Requirements for the nuclear entry of polyplexes and nanoparticles during mitosis

Nanomaterials in Medicine: Understanding Cellular Uptake, Localization, and Retention for Enhanced Disease Diagnosis and Therapy

Nanomaterials (NMs) have emerged as promising tools for disease diagnosis and therapy due to their unique physicochemical properties. To maximize the effectiveness and design of NMs-based medical applications, it is essential to comprehend the complex mechanisms of cellular uptake, subcellular localization, and cellular retention. This review illuminates the various pathways that NMs take to get from the extracellular environment to certain intracellular compartments by investigating the various mechanisms that underlie their interaction with cells. The cellular uptake of NMs involves complex interactions with cell membranes, encompassing endocytosis, phagocytosis, and other active transport mechanisms. Unique uptake patterns across cell types highlight the necessity for customized NMs designs. After internalization, NMs move through a variety of intracellular routes that affect where they are located subcellularly. Understanding these pathways is pivotal for enhancing the targeted delivery of therapeutic agents and imaging probes. Furthermore, the cellular retention of NMs plays a critical role in sustained therapeutic efficacy and long-term imaging capabilities. Factors influencing cellular retention include nanoparticle size, surface chemistry, and the cellular microenvironment. Strategies for prolonging cellular retention are discussed, including surface modifications and encapsulation techniques. In conclusion, a comprehensive understanding of the mechanisms governing cellular uptake, subcellular localization, and cellular retention of NMs is essential for advancing their application in disease diagnosis and therapy. This review provides insights into the intricate interplay between NMs and biological systems, offering a foundation for the rational design of next-generation nanomedicines.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

A Nanomedicine Structure-Activity Framework for Research, Development, and Regulation of Future Cancer Therapies

Despite their clinical success in drug delivery applications, the potential of theranostic nanomedicines is hampered by mechanistic uncertainty and a lack of science-informed regulatory guidance. Both the therapeutic efficacy and the toxicity of nanoformulations are tightly controlled by the complex interplay of the nanoparticle's physicochemical properties and the individual patient/tumor biology; however, it can be difficult to correlate such information with observed outcomes. Additionally, as nanomedicine research attempts to gradually move away from large-scale animal testing, the need for computer-assisted solutions for evaluation will increase. Such models will depend on a clear understanding of structure-activity relationships. This review provides a comprehensive overview of the field of cancer nanomedicine and provides a knowledge framework and foundational interaction maps that can facilitate future research, assessments, and regulation. By forming three complementary maps profiling nanobio interactions and pathways at different levels of biological complexity, a clear picture of a nanoparticle's journey through the body and the therapeutic and adverse consequences of each potential interaction are presented.

Mineralized vectors for gene therapy

There is an intense interest in developing materials for safe and effective delivery of polynucleotides using non-viral vectors. Mineralization of organic templates has long been used to produce complex materials with outstanding biocompatibility. However, a lack of control over mineral growth has limited the applicability of mineralized materials to a few in vitro applications. With better control over mineral growth and surface functionalization, mineralized vectors have advanced significantly in recent years. Here, we review the recent progress in chemical synthesis, physicochemical properties, and applications of mineralized materials in gene therapy, focusing on structure-function relationships. We contrast the classical understanding of the mineralization mechanism with recent ideas of mineralization. A brief introduction to gene delivery is summarized, followed by a detailed survey of current mineralized vectors. The vectors derived from calcium phosphate are articulated and compared to other minerals with unique features. Advanced mineral vectors derived from templated mineralization and specialty coatings are critically analyzed. Mineral systems beyond the co-precipitation are explored as more complex multicomponent systems. Finally, we conclude with a perspective on the future of mineralized vectors by carefully demarcating the boundaries of our knowledge and highlighting ambiguous areas in mineralized vectors. STATEMENT OF SIGNIFICANCE: Therapy by gene-based medicines is increasingly utilized to cure diseases that are not alleviated by conventional drug therapy. Gene medicines, however, rely on macromolecular nucleic acids that are too large and too hydrophilic for cellular uptake. Without tailored materials, they are not functional for therapy. One emerging class of nucleic acid delivery system is mineral-based materials. The fact that they can undergo controlled dissolution with minimal footprint in biological systems are making them attractive for clinical use, where safety is utmost importance. In this submission, we will review the emerging synthesis technology and the range of new generation minerals for use in gene medicines.

