Polymer nanocarriers for the delivery of small fragments of nucleic acids: oligonucleotides and siRNA

Nanotechnology-based Nose-to-brain Delivery in Epilepsy: A NovelApproach to Diagnosis and Treatment

Epilepsy is a serious neurological disease, and scientists have a significant challenge in developing a noninvasive treatment for the treatment of epilepsy. The goal is to provide novel ideas for improving existing and future anti-epileptic medications. The injection of nano treatment via the nose to the brain is being considered as a possible seizure control method. Various nasal medicine nanoformulations have the potential to cure epilepsy. Investigations with a variety of nose-to-brain dosing methods for epilepsy treatment have yielded promising results. After examining global literature on nanotechnology and studies, the authors propose nasal administration with nanoformulations as a means to successfully treat epilepsy. The goal of this review is to look at the innovative application of nanomedicine for epilepsy treatment via nose-to-brain transfer, with a focus on the use of nanoparticles for load medicines. When nanotechnology is combined with the nose to brain approach, treatment efficacy can be improved through site specific delivery. Furthermore, this technique of administration decreases adverse effects and patient noncompliance encountered with more traditional procedures.

Protein corona investigations of polyplexes with varying hydrophobicity - From method development to in vitro studies

In the field of non-viral drug delivery, polyplexes (PXs) represent an advanced investigated and highly promising tool for the delivery of nucleic acids. Upon encountering physiological fluids, they adsorb biological molecules to form a protein corona (PC), that influence PXs biodistribution, transfection efficiencies and targeting abilities. In an effort to understand protein - PX interactions and the effect of PX material on corona composition, we utilized cationic branched 10 kDa polyethyleneimine (b-PEI) and a hydrophobically modified nylon-3 polymer (NM0.2/CP0.8) within this study to develop appropriate methods for PC investigations. A centrifugation procedure for isolating hard corona - PX complexes (PCPXs) from soft corona proteins after incubating the PXs in fetal bovine serum (FBS) for PC formation was successfully optimized and the identification of proteins by a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method clearly demonstrated that the PC composition is affected by the underlying PXs material. With regard to especially interesting functional proteins, which might be able to induce active targeting effects, several candidates could be detected on b-PEI and NM0.2/CP0.8 PXs. These results are of high interest to better understand how the design of PXs impacts the PC composition and subsequently PCPXs-cell interactions to enable precise adjustment of PXs for targeted drug delivery.

Recent advancements in design of nucleic acid nanocarriers for controlled drug delivery

Research of nanoscale nucleic acid carriers has garnered attention in recent years due to their distinctive and controllable properties. However, current knowledge is limited in how we can efficiently utilize these systems for clinical applications. Several researchers have pioneered new and innovative nanocarrier drug delivery systems, but understanding physiochemical properties and behavior in vivo is vital to implementing them as clinical drug delivery platforms. In this review, we outline the most significant innovations in the synthesis, physical properties, and utilization of nucleic acid nanocarriers in the past 5 years, addressing the crucial properties which improve nanocarrier characteristics, delivery, and drug release. The challenges of controlling the transport of nucleic acid nanocarriers and therapeutic release for biological applications are outlined. Barriers which inhibit effective transport into tissue are discussed with emphasis on the modifications needed to overcome such obstacles. The novel strategies discussed in this work summarize the pivotal features of modern nucleic nanocarriers and postulate where future developments could revolutionize the translation of these tools into a clinical setting.

Defining Endocytic Pathways of Fucoidan-Coated PIBCA Nanoparticles from the Design of their Surface Architecture

Purpose

This work investigated the endocytic pathways taken by poly(isobutylcyanoacrylate) (PIBCA) nanoparticles differing in their surface composition and architecture, assuming that this might determine their efficiency of intracellular drug delivery.

Methods

Nanoparticles (A0, A25, A100, R0, R25 ) were prepared by anionic or redox radical emulsion polymerization using mixtures of dextran and fucoidan (0, 25, 100 % in fucoidan). Cell uptake was evaluated by incubating J774A.1 macrophages with nanoparticles. Endocytic pathways were studied by incubating cells with endocytic pathway inhibitors (chlorpromazine, genistein, cytochalasin D, methyl-ß-cyclodextrin and nocodazole) and nanoparticle uptake was evaluated by flow cytometry and confocal microscopy.

Results

The fucoidan-coated PIBCA nanoparticles A₂₅ were internalized 3-fold more efficiently than R₂₅ due to the different architecture of the fucoidan chains presented on the surface. Different fucoidan density and architecture led to different internalization pathway preferred by the cells. Large A₁₀₀ nanoparticles with surface was covered with fucoidan chains in a loop and train configuration were internalized the most efficiently, 47-fold compared with A₀, and 3-fold compared with R₀ and R₂₅ through non-endocytic energy-independent pathways and reached the cell cytoplasm.

Conclusion

Internalization pathways of PIBCA nanoparticles by J774A.1 macrophages could be determined by nanoparticle fucoidan surface composition and architecture. In turn, this influenced the extent of internalization and localization of accumulated nanoparticles within cells. The results are of interest for rationalizing the design of nanoparticles for potential cytoplamic drug delivery by controlling the nature of the nanoparticle surface.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-022-03202-4.

Targeting Engineered Nanoparticles for Breast Cancer Therapy

Breast cancer (BC) is the second most common cancer in women globally after lung cancer. Presently, the most important approach for BC treatment consists of surgery, followed by radiotherapy and chemotherapy. The latter therapeutic methods are often unsuccessful in the treatment of BC because of their various side effects and the damage incurred to healthy tissues and organs. Currently, numerous nanoparticles (NPs) have been identified and synthesized to selectively target BC cells without causing any impairments to the adjacent normal tissues or organs. Based on an exploratory study, this comprehensive review aims to provide information on engineered NPs and their payloads as promising tools in the treatment of BC. Therapeutic drugs or natural bioactive compounds generally incorporate engineered NPs of ideal sizes and shapes to enhance their solubility, circulatory half-life, and biodistribution, while reducing their side effects and immunogenicity. Furthermore, ligands such as peptides, antibodies, and nucleic acids on the surface of NPs precisely target BC cells. Studies on the synthesis of engineered NPs and their impact on BC were obtained from PubMed, Science Direct, and Google Scholar. This review provides insights on the importance of engineered NPs and their methodology for validation as a next-generation platform with preventive and therapeutic effects against BC.

Current Designs and Developments of Fucoidan-based Formulations for Cancer Therapy

BACKGROUND

Natural nanostructure materials have been involved in antitumor drug delivery systems due to their biocompatibility, biodegradation, and bioactive properties.

