Synergistic anti-tumor activity of paclitaxel-incorporated conjugated linoleic acid-coupled poloxamer thermosensitive hydrogel in vitro and in vivo

CXCR4 Targeting Nanoplatform for Transcriptional Activation of Latent HIV-1 Infected T Cells

Antiretroviral drugs are limited in their ability to target latent retroviral reservoirs in CD4+ T cells, highlighting the need for a T cell-targeted drug delivery system that activates the transcription of inactivated viral DNA in infected cells. Histone deacetylase inhibitors (HDACi) disrupt chromatin-mediated silencing of the viral genome and are explored in HIV latency reversal. But single drug formulations of HDACi are insufficient to elicit therapeutic efficacy, warranting combination therapy. Furthermore, protein kinase C activators (PKC) have shown latency reversal activity in HIV by activating the NF-κB signaling pathway. Combining HDACi (SAHA) with PKC (PMA) activators enhances HIV reservoir activation by promoting chromatin decondensation and subsequent transcriptional activation. In this study, we developed a mixed nanomicelle (PD-CR4) drug delivery system for simultaneous targeting of HIV-infected CD4+ T cells with two drugs, suberoylanilide hydroxamic acid (SAHA) and phorbol 12-myristate 13-acetate (PMA). SAHA is a HDACi that promotes chromatin decondensation, while PMA is a PKC agonist that enhances transcriptional activation. The physicochemical properties of the formulated PD-CR4 nanoparticles were characterized by NMR, CMC, DLS, and TEM analyses. Further, we investigated in vitro safety profiles, targeting efficacy, and transcriptional activation of inactivated HIV reservoir cells. Our results suggest that we successfully prepared a targeted PD system with dual drug loading. We have compared latency reversal efficacy of a single drug nanoformulation and combination drug nanoformulation. Final PD-SP-CR4 successfully activated infected CD4+ T cell reservoirs and showed enhanced antigen release from HIV reservoir T cells, compared with the single drug treatment group as expected. To summarize, our data shows PD-SP-CR4 has potential T cell targeting efficiency and efficiently activated dormant CD4+ T cells. Our data indicate that a dual drug-loaded particle has better therapeutic efficacy than a single loaded particle as expected. Hence, PD-CR4 can be further explored for HIV therapeutic drug delivery studies.

Injectable Poloxamer Hydrogels for Local Cancer Therapy

The widespread push to invest in local cancer therapies comes from the need to overcome the limitations of systemic treatment options. In contrast to intravenous administration, local treatments using intratumoral or peritumoral injections are independent of tumor vasculature and allow high concentrations of therapeutic agents to reach the tumor site with minimal systemic toxicity. Injectable biodegradable hydrogels offer a clear advantage over other delivery systems because the former requires no surgical procedures and promotes drug retention at the tumor site. More precisely, in situ gelling systems based on poloxamers have garnered considerable attention due to their thermoresponsive behavior, biocompatibility, ease of preparation, and possible incorporation of different anticancer agents. Therefore, this review focuses on the use of injectable thermoresponsive hydrogels based on poloxamers and their physicochemical and biological characterization. It also includes a summary of these hydrogel applications in local cancer therapies using chemotherapy, phototherapy, immunotherapy, and gene therapy.

Poloxam Thermosensitive Hydrogels Loaded with hFGF2-Linked Camelina Lipid Droplets Accelerate Skin Regeneration in Deep Second-Degree Burns

Burn injuries are difficult to manage due to the defect of large skin tissues, leading to major disability or even death. Human fibroblast growth factor 2 (hFGF2) is known to promote burn wound healing. However, direct administration of hFGF2 to the wound area would affect the bioactivity. To provide a supportive environment for hFGF2 and control its release in a steady fashion, in this research, we developed novel thermosensitive poloxam hydrogels delivered with hFGF2-linked Camelina lipid droplets (CLD-hFGF2 hydrogels). Cryopreserved scanning electron microscopy (SEM) results indicated that the incorporation of CLD-hFGF2 does not significantly affect the inner structure of hydrogels. The rheological properties showed that CLD-hFGF2 hydrogels gelated in response to temperature, thus optimizing the delivery method. In vitro, CLD-hFGF2 could be released from hydrogels for 3 days after drug delivery (the release rate was 72%), and the release solution could still promote the proliferation and migration of NIH3T3 cells. In vivo, compared with hydrogels alone or with direct CLD-hFGF2 administration, CLD-hFGF2 hydrogels had the most obvious effect on deep second-degree burn wound healing. This work indicates that CLD-hFGF2 hydrogels have potential application value in burn wound healing.

Perspectives and potential applications of endophytic microorganisms in cultivation of medicinal and aromatic plants

Ensuring food and nutritional security, it is crucial to use chemicals in agriculture to boost yields and protect the crops against biotic and abiotic perturbations. Conversely, excessive use of chemicals has led to many deleterious effects on the environment like pollution of soil, water, and air; loss of soil fertility; and development of pest resistance, and is now posing serious threats to biodiversity. Therefore, farming systems need to be upgraded towards the use of biological agents to retain agricultural and environmental sustainability. Plants exhibit a huge and varied niche for endophytic microorganisms inside the planta, resulting in a closer association between them. Endophytic microorganisms play pivotal roles in plant physiological and morphological characteristics, including growth promotion, survival, and fitness. Their mechanism of action includes both direct and indirect, such as mineral phosphate solubilization, fixating nitrogen, synthesis of auxins, production of siderophore, and various phytohormones. Medicinal and aromatic plants (MAPs) hold a crucial position worldwide for their valued essential oils and several phytopharmaceutically important bioactive compounds since ancient times; conversely, owing to the high demand for natural products, commercial cultivation of MAPs is on the upswing. Furthermore, the vulnerability to various pests and diseases enforces noteworthy production restraints that affect both crop yield and quality. Efforts have been made towards enhancing yields of plant crude drugs by improving crop varieties, cell cultures, transgenic plants, etc., but these are highly cost-demanding and time-consuming measures. Thus, it is essential to evolve efficient, eco-friendly, cost-effective simpler approaches for improvement in the yield and health of the plants. Harnessing endophytic microorganisms as biostimulants can be an effective and alternative step. This review summarizes the concept of endophytes, their multidimensional interaction inside the host plant, and the salient benefits associated with endophytic microorganisms in MAPs.

