Protein Delivery into the Cell Cytosol using Non-Viral Nanocarriers

Synergistic Effects of Polycationic and Polyfluorinated Functionalities for Efficient Intracellular Protein Delivery

Intracellular protein therapy is a promising strategy in biologics, including vaccine development, gene editing, and cancer therapeutics. However, protein-based drug delivery remains a significant challenge, particularly in penetrating cell barriers to reach intracellular targets. Inspired by transport adjuvants, we designed a series of polymeric vectors to achieve efficient functional protein trafficking with low cytotoxicity. With an adequate combination of guanidinium and fluorocarbon functionalities, a synergistic improvement of intracellular delivery is achieved in terms of both high intracellular transport and low cellular toxicity. The observed synergistic outcomes highlight new opportunities for delivery vehicle optimizations of intracellular biologics.

Emerging Role of Noncovalent Interactions and Disulfide Bond Formation in the Cellular Uptake of Small Molecules and Proteins

Intracellular delivery of proteins and small molecules is an important barrier in the development of strategies to deliver functional proteins and therapeutics into the cells to realize their full potential in biotechnology, biomedicine, cell-based therapies, and gene editing protein systems. Most of the intracellular protein delivery strategies involve the conjugation of cell penetrating peptides to enable the permeability of plasma membrane of mammalian cells to allow proteins to enter cytosol. The conjugations of small molecules such as (p-methylphenyl) glycine, pyrenebutyrate and cysteines are used for the same purpose. Molecular level interactions are governed mostly by ionic (cationic/anionic), covalent and noncovalent interactions with various molecular entities of glycocalyx matrix on plasma membrane lipid bilayer. Although the role of noncovalent interactions in cellular uptake is not fully understood, several recent advances have focused on the noncovalent interaction-based strategies of intracellular delivery of small molecules and proteins into mammalian cells. These are achieved by simple modification of protein surfaces with chemical moieties which can form noncovalent interactions other than hydrogen bonding. In this review, we describe the recent advances and the mechanistic aspects of intracellular delivery and role of noncovalent interactions in the cellular uptake of proteins and small molecules.

A high-capacity combination of Pluronic L64-Cupping for intramuscular gene delivery

Intramuscular injection of plasmid DNA (pDNA) is a promising approach for gene therapy, but its efficiency is hindered by both extracellular and intracellular barriers. The extracellular matrix (ECM), including collagens and nucleases, obstructs pDNA penetration, while intracellular challenges include crossing the plasma membrane, escaping endosomes, and reaching the nucleus. Though non-viral carriers like polymers and cationic lipids have been developed, they often fail to address both barriers simultaneously, leading to poor gene transfer in vivo. Physical methods exist but may damage tissues and cause patient discomfort. Here, we introduce a Pluronic L64-Cupping (L/C) gene delivery system that enhances pDNA delivery by sequentially overcoming ECM diffusion, membrane permeabilization, and intracellular transfection. After intramuscular injection of the pDNA-Pluronic L64 mixture, negative pressure is applied to the injection site, significantly boosting reporter gene expression and sustaining it for at least 42 days. Additionally, this system effectively induces HBsAb production in mice, offering a safe, efficient, and cost-effective platform for both laboratory and clinical gene therapy applications.

Enhanced Intracellular Protein Activity by Caveolae-Mediated Endocytosis of Conjugated Polymer/Protein Complexes

Conjugated polymers (CPs) with rigid hydrophobic backbones and polar side chains are known for their efficient cellular entry using various endocytic pathways. Here, the efficient delivery of ribonuclease A (RNase A) into the cytosol of a model cancer cell using a charge-neutral CP with phenyl carbamoylated guanidine (Ph-CG) group at the end of a short ethylene oxide side chain is described. This unique combination of the hydrophobic backbone and the polar nonionic side chain facilitates efficient protein complex formation and subsequent cellular entry through a non-lysosomal pathway, leading to concentration-dependent cell viability inhibition at a half-maximal effective concentration of 0.07 µg mL-1 (or 5 nm). This work demonstrates the potential of CPs as carriers for intracellular protein delivery and the importance of the end functional group of protein carriers.