METHODS

These materials have contributed to advanced drug delivery systems in the roles of both bioactive compounds and delivery nanocarriers. Fucoidan, a valuable ocean material used in drug delivery systems, has been exploited in research on cancer and a variety of other diseases.

RESULTS

Although the uniqueness, structure, properties, and health benefits of fucoidan have been mentioned in various prominent reviews, current developments and designs of fucoidan-based formulations still need to be assessed to further develop an effective anticancer therapy. In this review, current important formulations using fucoidan as a functional material and as an anticancer agent will be discussed. This article will also provide a brief principle of the methods that incorporate functional nanostructure materials in formulations exploiting fucoidan.

CONCLUSION

Current research and future perspectives on the use of fucoidan in anticancer therapy will advance innovative and important products for clinical uses.

Intranasal Delivery of Nanoformulations: A Potential Way of Treatment for Neurological Disorders

Although the global prevalence of neurological disorders such as Parkinson’s disease, Alzheimer’s disease, glioblastoma, epilepsy, and multiple sclerosis is steadily increasing, effective delivery of drug molecules in therapeutic quantities to the central nervous system (CNS) is still lacking. The blood brain barrier (BBB) is the major obstacle for the entry of drugs into the brain, as it comprises a tight layer of endothelial cells surrounded by astrocyte foot processes that limit drugs’ entry. In recent times, intranasal drug delivery has emerged as a reliable method to bypass the BBB and treat neurological diseases. The intranasal route for drug delivery to the brain with both solution and particulate formulations has been demonstrated repeatedly in preclinical models, including in human trials. The key features determining the efficacy of drug delivery via the intranasal route include delivery to the olfactory area of the nares, a longer retention time at the nasal mucosal surface, enhanced penetration of the drugs through the nasal epithelia, and reduced drug metabolism in the nasal cavity. This review describes important neurological disorders, challenges in drug delivery to the disordered CNS, and new nasal delivery techniques designed to overcome these challenges and facilitate more efficient and targeted drug delivery. The potential for treatment possibilities with intranasal transfer of drugs will increase with the development of more effective formulations and delivery devices.

Counterion of Chitosan Influences Thermodynamics of Association of siRNA with a Chitosan-Based siRNA Carrier

PURPOSE

The work aimed to compare quality of a siRNA carrier prepared with chitosan of two different sources having similar degree of deacetylation and molecular weights. Differences were analyzed from thermodynamic characteristics of interactions with siRNA.

METHODS

The siRNA carrier (chitosan-coated poly(isobutylcyanoacrylate) nanoparticles) was prepared with home-prepared, CS_Lab, and commercial, CS_Com, chitosans. Chitosan counterion was identified and chitosans CS_Commod1 and CS_Commod2 were obtained from CS_Com exchanging counterion with that found on CS_Lab. Carrier quality was checked considering the size, zeta potential and siRNA association capacity by gel electrophoresis. Thermodynamic parameters of interactions between siRNA and chitosans in solution or immobilized at the carrier surface were determined by isothermal titration calorimetry (ITC).

RESULTS

CS_Lab and CS_Commod2 having a high content of acetate counterion associated better siRNA than CS_Com and CS_Commod1 which counterion included mainly chloride. ITC measurements indicated that siRNA interactions with chitosan and the siRNA carrier were driven by entropic phenomena including dehydration, but thermodynamic parameters of interactions clearly differed according to the nature of the counterion of chitosan. The influence of chitosan counterions was interpreted considering their different lyotropic character.

CONCLUSION

Association of siRNA with our siRNA carrier was influenced by the nature of counterions associated with chitosan. Driven by entropic phenomena including dehydration, interactions were favored by acetate counterion. Although more work would be needed to decipher the influence of the counterion of chitosan during association with siRNA, it was pointed out as a new critical attribute of chitosan to consider while formulating siRNA carrier with this polysaccharide.

The Impact of Nylon-3 Copolymer Composition on the Efficiency of siRNA Delivery to Glioblastoma Cells

Glioblastoma multiforme is a devastating disease that has attracted enormous attention due to poor prognosis and high recurrence. Small interfering RNA (siRNA) in principle offers a promising therapeutic approach by the downregulation of disease-related genes via RNA interference. For efficient siRNA delivery to target sites, cationic polymers are often used in preclinical studies for the protection of siRNA and complex formation based on electrostatic interactions. In an effort to develop biocompatible and efficient nanocarriers with a translational outlook for optimal gene silencing at reduced toxicity, we synthesized two sets of nylon-3 copolymers with variable cationic content (DM or NM monomer) and hydrophobic subunits (CP monomer) and evaluated their suitability for in vitro siRNA delivery into glioblastoma cells. DM_0.4/CP_0.6 and NM_0.4/CP_0.6 polymers with similar subunit ratios were synthesized to compare the effect of different cationic subunits. Additionally, we utilized NM_0.2/CP_0.8 polymers to evaluate the impact of the different hydrophobic content in the polymer chain. The siRNA condensation ability and polymer–siRNA complex stability was evaluated by unmodified and modified SYBR gold assays, respectively. Further physicochemical characteristics, e.g., particle size and surface charge, were evaluated by dynamic light scattering and laser Doppler anemometry, whereas a relatively new method for polyplex size distribution analysis—tunable resistive pulse sensing—was additionally developed and compared to DLS measurements. Transfection efficiencies, the route of cell internalization, and protein knockdown abilities in glioblastoma cells were investigated by flow cytometry. Furthermore, cellular tolerability was evaluated by MTT and LDH assays. All the polymers efficiently condensed siRNA at N/P ratios of three, whereas polymers with NM cationic subunits demonstrated smaller particle size and lower polyplex stability. Furthermore, NM_0.2/CP_0.8 polyplexes with the highest hydrophobic content displayed significantly higher cellular internalization in comparison to more cationic formulations and successful knockdown capabilities. Detailed investigations of the cellular uptake route demonstrated that these polyplexes mainly follow clathrin-mediated endocytotic uptake mechanisms, implying high interaction capacity with cellular membranes. Taken together with conducive toxicity profiles, highly hydrophobic nylon-3 polymers provide an appropriate siRNA delivery agent for the potential treatment of glioblastoma.

Current Transport Systems and Clinical Applications for Small Interfering RNA (siRNA) Drugs

Small interfering RNAs (siRNAs) are an attractive new agent with potential as a therapeutic tool because of its ability to inhibit specific genes for many conditions, including viral infections and cancers. However, despite this potential, many challenges remain, including off-target effects, difficulties with delivery, immune responses, and toxicity. Traditional genetic vectors do not guarantee that siRNAs will silence genes in vivo. Rational design strategies, such as chemical modification, viral vectors, and non-viral vectors, including cationic liposomes, polymers, nanocarriers, and bioconjugated siRNAs, provide important opportunities to overcome these challenges. We summarize the results of research into vector delivery of siRNAs as a therapeutic agent from their design to clinical trials in ophthalmic diseases, cancers, respiratory diseases, and liver virus infections. Finally, we discuss the current state of siRNA delivery methods and the need for greater understanding of the requirements.

