Mitochondrial nanomedicine: Subcellular organelle-specific delivery of molecular medicines.

As mitochondria network together to act as the master sensors and effectors of apoptosis, ATP production, reactive oxygen species management, mitophagy/autophagy, and homeostasis; this organelle is an ideal target for pharmaceutical manipulation. Mitochondrial dysfunction contributes to many diseases, for example, ß-amyloid has been shown to interfere with mitochondrial protein import and induce apoptosis in Alzheimer's Disease while some forms of Parkinson's Disease are associated with dysfunctional mitochondrial PINK1 and Parkin proteins. Mitochondrial medicine has applications in the treatment of an array of pathologies from cancer to cardiovascular disease. A challenge of mitochondrial medicine is directing therapies to a subcellular target. Nanotechnology based approaches combined with mitochondrial targeting strategies can greatly improve the clinical translation and effectiveness of mitochondrial medicine. This review discusses mitochondrial drug delivery approaches and applications of mitochondrial nanomedicines. Nanomedicine approaches have the potential to drive the success of mitochondrial therapies into the clinic.

Cluster of Differentiation 44 Targeted Hyaluronic Acid Based Nanoparticles for MDR1 siRNA Delivery to Overcome Drug Resistance in Ovarian Cancer.

PURPOSE: Approaches for the synthesis of biomaterials to facilitate the delivery of "biologics" is a major area of research in cancer therapy. Here we designed and characterized a hyaluronic acid (HA) based self-assembling nanoparticles that can target CD44 receptors overexpressed on multidrug resistance (MDR) ovarian cancer. The nanoparticle system is composed of HA-poly(ethyleneimine)/HA-poly(ethylene glycol) (HA-PEI/HA-PEG) designed to deliver MDR1 siRNA for the treatment of MDR in an ovarian cancer model. METHODS: HA-PEI/HA-PEG nanoparticles were synthesized and characterized, then the cellular uptake and knockdown efficiency of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles was further determined. A human xenograft MDR ovarian cancer model was established to evaluate the effects of the combination of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles and paclitaxel on MDR tumor growth. RESULTS: Our results demonstrated that HA-PEI/HA-PEG nanoparticles successfully targeted CD44 and delivered MDR1 siRNA into OVCAR8TR (established paclitaxel resistant) tumors. Additionally, HA-PEI/HA-PEG nanoparticles loaded with MDR1 siRNA efficiently down-regulated the expression of MDR1 and P-glycoprotein (Pgp), inhibited the functional activity of Pgp, and subsequently increased cell sensitivity to paclitaxel. HA-PEI/HA-PEG/MDR1 siRNA nanoparticle therapy followed by paclitaxel treatment inhibited tumor growth in MDR ovarian cancer mouse models. CONCLUSIONS: These findings suggest that this CD44 targeted HA-PEI/HA-PEG nanoparticle platform may be a clinicaly relevant gene delivery system for systemic siRNA-based anticancer therapeutics for the treatment of MDR cancers.

High-Grade Endometrial Cancer: Molecular Subtypes, Current Challenges, and Treatment Options.

Although many recent advancements have been made in women's health, perhaps one of the most neglected areas of research is the diagnosis and treatment of high-grade endometrial cancer (EnCa). The molecular classification of EnCa in concert with histology was a major step forward. The integration of profiling for mismatch repair deficiency and Human Epidermal Growth Factor 2 (HER2) overexpression, can further inform treatment options, especially for drug resistant recurrent disease. Recent early phase trials suggest that regardless of subtype, combination therapy with agents that have distinct mechanisms of action is a fruitful approach to the treatment of high-grade EnCa. Unfortunately, although the importance of diagnosis and treatment of high-grade EnCa is well recognized, it is understudied compared to other gynecologic and breast cancers. There remains a tremendous need to couple molecular profiling and biomarker development with promising treatment options to inform new treatment strategies with higher efficacy and safety for all who suffer from high-grade recurrent EnCa.

Combination Organelle Mitochondrial Endoplasmic Reticulum Therapy (COMET) for Multidrug Resistant Breast Cancer.

