A nanocarrier system for the delivery of nucleic acids targeted to a pancreatic beta cell line

On-demand release of insulin using glucose-responsive chitosan-based three-compartment microspheres

Various injectable glucose-responsive insulin release systems, including microspheres, have been developed to achieve insulin release for over a day. However, a major challenge is on-demand release insulin, which is closely related to the degradation rate of the delivery vehicle. Herein, chitosan-based three-compartment microspheres (TCMs) were fabricated using gas-shearing microfluidics. Glucose reacts with glucose oxidase (GOD) to generate gluconic acid, and chitosan degrades under acidic conditions to release insulin. The chitosan concentration in each compartment is adjusted to have gradient pH response ranges. Low, medium and high concentrations of insulin are encapsulated in low, medium and high concentration chitosan compartments respectively. The number of compartments involved in insulin release increases from one to three as blood glucose rises. Compared with single one-compartment microspheres (OCMs), TCMs maintain structural integrity and drug action for a longer duration. In vitro experiments have proven the on-demand release of insulin and excellent biocompatibility of TCMs. In chemically induced type 2 diabetes cell models, TCMs demonstrated long-term regulation of blood glucose levels for 20 to 35 h. This work presents a novel concept of constructing three compartments in microspheres to release insulin on-demand, and is highly attractive for research on insulin analogs and other related application.

Delivery of therapeutic agents and cells to pancreatic islets: Towards a new era in the treatment of diabetes

Pancreatic islet cells, and in particular insulin-producing beta cells, are centrally involved in the pathogenesis of diabetes mellitus. These cells are of paramount importance for the endocrine control of glycemia and glucose metabolism. In Type 1 Diabetes, islet beta cells are lost due to an autoimmune attack. In Type 2 Diabetes, beta cells become dysfunctional and insufficient to counterbalance insulin resistance in peripheral tissues. Therapeutic agents have been developed to support the function of islet cells, as well as to inhibit deleterious immune responses and inflammation. Most of these agents have undesired effects due to systemic administration and off-target effects. Typically, only a small fraction of therapeutic agent reaches the desired niche in the pancreas. Because islets and their beta cells are scattered throughout the pancreas, access to the niche is limited. Targeted delivery to pancreatic islets could dramatically improve the therapeutic effect, lower the dose requirements, and lower the side effects of agents administered systemically. Targeted delivery is especially relevant for those therapeutics for which the manufacturing is difficult and costly, such as cells, exosomes, and microvesicles. Along with therapeutic agents, imaging reagents intended to quantify the beta cell mass could benefit from targeted delivery. Several methods have been developed to improve the delivery of agents to pancreatic islets. Intra-arterial administration in the pancreatic artery is a promising surgical approach, but it has inherent risks. Targeted delivery strategies have been developed based on ligands for cell surface molecules specific to islet cells or inflamed vascular endothelial cells. Delivery methods range from nanocarriers and vectors to deliver pharmacological agents to viral and non-viral vectors for the delivery of genetic constructs. Several strategies demonstrated enhanced therapeutic effects in diabetes with lower amounts of therapeutic agents and lower off-target side effects. Microvesicles, exosomes, polymer-based vectors, and nanocarriers are gaining popularity for targeted delivery. Notably, liposomes, lipid-assisted nanocarriers, and cationic polymers can be bioengineered to be immune-evasive, and their advantages to transport cargos into target cells make them appealing for pancreatic islet-targeted delivery. Viral vectors have become prominent tools for targeted gene delivery. In this review, we discuss the latest strategies for targeted delivery of therapeutic agents and imaging reagents to pancreatic islet cells.

