy.

Peptide-functionalized liposomes as therapeutic and diagnostic tools for cancer treatment

Clinically efficacious medication in anticancer therapy has been successfully designed with liposome-based nanomedicine. The liposomal formulation in cancer drug delivery can be facilitated with a functionalized peptide that mediates the specific drug delivery opportunities with increased drug penetrability, specific accumulation in the targeted site, and enhanced therapeutic efficacy. This review aims to focus on recent advances in peptide-functionalized liposomal formulation techniques in cancer diagnosis and treatment regarding recently published literature. It also will highlight different aspects of novel liposomal formulation techniques that incorporate surface functionalization with peptides for better anticancer effect and current challenges in peptide-functionalized liposomal drug formulation.

Cell-penetrating peptides in oncologic pharmacotherapy: A review

Cancer is the second leading cause of death in the world and its treatment is extremely challenging, mainly due to its complexity. Cell-Penetrating Peptides (CPPs) are peptides that can transport into the cell a wide variety of biologically active conjugates (or cargoes), and are, therefore, promising in the treatment and in the diagnosis of several types of cancer. Some notable examples are TAT and Penetratin, capable of penetrating the central nervous system (CNS) and, therefore, acting in cancers of this system, such as Glioblastoma Multiforme (GBM). These above-mentioned peptides, conjugated with traditional chemotherapeutic such as Doxorubicin (DOX) and Paclitaxel (PTX), have also been shown to induce apoptosis of breast and liver cancer cells, as well as in lung cancer cells, respectively. In other cancers, such as esophageal cancer, the attachment of Magainin 2 (MG2) to Bombesin (MG2B), another CPP, led to pronounced anticancer effects. Other examples are CopA3, that selectively decreased the viability of gastric cancer cells, and the CPP p28. Furthermore, in preclinical tests, the anti-tumor efficacy of this peptide was evaluated on human breast cancer, prostate cancer, ovarian cancer, and melanoma cells in vitro, leading to high expression of p53 and promoting cell cycle arrest. Despite the numerous in vitro and in vivo studies with promising results, and the increasing number of clinical trials using CPPs, few treatments reach the expected clinical efficacy. Usually, their clinical application is limited by its poor aqueous solubility, immunogenicity issues and dose-limiting toxicity. This review describes the most recent advances and innovations in the use of CPPs in several types of cancer, highlighting their crucial importance for various purposes, from therapeutic to diagnosis. Further clinical trials with these peptides are warranted to examine its effects on various types of cancer.

Doxorubicin-Loaded In Situ Gel Combined with Biocompatible Hydroxyethyl Cellulose Hemostatic Gauze for Controlled Release of Drugs and Prevention of Breast Cancer Recurrence Postsurgery

Biodegradable hemostatic gauze used for surgical hemostasis has attracted great interest due to its excellent compliance and local anti-inflammatory and therapeutic effects when combined with drugs. Herein, we demonstrate the successful fabrication of water-soluble absorbed cellulose hemostatic material by introducing a biocompatible hydroxyethyl cellulose (HEC) hemostasis gauze into doxorubicin-loaded in situ gel (GEL(DOX)) for the prevention of breast cancer recurrence after surgical tumor resection. The present results show that HEC has a shorter metabolic period, no anaphylaxis and peripheral nerve toxicity, and possesses more advantages than oxidative regenerated cellulose hemostasis gauze, a commercially available product in market. HEC is of the physical hemostasis in mechanism, which does not induce physiological hemostasis and hemolysis. In addition, the combination of HEC with GEL(DOX) not only stops the bleeding efficiently, but also effectively reduces the proliferation of tumor with no cardiac toxic and bone marrow suppression. After treatment, the tumor inhibition rate is up to 90%, resulting in prolonged survival time to 58 days. In conclusion, HEC hemostatic gauze has a broad prospect in clinical application due to its perfect biocompatibility, and we envision that it is a new strategy for the prevention of breast cancer to implant HEC hemostatic gauze containing GEL(DOX) at the postoperative site after surgery.