It is time for the story of mitochondria and intracellular communication in multidrug resistant cancer to be rewritten. Herein we characterize the extent and cellular advantages of mitochondrial network fusion in multidrug resistant (MDR) breast cancer and have designed a novel nanomedicine that disrupts mitochondrial network fusion and systematically manipulates organelle fusion and function. Combination Organelle Mitochondrial Endoplasmic reticulum Therapy (COMET) is an innovative translational nanomedicine for treating MDR triple negative breast cancer (TNBC) that has superior safety and equivalent efficacy to the current standard of care (paclitaxel). Our study has demonstrated that the increased mitochondrial networks in MDR TNBC contribute to apoptotic resistance and network fusion is mediated by mitofusin2 (MFN2) on the outer mitochondrial membrane. COMET consists of three components; Mitochondrial Network Disrupting (MiND) nanoparticles (NPs) that are loaded with an anti-MFN2 peptide, tunicamycin, and Bam7. The therapeutic rationale of COMET is to reduce the apoptotic threshold in MDR cells with MiND NPs, followed by inducing the endoplasmic reticulum mediated unfolded protein response (UPR) by stressing MDR cells with tunicamycin, and finally, directly inducing mitochondrial apoptosis with Bam7 which is a specific bcl-2 Bax activator. MiND NPs are PEGylated liposomes with the 21 amino acid (2577.98 MW) anti-MFN2 peptide compartmentalized in the aqueous core. Hypoxia (0.5% oxygen) was used to create MDR derivatives of MDA-MB-231 cells and BT-549 cells. Mitochondrial networks were quantified using 3D analysis of 60× live cell images acquired with a Keyence BZ-X710 microscope and MiND NPs effectively fragmented mitochondrial networks in drug sensitive and MDR TNBC cells. The IC50 values, combination index, and dose reduction index derived from dose response studies demonstrate that MiND NPs decrease the apoptotic threshold of both drug sensitive and MDR TNBC cells and COMET is a synergistic drug combination. Complex V (ATP synthase) extracted from bovine cardiac mitochondria was used to assess the effect of MiND NPs on OXPHOS; both MiND NPs and anti-MFN2 peptide solution significantly decrease the activity of mitochondrial complex V and decrease the capacity of OXPHOS. A BacMam viral vector based fluorescent biosensor was used to quantify the unfolded protein response (UPR) at the level of the endoplasmic reticulum and tunicamycin specifically induces the UPR in drug sensitive and MDR TNBC cells. A caspase 3 colorimetric assay demonstrated that the synergistic triple drug combination of COMET increases the ability of Bam7 to specifically induce apoptosis. Dose limiting toxicity and off target effects are a significant challenge for current chemotherapy regimens including paclitaxel. COMET has significantly lower cytotoxicity than paclitaxel in human embryonic kidney epithelial cells and has the potential to fulfill the clinical need for safer cancer therapeutics. COMET is a promising early stage translational nanomedicine for treating MDR TNBC. Manipulating intracellular communication and organelle fusion is a novel approach to treating MDR cancer. The data from this study has rewritten the story of mitochondria, organelle fusion, and intracellular communication and by targeting this intersection, COMET is an exciting new chapter in cancer therapeutics that could transform the clinical outcome of MDR TNBC.

Lessons learned from the SARS-CoV-2 pandemic; from nucleic acid nanomedicines, to clinical trials, herd immunity, and the vaccination divide.

INTRODUCTION: In November 2019, the idea of a zoonotic virus crossing over to human transmission in a seafood market in Wuhan, China, and then soaring across the globe to claim over 6.3 million lives and persisting to date, seemed more like wild science fiction than a future reality. As the SARS-CoV-2 pandemic continues, it is important to hallmark the imprints the pandemic has made on science. AREAS COVERED: This review covers the biology of SARS-CoV-2, vaccine formulations and trials, the concept of 'herd resistance,' and the vaccination divide. EXPERT OPINION: The SARS-CoV-2 pandemic has changed the landscape of medicine. The rapid approval of SARS-CoV-2 vaccines has changed the culture of drug development and clinical approvals. This change is already leading to more accelerated trials. The RNA vaccines have opened the market for nucleic acid therapies and the applications are limitless - from cancer to influenza. A phenomenon that has occurred is that the low efficacy of current vaccines and the rapid mutation rate of the virus is preventing herd immunity from being attained. Instead, herd resistance is being acquired. Even with future, more effective vaccines, anti-vaccination attitudes will continue to challenge the quest for SARS-CoV-2 herd immunity.