Nanoparticles to target asthma

Asthma is a heterogeneous chronic lung disease that affects nearly 340 million people globally. Airway hyperresponsiveness, remodeling (thickening and fibrosis), and mucus hypersecretion are some hallmarks of asthma. With several current treatments having serious side effects from long-term use and a proportion of patients with uncontrolled asthma, there is an urgent need for new therapies. With an increasing understanding of asthma pathophysiology, there is a recognized need to target therapies to specific cell types of the airway, which necessitates the identification of delivery systems that can overcome increased mucus and thickened airways. Nanoparticles (NPs) that are highly customizable (material, size, charge, and surface modification) are a potential solution for delivery systems of a wide variety of cargoes (nucleic acids, proteins, and/or small molecules), as well as sole therapeutics for asthma. However, there is a need to consider the safety of the NPs in terms of potential for inflammation, toxicity, nonspecific targets, and accumulation in organs. Ongoing clinical trials using NPs, some FDA-approved for therapeutics in other diseases, provide confidence regarding the potential safety and efficacy of NPs in asthma treatment. This review highlights the current state of the use of NPs in asthma, identifying opportunities for further improvements in NP design and utilization for targeting this chronic lung disease.

A small-molecule carrier for the intracellular delivery of a membrane-impermeable protein with retained bioactivity

Intracellular protein delivery has the potential to revolutionize cell-biological research and medicinal therapy, with broad applications in bioimaging, disease treatment, and genome editing. Herein, we demonstrate successful delivery of a functional protein, cytochrome c (CYC), by using a boron cluster anion as molecular carrier of the superchaotropic anion type (B12Br11OPr2-). CYC was delivered into lipid bilayer vesicles as well as living cells, with a cellular uptake ratio approaching 90%. Mechanistic studies showed that CYC was internalized into cells through a permeation pathway directly into the cytoplasm, bypassing endosomal entrapment. Upon carrier-assisted internalization, CYC retained its bioactivity, as reflected by an induced cell apoptosis rate of 25% at low dose (1 µM). This study furbishes a direct protein delivery method by a molecular carrier with high efficiency, confirming the potential of inorganic cluster ions as protein transport vehicles with an extensive range of future cell-biological or biomedical applications.

The Pvc15 ATPase selectively associates effector proteins with the Photorhabdus virulence cassette

The Photorhabdus virulence cassette (PVC) is an extracellular contractile injection system. In the producing bacterium, N-terminal signal peptides enable effector 'payloads' to be loaded into the PVC's hollow tube-facilitated by the 'ATPases associated with diverse cellular activities' (AAA) ATPase, Pvc15-ready for injection of the toxin or virulence factor into eukaryotic cytosols. Pvc15's function and its interaction with the signal peptide were unclear. This study describes the signal peptide diversity in extracellular contractile injection system clades and interrogates the Pvc15-signal peptide interaction using ATPase assays, cell respiratory assays and western blot quantification of Escherichia coli lysates and co-purifications of PVCs with their payloads. This study found that extracellular contractile injection system signal peptides can be grouped according to sequence alignment, owing to potentially homologous loading mechanisms. Pvc15 contains three domains, including tandem AAA domains D1 and D2. By constructing Pvc15 mutants, we found that while each domain is necessary for PVC-payload loading, domain D2 is the sole bioactive ATPase domain and rescues unstable payloads via the signal peptide. Finally, truncating the signal peptide abolishes Pvc15-dependent PVC loading and has varying effects on payload stability. This study provides crucial insights into extracellular contractile injection system effector loading mechanisms and their ATPase chaperones, and suggests that these devices could be bioengineered for injection of therapeutic proteins into human cells.

Polymers of functionalized diaminopropionic acid are efficient mediators of active exogenous enzyme delivery into cells

Delivery of active protein especially enzyme is one of the major therapeutic challenge. Replacing or substituted invalid/improper acting protein offer fast and effective treatment of disease. Herein, we describe the synthesis and properties of biotinylated peptidomimetics consisting of oxoacid-modified 2,3, L-diaminopropionic acid residues with guanidine groups on its side chains. Electrophoretic analysis showed that the obtained compounds interact with FITC-labeled streptavidin or a streptavidin-β-galactosidase hybrid in an efficient manner. Complexes formed by the abovementioned molecules are able to cross the cell membranes of cancer or healthy cells and show promising compatibility with live cells. Analysis of β-galactosidase activity inside the cells revealed surprisingly high levels of active enzyme in complex-treated cells compared to controls. This observation was confirmed by immunochemical studies in which the presence of β-galactosidase was detected in the membrane and vesicles of the cells.