A journey through the emergence of nanomedicines with poly(alkylcyanoacrylate) based nanoparticles

Starting in the late 1970s, the pioneering work of Patrick Couvreur gave birth to the first biodegradable nanoparticles composed of a biodegradable synthetic polymer. These nanoparticles, made of poly(alkylcyanoacrylate) (PACA), were the first synthetic polymer-based nanoparticulate drug carriers undergoing a phase III clinical trial so far. Analyzing the journey from the birth of PACA nanoparticles to their clinical evaluation, this paper highlights their remarkable adaptability to bypass various drug delivery challenges found on the way. At present, PACA nanoparticles include a wide range of nanoparticles that can associate drugs of different chemical nature and can be administered in vivo by different routes. The most recent technologies giving the nanoparticles customised functions could also be implemented on this family of nanoparticles. Through different examples, this paper discusses the seminal role of the PACA nanoparticles' family in the development of nanomedicines.

Investigation of compacted DNA structures induced by Na+ and K+ monovalent cations using biological nanopores

In aqueous solutions, an elongated, negatively charged DNA chain can quickly change its conformation into a compacted globule in the presence of positively charged molecules, or cations. This well-known process, called DNA compaction, is a method with great potential for gene therapy and delivery. Experimental conditions to induce these compacted DNA structures are often limited to the use of common compacting agents, such as cationic surfactants, polymers, and multivalent cations. In this study, we show that in highly concentrated buffers of 1 M monovalent cation solutions at pH 7.2 and 10, biological nanopores allow real-time sensing of individual compacted structures induced by K⁺ and Na⁺, the most abundant monovalent cations in human bodies. Herein, we studied the ratio between compacted and linear structures for 15-mer single-stranded DNA molecules containing only cytosine nucleotides, optimizing the probability of linear DNA chains being compacted. Since the binding affinity of each nucleotide to cation is different, the ability of the DNA strand to fold into a compacted structure greatly depends on the type of cations and nucleotides present. Our experimental results compare favorably with findings from previous molecular dynamics simulations for the DNA compacting potential of K⁺ and Na⁺ monovalent cations. We estimate that the majority of single-stranded DNA molecules in our experiment are compacted. From the current traces of nanopores, the ratio of compacted DNA to linear DNA molecules is approximately 30 : 1 and 15 : 1, at a pH of 7.2 and 10, respectively. Our comparative studies reveal that Na⁺ monovalent cations have a greater potential of compacting the 15C-ssDNA than K⁺ cations.

In vitro and in vivo delivery of siRNA via VIPER polymer system to lung cells

The block copolymer VIPER (virus-inspired polymer for endosomal release) has been reported to be a promising novel delivery system of DNA plasmids both in vitro and in vivo. VIPER is comprised of a polycation segment for condensation of nucleic acids as well as a pH-sensitive segment that exposes the membrane lytic peptide melittin in acidic environments to facilitate endosomal escape. The objective of this study was to investigate VIPER/siRNA polyplex characteristics, and compare their in vitro and in vivo performance with commercially available transfection reagents and a control version of VIPER lacking melittin. VIPER/siRNA polyplexes were formulated and characterized at various charge ratios and shown to be efficiently internalized in cultured cells. Target mRNA knockdown was confirmed by both flow cytometry and qRT-PCR and the kinetics of knockdown was monitored by live cell spinning disk microscopy, revealing knockdown starting by 4 h post-delivery. Intratracheal instillation of VIPER particles formulated with sequence specific siRNA to the lung of mice resulted in a significantly more efficient knockdown of GAPDH compared to treatment with VIPER particles formulated with scrambled sequence siRNA. We also demonstrated using pH-sensitive labels that VIPER particles experience less acidic environments compared to control polyplexes. In summary, VIPER/siRNA polyplexes efficiently deliver siRNA in vivo resulting in robust gene silencing (>75% knockdown) within the lung.

Inhibition of Glomerular Mesangial Cell Proliferation by siPDGF-B- and siPDGFR-β-Containing Chitosan Nanoplexes

Mesangioproliferative glomerulonephritis is a disease that has a high incidence in humans. In this disease, the proliferation of glomerular mesangial cells and the production of extracellular matrix are important. In recent years, the RNAi technology has been widely used in the treatment of various diseases due to its capability to inhibit the gene expression with high specificity and targeting. The objective of this study was to decrease mesangial cell proliferation by knocking down PDGF-B and its receptor, PDGFR-β. To be able to use small interfering RNAs (siRNAs) in the treatment of this disease successfully, it is necessary to develop appropriate delivery systems. Chitosan, which is a biopolymer, is used as a siRNA delivery system in kidney drug targeting. In order to deliver siRNA molecules targeted at PDGF-B and PDGFR-β, chitosan/siRNA nanoplexes were prepared. The in vitro characterization, transfection studies, and knockdown efficiencies were studied in immortalized and primary rat mesangial cells. In addition, the effects of chitosan nanoplexes on mesangial cell proliferation and migration were investigated. After in vitro transfection, the PDGF-B and PDGFR-β gene silencing efficiencies of PDGF-B and PDGFR-β targeting siRNA-containing chitosan nanoplexes were 74 and 71% in immortalized rat mesangial cells and 66 and 62% in primary rat mesangial cells, respectively. siPDGF-B- and siPDGFR-β-containing nanoplexes indicated a significant decrease in mesangial cell migration and proliferation. These results suggested that mesangial cell proliferation may be inhibited by silencing of the PDGF-B signaling pathway. Gene silencing approaches with chitosan-based gene delivery systems have promise for the efficient treatment of renal disease.

Noninvasive delivery of oligonucleotide by penetratin-modified polyplexes to inhibit protein expression of intraocular tumor

Our present study aimed to develop an antisense oligonucleotide (ASO) delivery system to achieve gene silencing in intraocular tumor via topical instillation. ASO specific for luciferase was chosen as model drug, polyamidoamine (PG5) was employed to condense ASO, and penetratin (Pene) was used to enhance cellular uptake. Nanoscale PG5/ASO/Pene polyplex was stabilized via noncovalent bonding. In vitro evaluations indicated that PG5/ASO/Pene exhibited improved cell-penetrating and gene silencing ability compared with naked ASO and PG5/ASO. Subcutaneous and orthotopic tumor models expressing luciferase were established in nude mice. After treated by PG5/ASO/Pene, immunohistochemical results of subcutaneous tumors showed significant inhibition of luciferase expression via peritumoral injection, and bioluminescence from orthotopic tumor was obviously weakened via topical instillation. To date, few works were successful in noninvasive treatment of intraocular diseases using antisense strategy, this penetratin-modified polyplex could be a promising vector to inhibit protein expression by effectively delivering ASOs into the eye.

