Redox Responsive Polymersomes for Enhanced Doxorubicin Delivery.

In the present investigation, the potential of a novel, self-assembled, biocompatible, and redox-sensitive copolymer system with disulfide bond was explored for doxorubicin (DOX) delivery through polymersome nanostructures of ∼120 nm. The polymer system was synthesized with less steps, providing a high yield of 86%. The developed polymersomes showed admirable biocompatibility with high dose tolerability in vitro and in vivo. The colloidal stability of DOX-loaded polymersomes depicted a stable and uniform particle size over a period of 72 h. The cellular internalization of polymersomes was assessed in HeLa and MDA-MB-231 cell lines, where enhanced cellular internalization was observed. The dose-dependent cytotoxicity was observed for DOX-loaded polymersomes by MTT cytotoxicity assay in the above cell lines. The tumor suppression studies were assessed in Ehrlich ascites tumor (EAT) carrying Swiss albino mice, where polymersomes exhibited a 7.16-fold reduction in tumor volume correlated with control and 5.39-fold higher tumor inhibition capacity compared to conventional chemotherapy (free DOX treatment). The developed polymersomes gave safer insights concerning DOX associated toxicities by histopathology and serum biochemistry analysis. Thus, results focus on the potential of redox responsive polymersomes for efficacious and improved DOX therapy with enhanced antitumor activity and insignificant cardiotoxicity which can be translated to clinical settings.

Comparative Assessment of Active Targeted Redox Sensitive Polymersomes Based on pPEGMA-S-S-PLA Diblock Copolymer with Marketed Nanoformulation.

In the present work, polymersomes based on self-assembled, folate-targeted, redox-responsive, ATRP-based amphiphilic diblock copolymer poly(polyethylene glycol)-S-S-polylactide with disulfide linkage were developed for efficient doxorubicin (DOX) delivery and compared with marketed DOXIL nanoformulation. The polymersomes formulation was optimized by quality by design approach providing monodisperse nanostructures of ∼110 nm and enhanced DOX loading of ∼20%. Polymersomes showed excellent stability as per the ICH guidelines over the extended storage period of 3 months. The in vitro drug release profile confirmed the redox sensitive behavior of polymersomes providing ∼80% drug release in endosomal pH 5 with 10 mmol GSH as compared to ∼20% release at pH 7.4. The targeted polymersomes achieved enhanced cellular internalization in folate receptor overexpressing cell lines, MDA-MB-231 and HeLa, providing ∼24% higher tumor reduction than DOXIL in Ehrlich ascites tumor bearing Swiss albino mice.

ATRP Fabricated and Short Chain Polyethylenimine Grafted Redox Sensitive Polymeric Nanoparticles for Codelivery of Anticancer Drug and siRNA in Cancer Therapy.

To overcome the limitations of conventional chemotherapy, nanoparticle-mediated combinatorial delivery of siRNA and drugs represents a new approach to overcome its associated side effects. Designing safe and efficient vehicles for their codelivery has emerged as a potential challenge in the clinical translation of these formulations. Herein, we have demonstrated a novel "two-in-one" polyplex nanosystem developed from redox sensitive, short chain polyethylenimine modified poly[(poly(ethylene)glycol methacrylate]-s-s-polycaprolactone copolymer synthesized by atom-transfer free-radical polymerization (ATRP), which can deliver doxorubicin and polo-like kinase I (plk1) siRNA, simultaneously for an enhanced chemotherapeutic effect. The nanoparticles were found to be stable at physiological buffer with and without fetal bovine serum (FBS). The developed polymeric nanosystem was found to be biocompatible and hemocompatible in vitro and in vivo at repeated dose administrations. The polymer could easily self-assemble into ∼100 nm spherical nanoparticles with enhanced doxorubicin loading (∼18%) and effective siRNA complexation at a polymer to siRNA weight ratio of 15. The doxorubicin loaded nanoparticles exhibited ∼4-fold higher drug release in endosomal pH (pH 5) containing 10 mmol of GSH compared to pH 7.4, depicting their redox-sensitive behavior. The polyplexes were capable of delivering both cargos simultaneously to cancer cells in vitro as observed by their excellent colocalization in the cytoplasm of MDA-MB-231 and HeLa cells using confocal laser microscopy. Moreover, in vitro transfection of the cells with polyplexes exhibited 50-70% knockdown of plk1-mRNA expression in both cell lines. In vivo administration of the drug loaded polyplexes to EAT tumor bearing (EAT, Ehrlich ascites tumor) Swiss albino mice showed a ∼29-fold decrease in percent tumor volume in comparison to the control group. The results highlight the therapeutic potential of the polyplexes as a combined delivery of doxorubicin and plk1-siRNA in cancer therapy.