Hydrotropic Hydrogels Prepared from Polyglycerol Dendrimers: Enhanced Solubilization and Release of Paclitaxel

Polyglycerol dendrimers (PGD) exhibit unique properties such as drug delivery, drug solubilization, bioimaging, and diagnostics. In this study, PGD hydrogels were prepared and evaluated as devices for controlled drug release with good solubilization properties. The PGD hydrogels were prepared by crosslinking using ethylene glycol diglycidylether (EGDGE). The concentrations of EGDGE and PGDs were varied. The hydrogels were swellable in ethanol for loading paclitaxel (PTX). The amount of PTX in the hydrogels increased with the swelling ratio, which is proportional to EGDGE/OH ratio, meaning that heterogeneous crosslinking of PGD made high dense region of PGD molecules in the matrix. The hydrogels remained transparent after loading PTX and standing in water for one day, indicating that PTX was dispersed in the hydrogels without any crystallization in water. The results of FTIR imaging of the PTX-loaded PGD hydrogels revealed good dispersion of PTX in the hydrogel matrix. Sixty percent of the loaded PTX was released in a sink condition within 90 min, suggesting that the solubilized PTX would be useful for controlled release without any precipitation. Polyglycerol dendrimer hydrogels are expected to be applicable for rapid release of poorly water-soluble drugs, e.g., for oral administration.

Enhanced Intracellular Delivery of Curcumin by Chitosan-Lipoic Acid as Reduction-Responsive Nanoparticles

AIMS

Enhancement of anti-tumor activity of the chemotherapeutic agent CUR by redoxsensitive nanoparticle to get a deeper insight into cancer therapy.

BACKGROUND

Tumor targetability and stimulus are widely used to study the delivery of drugs for cancer diagnosis and treatment because poor cellular uptake and inadequate intracellular drug release lead to inefficient delivery of anticancer agents to tumor tissue.

OBJECTIVE

Studies distinguishing between tumor and normal tissues or redox-sensitive systems using glutathione (GSH) as a significant signal.

METHODS

In this study, we designed Chitosan-Lipoic acid Nanoparticles (CS-LANPs) to improve drug delivery for breast cancer treatment by efficient delivery of Curcumin (CUR). The properties of blank CS-LANPs were studied in detail. The size and the Polydispersity Index (PDI) of the CS-LANPs were optimized.

RESULTS

The results indicate the mean size and PDI of the blank CS-LANPs were around 249 nm and 0.125, respectively. However, the Drug Loading (DL) and Encapsulation Efficiency (EE) of the CSLANPs were estimated to be about 18.22% and 99.80%, respectively. Compared to non-reductive conditions, the size of reduction-sensitive CS-LANPs increased significantly under reductive conditions. Therefore, the drug release of CS-LANPs in the presence of glutathione was much faster than that of non-GSH conditions .Moreover, the antitumor effect of CS-LANPs on MCF-7 cells was determined in vitro by MTT assay, cell cytotoxicity, Caspase-3 Assay, detection of mitochondrial membrane potential and quantification of apoptosis incidence.

CONCLUSION

CS-LANPs showed a remarkably increased accumulation in tumor cells and had a better tumor inhibitory activity in vitro. CS-LANPs could successfully deliver drugs to cancer cells and revealed better efficiency than free CUR.

A difunctional Pluronic®127-based in situ formed injectable thermogels as prolonged and controlled curcumin depot, fabrication, in vitro characterization and in vivo safety evaluation

Curcumin has been reported to be used widely against many types of pathological conditions in clinics. However, due to its limitations such as poor solubility, poor oral absorption and low stability have limited its applications. In the current study, a series of novel chemically cross-linkable depot gel formulations were developed based on thermoresponsive micellar polymer (Pluronic^®127) with polyelectrolyte hydrophilic monomer, that is, 2-acrylamido-2-methylpropane sulfonic acid by cold and in situ grafting polymerization method. The formulations were aimed to deliver curcumin at controlled rate from in situ formed depot after administration through subcutaneous route in vivo. The sol-gel phase transitions of formulations were observed by rheological analysis, tube titling and optical transmittance measurements. Maximum swelling of gel formulations was observed at pH 7.4 and below CGT, that is, 25 °C. The in vitro release profile exhibits maximum drug release at pH 7.4 and 25 °C owing to relaxed gel state. In vitro degradation profile of gel formulations showed controlled degradation rate. Cell growth inhibition study confirmed the biocompatibility and safe nature of bare gel formulations against L929 cell lines. In vitro cytotoxic study showed that curcumin loaded in gel formulation has controlled pharmacological activity against HeLa and MCF-7 cancer cells as compared to free drug solution. The IC₅₀ values calculated for pure curcumin solution (30 ± 0.77 µg/ml for HeLa and 27 ± 0.39 µg/ml for MCF-7) were found higher in comparison to curcumin-loaded thermogels against HeLa (19 ± 0.28 µg/ml and 23 ± 0.81 µg/ml) and MCF-7 (22 ± 0.54 µg/ml and 21 ± 0.49 µg/ml). Histopathological and hematological analysis showed the biocompatible nature of hydrogels. Structural confirmation was done by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (¹H NMR). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the thermal stability of the gel formulation. The porous structure of gel formulations was assessed by scanning electron microscopic (SEM) analysis. Results concluded that newly developed gel formulations have thermoresponsive behavior with phase transition at body temperature and can be used as in situ controlled drug depot.