Degradable polyesters via ring-opening polymerization of functional valerolactones for efficient gene delivery

Degradable polymers as gene and drug carriers are emerging as one of the most promising types of materials in the biomedical and pharmaceutical areas.

Building the design, translation and development principles of polymeric nanomedicines using the case of clinically advanced poly(lactide(glycolide))-poly(ethylene glycol) nanotechnology as a model: An industrial viewpoint

The design of the first polymeric nanoparticles could be traced back to the 1970s, and has thereafter received considerable attention, as evidenced by the significant increase of the number of articles and patents in this area. This review article is an attempt to take advantage of the existing literature on the clinically tested and commercialized biodegradable PLA(G)A-PEG nanotechnology as a model to propose quality building and outline translation and development principles for polymeric nano-medicines. We built such an approach from various building blocks including material design, nano-assembly - i.e. physicochemistry of drug/nano-object association in the pharmaceutical process, and release in relevant biological environment - characterization and identification of the quality attributes related to the biopharmaceutical properties. More specifically, as envisaged in a translational approach, the reported data on PLA(G)A-PEG nanotechnology have been structured into packages to evidence the links between the structure, physicochemical properties, and the in vitro and in vivo performances of the nanoparticles. The integration of these bodies of knowledge to build the CMC (Chemistry Manufacturing and Controls) quality management strategy and finally support the translation to proof of concept in human, and anticipation of the industrialization takes into account the specific requirements and biopharmaceutical features attached to the administration route. From this approach, some gaps are identified for the industrial development of such nanotechnology-based products, and the expected improvements are discussed. The viewpoint provided in this article is expected to shed light on design, translation and pharmaceutical development to realize their full potential for future clinical applications.

NF-κB decoy polyplexes decrease P-glycoprotein-mediated multidrug resistance in colorectal cancer cells

Multidrug resistance (MDR), a major cause for chemotherapy failure, has been linked to upregulation of ATP-dependent membrane efflux systems that limit intracellular accumulation of cytotoxic anticancer agents. P-glycoprotein (P-gp) encoded by the human ABCB1 gene was the first efflux transporter identified to contribute to MDR. ABCB1 gene expression is correlated with constitutive activation of the NF-κB signaling pathway in tumor cells. The objective of this research is to modulate P-gp activity in colon cancer cells using NF-κB decoy oligodeoxynucleotides (ODNs) that are effectively delivered into the nucleus of colorectal cancer cells by self-assembling nonviral nanoparticles comprising the novel poly[N-(2-hydroxypropyl)methacrylamide]-poly(N,N-dimethylaminoethylmethacrylate) diblock copolymer (pHPMA-b-pDMAEMA). Ethidium bromide intercalation and gel retardation assays demonstrated high DNA condensation capacity of pHPMA-b-pDMAEMA. Nanoparticles prepared with and without decoy ODNs did not significantly compromise cellular safety at N/P ratios ⩽4. Transfection efficiency of pHPMA-b-pDMAEMA polyplexes (N/P=4) in Caco-2 cells was comparable to TurboFect transfection standard, resulting in a 98% reduction in P-gp protein levels. As a pharmacodynamic consequence, intracellular accumulation of the P-gp substrate Rhodamine123 significantly increased by almost twofold. In conclusion, NF-κB ODN polyplexes fabricated with pHPMA-b-pDMAEMA polymer effectively reduced P-gp-mediated efflux activity in Caco-2 cells, suggesting successful interference with NF-κB-binding sites in the promoter region of the ABCB1 gene.

Biodistribution and Pharmacokinetics Study of siRNA-loaded Anti-NTSR1-mAb-functionalized Novel Hybrid Nanoparticles in a Metastatic Orthotopic Murine Lung Cancer Model

Small interfering RNA (siRNA) is effective in silencing critical molecular pathways in cancer. The use of this tool as a treatment modality is limited by lack of an intelligent carrier system to enhance the preferential delivery of this molecule to specific targets in vivo. In the present study, the in vivo behavior of novel anti-NTSR1-mAb-functionalized antimutant K-ras siRNA-loaded hybrid nanoparticles, delivered by i.p. injection to non-small-cell lung cancer in mice models, was investigated and compared to that of a naked siRNA formulation. The siRNA in anti-NTSR1-mAb-functionalized hybrid nanoparticles was preferentially accumulated in tumor-bearing lungs and metastasized tumor for at least 48 hours while the naked siRNA formulation showed lack of preferential accumulation in all of the organs monitored. The plasma terminal half-life of nanoparticle-delivered siRNA was 11 times higher (17-1.5 hours) than that of the naked siRNA formulation. The mean residence time and AUClast were 3.4 and 33 times higher than the corresponding naked siRNA formulation, respectively. High-performance liquid chromatography analysis showed that the hybrid nanoparticle carrier system protected the encapsulated siRNA against degradation in vivo. Our novel anti-NTSR1-mAb-functionalized hybrid nanoparticles provide a useful platform for in vivo targeting of siRNA for both experimental and clinical purposes.

Enzymatic PEGylated Poly(lactone-co-β-amino ester) Nanoparticles as Biodegradable, Biocompatible and Stable Vectors for Gene Delivery

We have developed new, efficient gene delivery systems based on PEGylated poly(lactone-co-β-amino ester) block copolymers that are biodegradable, stable and low in toxicity. The PEG-poly[PDL-co-3-(4-(methylene)piperidin-1-yl)propanoate] (PEG-PPM) diblock and PPM-PEG-PPM triblock copolymers with various compositions were synthesized in one step via lipase-catalyzed copolymerization of ω-pentadecalactone (PDL) and ethyl 3-(4-(hydroxymethyl)piperidin-1-yl)propanoate (EHMPP) with an appropriate PEG (MeO-PEG-OH or HO-PEG-OH). The amphiphilic block copolymers are capable of condensing DNA in aqueous medium via a self-assembly process to form polyplex micelle nanoparticles with desirable particle sizes (70-140 nm). These micelles possess low CMC values and are stable in the medium containing serum protein molecules (FBS). Among the PEG-PPM and PPM-PEG-PPM micelles, the PEG-PPM-15% PDL micelle particles exhibited high DNA-binding ability, the fastest cellular uptake rate and highest gene transfection efficacy. Flow cytometry analysis shows that LucDNA/PEG-PPM-15% PDL polyplex micelles can effectively escape from endosomal degradation after cellular uptake likely due to the presence of the tertiary amine groups in the copolymer chains that act as proton sponges. In vitro cytotoxicity and hemolysis assay experiments indicate that all copolymer samples are nonhemolytic and have minimal toxicity toward COS-7 cells within the polymer concentration range (≤200 μg/mL) used for the gene transfection. These results demonstrate that the PEGylated poly(lactone-co-β-amino ester) block copolymers are promising new vectors for gene delivery applications.