Liposome-ligand conjugates: a review on the current state of art

Early researchers focussed on developing stimuli-responsive liposomes in order to manipulate drug release at the site of action or under certain conditions. In recent times, a great deal of efforts has been made to modify the surface of liposomes with ligands for the purpose of achieving targeted drug delivery. Due to the morphology of liposomes, their surfaces can be engineered by attaching molecules such as oligosaccharides, peptides, antibodies, antigens and oligonucleotides to the bilayer structure. Over the years, a number of techniques including the use of covalent and non-covalent linkages have been utilised in designing ligand-liposome conjugates. In this review, various strategies for the functionalisation of liposomes as well as the different types of ligand-liposome conjugates have been discussed. Finally, the pros and cons of conjugation in liposomes are concisely summarised.

Bufalin-Loaded PEGylated Liposomes: Antitumor Efficacy, Acute Toxicity, and Tissue Distribution

Bufalin, derived from Venenum Bufonis, exerts antitumor effects but has low bioavailability and adverse effects when administered as a single agent. The purpose of this study was to evaluate the physical and chemical properties, antitumor efficacy, general pharmacology, acute toxicity, and tissue distribution profile of bufalin-loaded PEGylated liposomes (BF/PEG-LP), which were prepared in a previous study. To evaluate the safety of the preparation, a red blood cell hemolysis test was performed, which indicated that the hemolysis rate of BF/PEG-LP was significantly lower than that of bufalin alone. Cell viability assay revealed that the blank liposomes were nontoxic. In an in vitro experiment, BF/PEG-LP dose-dependently induced the apoptosis of HepG2, HCT116, A549, and U251 cancer cells, with half-maximal inhibitory concentration (IC₅₀) values of 21.40 ± 2.39, 21.00 ± 3.34, 43.39 ± 6.43, and 31.14 ± 2.58 ng/mL, respectively, at 24 h. Tumor xenograft experiments in nude mice showed that BF/PEG-LP significantly inhibited the growth of U251 cells. Pharmacological evaluation revealed that BF/PEG-LP impacted the general behavior, independent activities, and coordination of mice after a week of administration compared with those of mice in the control group. In an acute toxicity test, the median lethal concentration (LD₅₀) of BF and BF/PEG-LP in mice was 0.156 and 3.03 mg/kg, respectively. Tissue distribution profiles showed that the BF concentration in brain tissue was 20% higher, whereas that in heart tissue was 30% lower when BF/PEG-LP was administered to mice compared with BF. Thus, BF/PEG-LP exhibited lower hemolysis and cytotoxicity and improved pharmacokinetic and antitumor properties compared with bufalin alone, indicating its potential for future pharmacological application, particularly for glioma treatment.

Preparation and Evaluation of Liposomes Co-Loaded with Doxorubicin, Phospholipase D Inhibitor 5-Fluoro-2-Indolyl Deschlorohalopemide (FIPI) and D-Alpha Tocopheryl Acid Succinate (α-TOS) for Anti-Metastasis

Tumor metastasis has become a key obstacle to cancer treatment, which causes high mortality. Nowadays, it involves multiple complex pathways, and conventional treatments are not effective due to fewer targets. The aims of the present study were to construct a novel liposome delivery system co-loading a specific PLD inhibitor 5-fluoro-2-indolyldes-chlorohalopemide (FIPI) in combination with antitumor drug doxorubicin (DOX) and functional excipient D-alpha tocopheryl acid succinate (α-TOS) for anti-metastasis. In this study, the liposomes containing three components (DFT-Lip) with different physicochemical properties were successfully prepared by film dispersion method combined with pH-gradient method. Physicochemical parameters such as particles size, potential, encapsulation efficiency, stability, and release profiles were investigated. In vitro and in vivo anti-metastasis effectiveness against highly metastatic breast cancer MDA-MB-231 cell line was evaluated. The liposomes showed uniform particle size (approximately 119 nm), high drug encapsulation efficiency (> 90%), slow release characteristics and stability. In vitro anti-tumor cell metastasis study demonstrated DFT-Lip could greatly inhibit motility, migration and invasion of MDA-MB-231 cells compared to other liposomes, predicting a synergistic anti-tumor metastasis effect between FIPI with α-TOS in liposomes. In vivo anti-metastasis study showed that DFT-Lip prevented the initiation and the progression of metastasis of high metastatic breast cancer. These results suggested that the liposomes containing DOX, FIPI, and α-TOS might be a promising strategy for metastatic tumor therapy in clinics.