Enhanced absorption, and efficacy of oral self-assembled paclitaxel nanocochleates in multi-drug resistant colon cancer

Chemotherapy in drug-resistant cancers remains a challenge. Owing to associated poor bioavailability, oral administration of hydrophobic anticancer drugs like paclitaxel has been quite challenging, with the scenario being further complicated by Pgp efflux in drug-resistant tumours. We developed a novel nanocochleates (CPT) system encapsulating paclitaxel (PTX) to treat resistant colon cancer by oral administration. PTX encapsulated nanocochleates (PTX-CPT), made up of phosphatidylserine in size range of 350-600 nm with -20 ± 5.2 mV zeta potential were protected from degradation at acidic gastric pH and showed sustained PTX release over 48 h under intestinal pH condition. In vitro cytotoxicity studies on HCT-116 & HCT-15 cells (multi-drug resistant) established IC50 value of <10 and 69 nM, respectively, which was significantly lower when compared to commercial Taxol formulation. Further, the in vivo efficacy with five oral doses of 30 mg/kg PTX-CPT in an HCT-15 drug-resistant colon cancer xenograft mouse model showed more than 25 fold reduction in the tumour growth inhibition as compared to intravenous Taxol which showed just 1.94% inhibition. Interestingly, PTX-CPT treated mice also showed significantly lower proliferation index and microvessel density when compared to Taxol treated mice. Nanocochleates showed lower toxicity with at LD-50 value greater than 300 mg/kg as described in OECD 423 guideline. The enhanced efficacy of PTX-CPT speculated due to its internalization by active endocytosis, ability to escape Pgp efflux, and due to a combined effect of the pro-apoptotic and antiangiogenic role. Taken together, the results suggested the PTX-CPT a promising strategy for efficiently treating drug-resistant colon cancer orally.

Formulation strategies to modulate drug release from poloxamer based in situ gelling systems

Introduction: Poloxamer based in situ gelling systems offer numerous advantages in drug delivery; however, their application as prolonged-release delivery platforms is limited mainly due to their weak mechanical properties and the interconnected aqueous network causing fast gel erosion and drug diffusion.Area covered: The focus of this review is to provide an insightful discussion on the formulation strategies that can be employed to sustain/prolong the drug release from poloxamer based in situ gelling systems. The review also outlines the formulation factors, influencing drug release from these systems.Expert opinion: The nature, composition, and concentration of poloxamers are the most critical factors in defining the rate of drug release from an in situ gelling matrix. Hydrophobic gel matrices have compact micellar arrangements resulting in slow diffusion and erosion. Depending on the intended clinical application, gel characteristics can be modulated, either by physical blending or by chemical crosslinking with additive materials, to slow release and improve residence time at the administration site. Incorporating drug-loaded particles into poloxamer gels sustains drug release by creating multiple rate-limiting release barriers. Chemical modification of poloxamers appears to be a promising strategy to obtain prolonged sustained release for parenteral application without compromising the rheological properties of the formulation.

Thermoresponsive gating membranes embedded with liquid crystal(s) for pulsatile transdermal drug delivery: An overview and perspectives

Due to the circadian rhythm regulation of almost every biological process in the human body, physiological and biochemical conditions vary considerably over the course of a 24-h period. Thus, optimal drug delivery and therapy should be effectively controlled to achieve the desired therapeutic plasma concentrations and therapeutic drug responses at the required time according to chronopharmacological concepts, rather than continuous maintenance of constant drug concentrations for an extended time period. For many drugs, it is not always necessary to constantly deliver a drug into the human body under disease conditions due to rhythmic variations. Pulsatile drug delivery systems (PDDSs) have been receiving more attention in pharmaceutical development by providing a predetermined lag period, followed by a fast or rate-controlled drug release after application. PDDSs are characterized by a programmed drug release, which may release a drug at repeatable pulses to match the biological and clinical needs of a given disease therapy. This review article focuses on thermoresponsive gating membranes embedded with liquid crystals (LCs) for transdermal drug delivery using PDDS technology. In addition, the principal rationale and the advanced approaches for the use of PDDSs, the marketed products of chronotherapeutic DDSs with pulsatile function designed by various PDDS technologies, pulsatile drug delivery designed with thermoresponsive polymers, challenges and opportunities of transdermal drug delivery, and novel approaches of LC systems for drug delivery are reviewed and discussed. A brief overview of all academic research articles concerning single LC- or binary LC-embedded thermoresponsive membranes with a switchable on-off permeation function through topical application by an external temperature control, which may modulate the dosing interval and administration time according to the therapeutic needs of the human body, is also compiled and presented. In the near future, since thermal-based approaches have become a well-accepted method to enhance transdermal delivery of different water-soluble drugs and macromolecules, a combination of the thermal-assisted approach with thermoresponsive LCs membranes will have the potential to improve PDDS applications but still poses a great challenge.

Preparation of Immunotherapy Liposomal-Loaded Thermal-Responsive Hydrogel Carrier in the Local Treatment of Breast Cancer

To reduce the side effects of immune drugs and the sustainable release of immune drugs on local parts, we have designed an injectable thermal-sensitive hydrogel containing an imiquimod-loaded liposome system. In the extracellular environment of tumor tissues (pH 6.4), 50% of the drug was released from the carrier, which could be a result of the morphological changes of the liposomal microstructure in the acidic environment. According to the results in animals, the drug-containing liposomes combined with hydrogel can be effectively applied in breast cancer therapy to delay the growth of tumors as well as to dramatically reduce the death rate of mice.

Harmonious Biomaterials for Development of In situ Approaches for Locoregional Delivery of Anti-cancer Drugs: Current Trends

Locoregional drug delivery is a novel approach for the effective delivery of anti-cancer agents as it exposes the tumors to high concentration of drugs. In situ gelling systems have fetched paramount attention in the field of localized cancer chemotherapy due to their targeted delivery, ease of preparation, prolonged or sustained drug release and improved patient compliance. Numerous polymers have been investigated for their properties like swelling along with biodegradation, drug release and physicochemical properties for successful targeting of the drugs at the site of implantation. The polymers such as chitosan, Hyaluronic Acid (HA), poloxamer, Poly Glycolic Lactic Acid (PGLA) and Poly Lactic Acid (PLA) tend to form in situ hydrogels and have been exploited to develop localized delivery vehicles. These formulations are administered in the solution form and on exposure to physiological environment such as temperature, pH or ionic composition they undergo phase conversion into a hydrogel drug depot. The use of in situ gelling approach has provided prospects to increase overall survival and life quality of cancer patient by enhancing the bioavailability of drug to the site of tumor by minimizing the exposure to normal cells and alleviating systemic side effects. Because of its favorable safety profile and clinical benefits, United States Food and Drug Administration (U.S. FDA) has approved polymer based in situ systems for prolonged locoregional activity. This article discusses the rationale for developing in situ systems for targeted delivery of anti-cancer agents with special emphasis on types of polymers used to formulate the in situ system. In situ formulations for locoregional anti-cancer drug delivery that are marketed and are under clinical trials have also been discussed in detail in this article.