A Hybrid Nanotube Stamp System in Intracellular Protein Delivery for Cancer Treatment and NMR Analytical Techniques

In contrast to intracellular gene transfer, the direct delivery of expressed proteins is a significantly challenging yet essential technique for elucidating cellular functions, including protein complex structure, liquid-liquid phase separation, therapeutic applications, and reprogramming. In this study, we developed a hybrid nanotube (HyNT) stamp system that physically inserts the HyNTs into adhesive cells, enabling the injection of target molecules through HyNT ducts. This system demonstrates the capability to deliver multiple proteins, such as lactate oxidase (LOx) and ubiquitin (UQ), to approximately 1.8 × 107 adhesive cells with a delivery efficiency of 89.9% and a viability of 97.1%. The delivery of LOx enzyme into HeLa cancer cells induced cell death, while enzyme-delivered healthy cells remained viable. Furthermore, our stamp system can deliver an isotope-labeled UQ into adhesive cells for detection by nuclear magnetic resonance (NMR).

Nano-revolution in hepatocellular carcinoma: A multidisciplinary odyssey - Are we there yet?

In this editorial we comment on the review by Zhou et al reviewing the landscape of nanomedicine in the treatment of hepatocellular carcinoma (HCC). We focus on the immense potential of nanotechnology, particularly ligand-receptor mediated nanotherapy, in revolutionizing the treatment landscape of HCC. Despite advancements in multidisciplinary treatment, HCC remains a significant global health challenge. Ligand-mediated nanotherapy offers the opportunity for precise drug delivery to tumor sites, targeting specific receptors overexpressed in HCC cells, thereby enhancing efficacy and minimizing side effects. Overcoming drug resistance and aggressive tumor biology is facilitated by nanomedicine, bypassing traditional hurdles encountered in chemotherapy. Examples include targeting glypican-3, asialoglycoprotein, transferrin receptor or folic acid receptors, capitalizing on their over-expression in tumor cells. The ability for multi-receptor targeting through dual-ligand nanoparticle modification holds the prospect of further enhancement in specificity and efficacy of directed therapy. However, challenges including immune responses, reproducibility in nanoparticle synthesis, and production scalability remain. Future directions involve refining targeting strategies, improving drug release mechanisms, and streamlining production processes to enable personalized and multifunctional nanotherapies. Overall, the integration of nanotherapy in HCC treatment holds immense promise, but continued partnership and effort are needed in offering hope for more effective, precise, and accessible clinical care in the management of HCC.

Metabolic Modulation of Kynurenine Based on Kynureninase-Loaded Nanoparticle Depot Overcomes Tumor Immune Evasion in Cancer Immunotherapy

Evading recognition of immune cells is a well-known strategy of tumors used for their survival. One of the immune evasion mechanisms is the synthesis of kynurenine (KYN), a metabolite of tryptophan, which suppresses the effector T cells. Therefore, lowering the KYN concentration can be an efficient antitumor therapy by restoring the activity of immune cells. Recently, kynureninase (KYNase), which is an enzyme transforming KYN into anthranilate, was demonstrated to show the potential to decrease KYN concentration and inhibit tumor growth. However, due to the limited bioavailability and instability of proteins in vivo, it has been challenging to maintain the KYNase concentration sufficiently high in the tumor microenvironment (TME). Here, we developed a nanoparticle system loaded with KYNase, which formed a Biodegradable and Implantable Nanoparticle Depot named 'BIND' following subcutaneous injection. The BIND sustainably supplied KYNase around the TME while located around the tumor, until it eventually degraded and disappeared. As a result, the BIND system enhanced the proliferation and cytokine production of effector T cells in the TME, followed by tumor growth inhibition and increased mean survival. Finally, we showed that the BIND carrying KYNase significantly synergized with PD-1 blockade in three mouse models of colon cancer, breast cancer, and melanoma.