Complex pBAE nanoparticles cell trafficking: tracking both position and composition using super resolution microscopy

Nanomedicine emerged some decades ago with the hope to be the solution for most unmet medical needs. However, tracking materials at nanoscale is challenging to their reduced size, below the resolution limit of most conventional techniques. In this context, we propose the use of direct stochastic optical reconstruction microscopy (dSTORM) to study time stability and cell trafficking after transfection of oligopeptide end‐modified poly(β‐aminoester) (OM‐pBAE) nanoparticles. We selected different combinations of cationic end oligopeptides (arginine – R; histidine – H; and lysine – K) among polymer libraries, since the oligopeptide combination demonstrated to be useful for different applications, such as vaccination and gene silencing. We demonstrate that their time evolution as well as their cell uptake and trafficking are dependent on the oligopeptide. This study opens the pave to broad mechanistic studies at nanoscale that could enable a rational selection of specific pBAE nanoparticles composition after determining their stability and cell trafficking.

Mineralized polyplexes for gene delivery: Improvement of transfection efficiency as a consequence of calcium incubation and not mineralization

Gene therapy is an emerging field in which nucleic acids are used to control protein expression. The necessity of delivering nucleic acids to specific cell types and intracellular sites demands the use of highly specialized gene carriers. As a carrier modification technique, mineralization has been successfully used to modify viral and non-viral carriers, providing new properties that ultimately aim to increase the transfection efficiency. However, for the specific case of polyplexes used in gene therapy, recent literature shows that interaction with calcium, a fundamental step of mineralization, might be effective to increase transfection efficiency, leaving an ambiguity about of the role of mineralization for this type of gene carriers. To answer this question and to reveal the properties responsible for increasing transfection efficiency, we mineralized poly(aspartic acid) coated polyplexes at various CaCl₂ and Na₃PO₄ concentrations, and evaluated the resultant carriers for physicochemical and morphological characteristics, as well as transfection and delivery efficiency with MC3T3-E1 mouse osteoblastic cells. We found that both mineralization and calcium incubation positively affected the transfection efficiency and uptake of polyplexes in MC3T3-E1 cells. However, this effect originated from the properties achieved by polyplexes after the calcium incubation step that are maintained after mineralization, including particle size increase, improved pDNA binding, and adjustment of zeta potential. Considering that mineralization can be a longer process than calcium incubation, we find that calcium incubation might be sufficient and preferred if improved transfection efficiency in vitro is the only effect desired.

Polymeric delivery systems for nucleic acid therapeutics: Approaching the clinic

Gene therapy using nucleic acids has many clinical applications for the treatment of diseases with a genetic origin as well as for the development of innovative vaccine formulations. Since nucleic acids in their free form are rapidly degraded by nucleases present in extracellular matrices, have poor pharmacokinetics and hardly pass cellular membranes, carrier systems are required. Suitable carriers that protect the nucleic acid payload against enzymatic attack, prolong circulation time after systemic administration and assist in cellular binding and internalization are needed to develop nucleic acid based drug products. Viral vectors have been investigated and are also clinically used as delivery vehicles. However, some major drawbacks are associated with their use. Therefore there has been substantial attention on the use of non-viral carrier systems based on cationic lipids and polymers. This review focuses on the properties of polymer-based nucleic acid formulations, also referred as polyplexes. Different polymeric systems are summarized, and the cellular barriers polyplexes encounter and ways to tackle these are discussed. Finally attention is given to the clinical status of non-viral nucleic acid formulations.

Mechanistic Approaches of Internalization, Subcellular Trafficking, and Cytotoxicity of Nanoparticles for Targeting the Small Intestine

Targeting the small intestine employing nanotechnology has proved to be a more effective way for site-specific drug delivery. The drug targeting to the small intestine can be achieved via nanoparticles for its optimum bioavailability within the systemic circulation. The small intestine is a remarkable candidate for localized drug delivery. The intestine has its unique properties. It has a less harsh environment than the stomach, provides comparatively more retention time, and possesses a greater surface area than other parts of the gastrointestinal tract. This review focuses on elaborating the intestinal barriers and approaches to overcome these barriers for internalizing nanoparticles and adopting different cellular trafficking pathways. We have discussed various factors that contribute to nanocarriers' cellular uptake, including their surface chemistry, surface morphology, and functionalization of nanoparticles. Furthermore, the fate of nanoparticles after their uptake at cellular and subcellular levels is also briefly explained. Finally, we have delineated the strategies that are adopted to determine the cytotoxicity of nanoparticles.