Role of hypoxia and glycolysis in the development of multi-drug resistance in human tumor cells and the establishment of an orthotopic multi-drug resistant tumor model in nude mice using hypoxic pre-conditioning.

BACKGROUND: The development of multi-drug resistant (MDR) cancer is a significant challenge in the clinical treatment of recurrent disease. Hypoxia is an environmental selection pressure that contributes to the development of MDR. Many cancer cells, including MDR cells, resort to glycolysis for energy acquisition. This study aimed to explore the relationship between hypoxia, glycolysis, and MDR in a panel of human breast and ovarian cancer cells. A second aim of this study was to develop an orthotopic animal model of MDR breast cancer. METHODS: Nucleic and basal protein was extracted from a panel of human breast and ovarian cancer cells; MDR cells and cells pre-exposed to either normoxic or hypoxic conditions. Western blotting was used to assess the expression of MDR markers, hypoxia inducible factors, and glycolytic proteins. Tumor xenografts were established in the mammary fat pad of nu/nu mice using human breast cancer cells that were pre-exposed to either hypoxic or normoxic conditions. Immunohistochemistry was used to assess the MDR character of excised tumors. RESULTS: Hypoxia induces MDR and glycolysis in vitro, but the cellular response is cell-line specific and duration dependent. Using hypoxic, triple-negative breast cancer cells to establish 100 mm3 tumor xenografts in nude mice is a relevant model for MDR breast cancer. CONCLUSION: Hypoxic pre-conditiong and xenografting may be used to develop a multitude of orthotopic models for MDR cancer aiding in the study and treatment of the disease.

Development of EGFR-targeted polymer blend nanocarriers for combination paclitaxel/lonidamine delivery to treat multi-drug resistance in human breast and ovarian tumor cells.

Multi-drug resistant (MDR) cancer is a significant clinical obstacle and is often implicated in cases of recurrent, nonresponsive disease. Targeted nanoparticles were made by synthesizing a poly(D,L-lactide-co-glycolide)/poly(ethylene glycol)/epidermal growth factor receptor targeting peptide (PLGA/PEG/EGFR-peptide) construct for incorporation in poly(epsilon-caprolactone) (PCL) nanoparticles. MDR was induced in a panel of nine human breast and ovarian cancer cell lines using hypoxia. EGFR-targeted polymer blend nanoparticles were shown to actively target EGFR overexpressing cell lines, especially upon induction of hypoxia. The nanoparticles were capable of sustained drug release. Combination therapy with lonidamine and paclitaxel significantly improved the therapeutic index of both drugs. Treatment with a nanoparticle dose of 1 µM paclitaxel/10 µM lonidamine resulted in less than 10% cell viability for all hypoxic/MDR cell lines and less than 5% cell viability for all normoxic cell lines. Comparatively, treatment with 1 µM paclitaxel alone was the approximate IC50 value of the MDR cells while treatment with lonidamine alone had very little effect. The PLGA/PEG/EGFR-peptide delivery system actively targets a MDR cell by exploiting the expression of EGFR. This system treats MDR by inhibiting the Warburg effect and promoting mitochondrial binding of pro-apoptotic Bcl-2 proteins (lonidamine), while hyperstabilizing microtubules (paclitaxel). This nanocarrier system actively targets a MDR associated phenotype (EGFR receptor overexpression), further enhancing the therapeutic index of both drugs and potentiating the use of lonidamine/paclitaxel combination therapy in the treatment of MDR cancer.

Nanoparticles: a promising modality in the treatment of sarcomas.

Improvements in surgical technique, chemotherapy, and radiotherapy have enhanced the prognosis of sarcoma patients, but have since reached a plateau in recent years. Novel approaches have been sought but with limited results. Nanomedicine offers solutions in diverse areas of sarcoma therapy including diagnosis and treatment. Several varieties of nanoparticles, including multifunctional nanoparticles, are available that localize the biodistribution of conventional chemotherapeutics to the tumor site. Also, nanoparticles loaded with chemotherapeutic drugs have the ability to overcome drug resistance which is a major obstacle impeding the progress of the treatment. Multifunctional nanoparticles, which have the potential to further augment the bioavailability of drugs, are being actively investigated. In this review, we will discuss the application of nanoparticles for improving the treatment of sarcoma patients.