Receptor-Targeted Dual pH-Triggered Intracellular Protein Transfer

Protein therapeutics are of widespread interest due to their successful performance in the current pharmaceutical and medical fields, even though their broad applications have been hindered by the lack of an efficient intracellular delivery approach. Herein, we fabricated an active-targeted dual pH-responsive delivery system with favorable tumor cell entry augmented by extracellular pH-triggered charge reversal and tumor receptor targeting and pH-controlled endosomal release in a traceless fashion. As a traceable model protein, the enhanced green fluorescent protein (eGFP) bearing a nuclear localization signal was covalently coupled with a pH-labile traceless azidomethyl-methylmaleic anhydride (AzMMMan) linker followed by functionalization with different molar equivalents of two dibenzocyclooctyne-octa-arginine-cysteine (DBCO-R8C)-modified moieties: polyethylene glycol (PEG)-GE11 peptide for epidermal growth factor receptor-mediated targeting and melittin for endosomal escape. The cationic melittin domain was masked with tetrahydrophthalic anhydride revertible at mild acidic pH 6.5. At the optimally balanced ratio of functional units, the on-demand charge conversion at tumoral extracellular pH 6.5 in combination with GE11-mediated targeting triggered enhanced electrostatic cellular attraction by the R8C cell-penetrating peptides and melittin, as demonstrated by strongly enhanced cellular uptake. Successful endosomal release followed by nuclear localization of the eGFP cargo was obtained by taking advantage of melittin-mediated endosomal escape and rapid traceless release from the AzMMMan linker. The effectiveness of this multifunctional bioresponsive system suggests a promising strategy for delivery of protein drugs toward intracellular targets. A possible therapeutic relevance was indicated by an example of cytosolic delivery of cytochrome c initiating the apoptosis pathway to kill cancer cells.

CRISPR/Cas gene editing and delivery systems for cancer therapy

CRISPR/Cas systems stand out because of simplicity, efficiency, and other superiorities, thus becoming attractive and brilliant gene-editing tools in biomedical field including cancer therapy. CRISPR/Cas systems bring promises for cancer therapy through manipulating and engineering on tumor cells or immune cells. However, there have been concerns about how to overcome the numerous physiological barriers and deliver CRISPR components to target cells efficiently and accurately. In this review, we introduced the mechanisms of CRISPR/Cas systems, summarized the current delivery strategies of CRISPR/Cas systems by physical methods, viral vectors, and nonviral vectors, and presented the current application of CRISPR/Cas systems in cancer clinical treatment. Furthermore, we discussed prospects related to delivery approaches of CRISPR/Cas systems. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Mechanisms and research advances in mRNA antibody drug-mediated passive immunotherapy

Antibody technology is widely used in the fields of biomedical and clinical therapies. Nonetheless, the complex in vitro expression of recombinant proteins, long production cycles, and harsh storage conditions have limited their applications in medicine, especially in clinical therapies. Recently, this dilemma has been overcome to a certain extent by the development of mRNA delivery systems, in which antibody-encoding mRNAs are enclosed in nanomaterials and delivered to the body. On entering the cytoplasm, the mRNAs immediately bind to ribosomes and undergo translation and post-translational modifications. This process produces monoclonal or bispecific antibodies that act directly on the patient. Additionally, it eliminates the cumbersome process of in vitro protein expression and extends the half-life of short-lived proteins, which significantly reduces the cost and duration of antibody production. This review focuses on the benefits and drawbacks of mRNA antibodies compared with the traditional in vitro expressed antibodies. In addition, it elucidates the progress of mRNA antibodies in the prevention of infectious diseases and oncology therapy.