Nuclear-targeted gold nanoparticles enhance cancer cell radiosensitization

Radiation therapy aims to kill or inhibit proliferation of cancer cells while sparing normal cells. To enhance radiosensitization, we developed 40 nm-sized gold nanoparticles targeting the nucleus. We exploited a strategy that combined RGD and NLS peptides respectively targeting cancer cell and the nucleus to initiate cell-death activated by x-ray irradiation. We observed that the modified gold nanoparticles were either translocated in the nuclei or accumulated in the vicinity of the nuclei. We demonstrated that x-ray irradiation at 225 kVp energy reduced cell proliferation by 3.8-fold when the nuclear targeted gold nanoparticles were used. We determined that the radiation dose to have a 10% survival fraction was reduced from 11.0 Gy to 7.1 Gy when 10.0 µg ml^-1 of the NLS/RGD/PEG-AuNP was incubated with A549 cancer cells. We conclude that the peptide-modified gold nanoparticles targeting the nucleus significantly enhance radiosensitization.

Outer membrane vesicles derived from E. coli as novel vehicles for transdermal and tumor targeting delivery

Transdermal drug delivery is favored in clinical therapy because of its ability to overcome the shortcomings of the first pass elimination of the liver caused by traditional oral administration and the irreversibility of the injection. However, skin stratum corneum (SC) forms a big barrier that precludes most of the biomacromolecules. Herein, we propose the engineering of transformed Escherichia coli (E. coli) derived outer membrane vesicles, detoxified by lysozymes (named TEVs) as the carrier for transdermal drug delivery. TEVs were derived from transgenic E. coli and then modified by an integrin alpha(v)beta(3) (αvβ3) targeting peptide and co-loaded with indocyanine green (ICG) (P-TEVs-G). TEVs were shown to have excellence in penetrating through intact SC without any additional enhancement, followed by targeting of melanoma cells. TEVs are promising nanoplatforms for transdermal and tumor targeting drug delivery with high efficacy and biosafety, possessing great potential in the treatment of superficial tumors.

Targeting DNA to the endoplasmic reticulum efficiently enhances gene delivery and therapy

Gene therapy mediated by non-viral carriers is gaining an increasing popularity due to its high biosafety and the convenience of production on a large scale, yet inefficient gene delivery is a limiting obstacle. Few gene vectors can avoid the endosome-lysosome route, and as a result, their DNA payloads are easily decomposed during transfection. Herein, a peptide (pardaxin, PAR)-modified cationic liposome (PAR-Lipo) targeting the endoplasmic reticulum (ER) was developed for improving the gene delivery efficiency. Interestingly, compared to non-PAR-modified cationic liposomes (Non-Lipos) and Lipofectamine 2000 (Lipo 2000, a commercial genetic vector), PAR-Lipos showed remarkably higher gene delivery efficiency in vitro and better antitumor efficacy in vivo. It was demonstrated that PAR-Lipos could be accumulated into the ER via a non-lysosome intracellular route after cellular internalization, which induced the retention of the DNA payload in the ER close to the nucleus, while Non-Lipos, like most conventional cationic carriers, mainly presented lysosomal retention after their endocytosis. The unique intracellular transport behavior of PAR-Lipos can enhance the protection of the DNA payload, prolong their residence time in the cell, and promote their entry into the nucleus relying on the intimate relationship between the ER and nuclear membrane, which is the explanation for the enhanced gene-therapy effect mediated by PAR-Lipos. Our research may provide alternative means of efficiently delivering genes in cells.