A personalized and long-acting local therapeutic platform combining photothermal therapy and chemotherapy for the treatment of multidrug-resistant colon tumor

BACKGROUND

Local photothermal therapy (PTT) provides an easily applicable, noninvasive adjunctive therapy for colorectal cancer (CRC), especially when multidrug resistance (MDR) occurs. However, using PTT alone does not result in complete tumor ablation in many cases, thus resulting in tumor recurrence and metastasis.

MATERIALS AND METHODS

In this study, we aim to develop a personalized local therapeutic platform combining PTT with long-acting chemotherapy for the treatment of MDR CRC. The platform consists of polyethylene glycol (PEG)-coated gold nanorods (PEG-GNRs) and D-alpha-tocopheryl PEG 1000 succinate (TPGS)-coated paclitaxel (PTX) nanocrystals (TPGS-PTX NC), followed by the incorporation into an in situ hydrogel (gel) system (GNRs-TPGS-PTX NC-gel) before injection. After administration, PEG-GNRs can exert quick and efficient local photothermal response under near-infrared laser irradiation to shrink tumor; TPGS-PTX NC then provides a long-acting chemotherapy due to the sustained release of PTX along with the P-glycoprotein inhibitor TPGS to reverse the drug resistance.

RESULTS

The cytotoxicity studies showed that the IC50 of GNRs-TPGS-PTX NC-gel with laser irradiation decreased to ~178-folds compared with PTX alone in drug-resistant SW620 AD300 cells. In the in vivo efficacy test, after laser irradiation, the GNRs-TPGS-PTX NC-gel showed similar tumor volume inhibition compared with GNRs-gel at the beginning. However, after 14 days, the tumor volume of the mice treated with GNRs-gel quickly increased, while that of the mice treated with GNRs-TPGS-PTX NC-gel remained controllable due to the long-term chemotherapeutic effect of TPGS-PTX NC. The mice treated with GNRs-TPGS-PTX NC-gel also showed no weight loss and obvious organ damages and lesions during the treatment, indicating a low systemic side effect profile and a good biocompatibility.

CONCLUSION

Overall, the nano-complex may serve as a promising local therapeutic patch against MDR CRC with one-time dosing to achieve a long-term tumor control. The doses of PEG-GNRs and TPGS-PTX NC can be easily adjusted before use according to patient-specific characteristics potentially making it a personalized therapeutic platform.

Biopolymers for Antitumor Implantable Drug Delivery Systems: Recent Advances and Future Outlook

In spite of remarkable improvements in cancer treatments and survivorship, cancer still remains as one of the major causes of death worldwide. Although current standards of care provide encouraging results, they still cause severe systemic toxicity and also fail in preventing recurrence of the disease. In order to address these issues, biomaterial-based implantable drug delivery systems (DDSs) have emerged as promising therapeutic platforms, which allow local administration of drugs directly to the tumor site. Owing to the unique properties of biopolymers, they have been used in a variety of ways to institute biodegradable implantable DDSs that exert precise spatiotemporal control over the release of therapeutic drug. Here, the most recent advances in biopolymer-based DDSs for suppressing tumor growth and preventing tumor recurrence are reviewed. Novel emerging biopolymers as well as cutting-edge polymeric microdevices deployed as implantable antitumor DDSs are discussed. Finally, a review of a new therapeutic modality within the field, which is based on implantable biopolymeric DDSs, is given.

Thermoresponsive Hydrogels and Their Biomedical Applications: Special Insight into Their Applications in Textile Based Transdermal Therapy

Various natural and synthetic polymers are capable of showing thermoresponsive properties and their hydrogels are finding a wide range of biomedical applications including drug delivery, tissue engineering and wound healing. Thermoresponsive hydrogels use temperature as external stimulus to show sol-gel transition and most of the thermoresponsive polymers can form hydrogels around body temperature. The availability of natural thermoresponsive polymers and multiple preparation methods of synthetic polymers, simple preparation method and high functionality of thermoresponsive hydrogels offer many advantages for developing drug delivery systems based on thermoresponsive hydrogels. In textile field applications of thermoresponsive hydrogels, textile based transdermal therapy is currently being applied using drug loaded thermoresponsive hydrogels. The current review focuses on the preparation, physico-chemical properties and various biomedical applications of thermoresponsive hydrogels based on natural and synthetic polymers and especially, their applications in developing functionalized textiles for transdermal therapies. Finally, future prospects of dual responsive (pH/temperature) hydrogels made by these polymers for textile based transdermal treatments are mentioned in this review.

Thermoresponsive Hydrogels and Their Biomedical Applications: Special Insight into Their Applications in Textile Based Transdermal Therapy

Various natural and synthetic polymers are capable of showing thermoresponsive properties and their hydrogels are finding a wide range of biomedical applications including drug delivery, tissue engineering and wound healing. Thermoresponsive hydrogels use temperature as external stimulus to show sol-gel transition and most of the thermoresponsive polymers can form hydrogels around body temperature. The availability of natural thermoresponsive polymers and multiple preparation methods of synthetic polymers, simple preparation method and high functionality of thermoresponsive hydrogels offer many advantages for developing drug delivery systems based on thermoresponsive hydrogels. In textile field applications of thermoresponsive hydrogels, textile based transdermal therapy is currently being applied using drug loaded thermoresponsive hydrogels. The current review focuses on the preparation, physico-chemical properties and various biomedical applications of thermoresponsive hydrogels based on natural and synthetic polymers and especially, their applications in developing functionalized textiles for transdermal therapies. Finally, future prospects of dual responsive (pH/temperature) hydrogels made by these polymers for textile based transdermal treatments are mentioned in this review.

Preclinical development of drug delivery systems for paclitaxel-based cancer chemotherapy

Paclitaxel (PTX) is one of the most successful drugs ever used in cancer chemotherapy, acting against a variety of cancer types. Formulating PTX with Cremophor EL and ethanol (Taxol®) realized its clinical potential, but the formulation falls short of expectations due to side effects such as peripheral neuropathy, hypotension, and hypersensitivity. Abraxane®, the albumin bound PTX, represents a superior replacement of Taxol® that mitigates the side effects associated with Cremophor EL. While Abraxane® is now considered a gold standard in chemotherapy, its 21% response rate leaves much room for further improvement. The quest for safer and more effective cancer treatments has led to the development of a plethora of innovative PTX formulations, many of which are currently undergoing clinical trials. In this context, we review recent development of PTX drug delivery systems and analyze the design principles underpinning each delivery strategy. We chose several representative examples to highlight the opportunities and challenges of polymeric systems, lipid-based formulations, as well as prodrug strategies.