Intracellular protein delivery: New insights into the therapeutic applications and emerging technologies

The inability to cross the plasma membranes traditionally limited the therapeutic use of recombinant proteins. However, in the last two decades, novel technologies made delivering proteins inside the cells possible. This allowed researchers to unlock intracellular targets, once considered 'undruggable', bringing a new research area to emerge. Protein transfection systems display a large potential in a plethora of applications. However, their modality of action is often unclear, and cytotoxic effects are elevated, whereas experimental conditions to increase transfection efficacy and cell viability still need to be identified. Furthermore, technical complexity often limits in vivo experimentation, while challenging industrial and clinical translation. This review highlights the applications of protein transfection technologies, and then critically discuss the current methodologies and their limitations. Physical membrane perforation systems are compared to systems exploiting cellular endocytosis. Research evidence of the existence of either extracellular vesicles (EVs) or cell-penetrating peptides (CPPs)- based systems, that circumvent the endosomal systems is critically analysed. Commercial systems, novel solid-phase reverse protein transfection systems, and engineered living intracellular bacteria-based mechanisms are finally described. This review ultimately aims at finding new methodologies and possible applications of protein transfection systems, while helping the development of an evidence-based research approach.

The improving strategies and applications of nanotechnology-based drugs in hepatocellular carcinoma treatment

Hepatocellular carcinoma (HCC) is one of the leading causes of tumor-related death worldwide. Conventional treatments for HCC include drugs, radiation, and surgery. Despite the unremitting efforts of researchers, the curative effect of HCC has been greatly improved, but because HCC is often found in the middle and late stages, the curative effect is still not satisfactory, and the 5-year survival rate is still low. Nanomedicine is a potential subject, which has been applied to the treatment of HCC and has achieved promising results. Here, we summarized the factors affecting the efficacy of drugs in HCC treatment and the strategies for improving the efficacy of nanotechnology-based drugs in HCC, reviewed the recent applications' progress on nanotechnology-based drugs in HCC treatment, and discussed the future perspectives and challenges of nanotechnology-based drugs in HCC treatment.

Cellular Internalization and Exiting Behavior of Zwitterionic 4-Armed Star-Shaped Polymers

The zwitterionic phospholipid polymer poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB) is amphiphilic copolymer, and it has been reported to directly penetrate cell membranes and have good cytocompatibility. Conventional PMBs are linear-type random copolymers that are polymerized by a free radical polymerization technique. In contrast, star-shaped polymers, or simple branched-type polymers, have unique properties compared to the linear types, for example, a viscosity based on the effect of the excluded volume. In this study, a branched architecture was introduced into a PMB molecular structure, and a 4-armed star-shaped PMB (4armPMB) was synthesized by an atom transfer radical polymerization (ATRP) technique known as living radical polymerization. Linear-type PMB was also synthesized using ATRP. The effects of the polymer architecture on cytotoxicity and cellular uptake were investigated. Both 4armPMB and LinearPMB were successfully synthesized, and these polymers were verified to be water soluble. Pyrene fluorescence in the polymer solution indicated that the architecture had no effect on the behavior of the polymer aggregates. In addition, these polymers caused no cytotoxicity or cell membrane damage. The 4armPMB and LinearPMB penetrated into the cells after a short incubation period, with similar rates. In contrast, the 4armPMB showed a quicker back-diffusion from the cells than that of LinearPMB. The 4armPMB showed fast cellular internalization and exiting behaviors.

Intracellular delivery of therapeutic proteins. New advancements and future directions

Achieving the full potential of therapeutic proteins to access and target intracellular receptors will have enormous benefits in advancing human health and fighting disease. Existing strategies for intracellular protein delivery, such as chemical modification and nanocarrier-based protein delivery approaches, have shown promise but with limited efficiency and safety concerns. The development of more effective and versatile delivery tools is crucial for the safe and effective use of protein drugs. Nanosystems that can trigger endocytosis and endosomal disruption, or directly deliver proteins into the cytosol, are essential for successful therapeutic effects. This article aims to provide a brief overview of the current methods for intracellular protein delivery to mammalian cells, highlighting current challenges, new developments, and future research opportunities.