Nanocarriers targeting the diseases of the pancreas

Diseases of the pancreas include acute and chronic pancreatitis, exocrine pancreatic insufficiency, diabetes and pancreatic cancer. These pathologies can be difficult to treat due to the innate properties of the pancreas, its structure and localization. The need for effective targeting of the pancreatic tissue by means of nanoparticles delivering therapeutics is a major focus area covered and discussed in this review. Most common diseases of the pancreas do not have specific and direct medical treatment option, and existing treatment options are generally aimed at relieving symptoms. Diabetes has different treatment options for different subtypes based on insulin having stability problems and requiring injections reducing patient compliance. Pancreatic cancer progresses silently and can only be diagnosed in advanced stages. Therefore, survival rate of patients is very low. Gemcitabine and FOLFIRINOX treatment regimens, the most commonly used clinical standard treatments, are generally insufficient due to the chemoresistance that develops in cancer cells and also various side effects. Therefore new treatment options for pancreatic cancer are also under focus. Overcoming drug resistance and pancreatic targeting can be achieved with active and passive targeting methods, and a more effective and safer treatment regimen can be provided at lower drug doses. This review covers the current literature and clinical trials concerning pancreatic drug delivery systems in the nanoscale focusing on the challenges and opportunities provided by these smart delivery systems.

Resveratrol-Encapsulated Mitochondria-Targeting Liposome Enhances Mitochondrial Respiratory Capacity in Myocardial Cells

The development of drug delivery systems for use in the treatment of cardiovascular diseases is an area of great interest. We report herein on an evaluation of the therapeutic potential of a myocardial mitochondria-targeting liposome, a multifunctional envelope-type nano device for targeting pancreatic β cells (β-MEND) that was previously developed in our laboratory. Resveratrol (RES), a natural polyphenol compound that has a cardioprotective effect, was encapsulated in the β-MEND (β-MEND (RES)), and its efficacy was evaluated using rat myocardioblasts (H9c2 cells). The β-MEND (RES) was readily taken up by H9c2 cells, as verified by fluorescence-activated cell sorter data, and was observed to be colocalized with intracellular mitochondria by confocal laser scanning microscopy. Myocardial mitochondrial function was evaluated by a Seahorse XF Analyzer and the results showed that the β-MEND (RES) significantly activated cellular maximal respiratory capacity. In addition, the β-MEND (RES) showed no cellular toxicity for H9c2 cells as evidenced by Premix WST-1 assays. This is the first report of the use of a myocardial mitochondria-targeting liposome encapsulating RES for activating mitochondrial function, which was clearly confirmed based on analyses using a Seahorse XF Analyzer.

New Advances in the Research of Resistance to Neoadjuvant Chemotherapy in Breast Cancer

Breast cancer has an extremely high incidence in women, and its morbidity and mortality rank first among female tumors. With the increasing development of medicine today, the clinical application of neoadjuvant chemotherapy has brought new hope to the treatment of breast cancer. Although the efficacy of neoadjuvant chemotherapy has been confirmed, drug resistance is one of the main reasons for its treatment failure, contributing to the difficulty in the treatment of breast cancer. This article focuses on multiple mechanisms of action and expounds a series of recent research advances that mediate drug resistance in breast cancer cells. Drug metabolizing enzymes can mediate a catalytic reaction to inactivate chemotherapeutic drugs and develop drug resistance. The drug efflux system can reduce the drug concentration in breast cancer cells. The combination of glutathione detoxification system and platinum drugs can cause breast cancer cells to be insensitive to drugs. Changes in drug targets have led to poorer efficacy of HER2 receptor inhibitors. Moreover, autophagy, epithelial–mesenchymal transition, and tumor microenvironment can all contribute to the development of resistance in breast cancer cells. Based on the relevant research on the existing drug resistance mechanism, the current treatment plan for reversing the resistance of breast cancer to neoadjuvant chemotherapy is explored, and the potential drug targets are analyzed, aiming to provide a new idea and strategy to reverse the resistance of neoadjuvant chemotherapy drugs in breast cancer.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

Stable duplex-linked antisense targeting miR-148a inhibits breast cancer cell proliferation