Nanotechnology and immunoengineering: How nanotechnology can boost CAR-T therapy

Chimeric antigen receptor (CAR) therapy has achieved remarkable clinical efficacy against hematological cancers and has been approved by FDA for treatment of B-cell tumors. However, the complex manufacturing process and limited success in solid tumors hamper its widespread applications, thus prompting the development of new strategies for overcoming the abovementioned hurdles. In the last decade, nanotechnology has provided sustainable strategies for improving cancer immunotherapy through vaccine development and delivery of immunomodulatory drugs. Nanotechnology can boost CAR-T therapy and may overcome the existing challenges by emerging as a carrier for CAR-T therapy or in combination with CAR-T, it may inhibit solid tumors more effectively than conventional approaches. The revealing of cellular mechanisms, barriers and potential strategies that could be used to manipulate and/or modify cells would enable unprecedented advances in nanotechnology for biologics delivery. This review outlines the journey and barriers of nanoparticles (NPs) across the cell. Subsequently, the approaches to tackle the barriers and strategies to modulate NPs as a carrier for CAR-T therapy are discussed. Finally, the role of NPs in CAR-T therapy and the potential challenges are summarized. This review aims to provide the readers with a detailed overview of NP-based CAR-T therapy research and distil this information into an accessible form conducive to design desired CAR-T therapy using NP approach. STATEMENT OF SIGNIFICANCE: Chimeric antigen receptor (CAR) T-cell therapy is the most vibrant field in immuno-oncology today, with enormous benefits to patients with B-cell malignancies. However, a rapid and straightforward procedure for CAR-T generation is an exigent need to broaden its therapeutic avenue. Nanotechnology has emerged as a novel alternative approach for CAR-T generation. To the best of our knowledge, this is the first in-depth review that briefly highlights the various aspects of nanotechnology in CAR-T therapy, including the strategies to brand NPs as an effective carrier for CAR cargo, its potential advantages, challenges, and future roadmap. It provides readers with a detailed overview of NP-based CAR-T therapy research, and researchers would be able to distill this information into an accessible form conducive to design the desired CAR therapy using the nanotechnology approach.

Polystyrene nanoparticles may affect cell mitosis and compromise early embryo development in mammals

A great interest surrounds the development of nanoparticles (NPs) for biomedical applications such as drug delivery and cancer therapy. However, the interplay between nanoscale materials and biological systems and the associated hazards have not been completely clarified yet. In this study, bovine oviductal epithelial cells (BOECs) and embryos were used as in vitro models to investigate whether cell mitosis and early mammalian embryo development could be affected by the exposure to polystyrene (PS) nanoparticles. Analysis of the karyotype performed on BOECs exposed to PS-NPs did not show chromosomal anomalies compared to the control, although more tetraploid metaphase plates were observed in the former. In vitro fertilization experiments designed to understand whether exposure to PS-NPs could affect pre-implantation development showed that incubation with PS-NPs decreased 8-cell embryo and blastocyst rate in dose-dependent fashion. The quality of the blastocysts in terms of mean cell percent blastomeres with fragmented DNA was the same in exposed blastocysts compared to controls. These results show that the exposure to PS-NPs may impair development. In turn, this may affect the rate of mitosis in embryos and yield a lower developmental competence to reach the blastocyst stage. This suggests that release in the environment and the subsequent accumulation of PS-NPs into living organisms should be carefully monitored to prevent cytotoxic effects that may compromise their reproduction rates.

Tracking the DNA complexation state of pBAE polyplexes in cells with super resolution microscopy

The future of gene therapy relies on the development of efficient and safe delivery vectors. Poly(β-amino ester)s are promising cationic polymers capable of condensing oligonucleotides into nanoparticles - polyplexes - and deliver them into the cell nucleus, where the gene material would be expressed. The complexation state during the crossing of biological barriers is crucial: polymers should tightly complex DNA before internalization and then release to allow free DNA to reach the nucleus. However, measuring the complexation state in cells is challenging due to the nanometric size of polyplexes and the difficulties to study the two components (polymer and DNA) independently. Here we propose a method to visualize and quantify the two components of a polyplex inside cells, with nanometre scale resolution, using two-colour direct stochastic reconstruction super-resolution microscopy (dSTORM). With our approach, we tracked the complexation state of pBAE polyplexes from cell binding to DNA release and nuclear entry revealing time evolution and the final fate of DNA and pBAE polymers in mammalian cells.

Engineered Polymeric Materials for Biological Applications: Overcoming Challenges of the Bio-Nano Interface

Nanomedicine has generated significant interest as an alternative to conventional cancertherapy due to the ability for nanoparticles to tune cargo release. However, while nanoparticletechnology has promised significant benefit, there are still limited examples of nanoparticles inclinical practice. The low translational success of nanoparticle research is due to the series ofbiological roadblocks that nanoparticles must migrate to be effective, including blood and plasmainteractions, clearance, extravasation, and tumor penetration, through to cellular targeting,internalization, and endosomal escape. It is important to consider these roadblocks holistically inorder to design more effective delivery systems. This perspective will discuss how nanoparticlescan be designed to migrate each of these biological challenges and thus improve nanoparticledelivery systems in the future. In this review, we have limited the literature discussed to studiesinvestigating the impact of polymer nanoparticle structure or composition on therapeutic deliveryand associated advancements. The focus of this review is to highlight the impact of nanoparticlecharacteristics on the interaction with different biological barriers. More specific studies/reviewshave been referenced where possible.