Combining doxorubicin-nanobubbles and shockwaves for anaplastic thyroid cancer treatment: preclinical study in a xenograft mouse model

Anaplastic thyroid cancer is one of the most lethal diseases, and a curative therapy does not exist. Doxorubicin, the only drug approved for anaplastic thyroid cancer treatment, has a very low response rate and causes numerous side effects among which cardiotoxicity is the most prominent. Thus, doxorubicin delivery to the tumor site could be an import goal aimed to improve the drug efficacy and to reduce its systemic side effects. We recently reported that, in human anaplastic thyroid cancer cell lines, combining doxorubicin-loaded nanobubbles with extracorporeal shock waves, acoustic waves used in lithotripsy and orthopedics without side effects, increased the intracellular drug content and in vitro cytotoxicity. In the present study, we tested the efficacy of this treatment on a human anaplastic thyroid cancer xenograft mouse model. After 21 days, the combined treatment determined the greatest drug accumulation in tumors with consequent reduction of tumor volume and weight, and an extension of the tumor doubling time. Mechanistically, the treatment induced tumor apoptosis and decreased cell proliferation. Finally, although doxorubicin caused the increase of fibrosis markers and oxidative stress in animal hearts, loading doxorubicin into nanobubbles avoided these effects preventing heart damage. The improvement of doxorubicin anti-tumor effects together with the prevention of heart damage suggests that the combination of doxorubicin-loaded nanobubbles with extracorporeal shock waves might be a promising drug delivery system for anaplastic thyroid cancer treatment.

A Review of Injectable Polymeric Hydrogel Systems for Application in Bone Tissue Engineering

Biodegradable, stimuli-responsive polymers are essential platforms in the field of drug delivery and injectable biomaterials for application of bone tissue engineering. Various thermo-responsive hydrogels display water-based homogenous properties to encapsulate, manipulate and transfer its contents to the surrounding tissue, in the least invasive manner. The success of bioengineered injectable tissue modified delivery systems depends significantly on their chemical, physical and biological properties. Irrespective of shape and defect geometry, injectable therapy has an unparalleled advantage in which intricate therapy sites can be effortlessly targeted with minimally invasive procedures. Using material testing, it was found that properties of stimuli-responsive hydrogel systems enhance cellular responses and cell distribution at any site prior to the transitional phase leading to gelation. The substantially hydrated nature allows significant simulation of the extracellular matrix (ECM), due to its similar structural properties. Significant current research strategies have been identified and reported to date by various institutions, with particular attention to thermo-responsive hydrogel delivery systems, and their pertinent focus for bone tissue engineering. Research on future perspective studies which have been proposed for evaluation, have also been reported in this review, directing considerable attention to the modification of delivering natural and synthetic polymers, to improve their biocompatibility and mechanical properties.

Drug-conjugated polymers as gene carriers for synergistic therapeutic effect

The ability to safely and effectively transfer gene into cells is the fundamental goal of gene delivery. In spite of the best efforts of researchers around the world, gene therapy has limited success. This may be because of several limitations of delivering gene which is one of the greatest technical challenges in the modern medicine. To address these issues, many efforts have been made to bind drugs and genes together by polymers for co-delivery to achieve synergistic effect. Usually, binding interaction of drugs with polymers is either physical or chemical. In case of drug-polymer physical interaction, the efficiency of drugs generally decreases because of separation of drugs from polymers in vivo whenever it comes in contact with charged biofluid/s or cells. While chemical interaction of drug-polymer overcomes the aforementioned obstacle, several problems such as steric hindrance, solubility, and biodegradability hinder it to develop as gene carrier. Considering these benefits and pitfalls, the objective of this review is to discuss the possible extent of drug-conjugated polymers as safe and efficient gene delivery carriers for achieving synergistic effect to combat various genetic disorders.

Recent progress in biomedical applications of Pluronic (PF127): Pharmaceutical perspectives

Most of the administered anti-cancer drugs are hydrophobic in nature and are known to have poor water solubility, short residence time, rapid clearance from the body and systemic side effects. Polymeric-based targeted particulate carrier system has shown to directly deliver the encapsulated anti-cancer drug to the desired site of action and prevent the interaction of encapsulated drug with the normal cells. Pluronic F127 (PF127) has been widely investigated for its broad-range of therodiagnostic applications in biomedical and pharmaceutical sciences, but rapid dissolution in the physiological fluids, short residence time, rapid clearance, and weak mechanical strength are the main shortcomings that are associated with PF127 and have recently been overcome by making various modifications in the structure of PF127 notably through preparation of PF127-based mixed polymeric micelles, PF127-conjugated nanoparticles and PF127-based hydrophobically modified thermogels. In this article, we have briefly discussed the recent studies that have been conducted on various anti-cancer drugs using PF127 as nano-carrier modified with other copolymers and/or conjugated with magnetic nanoparticles. The key findings of these studies demonstrated that the modified form of PF127 can significantly increase the stability of incorporated hydrophobic drugs with enhanced in vitro cytotoxicity and cellular uptake of anti-cancer drugs. Moreover, the modified form of PF127 has also shown its therapeutic potentials as therodiagnostics in various types of tumors and cancers. Hence, it can be concluded that the modified form of PF127 exhibits significant therodiagnostic effects with increased tumor-specific delivery of anti-cancer drugs having minimal toxic effects as compared to PF127 alone and/or other copolymers.