Pharmacokinetics and biodistribution of lonidamine/paclitaxel loaded, EGFR-targeted nanoparticles in an orthotopic animal model of multi-drug resistant breast cancer.

The aim of this study was to assess the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with the anticancer drugs lonidamine and paclitaxel. Plasma, tumor, and tissue distribution profiles were quantified in an orthotopic animal model of multidrug-resistant breast cancer and were compared to treatment with nontargeted nanoparticles and to treatment with drug solution. A poly(d,l-lactide-co-glycolide)-poly(ethylene glycol)-EGFR targeting peptide (PLGA-PEG-EFGR peptide) construct was synthesized for incorporation in poly(ɛ-caprolactone) particles to achieve active EGFR targeting. An isocratic high-pressure liquid chromatography method was developed to quantify lonidamine and paclitaxel in mice plasma, tumors, and vital organs. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, particularly for lonidamine delivery. The first target site of accumulation was the liver, followed by the kidneys, and then the tumor mass; maximal tumor accumulation occured at 3 hours after administration. Lonidamine-paclitaxel combination therapy administered via EGFR-targeted polymer-blend nanocarriers may become a viable platform for the future treatment of multidrug-resistant cancer. FROM THE CLINICAL EDITOR: In this study the biodistribution and pharmacokinetics of epidermal growth factor receptor (EGFR)-targeted polymer-blend nanoparticles loaded with lonidamine and paclitaxel were assessed. The targeted nanoparticles demonstrated a superior pharmacokinetic profile relative to drug solution and nontargeted nanoparticles, paving the way to new therapeutic approaches for multidrug-resistant malignancies.

Clinical approval of nanotechnology-based SARS-CoV-2 mRNA vaccines: impact on translational nanomedicine.

One year after the first human case of SARS-CoV-2, two nanomedicine-based mRNA vaccines have been fast-tracked, developed, and have received emergency use authorization throughout the globe with more vaccine approvals on the heels of these first two. Several SARS-CoV-2 vaccine compositions use nanotechnology-enabled formulations. A silver lining of the COVID-19 pandemic is that the fast-tracked vaccine development for SARS-CoV-2 has advanced the clinical translation pathway for nanomedicine drug delivery systems. The laboratory science of lipid-based nanoparticles was ready and rose to the clinical challenge of rapid vaccine development. The successful development and fast tracking of SARS-CoV-2 nanomedicine vaccines has exciting implications for the future of nanotechnology-enabled drug and gene delivery; it demonstrates that nanomedicine is necessary and critical to the successful delivery of advanced molecular therapeutics such as nucleic acids, it is establishing the precedent of safety and the population effect of phase four clinical trials, and it is laying the foundation for the clinical translation of more complex, non-lipid nanomedicines. The development, fast-tracking, and approval of SARS-CoV-2 nanotechnology-based vaccines has transformed the seemingly daunting challenges for clinically translating nanomedicines into measurable hurdles that can be overcome. Due to the tremendous scientific achievements that have occurred in response to the COVID-19 pandemic, years, perhaps even decades, have been streamlined for certain translational nanomedicines.

Technologies and Standardization in Research on Extracellular Vesicles.

Extracellular vesicles (EVs) are phospholipid bilayer membrane-enclosed structures containing RNAs, proteins, lipids, metabolites, and other molecules, secreted by various cells into physiological fluids. EV-mediated transfer of biomolecules is a critical component of a variety of physiological and pathological processes. Potential applications of EVs in novel diagnostic and therapeutic strategies have brought increasing attention. However, EV research remains highly challenging due to the inherently complex biogenesis of EVs and their vast heterogeneity in size, composition, and origin. There is a need for the establishment of standardized methods that address EV heterogeneity and sources of pre-analytical and analytical variability in EV studies. Here, we review technologies developed for EV isolation and characterization and discuss paths toward standardization in EV research.