MicroRNAs (miRNAs) regulate cancer cell proliferation by binding directly to the untranslated regions of messenger RNA (mRNA). MicroRNA-148a (miR-148a) is expressed at low levels in breast cancer (BC). However, little attention has been paid to the sequestration of miR-148a. Here, we performed a knockdown of miR-148a using anti-miRNA oligonucleotides (AMOs) and investigated the effect on BC cell proliferation. BC cell proliferation was significantly suppressed by AMO flanked by interstrand cross-linked duplexes (CL-AMO), whereas single-stranded and commercially available AMOs had no effect. The suppression was caused by sequestering specifically miR-148a. Indeed, miR-148b, another member of the miR-148 family, was not affected. Importantly, the downregulation of miR-148a induced a greater and longer-lasting inhibition of BC cell proliferation than the targeting of oncogenic microRNA-21 (miR-21) did. We identified thioredoxin-interacting protein (TXNIP), a tumor suppressor gene, as a target of miR-148a and showed that CL-AMO provoked an increase in TXNIP mRNA expression. This study provide evidence that lowly expressed miRNAs such as miR-148a have an oncogenic function and might be a promising target for cancer treatment.

Targeting the Mitochondrial Genome Via a MITO-Porter : Evaluation of mtDNA and mtRNA Levels and Mitochondrial Function

Genetic mutations and defects in mitochondrial DNA (mtDNA) are associated with certain types of mitochondrial dysfunctions, ultimately resulting in the emergence of a variety of human diseases. To achieve an effective mitochondrial gene therapy, it will be necessary to deliver therapeutic agents to the innermost mitochondrial space (the mitochondrial matrix), which contains the mtDNA pool. We recently developed a MITO-Porter, a liposome-based nanocarrier that delivers cargo to mitochondria via a membrane-fusion mechanism. In this chapter, we discuss the methodology used to deliver bioactive molecules to the mitochondrial matrix using a Dual Function (DF)-MITO-Porter, a liposome-based nanocarrier that delivers it cargo by means of a stepwise process, and an evaluation of mtDNA levels and mitochondrial activities in living cells. We also discuss mitochondrial gene silencing by the mitochondrial delivery of antisense RNA oligonucleotide (ASO) targeting mtDNA-encoded mRNA using the MITO-Porter system.

A nanocarrier for the mitochondrial delivery of nucleic acids to cardiomyocytes

Cardiomyopathy caused by mitochondrial dysfunction associated with the mutation/deletion of mitochondrial DNA has been reported, and nucleic acid therapy targeting cardiac mitochondria represents a possible therapy for treating these diseases. Such a treatment, however, has not yet been achieved because delivering nucleic acids to mitochondria of cardiac muscle is difficult. In this study, H9c2 cells a type of rat cardiac myoblasts, were used as model cardiac muscle cells. The use of a lipid composition used to prepare the β-MEND (where MEND denotes multifunctional envelope-type nano device) permitted the particles to be efficiently internalized by H9c2 cells, as evidenced by flow cytometry analyses. Intracellular observations by confocal laser scanning microscopy showed that the β-MEND efficiently accumulated in mitochondria of H9c2 cells. We also constructed an RP/β-MEND that contained a mitochondrial RNA aptamer to achieve mitochondrial delivery in H9c2 cells. The successful direct mitochondrial transfection of exogenous RNA was confirmed using these carrier systems, based on PCR experiments after reverse transcription. Thus, the β-MEND holds promise as a direct mitochondrial transfection system for delivering nucleic acids targeted to H9c2 cells.