Sulfatide-containing lipid perfluorooctylbromide nanoparticles as paclitaxel vehicles targeting breast carcinoma

Targeted nanoparticle (NP) delivery vehicles are emerging technologies, the full potential of which has yet to be realized. Sulfatide is known to bind to extracellular matrix glycoproteins that are highly expressed in breast tumors. In this study, we report for the first time the combination of sulfatide and lipid perfluorooctylbromide NPs as a targeted breast cancer delivery vehicle for paclitaxel (PTX). PTX-sulfatide-containing lipid perfluorooctylbromide NPs (PTX-SNPs) were prepared using the emulsion/solvent evaporation method. PTX-SNPs exhibited a spherical shape, small particle size, high encapsulation efficiency, and a biphasic release in phosphate-buffered solution. The cytotoxicity study and cell apoptosis assay revealed that blank sulfatide-containing lipid perfluorooctylbromide NPs (SNPs) had no cytotoxicity, whereas PTX-SNPs had greater EMT6 cytotoxicity levels than PTX-lipid perfluorooctylbromide NPs (PTX-NPs) and free PTX. An in vitro cellular uptake study revealed that SNPs can deliver greater amounts of drug with more efficient and immediate access to intracellular targets. In vivo biodistribution measured using high-performance liquid chromatography confirmed that the PTX-SNPs can target breast tumor tissues to increase the accumulation of PTX in these tissues. The in vivo tumor inhibition ability of PTX-SNPs was remarkably higher than PTX-NPs and free PTX. Furthermore, toxicity studies suggested that the blank SNPs had no systemic toxicity. All results suggested that SNPs may serve as efficient PTX delivery vehicles targeting breast carcinoma.

Thermosensitive hydrogels of poly(methyl vinyl ether-co-maleic anhydride) - Pluronic(®) F127 copolymers for controlled protein release

Thermosensitive hydrogels are of a great interest due to their many biomedical and pharmaceutical applications. In this study, we synthesized a new series of random poly (methyl vinyl ether-co-maleic anhydride) (Gantrez(®) AN, GZ) and Pluronic(®) F127 (PF127) copolymers (GZ-PF127), that formed thermosensitive hydrogels whose gelation temperature and mechanical properties could be controlled by the molar ratio of GZ and PF127 polymers and the copolymer concentration in water. Gelation temperatures tended to decrease when the GZm/PF127 ratio increased. Thus, at a fixed GZm/PF127 value, sol-gel temperatures decreased at higher copolymer concentrations. Moreover, these hydrogels controlled the release of proteins such as bovine serum albumin (BSA) and recombinant recombinant kinetoplastid membrane protein of Leishmania (rKMP-11) more than the PF127 system. Toxicity studies carried out in J774.2 macrophages showed that cell viability was higher than 80%. Finally, histopathological analysis revealed that subcutaneous administration of low volumes of these hydrogels elicited a tolerable inflammatory response that could be useful to induce immune responses against the protein cargo in the development of vaccine adjuvants.

Docetaxel-loaded thermoresponsive conjugated linoleic acid-incorporated poloxamer hydrogel for the suppression of peritoneal metastasis of gastric cancer

We evaluated the potential of a thermoresponsive hydrogel consisting of conjugated linoleic acid-coupled Pluronic F-127 (Plu-CLA) as a controlled release, intraperitoneal delivery system for docetaxel with the aim of treating peritoneal dissemination of gastric cancer. Previously, we established a peritoneal metastasis model that involves the injection of BALB/c mice with TMK1 human gastric cancer cells. One week after the TMK1 cells were injected, the mice were injected intraperitoneally with docetaxel alone or docetaxel-loaded Plu-CLA. Tumor progression and response to therapy were monitored by micro-positron emission tomography. The total number of peritoneal tumors and the ascites volume were also measured. Compared with docetaxel alone, the combination of docetaxel and Plu-CLA (docetaxel-Plu-CLA) significantly and synergistically reduced tumor cell survival. Docetaxel-Plu-CLA showed excellent anti-tumor activity, inducing apoptosis more potently than docetaxel alone. Docetaxel-Plu-CLA also significantly reduced the number of peritoneal metastatic nodules and increased survival in the peritoneal gastric cancer xenograft model. Our results show that intraperitoneal administration of docetaxel-Plu-CLA synergistically inhibits peritoneal metastasis and prolongs survival in a peritoneal gastric cancer model. Therefore, Plu-CLA is a potential intraperitoneal-route carrier for hydrophobic docetaxel for the effective treatment of peritoneal metastatic gastric cancer.

Adjustable degradation and drug release of a thermosensitive hydrogel based on a pendant cyclic ether modified poly(ε-caprolactone) and poly(ethylene glycol)co-polymer

The convenient and precise fabrication of drug-hydrogel formulations with satisfactory degradability and a well-controlled drug release profile are crucial factors for injectable hydrogel formulations in clinical applications. Here a new injectable thermosensitive hydrogel formed from poly(ε-caprolactone) (PCL)-poly(ethylene glycol)-poly(ε-caprolactone) amphiphilicco-polymers with 1,4,8-trioxa[4.6]spiro-9-undecanone (TOSUO) moieties incorporated in the poly(ε-caprolactone) (PCL)block (PECT) was constructed to provide a route to tailor the degradation and drug release behavior. The effect of hydrophilic cyclic ether moieties on the degradation of and drug release by PECT hydrogels were evaluated in vitro and in vivo. The results indicated that a freeze-dried powder of paclitaxel-loaded PECT nanoparticles rapidly dissolved in water at ambient temperature with slightly shaking and formed a stable injectable in situ drug-hydrogel formulation at body temperature, which is convenient for clinical operations because it avoids the need for pre-quenching or long-term incubation. The paclitaxel distribution was also more quantitative and homogeneous on entrapping paclitaxel in PECT nanoparticles. Further, the small number of pendant cyclic ether groups in PCL could decrease the cystallinity and hydrophobicity and, as a result, the in vitro and in vivo retention time of PECT hydrogels and the release of entrapped paclitaxel could be tuned from a few weeks to months by varying the amount of PTOSUO in the hydrophobic block. Significantly, paclitaxel-loaded PECT nanoparticles and free paclitaxel could be simultaneously released during the in vitro paclitaxel release from PECT hydrogels. A histopathological evaluation indicated that in vivo injected PECT hydrogels produced only a modest inflammatory response. Thus pendant cyclic ether modification of PCL could be an effective way to achieve the desired degradation and drug release profiles of amphiphilicco-polymer thermosensitive hydrogels and PECT hydrogels may be suitable for local drug delivery.