Self assembled dual responsive micelles stabilized with protein for co-delivery of drug and siRNA in cancer therapy.

Design of safe and efficient vehicles for the combinatorial delivery of drugs and genetic agents is an emerging requisite for achieving enhanced therapeutic effect in cancer. Even though several nanoplatforms have been explored for the co-delivery of drugs and genetic materials the translation of these systems to clinical phase is still a challenge, mainly due to tedious synthesis procedures, lack of serum stability, inefficient scalability etc. Here in, we report development of reduction and pH sensitive polymeric graft of low molecular weight poly (styrene -alt -maleic anhydride) and evaluation of its efficacy in co-delivering drug and siRNA. The polymer was modified with suitable components, which could help in overcoming various systemic and cellular barriers for successful co-delivery of drugs and nucleic acids to cancer cells, using simple chemical reactions. The polymeric derivative could easily self assemble in water to form smooth, spherical micellar structures, indicating their scalability. Doxorubicin and PLK-1 siRNA were selected as model drug and nucleic acid, respectively. Doxorubicin could be loaded in the self assembling micelles with an optimum loading content of ∼8.6% w/w and efficient siRNA complexation was achieved with polymer/siRNA weight ratios >40. The polyplexes were stabilized in physiological saline by coating with bovine serum albumin (BSA). Stable drug loaded nanoplexes, for clinical administration, could be easily formulated by gently dispersing them in physiological saline containing appropriate amount of albumin. Drug release from the nanoplexes was significantly enhanced at low pH (5) and in the presence of 10 mM glutathione (GSH) showing their dual stimuli sensitive nature. In vitro cell proliferation assay and in vivo tumor regression study have shown synergistic effect of the drug loaded nanoplexes in inhibiting cancer cell proliferation. Facile synthesis steps, scalability and ease of formulation depict excellent clinical translation potential of the proposed nanosystem.

Combinatorial delivery of superparamagnetic iron oxide nanoparticles (γFe2O3) and doxorubicin using folate conjugated redox sensitive multiblock polymeric nanocarriers for enhancing the chemotherapeutic efficacy in cancer cells.

Redox sensitive, folate conjugated multiblock polymeric system of (-PLGA-PEG-PLGA-urethane-ss-) demonstrated self-assembly into stable nanoplatforms. The polymeric nanocarriers were encapsulated with doxorubicin and highly crystalline γFe2O3 superparamagnetic iron oxide nanoparticles (SPIONs), for co-delivery of the same to cancer cells, with average particle size of ~170nm and zeta potential of ~-33mV. Furthermore, the designed formulation was evaluated for protein adsorption, hemo-cytocompatibility and stability. Glutathione (GSH) induced redox sensitivity of the nanocarriers was depicted by ~4.47 fold increase in drug release in the presence of 10mM GSH. In vitro cellular uptake studies of the designed nanocarriers showed synergistic cytotoxic effect in folate overexpressing cells (HeLa and MDA-MB-231), after subjecting the cells to radio frequency (RF) induced hyperthermia (~43°C). Negligible effect of the combinatorial therapy was observed in normal cells (L929). The developed polymeric system depicted facile synthesis, reproducibility and potential for achieving combinatorial and targeted delivery of drug and SPIONs to cancer cells. This combinatorial approach can help in achieving better therapeutic effect with minimal side effects of chemotherapy.