Systemic siRNA Nanoparticle-Based Drugs Combined with Radiofrequency Ablation for Cancer Therapy

PURPOSE

Radiofrequency thermal ablation (RFA) of hepatic and renal tumors can be accompanied by non-desired tumorigenesis in residual, untreated tumor. Here, we studied the use of micelle-encapsulated siRNA to suppress IL-6-mediated local and systemic secondary effects of RFA.

METHODS

We compared standardized hepatic or renal RFA (laparotomy, 1 cm active tip at 70 ± 2 °C for 5 min) and sham procedures without and with administration of 150 nm micelle-like nanoparticle (MNP) anti-IL6 siRNA (DOPE-PEI conjugates, single IP dose 15 min post-RFA, C57Bl mouse:3.5 ug/100ml, Fisher 344 rat: 20 ug/200 ul), RFA/scrambled siRNA, and RFA/empty MNPs. Outcome measures included: local periablational cellular infiltration (α-SMA+ stellate cells), regional hepatocyte proliferation, serum/tissue IL-6 and VEGF levels at 6-72 hr, and distant tumor growth, tumor proliferation (Ki-67) and microvascular density (MVD, CD34) in subcutaneous R3230 and MATBIII breast adenocarcinoma models at 7 days.

RESULTS

For liver RFA, adjuvant MNP anti-IL6 siRNA reduced RFA-induced increases in tissue IL-6 levels, α-SMA+ stellate cell infiltration, and regional hepatocyte proliferation to baseline (p < 0.04, all comparisons). Moreover, adjuvant MNP anti-IL6- siRNA suppressed increased distant tumor growth and Ki-67 observed in R3230 and MATBIII tumors post hepatic RFA (p<0.01). Anti-IL6 siRNA also reduced RFA-induced elevation in VEGF and tumor MVD (p < 0.01). Likewise, renal RFA-induced increases in serum IL-6 levels and distant R3230 tumor growth was suppressed with anti-IL6 siRNA (p < 0.01).

CONCLUSIONS

Adjuvant nanoparticle-encapsulated siRNA against IL-6 can be used to modulate local and regional effects of hepatic RFA to block potential unwanted pro-oncogenic effects of hepatic or renal RFA on distant tumor.

Nanocarrier mediated delivery of siRNA/miRNA in combination with chemotherapeutic agents for cancer therapy: current progress and advances

Chemotherapeutic agents have certain limitations when it comes to treating cancer, the most important being severe side effects along with multidrug resistance developed against them. Tumor cells exhibit drug resistance due to activation of various cellular level processes viz. activation of drug efflux pumps, anti-apoptotic defense mechanisms, etc. Currently, RNA interference (RNAi) based therapeutic approaches are under vibrant scrutinization to seek cancer cure. Especially small interfering RNA (siRNA) and micro RNA (miRNA), are able to knock down the carcinogenic genes by targeting the mRNA expression, which underlies the uniqueness of this therapeutic approach. Recent research focus in the regime of cancer therapy involves the engagement of targeted delivery of siRNA/miRNA in combinations with other therapeutic agents (such as gene, DNA or chemotherapeutic drug) for targeting permeability glycoprotein (P-gp), multidrug resistant protein 1 (MRP-1), B-cell lymphoma (BCL-2) and other targets that are mainly responsible for resistance in cancer therapy. RNAi-chemotherapeutic drug combinations have also been found to be effective against different molecular targets as well and can increase the sensitization of cancer cells to therapy several folds. However, due to stability issues associated with siRNA/miRNA suitable protective carrier is needed and nanotechnology based approaches have been widely explored to overcome these drawbacks. Furthermore, it has been univocally advocated that the co-delivery of siRNA/miRNA with other chemodrugs significantly enhances their capability to overcome cancer resistance compared to naked counterparts. The objective of this article is to review recent nanocarrier based approaches adopted for the delivery of siRNA/miRNA combinations with other anticancer agents (siRNA/miRNA/pDNA/chemodrugs) to treat cancer.

Delivery of antisense oligonucleotides using poly(alkylene oxide)-poly(propylacrylic acid) graft copolymers in conjunction with cationic liposomes

The clinical application of gene silencing is hindered by poor stability and low delivery efficiency of naked oligonucleotides. Here, we present the in vitro and in vivo behaviors of a rationally designed, ternary, self-assembled nanoparticle complex, consisting of an anionic copolymer, cationic DOTAP liposome, and antisense oligonucleotide (AON). The multifunctional copolymers are based on backbone poly(propylacrylic acid) (PPAA), a pH-sensitive hydrophobic polymer, with grafted poly(alkylene oxides) (PAOs) varying in extent of grafting and PAO chemistry. The nanoparticle complexes with PPAA-g-PAO copolymers enhance antisense gene silencing effects in A2780 human ovarian cancer cells. A greater amount of AON is delivered to ovarian tumor xenografts using the ternary copolymer-stabilized delivery system, compared to a binary DOTAP/AON complex, following intraperitoneal injection in mice. Further, intratumoral injection of the nanoparticle complexes containing 1 mol% grafted PAO reduced tumoral bcl-2 expression by up to 60%. The data for complexes across the set of PAO polymers support a strong role for the hydrophilic-lipophilic balance of the graft copolymer in achieving serum stability and cellular uptake. Based upon these results, we anticipate that this novel nanoparticle delivery system can be extended to the delivery of plasmid DNA, siRNA, or aptamers for preclinical and clinical development.

Improving transfection efficiency of ultrapure oligochitosan/DNA polyplexes by medium acidification

CONTEXT

Ultrapure oligochitosans (UOCs) have recently been reported as efficient nonviral vectors for corneal and retinal gene delivery. However, the influence of some physicochemical factors on the transfection efficiency, such as the pH, remains unclear. Deeper in vitro research of these factors could provide valuable information for future clinical applications.

OBJECTIVE

The aim of this study is to determine the influence of the pH decrease on the transfection efficiency of UOC/pDNA polyplexes in HEK293 and ARPE19 cells.

MATERIALS AND METHODS

We elaborated self-assembled UOC/pCMS-EGFP polyplexes. The influence of the most important factors on the particle size and the zeta potential was studied by an orthogonal experimental design. We evaluated, in vitro, the cellular uptake and the transfection efficiency by flow cytometry, and the cytotoxicity of the vectors by CCK-8 assay.