Histone-targeted gene transfer of bone morphogenetic protein-2 enhances mesenchymal stem cell chondrogenic differentiation

Skeletal tissue regeneration following traumatic injury involves a complex cascade of growth factor signals that direct the differentiation of mesenchymal stem cells (MSCs) within the fracture. The necessity for controlled and localized expression of these factors has highlighted the role gene therapy may play as a promising treatment option for bone repair. However, the design of nanocarrier systems that negotiate efficient intracellular trafficking and nuclear delivery represents a significant challenge. Recent investigations have highlighted the roles histone tail sequences play in directing nuclear delivery and activating DNA transcription. We previously established the ability to recapitulate these natural histone tail activities within non-viral nanocarriers, improving gene transfer and expression by enabling effective navigation to the nucleus via retrograde vesicular trafficking. Herein, we demonstrate that histone-targeting leads to ∼4-fold enhancements in osteogenic bone morphogenetic protein-2 (BMP-2) expression by MSCs over 6 days, as compared with standard polymeric transfection reagents. This improved expression augmented chondrogenesis, an essential first step in fracture healing. Importantly, significant enhancements of cartilage-specific protein expression were triggered by histone-targeted gene transfer, as compared with the response to treatment with equivalent amounts of recombinant BMP-2 protein. In fact, an ∼100-fold increase in recombinant BMP-2 was required to achieve similar levels of chondrogenic gene and protein expression. The enhancements in differentiation achieved using histone-targeting were in part enabled by an increase in transcription factor expression, which functioned to drive MSC chondrogenesis. These novel findings demonstrate the utility of histone-targeted gene transfer strategies to enable substantial reductions in BMP-2 dosing for bone regenerative applications.

STATEMENT OF SIGNIFICANCE

This contribution addresses significant limitations in non-viral gene transfer for bone regenerative applications by exploiting a novel histone-targeting approach for cell-triggered delivery that induces osteogenic BMP-2 expression coincident with the initiation of bone repair. During repair, proliferating MSCs respond to a complex series of growth factor signals that direct their differentiation along cellular lineages essential to mature bone formation. Although these MSCs are ideal targets for enhanced transfection during cellular mitosis, few non-viral delivery approaches exist to enable maximization of this effect. Accordingly, this contribution seeks to utilize our histone-targeted nanocarrier design strategy to stimulate BMP-2 gene transfer in dividing MSCs. This gene-based approach leads to significantly augmented MSC chondrogenesis, an essential first step in bone tissue repair.

Enhancement of Angiogenesis by Ultrasound-Targeted Microbubble Destruction Combined with Nuclear Localization Signaling Peptides in Canine Myocardial Infarction

Objective

This study aimed to develop a gene delivery system using ultrasound-targeted microbubbles destruction (UTMD) combined with nuclear localization signal (NLS) and investigate its efficacy and safety for therapeutic angiogenesis in canine myocardial infarction (MI) model.

Methods

Fifty MI dogs were randomly divided into 5 groups and transfected with Ang-1 gene plasmid: (i) group A: only injection of microbubbles and Ang-1 plasmid; (ii) group B: only UTMD mediated gene transfection; (iii) group C: UTMD combined with classical NLS mediated gene transfection; (iv) group D: UTMD combined with mutational NLS mediated transfection; and (v) group E: UTMD combined with classical NLS in the presence of a nucleus transport blocker. The mRNA and protein expression of Ang-1 gene, microvessel density (MVD) cardiac troponin I (cTnI), and cardiac function were determined after transfection.

Results

The expression of mRNA and protein of Ang-1 gene in group C was significantly higher than that of the other groups (all P < 0.01). The MVD of group C was 10.2-fold of group A and 8.1-fold of group E (P < 0.01). The cardiac function in group C was significant improvement without cTnI rising.

Conclusions

The gene delivery system composed of UTMD and NLS is efficient and safe.