Genetic and epigenetic strategies for advancing ovarian cancer immunotherapy.

INTRODUCTION: Immuno-oncology is currently the most popular field of cancer research and development. The surge of interest in immuno-oncology stems from recent clinical approvals and successes in clinical trials with new immuno-therapeutics and parallels a global trending interest in immunology. Among the current immunotherapeutic modalities, immune checkpoint inhibitors (ICPIs) are some of the most prominent agents that strengthens the activity of our adaptive immune system, and has demonstrated success in treating different types of cancer. With significant promises in melanoma and other solid tumors, ICPIs have also been evaluated in ovarian cancer (OC). Contrary to expectations, their efficacy for treating OC is unfortunately very low. AREAS COVERED: In this review, immunotherapy response in OC will be evaluated in the context of disease genetics and epigenetics, with a focus on checkpoint blockade. Also, novel genetic and epigenetic therapies that show synergistic potential with current immunotherapies will be examined in detail. EXPERT OPINION: The low response rate of OC to current immune checkpoint therapies may be due to the highly immunosuppressive tumor microenvironment (TME) of the disease. The application of genetic and epigenetic agents can pave the way for overcoming this barrier in OC immunotherapy.

Hyaluronic acid targeting of CD44 for cancer therapy: from receptor biology to nanomedicine.

Cluster of differentiation-44 (CD44) is a ubiquitously present glycoprotein on the surface of mammalian cells that plays a significant role in a number of biological functions. Since the discovery that the receptor is over-expressed in a variety of solid tumors, such as pancreatic, breast and lung cancer, many studies have focused on methods for targeting CD44 in an attempt to improve drug delivery and discrimination between healthy and malignant tissue, while reducing residual toxicity and off-target accumulation. In this review, we describe CD44 receptor biology and its involvement in the different stages of tumor growth and metastasis, as well as methods currently used for targeting the receptor. Hyaluronic acid, the primary CD44 binding molecule, has proved a significant ally in developing nanocarriers that demonstrate preferential tumor accumulation and increased cell uptake. We outline a number of research approaches from the current literature that take advantage of hyaluronic acid's targeting ability and describe the possible advantages for each approach. The value of CD44 targeting can be easily appreciated from the number of different approaches that have reached clinical trials.

Exosome mediated communication within the tumor microenvironment.

It is clear that exosomes (endosome derived vesicles) serve important roles in cellular communication both locally and distally and that the exosomal process is abnormal in cancer. Cancer cells are not malicious cells; they are cells that represent 'survival of the fittest' at its finest. All of the mutations, abnormalities, and phenomenal adaptations to a hostile microenvironment, such as hypoxia and nutrient depletion, represent the astute ability of cancer cells to adapt to their environment and to intracellular changes to achieve a single goal - survival. The aberrant exosomal process in cancer represents yet another adaptation that promotes survival of cancer. Cancer cells can secrete more exosomes than healthy cells, but more importantly, the content of cancer cells is distinct. An illustrative distinction is that exosomes derived from cancer cells contain more microRNA than healthy cells and unlike exosomes released from healthy cells, this microRNA can be associated with the RNA-induced silencing complex (RISC) which is required for processing mature and biologically active microRNA. Cancer derived exosomes have the ability to transfer metastatic potential to a recipient cell and cancer exosomes function in the physical process of invasion. In this review we conceptualize the aberrant exosomal process (formation, content selection, loading, trafficking, and release) in cancer as being partially attributed to cancer specific differences in the endocytotic process of receptor recycling/degradation and plasma membrane remodeling and the function of the endosome as a signaling entity. We discuss this concept and, to advance comprehension of exosomal function in cancer as mediators of communication, we detail and discuss exosome biology, formation, and communication in health and cancer; exosomal content in cancer; exosomal biomarkers in cancer; exosome mediated communication in cancer metastasis, drug resistance, and interfacing with the immune system; and discuss the therapeutic manipulation of exosomal content for cancer treatment including current clinical trials of exosomal therapeutics. Often referred to as cellular nanoparticles, understanding exosomes, and how cancer cells use these cellular nanoparticles in communication is at the cutting edge frontier of advancing cancer biology.