Doxorubicin-loaded silk films: drug-silk interactions and in vivo performance in human orthotopic breast cancer

Breast cancer is the most common of all malignant diseases in women. Systemic chemotherapy provides low clinical benefit for locoregional control of the disease, while localised chemotherapy may provide a therapeutic advantage. In this study, doxorubicin-loaded silk films were directly applied to tumours. Affinity binding studies demonstrated that the adsorption of doxorubicin onto silk was partially dependent on crystallinity. By manipulating silk crystallinity, or β-sheet content, the doxorubicin release rate could be controlled ranging from immediate release to prolonged release over >4 weeks. The therapeutic impact of doxorubicin-loaded silk films on primary tumour growth and metastasis was assessed in mice using a humanised orthotopic breast cancer model (adenocarcinoma). Both soluble and stabilised silk films loaded with doxorubicin had a significantly greater primary tumour response than the equivalent dose of doxorubicin administered intravenously in the absence of the silk film carrier. In addition to reducing primary tumour growth, stabilised silk films loaded with doxorubicin also reduced metastatic spread and autopsy indicated that these films were not associated with any local or systemic toxicities. Collectively, these results suggest that the future use of this approach for localised chemotherapy is promising.

Glycyrrhizin-modified O-carboxymethyl chitosan nanoparticles as drug vehicles targeting hepatocellular carcinoma

Here we describe the O-carboxymethyl chitosan nanoparticles (CMCNP) modified by glycyrrhizin (GL) with various substitution degrees as hepatocellular carcinoma (HCC)-targeted delivery vehicles, which could efficiently deliver paclitaxel (PTX) into HCC. The resultant CMCNP-GL exhibited spherical in shape and high stability in plasma with fixed negative charged (~-30 mV) and a size range of 100-205 nm. PTX was loaded into CMCNP-GL with a maximal encapsulation efficiency of 83.7% and performed a biphasic release. CMCNP-GL promoted liver cancer SMMC-7721 cell internalization by approximate 10.0-fold as compared to unmodified CMCNP. Within 72 h, the IC(50) of PTX/CMCNP-GL, PTX/CMCNP, and PTX injection was 2.7-3.2, 8.1, and 13.5 μg/mL, respectively. Biodistribution experiments revealed that PTX/CMCNP-GL exerted significantly superior targeting to tumor than PTX/CMCNP. The in vivo tumor inhibition ratio of PTX/CMCNP-GL was 87.5%, showing remarkably higher than that of PTX/CMCNP (64.0%) and PTX injection (34.5%). CMCNP-GL with different substitution degrees possessed similar targeting property and therapeutic efficacy. Furthermore, toxicity studies suggested that blank CMCNP-GL had no systemic or hepatic toxicity.

Enhanced solubility and functionality of valrubicin (AD-32) against cancer cells upon encapsulation into biocompatible nanoparticles

Among numerous drug-delivery approaches, reconstituted high-density lipoprotein (rHDL) nanocarriers have proven particularly applicable for delivering highly hydrophobic drugs. In this study, we have investigated the enhancement of the therapeutic impact of valrubicin (AD-32), an antineoplastic agent that has been limited to intravesicular application against bladder cancer, despite the encouraging original preclinical data. Earlier studies validated the superior therapeutic efficacy of AD-32 over doxorubicin. In the present study, rHDL/AD-32 nanoparticles were formulated and characterized with regard to encapsulation efficiency, physicochemical properties, selective toxicity, and receptor-mediated uptake. The half maximal inhibitory concentration values (IC₅₀) for rHDL/AD-32 nanoparticles were 1.8 and 2.6 times lower than the free AD-32 for prostate (PC-3) and ovarian (SKOV-3) cancer cell lines, respectively, whereas nonmalignant cell lines demonstrated 5 and 1.48 times higher IC₅₀ doses with rHDL/AD-32 formulations. The data obtained demonstrated effective receptor- mediated uptake of AD-32 from the rHDL nanocarriers by PC-3 and SKOV-3 cancer cells via a targeted drug-delivery process. The rHDL/AD-32 formulation was stable for 6 months when stored at 4°C or at −20°C, as 92% of the AD-32 was retained in the nanoparticles. The findings from this study show that the rHDL/AD-32 formulation can overcome the solubility barriers of AD-32 and thus serve as an effective systemically administered chemotherapeutic agent.

Synergistic effects of Akt1 shRNA and paclitaxel-incorporated conjugated linoleic acid-coupled poloxamer thermosensitive hydrogel on breast cancer

The phosphoinositide 3-kinase/Akt1 signaling pathway has emerged as a target for cancer therapy. In this study, we aimed to develop a strategy to enhance Akt-targeted cancer therapy. We hypothesized that combination of Akt1-targeted therapy with conventional chemotherapy using paclitaxel-incorporated conjugated linoleic acid-coupled poloxamer thermosensitive hydrogel may have synergistic effects in cancer therapeutic efficiency compared with chemotherapy alone. In this study, we found that the combination of shAkt1 with paclitaxel exerted synergistic anti-cancer effects, thus, inhibiting the growth of human breast cancer cells, and breast cancer xenografts in mice as well. The combination therapy demonstrated enhanced anti-cancer effects through inhibiting Akt1 signaling and inducing apoptosis. Our results suggest that the presented strategy of combination of shAkt1 with paclitaxel may have a potential for treatment of breast cancer.

Synthesis and characterization of novel amphiphilic copolymer stearic acid-coupled F127 nanoparticles for nano-technology based drug delivery system

Pluronic, F127, amphiphilic block copolymers, are used for several applications, including drug delivery systems. The critical micelle concentration (CMC) of F127 is about 0.26-0.8 wt% so that the utility of F127 in nano-technology based drug delivery system is limited since the nano-sized micelles could dissociate upon dilution. Herein, stearic acid (SA) was simply coupled to F127 between the carboxyl group of SA and the hydroxyl group of F127, which formed a novel copolymer named as SA-coupled F127, with significantly lower CMC. Above the CMC 6.9 × 10(-5)wt%, SA-coupled F127 self-assembled stable nanoparticles with Zeta potential -36 mV. Doxorubicin (DOX)-loaded nanoparticles were made, with drug loading (DL) 5.7 wt% and Zeta potential -36 to -39 mV, and the nanoparticles exhibited distinct shape with the size distribution from 20 to 50 nm. DOX-loaded nanoparticles were relatively stable and exhibited DOX dependant cytotoxicity toward MCF-7 cells in vitro. These results suggest that SA-coupled F127 potentially could be applied as a nano-technology based drug delivery method.