Protective Effects of a Jellyfish-Derived Thioredoxin Fused with Cell-Penetrating Peptide TAT-PTD on H2O2-Induced Oxidative Damage

Thioredoxin (Trx) plays a critical role in maintaining redox balance in various cells and exhibits anti-oxidative, anti-apoptotic, and anti-inflammatory effects. However, whether exogenous Trx can inhibit intracellular oxidative damage has not been investigated. In previous study, we have identified a novel Trx from the jellyfish Cyanea capillata, named CcTrx1, and confirmed its antioxidant activities in vitro. Here, we obtained a recombinant protein, PTD-CcTrx1, which is a fusion of CcTrx1 and protein transduction domain (PTD) of HIV TAT protein. The transmembrane ability and antioxidant activities of PTD-CcTrx1, and its protective effects against H₂O₂-induced oxidative damage in HaCaT cells were also detected. Our results revealed that PTD-CcTrx1 exhibited specific transmembrane ability and antioxidant activities, and it could significantly attenuate the intracellular oxidative stress, inhibit H₂O₂-induced apoptosis, and protect HaCaT cells from oxidative damage. The present study provides critical evidence for application of PTD-CcTrx1 as a novel antioxidant to treat skin oxidative damage in the future.

Prospects of Using Protein Engineering for Selective Drug Delivery into a Specific Compartment of Target Cells

A large number of proteins are successfully used to treat various diseases. These include natural polypeptide hormones, their synthetic analogues, antibodies, antibody mimetics, enzymes, and other drugs based on them. Many of them are demanded in clinical settings and commercially successful, mainly for cancer treatment. The targets for most of the aforementioned drugs are located at the cell surface. Meanwhile, the vast majority of therapeutic targets, which are usually regulatory macromolecules, are located inside the cell. Traditional low molecular weight drugs freely penetrate all cells, causing side effects in non-target cells. In addition, it is often difficult to elaborate a small molecule that can specifically affect protein interactions. Modern technologies make it possible to obtain proteins capable of interacting with almost any target. However, proteins, like other macromolecules, cannot, as a rule, freely penetrate into the desired cellular compartment. Recent studies allow us to design multifunctional proteins that solve these problems. This review considers the scope of application of such artificial constructs for the targeted delivery of both protein-based and traditional low molecular weight drugs, the obstacles met on the way of their transport to the specified intracellular compartment of the target cells after their systemic bloodstream administration, and the means to overcome those difficulties.

Endosomal escape for cell-targeted proteins. Going out after going in

Protein-based nanocarriers are versatile and biocompatible drug delivery systems. They are of particular interest in nanomedicine as they can recruit multiple functions in a single modular polypeptide. Many cell-targeting peptides or protein domains can promote cell uptake when included in these nanoparticles through receptor-mediated endocytosis. In that way, targeting drugs to specific cell receptors allows a selective intracellular delivery process, avoiding potential side effects of the payload. However, once internalized, the endo-lysosomal route taken by the engulfed material usually results in full degradation, preventing their adequate subcellular localization, bioavailability and subsequent therapeutic effect. Thus, entrapment into endo-lysosomes is a main bottleneck in the efficacy of protein-drug nanomedicines. Promoting endosomal escape and preventing lysosomal degradation would make this therapeutic approach clinically plausible. In this review, we discuss the mechanisms intended to evade lysosomal degradation of proteins, with the most relevant examples and associated strategies, and the methods available to measure that effect. In addition, based on the increasing catalogue of peptide domains tailored to face this challenge as components of protein nanocarriers, we emphasize how their particular mechanisms of action can potentially alter the functionality of accompanying protein materials, especially in terms of targeting and specificity in the delivery process.

Electrochemical Single-Cell Protein Therapeutics Using a Double-Barrel Nanopipette

Single-cell protein therapeutics is expected to promote our in-depth understanding of how a specific protein with a therapeutic dosage treats the cell without population averaging. However, it has not yet been tackled by current single-cell nanotools. We address this challenge by the use of a double-barrel nanopipette, in which one lumen was used for electroosmotic cytosolic protein delivery and the other was customized for ionic evaluation of the consequence. Upon injection of protein DJ-1 through the delivery lumen, upregulation of the antioxidant protein could protect neural PC-12 cells against oxidative stress from phorbol myristate acetate exposure, as deduced by targeting of the cytosolic hydrogen peroxide by the detecting lumen. The nanotool developed in this study for single-cell protein therapeutics provides a perspective for future single-cell therapeutics involving different therapeutic modalities, such as peptides, enzymes and nucleic acids.