Journey to the Center of the Cell: Current Nanocarrier Design Strategies Targeting Biopharmaceuticals to the Cytoplasm and Nucleus

New biopharmaceutical molecules, potentially able to provide more personalized and effective treatments, are being identified through the advent of advanced synthetic biology strategies, sophisticated chemical synthesis approaches, and new analytical methods to assess biological potency. However, translation of many of these structures has been significantly limited due to the need for more efficient strategies to deliver macromolecular therapeutics to desirable intracellular sites of action. Engineered nanocarriers that encapsulate peptides, proteins, or nucleic acids are generally internalized into target cells via one of several endocytic pathways. These nanostructures, entrapped within endosomes, must navigate the intracellular milieu to orchestrate delivery to the intended destination, typically the cytoplasm or nucleus. For therapeutics active in the cytoplasm, endosomal escape continues to represent a limiting step to effective treatment, since a majority of nanocarriers trapped within endosomes are ultimately marked for enzymatic degradation in lysosomes. Therapeutics active in the nucleus have the added challenges of reaching and penetrating the nuclear envelope, and nuclear delivery remains a preeminent challenge preventing clinical translation of gene therapy applications. Herein, we review cutting-edge peptide- and polymer-based design strategies with the potential to enable significant improvements in biopharmaceutical efficacy through improved intracellular targeting. These strategies often mimic the activities of pathogens, which have developed innate and highly effective mechanisms to penetrate plasma membranes and enter the nucleus of host cells. Understanding these mechanisms has enabled advances in synthetic peptide and polymer design that may ultimately improve intracellular trafficking and bioavailability, leading to increased access to new classes of biotherapeutics.

How successful is nuclear targeting by nanocarriers?

The nucleus is ultimately the final target for many therapeutics treating various disorders including cancers, heart dysfunction and brain disorders. Owing to their specialized cell uptake and trafficking mechanisms, nanoparticles (NPs) allow drug targeting where degradation sensitive therapeutics could be delivered to their target tissues and cell in active form and sufficient concentration. However, it has recently become increasingly obvious that cytosolic internalization of a drug molecule does not entail its interaction with its subcellular target and hence careful nanoparticle design and optimization is required to enable nuclear targeting. This review, discusses the barriers to NP nuclear delivery; crossing the cell membrane, endo/lysosomal escape, cytoplasmic trafficking and finally nuclear entry focusing on how NP synthesis and modification could allow for bypassing each of the aforementioned barriers and successfully reaching the nucleus. Examples of nuclear targeted NPs are also discussed, stressing on the critical aspects of nuclear targeting and pointing out how the disease state might change the normal NP path and how such change could be exploited to increase efficiency of nuclear targeting. Finally, the criteria set for the evaluation of nanocarriers for nuclear delivery are discussed highlighting that quantitative rather than qualitative evaluation is required to evaluate how successful nanocarriers for nuclear delivery are, particularly with regards to the amount of drug delivered and released in the nucleus.

Importin-4 Regulates Gene Delivery by Enhancing Nuclear Retention and Chromatin Deposition by Polyplexes

For successful gene delivery, plasmid DNA must be able to access the nucleus in order to be transcribed. Numerous studies have shown that gene delivery occurs more readily in dividing cells, which is attributed to increased nuclear access when the nuclear envelope disassembles during mitosis; however, nonviral carriers continue to have low transfection efficiencies and require large quantities of DNA per cell to achieve reasonable gene transfer, even in dividing cells. Therefore, we hypothesized that using histone-derived nuclear localization sequences (NLS)s to target polyplexes might enhance nuclear delivery by facilitating interactions with histone effectors that mediate nuclear partitioning and retention during mitosis. We discovered a novel interaction between polyplexes linked to histone 3 (H3) N-terminal tail peptides and the histone nuclear import protein importin-4, as evidenced by strong spatial colocalization as well as significantly decreased transfection when importin-4 expression was reduced. A fraction of the histone-targeted polyplexes was also found to colocalize with the retrotranslocon of the endoplasmic reticulum, Sec61. Super resolution microscopy demonstrated a high level of polyplex binding to chromatin postmitosis, and there also was a significant decrease in the amount of chromatin binding following importin-4 knockdown. These results provide evidence that natural histone effectors mediate both nuclear entry and deposition on chromatin by histone-targeted polyplexes, and a translocation event from the endoplasmic reticulum into the cytosol may occur before mitosis to enable the polyplexes to interact with these essential cytoplasmic proteins.