EGF suppresses the expression of miR-124a in pancreatic β cell lines via ETS2 activation through the MEK and PI3K signaling pathways

Diabetes mellitus is characterized by pancreatic β cell dysfunction. Previous studies have indicated that epidermal growth factor (EGF) and microRNA-124a (miR-124a) play opposite roles in insulin biosynthesis and secretion by beta cells. However, the underlying mechanisms remain poorly understood. In the present study, we demonstrated that EGF could inhibit miR-124a expression in beta cell lines through downstream signaling pathways, including mitogen-activated protein kinase kinase (MEK) and phosphatidylinositol 3-kinase (PI3K) cascades. Further, the transcription factor ETS2, a member of the ETS (E26 transformation-specific) family, was identified to be responsible for the EGF-mediated suppression of miR-124a expression, which was dependent on ETS2 phosphorylation at threonine 72. Activation of ETS2 decreased miR-124a promoter transcriptional activity through the putative conserved binding sites AGGAANA/TN in three miR-124a promoters located in different chromosomes. Of note, ETS2 played a positive role in regulating beta cell function-related genes, including miR-124a targets, Forkhead box a2 (FOXA2) and Neurogenic differentiation 1 (NEUROD1), which may have partly been through the inhibition of miR-124 expression. Knockdown and overexpression of ETS2 led to the prevention and promotion of insulin biosynthesis respectively, while barely affecting the secretion ability. These results suggest that EGF may induce the activation of ETS2 to inhibit miR-124a expression to maintain proper beta cell functions and that ETS2, as a novel regulator of insulin production, is a potential therapeutic target for diabetes mellitus treatment.

A mitochondrial delivery system using liposome-based nanocarriers that target myoblast cells

Mitochondrial function is reduced in skeletal muscles of many patients with systemic diseases and it is difficult to deliver medicinal substances to mitochondria in such tissue. In this study, we report on attempts to develop liposome-based carriers for mitochondrial delivery using mouse myoblasts (C2C12) by varying the lipid composition of the carriers. We found that a liposome that contains an optimal lipid modified with the KALA peptide (a cellular uptake and mitochondrial targeting device) was the most effective nanocarrier for achieving mitochondrial delivery in C2C12 cells. We also report on successful mitochondrial transgene expression using the carriers encapsulating a mitochondrial DNA vector as we previously reported.

[A Nanocarrier System for Mitochondrial Delivery Targeted to a Pancreatic Beta Cell]

The destruction of β cells of pancreatic islets results in a reduced level of insulin secretion, thus resulting in the onset of diabetes. Diabetes caused by such a decrease in insulin secretion has been reported to be associated with mitochondrial dysfunction. Because of this, mitochondrial therapy would be expected to be a useful and productive strategy for the treatment of this disease. We previously reported the development of a MITO-Porter, a liposome-based nanocarrier that permits macromolecular cargos to be delivered into mitochondria via membrane fusion. In this presentation, we present our current findings on the development of a mitochondrial nanocarrier system aimed at the development of a novel method for treating and preventing diabetes. The system includes "a nanocarrier system for nucleic acids targeted to pancreatic β cells", and "an in vivo system for the delivery of nucleic acids targeting the pancreas". In this presentation, we propose the use of a "mitochondrial nanocarrier system" as a novel method for the treatment and prevention of diabetes, and discuss the contribution of mitochondrial nanocarrier systems to innovative drug development.

Squalene-PEG-Exendin as High-Affinity Constructs for Pancreatic Beta-Cells

Novel drug delivery systems targeting native, transplanted, or cancerous beta-cells are of utmost importance. Herein, we present new exendin-4 derivatives with modified unnatural amino acids at strategic positions within the polypeptide sequence. The modified peptides allowed modular orthogonal chemical modifications to attach imaging agents and amphiphilic squalene-PEG groups. The resulting conjugates, SQ-PEG-ExC₁-Cy5 and SQ-PEG-ExC₄₀-Cy5 fluorescence probes, display low nanomolar affinity to GLP-1R in fluorescence-based binding assays with EC₅₀ at 1.1 ± 0.2 and 0.8 ± 0.2 nM, respectively. Naturally expressing GLP-1R MIN6 cells and recombinantly transfected CHL-GLP-1R positive cells were specifically targeted by all of the new beta-cell probes in vitro. Specific islet targeting was observed after i.v. injection of SQ-PEG-ExC₁-Cy5 with SQ-PEG in normoglycemic mice ex vivo. Semiquantitative biodistribution analysis by epifluorescence indicated prolonged blood half-life (3.8 h) for the amphiphilic Ex conjugate. Liver and pancreas were identified as main biodistribution organs for SQ-PEG-ExC₁-Cy5.