Mitochondrial biology, targets, and drug delivery.

In recent years, mitochondrial medicine has emerged as a new discipline resting at the intersection of mitochondrial biology, pathology, and pharmaceutics. The central role of mitochondria in critical cellular processes such as metabolism and apoptosis has placed mitochondria at the forefront of cell science. Advances in mitochondrial biology have revealed that these organelles continually undergo fusion and fission while functioning independently and in complex cellular networks, establishing direct membrane contacts with each other and with other organelles. Understanding the diverse cellular functions of mitochondria has contributed to understanding mitochondrial dysfunction in disease states. Polyplasmy and heteroplasmy contribute to mitochondrial phenotypes and associated dysfunction. Residing at the center of cell biology, cellular functions, and disease pathology and being laden with receptors and targets, mitochondria are beacons for pharmaceutical modification. This review presents the current state of mitochondrial medicine with a focus on mitochondrial function, dysfunction, and common disease; mitochondrial receptors, targets, and substrates; and mitochondrial drug design and drug delivery with a focus on the application of nanotechnology to mitochondrial medicine. Mitochondrial medicine is at the precipice of clinical translation; the objective of this review is to aid in the advancement of mitochondrial medicine from infancy to application.

Targeted cancer therapy; nanotechnology approaches for overcoming drug resistance.

Recent advances in cancer molecular biology have resulted in parallel and unprecedented progress in the development of targeted cancer therapy. Targeted therapy can provide higher efficacy and lower toxicity than conventional chemotherapy for cancer. However, like traditional chemotherapy, molecularly targeted cancer therapy also faces the challenge of drug resistance. Multiple mechanisms are responsible for chemotherapy resistance in tumors, including over-expression of efflux transporters, somatic alterations of drug targets, deregulation of apoptosis, and numerous pharmacokinetic issues. Nanotechnology based approaches are proving to be efficacious in overcoming drug resistance in cancer. Combination of targeted therapies with nanotechnology approaches is a promising strategy to overcome targeted therapy drug resistance in cancer treatment. This review discusses the mechanisms of targeted drug resistance in cancer and discusses nanotechnology approaches to circumvent this resistance.

Therapeutic efficacy and safety of paclitaxel/lonidamine loaded EGFR-targeted nanoparticles for the treatment of multi-drug resistant cancer.

The treatment of multi-drug resistant (MDR) cancer is a clinical challenge. Many MDR cells over-express epidermal growth factor receptor (EGFR). We exploit this expression through the development of EGFR-targeted, polymer blend nanocarriers for the treatment of MDR cancer using paclitaxel (a common chemotherapeutic agent) and lonidamine (an experimental drug; mitochondrial hexokinase 2 inhibitor). An orthotopic model of MDR human breast cancer was developed in nude mice and used to evaluate the safety and efficacy of nanoparticle treatment. The efficacy parameters included tumor volume measurements from day 0 through 28 days post-treatment, terminal tumor weight measurements, tumor density and morphology assessment through hematoxylin and eosin staining of excised tumors, and immunohistochemistry of tumor sections for MDR protein markers (P-glycoprotein, Hypoxia Inducible Factor, EGFR, Hexokinase 2, and Stem Cell Factor). Toxicity was assessed by tracking changes in animal body weight from day 0 through 28 days post-treatment, by measuring plasma levels of the liver enzymes ALT (Alanine Aminotransferase) and LDH (lactate dehydrogenase), and by white blood cell and platelet counts. In these studies, this nanocarrier system demonstrated superior efficacy relative to combination (paclitaxel/lonidamine) drug solution and single agent treatments in nanoparticle and solution form. The combination nanoparticles were the only treatment group that decreased tumor volume, sustaining this decrease until the 28 day time point. In addition, treatment with the EGFR-targeted lonidamine/paclitaxel nanoparticles decreased tumor density and altered the MDR phenotype of the tumor xenografts. These EGFR-targeted combination nanoparticles were considerably less toxic than solution treatments. Due to the flexible design and simple conjugation chemistry, this nanocarrier system could be used as a platform for the development of other MDR cancer therapies; the use of this system for EGFR-targeted, combination paclitaxel/lonidamine therapy is an advance in personalized medicine.