RESULTS AND DISCUSSION

The pH of the medium strongly influences the physicochemical properties of the polyplexes, and by its modulation we are able to control their superficial charge. A significant increase on the cellular uptake and transfection efficiency of UOCs was obtained when the pH was acidified. Neither of our UOC/pCMS-EGFP polyplexes caused cytotoxicity; however, cells treated with Lipofectamine 2000™ showed decreased cell viability.

CONCLUSION

This kind of UOC vectors could be useful to transfect cells that are in an acidic environment, such as tumor cells. However, additional in vivo studies may be required in order to obtain an effective and safe medicine for nonviral gene therapy purpose.

Exploring the Solid State Properties of Enzymatic Poly(amine-co-ester) Terpolymers to Expand their Applications in Gene Transfection

Polymers bearing amino functional groups are an important class of materials capable of serving as non-viral carriers for DNA delivery to living cells. In this work biodegradable poly(amine-co-ester) terpolymers were synthesized via ring-opening and polycondensation copolymerization of lactone (ε-caprolactone (CL), ω-dodecalactone, ω-pentadecalactone (PDL), and ω-hexadecalactone) with diethyl sebacate (DES) and N-methyldiethanolamine (MDEA) in diphenyl ether, catalyzed by Candida antarctica lipase B (CALB). All lactone-DES-MDEA terpolymers had random distributions of lactone, sebacate, MDEA repeat units in the polymer chains. PDL-DES-MDEA terpolymers were studied in the composition range from 21 mol% to 90 mol% PDL whereas the terpolymers with other lactones were investigated at a single composition (80 mol% lactone). DSC and WAXS analyses showed that all investigated terpolymers crystallize in their respective homopolylactone crystal lattice. Terpolymers with large lactones and a high lactone content melt well above room temperature and are hard solids, whereas terpolymers with small lactones (e.g. CL) or with a low lactone content melt below/around ambient temperature and are waxy/gluey materials. Given the importance of hydrophobicity in influencing gene delivery, water contact angle measurements were carried out on lactone-DES-MDEA terpolymers showing that it is possible to tune the hydrophilic-to-hydrophobic balance by varying polymer composition and size of lactone units. To demonstrate the feasibility of using solid terpolymers as nanocarriers for DNA delivery, PDL-DES-MDEA copolymers with 65-90% PDL were successfully transformed into free-standing nanoparticles with average particle size ranging from 163 to 175 nm. Our preliminary results showed that LucDNA-loaded nanoparticles of the terpolymer with 65% PDL were effective for luciferase gene transfection of HEK293 cells.

Determination of key structure-activity relationships in siRNA delivery with a mixed micelle system

Short interfering ribonucleic acids (siRNAs) offer a highly specific and selective form of therapy for diseases with a genetic component; however the poor pharmacokinetic properties of the molecule have impeded its development into a therapeutic for use in vivo. Several different approaches have been taken to develop a successful siRNA delivery system but these systems lack the flexibility for easy optimisation. Here, we propose a polymeric nanoparticle (PNP) system consisting of two amphiphilic diblock copolymers which allow for the rapid determination of structure-activity relationships involving gene knockdown and toxicity. The diblock copolymers self-assemble into monodisperse micelles of defined hydrodynamic diameters ranging from 30 to 100 nm dependent on the copolymer ratio. A luciferase-based high throughput assay varying PNP composition, concentration and siRNA concentration allowed the rapid identification of efficient PNP formulations for adherent and suspension cell lines. Optimised PNPs efficiently knocked down a fusion oncogene in hard to transfect human leukaemic cells raising the possibility of targeting malignant cells in a cancer-specific fashion. This approach allows the optimum PNP formulation to be identified for different cell types and conditions.

Effect of N/P ratios on physicochemical stability, cellular association, and gene silencing efficiency for trimethyl chitosan/small interfering RNA complexes

N,N,N-Trimethyl chitosan (TMC) with 40% quaternization was used as a vector for small interfering RNA (siRNA) delivery. Nano-sized complexes were formed in water by mixing siRNA with TMC; the smallest particle sizes were obtained at a N/P ratio of 10. The complexes had a positive surface charge that increased with increases in the N/P ratio and leveled off at +20 mV with N/P ratios > 10. The majority of particles had a diameter <100 nm under transmission electron microscope (TEM). When the N/P ratio was >10, the binding efficiency of TMC with siRNA was >90%. In 25% fetal bovine serum, the TMC/siRNA complexes with N/P ratios of 10 and 20 were intact for 12 and 48 h, respectively. TMC/siRNA complexes with an N/P ratio > 5 efficiently entered the human embryonic kidney (HEK) 293 cells and trapped initially in the lysosomes, which could then relocate in the cytoplasm. Gene silencing, tested by using enhanced green fluorescent protein (EGFP), was reduced to ~60% by the complexes with N/P ratios of 10 and 20. Specific silencing was confirmed by dose dependency and nonsilencing effect of sequence-mismatch siRNA. No significant cytotoxicity was detected for the TMC/siRNA complexes. In this study, the influence of the N/P ratio on TMC/siRNA complexes was systematically investigated and TMC was found to be an effective vector for siRNA delivery using optimized formulations.

Investigation of the structural organization of cationic nanoemulsion/antisense oligonucleotide complexes

Atomic force microscopy image analysis and energy dispersive X-ray diffraction experiments were used to investigate the structural organization of cationic nanoemulsion/oligonucleotide complexes. Oligonucleotides targeting topoisomerase II gene were adsorbed on cationic nanoemulsions obtained by means of spontaneous emulsification procedure. Topographical analysis by atomic force microscopy allowed the observation of the nanoemulsion/oligonucleotide complexes through three-dimensional high-resolution images. Flattening of the oil droplets was observed, which was reduced in the complexes obtained at high amount of adsorbed oligonucleotides. In such conditions, complexes exhibit droplet size in the 600nm range. The oligonucleotides molecules were detected on the surface of the droplets, preventing their fusion during aggregation. A lamellar structure organization was identified by energy dispersive X-ray diffraction experiments. The presence of the nucleic acid molecules led to a disorganization of the lipid arrangement and an expansion in the lattice spacing, which was proportional to the amount of oligonucleotides added.

RNase non-sensitive and endocytosis independent siRNA delivery system: delivery of siRNA into tumor cells and high efficiency induction of apoptosis

To date, RNase degradation and endosome/lysosome trapping are still serious problems for siRNA-based molecular therapy, although different kinds of delivery formulations have been tried. In this report, a cell penetrating peptide (CPP, including a positively charged segment, a linear segment, and a hydrophobic segment) and a single wall carbon nanotube (SWCNT) are applied together by a simple method to act as a siRNA delivery system. The siRNAs first form a complex with the positively charged segment of CPP via electrostatic forces, and the siRNA-CPP further coats the surface of the SWCNT via hydrophobic interactions. This siRNA delivery system is non-sensitive to RNase and can avoid endosome/lysosome trapping in vitro. When this siRNA delivery system is studied in Hela cells, siRNA uptake was observed in 98% Hela cells, and over 70% mRNA of mammalian target of rapamycin (mTOR) is knocked down, triggering cell apoptosis on a significant scale. Our siRNA delivery system is easy to handle and benign to cultured cells, providing a very efficient approach for the delivery of siRNA into the cell cytosol and cleaving the target mRNA therein.