MITO-Porter for Mitochondrial Delivery and Mitochondrial Functional Analysis

Mitochondria are attractive organelles that have the potential to contribute greatly to medical therapy, the maintenance of beauty and health, and the development of the life sciences. Therefore, it would be expected that the further development of mitochondrial drug delivery systems (DDSs) would exert a significant impact on the medical and life sciences. To achieve such an innovative objective, it will be necessary to deliver various cargoes to mitochondria in living cells. However, only a limited number of approaches are available for accomplishing this. We recently proposed a new concept for mitochondrial delivery, a MITO-Porter, a liposome-based carrier that introduces macromolecular cargoes into mitochondria via membrane fusion. To date, we have demonstrated the utility of mitochondrial therapeutic strategy by MITO-Porter using animal models of diseases. We also showed that the mitochondrial delivery of antisense oligo-RNA by the MITO-Porter results in mitochondrial RNA knockdown and has a functional impact on mitochondria. Here, we summarize the current state of mitochondrial DDS focusing on our research and show some examples of mitochondrial functional regulations using mitochondrial DDS.

Lipid-Based Nanocarriers for RNA Delivery

RNA-interference (RNAi) agents such as small-interfering RNA (siRNA) and micro-RNA (miRNA) have strong potential as therapeutic agents for the treatment of a broad range of diseases such as malignancies, infections, autoimmune diseases and neurological diseases that are associated with undesirable gene expression. In recent years, several clinical trials of RNAi therapeutics especially siRNAs have been conducted with limited success so far. For systemic administration of these poorly permeable and easily degradable macromolecules, it is obvious that a safe and efficient delivery platform is highly desirable. Because of high biocompatibility, biodegradability and solid track record for clinical use, nanocarriers made of lipids and/or phospholipids have been commonly employed to facilitate RNA delivery. In this article, the key features of the major sub-classes of lipid-based nanocarriers, e.g. liposomes, lipid nanoparticles and lipid nanoemulsions, will be reviewed. Focus of the discussion is on the various challenges researchers face when developing lipid-based RNA nanocarriers, such as the toxicity of cationic lipids and issues related to PEGylated lipids, as well as the strategies employed in tackling these challenges. It is hoped that by understanding more about the pros and cons of these most frequently used RNA delivery systems, the pharmaceutical scientists, biomedical researchers and clinicians will be more successful in overcoming some of the obstacles that currently limit the clinical translation of RNAi therapy.

Tailoring the stealth properties of biocompatible polysaccharide nanocontainers

Fundamental development of a biocompatible and degradable nanocarrier platform based on hydroxyethyl starch (HES) is reported. HES is a derivative of starch and possesses both high biocompatibility and improved stability against enzymatic degradation; it is used to prepare nanocapsules via the polyaddition reaction at the interface of water nanodroplets dispersed in an organic miniemulsion. The synthesized hollow nanocapsules can be loaded with hydrophilic guests in its aqueous core, tuned in size, chemically functionalized in various pathways, and show high shelf life stability. The surface of the HES nanocapsules is further functionalized with poly(ethylene glycol) via different chemistries, which substantially enhanced blood half-life time. Importantly, methods for precise and reliable quantification of the degree of functionalization are also introduced, which enable the precise control of the chemistry on the capsules' surface. The stealth properties of these capsules is studied both in-vitro and in-vivo. The functionalized nanocapsules serve as a modular platform for specific cell targeting, as they show no unspecific up-taken by different cell types and show very long circulating time in blood (up to 72 h).

Biodegradable multi-liposomal containers

Structure of multiliposomal nanocontainer on base of anionic liposomes, polycation and polylactide.