A cooperative nano-CRISPR scaffold potentiates immunotherapy via activation of tumour-intrinsic pyroptosis

Efficient cancer immunotherapy depends on selective targeting of high bioactivity therapeutic agents to the tumours. However, delivering exogenous medication might prove difficult in clinical practice. Here we report a cooperative Nano-CRISPR scaffold (Nano-CD) that utilizes a specific sgRNA, selected from a functional screen for triggering endogenous GDSME expression, while releasing cisplatin to initiate immunologic cell death. Mechanistically, cascade-amplification of the antitumor immune response is prompted by the adjuvantic properties of the lytic intracellular content and enhanced by the heightened GDSME expression, resulting in pyroptosis and the release of tumor associated antigens. Neither of the single components provide efficient tumour control, while tumor growth is efficiently inhibited in primary and recurrent melanomas due to the combinatorial effect of cisplatin and self-supplied GSDME. Moreover, Nano-CD in combination with checkpoint blockade creates durable immune memory and strong systemic anti-tumor immune response, leading to disease relapse prevention, lung metastasis inhibition and increased survival in mouse melanomas. Taken together, our therapeutic approach utilizes CRISPR-technology to enable cell-intrinsic protein expression for immunotherapy, using GDSME as prototypic immune modulator. This nanoplatform thus can be applied to modulate further immunological processes for therapeutic benefit.

Direct Cytosolic Delivery of Citraconylated Proteins

Current intracellular protein delivery strategies face the challenge of endosomal entrapment and consequent degradation of protein cargo. Methods to efficiently deliver proteins directly to the cytosol have the potential to overcome this hurdle. Here, we report the use of a straightforward approach of protein modification using citraconic anhydride to impart an overall negative charge on the proteins, enabling them to assemble with positively charged nano vectors. This strategy uses anhydride-modified proteins to electrostatically form polymer-protein nanocomposites with a cationic guanidinium-functionalized polymer. These supramolecular self-assemblies demonstrated the efficient cytosolic delivery of modified proteins through a membrane fusion-like mechanism. This approach was validated on five cell lines and seven proteins as cargo. Retention of protein function was confirmed through efficient cell killing via the intracellular enzymatic activity of RNase A. This platform provides a versatile, straightforward, and single-step method of protein modification and efficient direct cytosolic protein delivery.

Comparison of Acoustofluidic and Static Systems for Ultrasound-Mediated Molecular Delivery to T Lymphocytes

Continuous-flow acoustofluidic technologies can potentially improve processing of T lymphocytes for cell therapies by addressing the limitations with viral and non-viral delivery methods. The objective of this study was to assess the intracellular delivery efficiency with acoustofluidic treatment compared with that of static ultrasound treatment. Optimization of parameters in acoustofluidic and static configurations was performed by assessing intracellular delivery of a fluorescent compound (calcein) in viable human Jurkat T lymphocytes. Ultrasound pressure and the concentration of cationic phospholipid-coated microbubbles influenced calcein delivery in both systems. In the static system, a treatment time of 45 s increased molecular delivery compared with 0-30 s (p < 0.01). Refined parameters were used to assess molecular delivery of small and large compounds (0.6-kDa calcein and 150-kDa fluorescein isothiocyanate-dextran, respectively) after ultrasound treatment with the acoustofluidic or static systems. Molecular delivery was similar with refined parameters for acoustofluidic treatment and static treatment (p > 0.05), even though acoustofluidic treatment had lower microbubble concentration (24 μg/mL vs. 94 μg/mL) and shorter treatment time (∼2-3 s vs. 45 s). This study indicates that the acoustofluidic system can significantly enhance intracellular molecular delivery, which could potentially enable acoustofluidic cell transfection during continuous flow processing for manufacture of cell therapies or other applications.