Preparation, characterisation and in vitro and in vivo evaluation of CD44-targeted chondroitin sulphate-conjugated doxorubicin PLGA nanoparticles

The purpose of this study was to ascertain the effect of chondroitin sulphate-modified doxorubicin (Dox) nanoparticles on enhancing the tumour-targeting effect and tumour growth inhibition effect of doxorubicin both in vitro and in vivo. The chondroitin sulphate-doxorubicin conjugate and its poly(lactic-co-glycolic acid) (PLGA) nanoparticles (CS-Dox-PLGA) were successfully synthesised, and then characterized by Fourier-transform infrared spectroscopy (FTIR), proton magnetic resonance (¹HNMR), thermogravimetric analysis/differential scanning calorimetry (TGA/DSC), transmission electron microscope (TEM), zeta potential and laser light scattering. Taking advantage of the enhanced permeability and CD44-mediated endocytosis, CS-Dox-PLGA showed excellent capacity for penetrating the peripheral tumour barrier and into the nucleus of tumour cells. The CS-Dox-PLGA cellular uptake was improved and exhibited a significantly higher level of cytotoxicity in U251 cells. After intravenous administration, the CS-Dox-PLGA showed good pharmacokinetic properties and excellent U251-induced tumour inhibition with low cardiac toxicity. Therefore, CS-Dox-PLGA with low cardiac toxicity and good anti-tumour ability might be a better choice for Dox in clinical practice.

Short Peptide-Mediated Brain-Targeted Drug Delivery with Enhanced Immunocompatibility

Peptide ligands have been exploited as versatile tools to facilitate targeted delivery of nanocarriers. However, the effects of peptide ligands on immunocompatibility and therapeutic efficacy of liposomes remain intricate. Here, a short and stable brain targeted peptide ligand D8 was modified on the surface of doxorubicin-loaded liposomes (D8-sLip/DOX), demonstrating prolonged blood circulation and lower liver distribution in comparison to the long and stable D-peptide ligand ^DCDX-modified doxorubicin-loaded liposomes (^DCDX-sLip/DOX) by mitigating natural IgM absorption. Despite the improved pharmacokinetic profiles, D8-sLip/DOX exhibited comparable brain targeting capacity in ICR mice and antiglioblastoma efficacy to ^DCDX-sLip/DOX in nude mice bearing intracranial glioblastoma. However, dramatic accumulation of ^DCDX-sLip/DOX in liver (especially during the first 8 h after intravenous injection) resulted in pathological symptoms, including nuclei swelling, necrosis of liver cells, and inflammation. These results suggest that short peptide ligand-mediated brain-targeted drug delivery systems possessing enhanced immunocompatibility are promising to facilitate efficient brain transport with improved biosafety.

Bleomycin-Loaded pH-Sensitive Polymer⁻Lipid-Incorporated Liposomes for Cancer Chemotherapy

Cancer chemotherapeutic systems with high antitumor effects and less adverse effects are eagerly desired. Here, a pH-sensitive delivery system for bleomycin (BLM) was developed using egg yolk phosphatidylcholine liposomes modified with poly(ethylene glycol)-lipid (PEG-PE) for long circulation in the bloodstream and 2-carboxycyclohexane-1-carboxylated polyglycidol-having distearoyl phosphatidylethanolamine (CHexPG-PE) for pH sensitization. The PEG-PE/CHexPG-PE-introduced liposomes showed content release responding to pH decrease and were taken up by tumor cells at a rate 2.5 times higher than that of liposomes without CHexPG-PE. BLM-loaded PEG-PE/CHexPG-PE-introduced liposomes exhibited comparable cytotoxicity with that of the free drug. Intravenous administration of these liposomes suppressed tumor growth more effectively in tumor-bearing mice than did the free drug and liposomes without CHexPG-PE. However, at a high dosage of BLM, these liposomes showed severe toxicity to the spleen, liver, and lungs, indicating the trapping of liposomes by mononuclear phagocyte systems, probably because of recognition of the carboxylates on the liposomes. An increase in PEG molecular weight on the liposome surface significantly decreased toxicity to the liver and spleen, although toxicity to the lungs remained. Further improvements such as the optimization of PEG density and lipid composition and the introduction of targeting ligands to the liposomes are required to increase therapeutic effects and to reduce adverse effects.