Chitosan Nanoparticles for Nuclear Targeting: The Effect of Nanoparticle Size and Nuclear Localization Sequence Density

Many recently discovered therapeutic proteins exert their main function in the nucleus, thus requiring both efficient uptake and correct intracellular targeting. Chitosan nanoparticles (NPs) have attracted interest as protein delivery vehicles due to their biocompatibility and ability to escape the endosomes offering high potential for nuclear delivery. Molecular entry into the nucleus occurs through the nuclear pore complexes, the efficiency of which is dependent on NP size and the presence of nuclear localization sequence (NLS). Chitosan nanoparticles of different sizes (S-NPs ≈ 25 nm; L-NP ≈ 150 nm) were formulated, and they were modified with different densities of the octapeptide NLS CPKKKRKV (S-NPs, 0.25, 0.5, 2.0 NLS/nm(2); L-NPs, 0.6, 0.9, 2 NLS/nm(2)). Unmodified and NLS-tagged NPs were evaluated for their protein loading capacity, extent of cell association, cell uptake, cell surface binding, and finally nuclear delivery efficiency in L929 fibroblasts. To avoid errors generated with cell fractionation and nuclear isolation protocols, nuclear delivery was assessed in intact cells utilizing Förster resonance energy transfer (FRET) fluorometry and microscopy. Although L-NPs showed ≈10-fold increase in protein loading per NP when compared to S-NPs, due to higher cell association and uptake S-NPs showed superior protein delivery. NLS exerts a size and density dependent effect on nanoparticle uptake and surface binding, with a general reduction in NP cell surface binding and an increase in cell uptake with the increase in NLS density (up to 8.4-fold increase in uptake of High-NLS-L-NPs (2 NLS/nm(2)) compared to unmodified L-NPs). However, for nuclear delivery, unmodified S-NPs show higher nuclear localization rates when compared to NLS modified NPs (up to 5-fold by FRET microscopy). For L-NPs an intermediate NLS density (0.9 NLS/nm(2)) seems to provide highest nuclear localization (3.7-fold increase in nuclear delivery compared to High-NLS-L-NPs). Results indicate that a higher NLS density does not result in maximum protein nuclear localization and that a universal optimal density for NPs of different sizes does not exist.

Histone-targeted Polyplexes Avoid Endosomal Escape and Enter the Nucleus During Postmitotic Redistribution of ER Membranes

Nonviral gene delivery is a promising therapeutic approach because of its safety and controllability, yet limited gene transfer efficacy is a common issue. Most nonviral strategies rely upon endosomal escape designs; however, endosomal escape is often uncorrelated with improved gene transfer and membranolytic structures are typically cytotoxic. Previously, we showed that histone-targeted polyplexes trafficked to the nucleus through an alternative route involving caveolae and the Golgi and endoplasmic reticulum (ER), using pathways similar to several pathogens. We hypothesized that the efficacy of these polyplexes was due to an increased utilization of native vesicular trafficking as well as regulation by histone effectors. Accordingly, using confocal microscopy and cellular fractionation, we determined that a key effect of histone-targeting was to route polyplexes away from clathrin-mediated recycling pathways by harnessing endomembrane transfer routes regulated by histone methyltransferases. An unprecedented finding was that polyplexes accumulated in Rab6-labeled Golgi/ER vesicles and ultimately shuttled directly into the nucleus during ER-mediated nuclear envelope reassembly. Specifically, super resolution microscopy and fluorescence correlation spectroscopy unequivocally indicated that the polyplexes remained associated with ER vesicles/membranes until mitosis, when they were redistributed into the nucleus. These novel findings highlight alternative mechanisms to subvert endolysosomal trafficking and harness the ER to enhance gene transfer.

The influence of polymer architecture on in vitro pDNA transfection

In the field of polymer-based gene delivery, the tuning potential of polymers by using different architectures like graft- and star-shaped polymers as well as self-assembled block copolymers is immense. In the last years numerous new polymer designs showed enhanced transfections properties in combination with a good biocompatibility.