Click modified amphiphilic graft copolymeric micelles of poly(styrene-alt-maleic anhydride) for combinatorial delivery of doxorubicin and plk-1 siRNA in cancer therapy.

The anti-apoptotic defense mechanism of cancer cells poses a major hurdle which makes chemotherapy less effective. Combinatorial delivery of drugs and siRNAs targeting anti-apoptotic proteins is a vital means for improving therapeutic effects. The present study aims at designing a suitable carrier which can effectively co-deliver doxorubicin and plk1 siRNA to tumor cells. Low molecular weight poly(styrene-alt-maleic anhydride) was chemically modified via a click reaction to obtain a cationic amphiphilic polymer for the co-delivery of therapeutic agents. Short glycol chains were utilized as linker molecules for grafting which in turn imparted a stealth nature and minimized plasma protein adsorption to the polymeric surface. Isonicotinic acid was grafted to the polymer due to its ability to penetrate the endolysosomal membrane and arginine-lysine conjugates were embedded for complexing siRNA. The polymer was able to self-assemble in to smooth, spherical micellar structures with a CMC of ∼3 µg mL-1. The particle size of the micelles was ∼14-30 nm as depicted using TEM and FESEM. Atomic force microscopic analysis showed an average height of ∼12 nm for the polymeric micelles. An optimum doxorubicin loading of ∼9% w/w was achieved with the micelles using a dialysis method. Effective complexation of siRNA occurred above a polymer/siRNA weight ratio of 10 without any significant change in the particle size. Doxorubicin and fluorescent labeled siRNA loaded micelles exhibited excellent co-localization within the cytoplasm of MCF-7 cells. The synergistic effect of the active agents in inhibiting tumor cell proliferation was depicted using an MTT assay and visualized using calcein/propidium iodide staining of the treated cells. Co-administration of doxorubicin and plk1 siRNA in EAT tumor bearing Swiss albino mice using the cationic micelles significantly enhanced the antitumor efficacy.

Development and evaluation of paclitaxel loaded PLGA:poloxamer blend nanoparticles for cancer chemotherapy.

This investigation described the development of novel PLGA:poloxamer blend nanoparticles for intravenous administration of paclitaxel in order to limit the cremophor-associated adverse effects. The developed formulation was well-characterized using various techniques including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. The nanoparticles had an average particle size around 180nm and zeta potential of -22.7mV. The in vitro release study of nanoparticles exhibited biphasic release pattern. The non-hemolytic potential of the nanoparticles indicated the suitability of the developed formulation for intravenous administration. The PLGA:poloxamer blend nanoparticles showed significantly improved cytotoxicity in cell lines (MCF-7 and Colo-205), as compared to free drug. Further, the developed formulation was stable under the accelerated storage conditions. In conclusion, the results indicated that the developed polymeric formulation is a novel and potential alternative for the paclitaxel delivery.

Paclitaxel formulations: challenges and novel delivery options.

Paclitaxel (PTX), a taxane plant product, is one of the most effective broad-spectrum anti-cancer agents and approved for the treatment of a variety of cancers including ovarian, breast, lung, head and neck as well as Kaposi's sarcoma. Poor aqueous solubility and serious side effects associated with commercial preparation of PTX (Taxol®) triggered the development of alternative PTX formulations. Over past three decades, plethora of research work has been published towards the development of cremophor free and efficient formulations. Various nanocarrier systems including nanoparticles, liposomes, micelles, bioconjugates and dendrimers have been employed in order to improve PTX solubility and eliminate undesired side effects. These nanocarriers offer the advantage of high degree of encapsulation and cellular uptake, escape from elimination by P-glycoprotein (P-gp) mediated efflux, and can be explored for targeted drug delivery. The potential of these nanocarriers is reflected by the fact that various nanocarriers of PTX are in different stages of clinical trials and a few have already been commercialized including Abraxane®, Lipusu and Genexol PM®. This review focuses on the various challenges associated with PTX formulation development, limitations of existing formulations and novel approaches for the development of alternative formulations for PTX and also highlights the development of novel formulations in clinical settings.