Phospholipid-modified polyethylenimine-based nanopreparations for siRNA-mediated gene silencing: implications for transfection and the role of lipid components

The clinical application of gene silencing mediated by small interfering RNA (siRNA) has been limited by the lack of efficient and safe carriers. Phospholipid modification of low molecular weight polyethylenimine (PEI 1.8 kDa) dramatically increased its gene down-regulation capacity while keeping cytotoxicity levels low. The silencing efficacy was highly dependent on the nature of the lipid grafted to PEI and the polymer/siRNA ratio employed. Phosphoethanolamine (DOPE and DPPE) and phosphocholine (PC) conjugation did not change the physicochemical properties and siRNA binding capacity of PEI complexes but had a large impact on their transfection and ability to down-regulate Green Fluorescent Protein (GFP) expression (60%, 30% and 5% decrease of GFP expression respectively). We found that the micelle-forming structure of DOPE and DPPE-PEI dramatically changed PEI's interaction with cell membranes and played a key role in promoting PEI 1.8 kDa transfection, completely ineffective in the absence of the lipid modification.

FROM THE CLINICAL EDITOR

While siRNA-based gene silencing methods could have numerous clinical applications, efficient delivery remains a major challenge. This team reports that DOPE-PEI and DPPE-PEI based micelle-forming nanostructures may be able to provide an efficient vector for siRNA transfection.

A review of the current status of siRNA nanomedicines in the treatment of cancer

RNA interference currently offers new opportunities for gene therapy by the specific extinction of targeted gene(s) in cancer diseases. However, the main challenge for nucleic acid delivery still remains its efficacy through intravenous administration. Over the last decade, many delivery systems have been developed and optimized to encapsulate siRNA and to specifically promote their delivery into tumor cells and improve their pharmacokinetics for anti-cancer purposes. This review aims to sum up the potential targets in numerous pathways and the properties of recently optimized siRNA synthetic nanomedicines with their preclinical applications and efficacy. Future perspectives in cancer treatment are discussed including promising concomitant treatment with chemotherapies or other siRNA. The outcomes in human clinical trials are also presented.

Targeting miRNAs to treat Hepatitis C Virus infections and liver pathology: Inhibiting the virus and altering the host

Hepatitis C Virus (HCV) infection-induced liver disease is a growing problem worldwide, and is the primary cause of liver failure requiring liver transplantation in North America. Improved therapeutic strategies are required to control and possibly eradicate HCV infections, and to modulate HCV-induced liver disease. Cellular microRNAs anneal to and regulate mRNA translation and stability and form a regulatory network that modulates virtually every cellular process. Thus, miRNAs are promising cellular targets for therapeutic intervention for an array of diseases including cancer, metabolic diseases, and virus infections. In this review we outline the features of miRNA regulation and how miRNAs may be targeted in strategies to modulate HCV replication and pathogenesis. In particular, we highlight miR-122, a miRNA that directly modulates the HCV life cycle using an unusual mechanism. This miRNA is very important since miR-122 antagonists dramatically reduced HCV titres in HCV-infected chimpanzees and humans and currently represents the most likely candidate to be the first miRNA-based therapy licensed for use. However, we also discuss other miRNAs that directly or indirectly alter HCV replication efficiency, liver cirrhosis, fibrosis and the development of hepatocellular carcinoma (HCC). We also discuss a few miRNAs that might be targets to treat HCV in cases of HCV/HIV co-infection. Finally, we review methods to deliver miRNA antagonists and mimics to the liver. In the future, it may be possible to design and deliver specific combinations of miRNA antagonists and mimics to cure HCV infection or to limit liver pathogenesis.

The delivery of thrombi-specific nanoparticles incorporating oligonucleotides into injured cerebrovascular endothelium

In acute vascular events, the endothelium derived tissue factor (TF) is the trigger of the coagulation cascade. In this study, EGFP-EGF1 protein-conjugated PEG-PLGA nanoparticle was employed as a TF targeting vehicle, the NF-κB decoy oligonucleotides (ODNs) was incorporated into it and the resulting EGF1-EGFP-NP-ODNs were evaluated as a vector for therapy of cortex infarction. At 2 h after transfection of TF expressed rat brain capillary endothelial cell, EGF1-EGFP-NP-ODNs was more efficiently internalized and located in the cytoplasm than NP-ODNs. At 4 h and 6 h after administration, ODNs were present in the nuclei and obviously inhibited the TF expression. At 6 h after i.v. administration in vivo, most EGF1-EGFP-NP were accumulated in the embolism vessels, distributed in the damaged endothelial cells and lowered the TF expression. At 24 h after i.v. administration, MR imaging of cortex infarcts were predominantly dwindled.

A calcium phosphate nanoparticle-based biocarrier for efficient cellular delivery of antisense oligodeoxynucleotides

Antisense oligodeoxynucleotides (ASODNs) can bind to some specific RNA of survivin can prevent the mRNA translation at the genetic level, which will inhibit survivin expression and make the cancer cells apoptosis. However, the ASODNs-based therapies are hampered by their instability to cellular nuclease and their weak intracellular penetration. Here we reported a calcium phosphate (CP)-based carrier to achieve efficient delivery of ASODNs into cells. In this study, we used a facile microemulsion approach to prepare spherical and porous ASODNs-CP nanoparticles (ASODNS-CPNPs) with the size of 50-70 nm in diameter, and their structure, morphology and composition were characterized by TEM, XRD, FTIR, ICP and DLS, UV-Vis spectroscopy and agarose gel electrophoresis. The results indicated that the nanoparticles have a high ASODNs loading capacity. Furthermore, cellular uptake and delivery efficiency of the ASODNS-CPNPs, as well as cellular apoptosis induced by the ASODNs doping into the calcium phosphate nanoparticles, were investigated by confocal laser scanning microscopy, biological TEM, flow cytometry, and MTT assay. Efficient intracellular delivery of the nanoparticles was observed. All these results suggested that the prepared calcium phosphate nanoparticles could be used as a promising biocarrier for delivery of ASODNs.