Energy independent uptake and release of polystyrene nanoparticles in primary mammalian cell cultures

Nanoparticle (NPs) delivery systems in vivo promises to overcome many obstacles associated with the administration of drugs, vaccines, plasmid DNA and RNA materials, making the study of their cellular uptake a central issue in nanomedicine. The uptake of NPs may be influenced by the cell culture stage and the NPs physical-chemical properties. So far, controversial data on NPs uptake have been derived owing to the heterogeneity of NPs and the general use of immortalized cancer cell lines that often behave differently from each other and from primary mammalian cell cultures. Main aims of the present study were to investigate the uptake, endocytosis pathways, intracellular fate and release of well standardized model particles, i.e. fluorescent 44 nm polystyrene NPs (PS-NPs), on two primary mammalian cell cultures, i.e. bovine oviductal epithelial cells (BOEC) and human colon fibroblasts (HCF) by confocal microscopy and spectrofluorimetric analysis. Different drugs and conditions that inhibit specific internalization routes were used to understand the mechanisms that mediate PS-NP uptake. Our data showed that PS-NPs are rapidly internalized by both cell types 1) with similar saturation kinetics; 2) through ATP-independent processes, and 3) quickly released in the culture medium. Our results suggest that PS-NPs are able to rapidly cross the cell membrane through passive translocation during both uptake and release, and emphasize the need to carefully design NPs for drug delivery, to ensure their selective uptake and to optimize their retainment in the targeted cells.

IgA kappa/IgA lambda heavy/light chain assessment in the management of patients with IgA myeloma

BACKGROUND

Accurate quantification of immunoglobulin A (IgA) monoclonal immunoglobulins by serum protein electrophoresis (SPEP) can be difficult and can impact the assessment of response among patients with multiple myeloma (MM). Therefore, there is a need to identify new assays that better reflect disease burden and response to treatment, and correlate with patient outcome. IgA Hevylite (HLC) measures IgA kappa and IgA lambda separately and provides precise quantitative measurements of the monoclonal IgA expression and polyclonal-isotype matched suppression. In the current study, the authors assessed the usefulness of these assays in the diagnosis of IgA MM and sought to comment on the prognostic value of the assays.

METHODS

A study of 157 patients with IgA MM for whom diagnostic samples were available was performed. HLC measurements were performed on a nephelometer and the results were compared with those of electrophoresis.

RESULTS

All presentation sera (100 IgA kappa specimens and 57 IgA lambda specimens) were found to have abnormal IgA HLC ratios (IgA kappa median ratio: 336.2 [range, 8.2-7353] and IgA lambda ratio: 0.011 [range, 0.0003-0.45]). In comparison, SPEP bands were quantifiable in only 105 of 157 samples (67%) (median, 28.5 g/L [range, 2.2 g/L-98 g/L]). Of the total of 157 patients, 12 patients (8%) presented with oligosecretory myeloma (<10 g/L; including 4 patients with nonquantifiable SPEP bands). HLC uniquely allows for the measurement of isotype paired suppression, which was found to be associated with shortened overall survival in the current study.

CONCLUSIONS

In the current study, IgA HLC ratios were found to be abnormal in all patients and the assay was able to produce quantifiable results in more MM sera than either SPEP or total IgA, potentially representing a solution to the issue of comigration and oligosecretory MM. These preliminary data require confirmation in larger prospective trials to validate the usefulness of IgA HLC.

Delivering colloidal nanoparticles to mammalian cells: a nano-bio interface perspective

Understanding the behavior of multifunctional colloidal nanoparticles capable of biomolecular targeting remains a fascinating challenge in materials science with dramatic implications in view of a possible clinical translation. In several circumstances, assumptions on structure-activity relationships have failed in determining the expected responses of these complex systems in a biological environment. The present Review depicts the most recent advances about colloidal nanoparticles designed for use as tools for cellular nanobiotechnology, in particular, for the preferential transport through different target compartments, including cell membrane, cytoplasm, mitochondria, and nucleus. Besides the conventional entry mechanisms based on crossing the cellular membrane, an insight into modern physical approaches to quantitatively deliver nanomaterials inside cells, such as microinjection and electro-poration, is provided. Recent hypotheses on how the nanoparticle structure and functionalization may affect the interactions at the nano-bio interface, which in turn mediate the nanoparticle internalization routes, are highlighted. In addition, some hurdles when this small interface faces the physiological environment and how this phenomenon can turn into different unexpected responses, are discussed. Finally, possible future developments oriented to synergistically tailor biological and chemical properties of nanoconjugates to improve the control over nanoparticle transport, which could open new scenarios in the field of nanomedicine, are addressed.