Multi-modal strategies for overcoming tumor drug resistance: hypoxia, the Warburg effect, stem cells, and multifunctional nanotechnology.

Inefficiencies in systemic drug delivery and tumor residence as well as micro-environmental selection pressures contribute to the development of multidrug resistance (MDR) in cancer. Characteristics of MDR include abnormal vasculature, regions of hypoxia, up-regulation of ABC-transporters, aerobic glycolysis, and an elevated apoptotic threshold. Nano-sized delivery vehicles are ideal for treating MDR cancer as they can improve the therapeutic index of drugs and they can be engineered to achieve multifunctional parameters. The multifunctional ability of nanocarriers makes them more adept at treating heterogeneous tumor mass than traditional chemotherapy. Nanocarriers also have preferential tumor accumulation via the EPR effect; this accumulation can be further enhanced by actively targeting the biological profile of MDR cells. Perhaps the most significant benefit of using nanocarrier drug delivery to treat MDR cancer is that nanocarrier delivery diverts the effects of ABC-transporter mediated drug efflux; which is the primary mechanism of MDR. This review discusses the capabilities, applications, and examples of multifunctional nanocarriers for the treatment of MDR. This review emphasizes multifunctional nanocarriers that enhance drug delivery efficiency, the application of RNAi, modulation of the tumor apoptotic threshold, and physical approaches to overcome MDR.

Inhibition of ABCB1 (MDR1) expression by an siRNA nanoparticulate delivery system to overcome drug resistance in osteosarcoma.

BACKGROUND: The use of neo-adjuvant chemotherapy in treating osteosarcoma has improved patients' average 5 year survival rate from 20% to 70% in the past 30 years. However, for patients who progress after chemotherapy, its effectiveness diminishes due to the emergence of multi-drug resistance (MDR) after prolonged therapy. METHODOLOGY/PRINCIPAL FINDINGS: In order to overcome both the dose-limiting side effects of conventional chemotherapeutic agents and the therapeutic failure resulting from MDR, we designed and evaluated a novel drug delivery system for MDR1 siRNA delivery. Novel biocompatible, lipid-modified dextran-based polymeric nanoparticles were used as the platform for MDR1 siRNA delivery; and the efficacy of combination therapy with this system was evaluated. In this study, multi-drug resistant osteosarcoma cell lines (KHOS(R2) and U-2OS(R2)) were treated with the MDR1 siRNA nanocarriers and MDR1 protein (P-gp) expression, drug retention, and immunofluoresence were analyzed. Combination therapy of the MDR1 siRNA loaded nanocarriers with increasing concentrations of doxorubicin was also analyzed. We observed that MDR1 siRNA loaded dextran nanoparticles efficiently suppresses P-gp expression in the drug resistant osteosarcoma cell lines. The results also demonstrated that this approach may be capable of reversing drug resistance by increasing the amount of drug accumulation in MDR cell lines. CONCLUSIONS/SIGNIFICANCE: Lipid-modified dextran-based polymeric nanoparticles are a promising platform for siRNA delivery. Nanocarriers loaded with MDR1 siRNA are a potential treatment strategy for reversing MDR in osteosarcoma.

Label-free Raman spectral imaging of intracellular delivery and degradation of polymeric nanoparticle systems.

Novel optical imaging methods, such as Raman microspectroscopy, have been gaining recognition in their ability to obtain noninvasively the distribution of biochemical components of a sample. Raman spectroscopy in combination with optical microscopy provides a label-free method to assess and image cellular processes, without the use of extrinsic fluorescent dyes. The submicrometer resolution of the confocal Raman instrumentation allows us to image cellular organelles on the scale of conventional microscopy. We used the technique to monitor subcellular degradation patterns of two biodegradable nanocarrier systems-poly(epsilon-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA). Our results suggest that both drug-delivery systems eventually are incorporated into Golgi-associated vesicles of late endosomes. These processes were monitored via the decrease of the molecule-characteristic peaks of PCL and PLGA. As the catabolic pathways proceed, shifts and variations in peak intensities and intensity ratios in the rendered Raman spectra unequivocally delineate their degradation patterns.