Anti-HIV-1 nanotherapeutics: promises and challenges for the future

The advent of highly active antiretroviral therapy (HAART) has significantly improved the prognosis for human immunodeficiency virus (HIV)-infected patients, however the adverse side effects associated with prolonged HAART therapy use continue. Although systemic viral load can be undetectable, the virus remains sequestered in anatomically privileged sites within the body. Nanotechnology-based delivery systems are being developed to target the virus within different tissue compartments and are being evaluated for their safety and efficacy. The current review outlines the various nanomaterials that are becoming increasingly used in biomedical applications by virtue of their robustness, safety, multimodality, and multifunctionality. Nanotechnology can revolutionize the field of HIV medicine by not only improving diagnosis, but also by improving delivery of antiretrovirals to targeted regions in the body and by significantly enhancing the efficacy of the currently available antiretroviral medications.

Formulation approaches to short interfering RNA and MicroRNA: challenges and implications

RNA interference has emerged as a potentially powerful tool in the treatment of genetic and acquired diseases by delivering short interfering RNA (siRNA) or microRNA (miRNA) to target genes, resulting in their silencing. However, many physicochemical and biological barriers have to be overcome to obtain efficient in vivo delivery of siRNA and miRNA molecules to the organ/tissue of interest, thereby enabling their effective clinical therapy. This review discusses the challenges associated with the use of siRNA and miRNA and describes the nonviral delivery strategies used in overcoming these barriers. More specifically, emphasis has been placed on those technologies that have progressed to clinical trials for both local and systemic siRNA and miRNA delivery.

Polymeric nanocarriers for controlled and enhanced delivery of therapeutic agents to the CNS

Polymeric nanocarriers are versatile structures that can be engineered to obtain high drug loading, good delivery yields and tunable release kinetics. Moreover, the particle surface can be modified for selective targeting of organs or tissues. In particular, polymeric nanocarriers can be conjugated with functional groups promoting translocation through the blood–brain barrier, thus providing a promising system to deliver therapeutic agents and/or diagnostic probes to the brain. Here we review recent literature on the preparation and characterization of polymeric nanoparticles as potential agents for drug delivery to the CNS, with an emphasis on materials chemistry and functionalization strategies for improved selectivity and delivery. Finally, we underline the immunotoxicological aspects of this class of nanostructured materials in view of potential clinical applications.

Self-assembly nanomicelles based on cationic mPEG-PLA-b-Polyarginine(R15) triblock copolymer for siRNA delivery

Due to the absence of safe and effective carriers for in vivo delivery, the applications of small interference RNA (siRNA) in clinic for therapeutic purposes have been limited. In this study, a biodegradable amphiphilic tri-block copolymer (mPEG(2000)-PLA(3000)-b-R(15)) composed of monomethoxy poly(ethylene glycol), poly(d,l-lactide) and polyarginine was synthesized and further self-assembled to cationic polymeric nanomicelles for in vivo siRNA delivery, with an average diameter of 54.30 ± 3.48 nm and a zeta potential of approximately 34.8 ± 1.77 mV. The chemical structures of the copolymers were well characterized by (1)H NMR spectroscopy and FT-IR spectra. In vitro cytotoxicity and hemolysis assays demonstrated that the polymeric nanomicelles showed greater cell viability and haemocompatibility than those of polyethyleneimine (PEI) or R(15) peptide. In vitro experiments demonstrated that EGFR targeted siRNA formulated in micelleplexes exhibited approximately 65% inhibition of EGFR expression on MCF-7 cells in a sequence-specific manner, which was comparable to Lipofectamine™ 2000. The results of intravenous administration showed Micelleplex/EGFR-siRNA significantly inhibited tumor growth in nude mice xenografted MCF-7 tumors, with a remarkable inhibition of EGFR expression. Furthermore, no positive activation of the innate immune responses and no significant body weight loss was observed during treatment suggested that this polymeric micelle delivery system is non-toxic. In conclusion, the present nanomicelles based on cationic mPEG(2000)-PLA(3000)-b-R(15) copolymer would be a safe and efficient nanocarrier for in vivo delivery of therapeutic siRNA.

Nanotechnology and the treatment of HIV infection

Suboptimal adherence, toxicity, drug resistance and viral reservoirs make the lifelong treatment of HIV infection challenging. The emerging field of nanotechnology may play an important role in addressing these challenges by creating drugs that possess pharmacological advantages arising out of unique phenomena that occur at the “nano” scale. At these dimensions, particles have physicochemical properties that are distinct from those of bulk materials or single molecules or atoms. In this review, basic concepts and terms in nanotechnology are defined, and examples are provided of how nanopharmaceuticals such as nanocrystals, nanocapsules, nanoparticles, solid lipid nanoparticles, nanocarriers, micelles, liposomes and dendrimers have been investigated as potential anti-HIV therapies. Such drugs may, for example, be used to optimize the pharmacological characteristics of known antiretrovirals, deliver anti-HIV nucleic acids into infected cells or achieve targeted delivery of antivirals to the immune system, brain or latent reservoirs. Also, nanopharmaceuticals themselves may possess anti-HIV activity. However several hurdles remain, including toxicity, unwanted biological interactions and the difficulty and cost of large-scale synthesis of nanopharmaceuticals.

Cell-penetrating peptides as versatile vehicles for oligonucleotide delivery

Short regulatory oligonucleotides (ONs) have a great therapeutic potential for the modulation of gene expression due to their high specificity and low toxicity. The major obstacles for in vivo clinical applications of ONs are the poor permeability of plasma membrane to nucleic acids and the sensitivity of ONs to enzymatic degradation. Hence, various delivery vehicles have been developed to ensure the transduction of ONs into cells. Among these, the cell-penetrating peptides (CPPs) have gained quickly broadening popularity as promising nonviral transmembrane delivery vectors. For coupling of nucleic acids to CPPs, two distinct strategies may be applied-covalent and noncovalent. The majority of earlier studies have used covalent coupling of CPPs to ONs. However, the number of studies demonstrating very high therapeutic potential of noncovalent complexes of ONs with novel CPP-based delivery vehicles is explosively increasing. In this review, the recent developments in the application of CPP-mediated oligonucleotide delivery by noncovalent strategy will be discussed.

Potential Use of Polyamidoamine Dendrimer Conjugates with Cyclodextrins as Novel Carriers for siRNA

Cyclodextrin (CyD)-based nanoparticles and polyamidoamine (PAMAM) starburst dendrimers (dendrimers) are used as novel carriers for DNA and RNA. Recently, small interfering RNA (siRNA) complex with β-CyD-containing polycations (CDP) having adamantine-PEG or adamantine-PEG-transferrin underwent a phase I study for treatment of solid tumors. Multifunctional dendrimers can be used for a wide range of biomedical applications, including the interaction and intracellular delivery of DNA and RNA. The present review will address the latest developments in dendrimer conjugates with cyclodextrins for siRNA delivery including the novel sustained release system.