Thermoreversible Pluronic F127-based hydrogel containing liposomes for the controlled delivery of paclitaxel: in vitro drug release, cell cytotoxicity, and uptake studies

Purpose

To develop an in situ gel system comprising liposome-containing paclitaxel (PTX) dispersed within the thermoreversible gel (Pluronic^® F127 gel) for controlled release and improved antitumor drug efficiency.

Methods

The dialysis membrane and membrane-less diffusion method were used to investigate the in vitro drug release behavior. Differential scanning calorimetry (DSC) thermal analysis was used to investigate the “micellization” and “sol/gel transition” process of in situ gel systems. In vitro cytotoxicity and drug uptake in KB cancer cells were determined by MTT, intercellular drug concentration, and fluorescence intensity assay.

Results

The in vitro release experiment performed with a dialysis membrane model showed that the liposomal gel exhibited the longest drug-release period compared with liposome, general gel, and commercial formulation Taxol^®. This effect is presumably due to the increased viscosity of liposomal gel, which has the effect of creating a drug reservoir. Both drug and gel release from the in situ gel system operated under zero-order kinetics and showed a correlation of release of PTX with gel, indicating a predominating release mechanism of the erosion type. Dispersing liposomes into the gel replaced larger gel itself for achieving the same gel dissolution rate. Both the critical micelle temperature and the sol/gel temperature, detected by DSC thermal analysis, were shifted to lower temperatures by adding liposomes. The extent of the shifts depended on the amount of embedded liposomes. MTT assay and drug uptake studies showed that the treatment with PTX-loaded liposomal 18% Pluronic F127 yielded cytotoxicities, intercellular fluorescence intensity, and drug concentration in KB cells much higher than that of conventional liposome, while blank liposomal 18% Pluronic F127 gel was far less than the Cremophor EL^® vehicle and empty liposomes.

Conclusions

A thermosensitive hydrogel with embedded liposome is a promising carrier for hydrophobic anticancer agents, to be used in parenteral formulations for treating local cancers.

The therapeutic efficacy of conjugated linoleic acid - paclitaxel on glioma in the rat

Considering the effects of conjugated linoleic acid (CLA) on anti-tumor and anti-angiogenic in brain tumor, synergistic anti-tumor activity with taxane as well as potential activity for transporting chemotherapeutic agents across the blood-brain barrier (BBB), the purpose of this study was to synthesize CLA-paclitaxel (CLA-PTX) conjugate which could reach to the brain tissue and target brain tumor. The CLA was covalently linked to PTX. The conjugate was stable in PBS and rat plasma in vitro and had no microtubule assembly activity in solution and slight effect of arresting cell cycle progression at the G(2)-M phase. The in vitro cytotoxicity of conjugate was lower than that of PTX (p < 0.05). The conjugate showed higher cellular uptake efficiency on C6 glioma cells. The entire pharmacokinetic index revealed the significant enhancement of the conjugate pharmacokinetics compared with that in PTX (p < 0.01). The conjugate, unlike PTX, could distribute in brain tissue and retained higher concentrations throughout 360 h. The anti-tumor efficacy in brain tumor-bearing rats after administering conjugate was significantly higher than that after giving Taxol (p < 0.01). In conclusion, this CLA-PTX conjugate showed great potential to become a new prodrug of PTX and the methodology can be applied to other anticancer drugs.

Injectable delivery system of 2-methoxyestradiol for breast cancer therapy using biodegradable thermosensitive poly(organophosphazene) hydrogel

2-Methoxyestradiol (2-ME) has been reported to have antiangiogenic and antitumor activity. Its biomedical application is limited due to its poor water solubility resulting in its low bioavailability. Poly(organophosphazenes) containing l-isoleucine ethyl ester, ethyl-2-(O-glycyl)lactate, and α-amino-ω-methoxy-poly(ethylene glycol) 550 were synthesized having M(W) of 35-38 kDa and polydispersity index of 2.38-2.73. Using a viscometer, the thermosensitivity useful for locally injectable drug delivery was verified. The aqueous polymer solution showed a sol state at a low temperature and transformed to a gel state at body temperature. The polymer solution (10 wt%) enhanced the solubility of 2-ME by about 10(4) times compared to that of phosphate buffered saline. 2-ME was released from the hydrogel mainly by diffusion, hydrophobic interaction, and surface erosion of the matrix. This release profile could be confirmed through an in vitro release test as a function of polymers and the concentration of 2-ME in hydrogels. By monitoring tumor volume and CD31 immunohistochemical staining in mouse orthotopic breast tumor (MDA-MB-231) model, it was found that the hydrogel containing a relatively low concentration (15 mg/kg) of 2-ME showed the improved antitumor and antiangiogenic activity relative to the original formulation. This research suggests that the developed formulation of poly(organophosphazenes) may have injectable carrier potentials for 2-ME and other lipophilic drugs.

Chitosan film containing poly(D,L-lactic-co-glycolic acid) nanoparticles: a platform for localized dual-drug release

PURPOSE

To characterize and evaluate chitosan film containing PLGA nanoparticles (NPs) as a platform for localized dual-drug release.

METHODS

Fluorescent Paclitaxel (FPTX), a hydrophobic drug, was incorporated into PLGA NPs. FPTX-loaded PLGA NPs and Carboxyfluorescein (CF), a hydrophilic model drug, were embedded into chitosan films. Release of CF and NPs from chitosan and release of FPTX from PLGA NPs were monitored by fluorescence. The stability of the platform was observed through SEM and dynamic light scattering (DLS).

RESULTS

Chitosan films containing CF and FPTX-loaded PLGA NPs showed a biphasic release profile. In the first phase, 78% of CF and 34% of NPs were released within few days. In the second phase, the release was slower, showing an additional release of 22% of CF and 18% of NPs after 3 weeks. SEM images and DLS measurements showed that NP release depends on film degradation rate. FPTX-loaded PLGA NPs showed the release of 19.8% of total drug in 2 days, and no additional release was detected in the next 26 days.

CONCLUSIONS

The ability of chitosan film containing PLGA NPs to coat gold surface and to incorporate and release two different drugs of different hydrophilicity make it a promising platform for localized dual-drug release.