Platinum-Coordinated Dual-Responsive Nanogels for Universal Drug Delivery and Combination Cancer Therapy

Developing a universal nanoplatform for efficient delivery of various drugs to target sites is urgent for overcoming various biological barriers and realizing combinational cancer treatment. Nanogels, with the advantages of both hydrogels and nanoparticles, may hold potential for addressing the above issue. Here, a dual-responsive nanogel platform (HPC nanogel) is constructed using β-cyclodextrin-conjugated hyaluronic acid (HA-βCD), polyethyleneimine (PEI), and cisplatin. HA-βCD and PEI compose the skeleton of the nanogel, and cisplatin molecules provide the junctions inside the skeleton, thus affording a multiple interactions-based nanogel. Besides, HA endows the nanogel with hyaluronidase (HAase)-responsiveness, and cisplatin guarantees the glutathione (GSH)-responsive ability, which make the nanogel a dual-responsive platform that can degrade and release the loaded drugs when encountering HAase or GSH. Additionally, the HPC nanogel possesses excellent small-molecule drug and protein loading and intracellular delivery capabilities. Especially, for proteins, their intracellular delivery via nanogels is not hindered by serum proteins, and the enzymes delivered into cells still maintain their catalytic activities. Furthermore, the nanogel can codeliver different cargoes to achieve "cocktail" chemotherapeutic efficacy and realize combination cancer therapy. Overall, the HPC nanogel can serve as a multifunctional platform capable of delivering desired drugs to treat cancer or other diseases.

Protein delivery to living cells by thermal stimulation for biophysical investigation

Studying biomolecules in their native environment represents the ideal sample condition for structural biology investigations. Here we present a novel protocol which allows to delivery proteins into eukaryotic cells through a mild thermal stimulation. The data presented herein show the efficacy of this approach for delivering proteins in the intracellular environment of mammalian cells reaching a concentration range suitable for successfully applying biophysical methods, such as double electron electron resonance (DEER) measurements for characterising protein conformations.

In vivo peptide-based delivery of a gene-modifying enzyme into cells of the central nervous system

We report on the successful delivery of the Cre recombinase enzyme in the neural cells of mice in vivo by simple coinjection with peptides derived from HIV-TAT. Cre delivery activates the expression of a reporter gene in both neurons and astrocytes of the cortex without tissue damage and with a transduction efficiency that parallels or exceeds that of a commonly used adeno-associated virus. Our data indicate that the delivery peptides mediate efficient endosomal leakage and cytosolic escape in cells that have endocytosed Cre. The peptides, therefore, act in trans and do not require conjugation to the payload, greatly simplifying sample preparation. Moreover, the delivery peptides are exclusively composed of natural amino acids and are consequently readily degradable and processed by cells. We envision that this approach will be beneficial to applications that require the transient introduction of proteins into cells in vivo.

Different Influences of Biotinylation and PEGylation on Cationic and Anionic Proteins for Spheroid Penetration and Intracellular Uptake to Cancer Cells

To better understand the effects of PEGylation and biotinylation on the delivery efficiency of proteins, the cationic protein lysozyme (LZ) and anionic protein bovine serum albumin (BSA) were chemically conjugated with poly(ethylene glycol) (PEG) and biotin-PEG to primary amine groups of proteins using N-hydroxysuccinimide reactions. Four types of protein conjugates were successfully prepared: PEGylated LZ (PEG-LZ), PEGylated BSA (PEG-BSA), biotin-PEG-conjugated LZ (Bio-PEG-LZ), and biotin-PEG-conjugated BSA (Bio-PEG-BSA). PEG-LZ and Bio-PEG-LZ exhibited a lower intracellular uptake than that of LZ in A549 human lung cancer cells (in a two-dimensional culture). However, Bio-PEG-BSA showed significantly improved intracellular delivery as compared to that of PEG-BSA and BSA, probably because of favorable interactions with cells via biotin receptors. For A549/fibroblast coculture spheroids, PEG-LZ and PEG-BSA exhibited significantly decreased tissue penetration as compared with that of unmodified proteins. However, Bio-PEG-BSA showed tissue penetration comparable to that of unmodified BSA. In addition, citraconlyated LZ (Cit-LZ) showed reduced spheroid penetration as compared to that of LZ, probably owing to a decrease in protein charge. Taken together, chemical conjugation of targeting ligands-PEG to anionic proteins could be a promising strategy to improve intracellular delivery and in vivo activity, whereas modifications of cationic proteins should be more delicately designed.

Hydrophobicity is a key determinant in the activity of arginine-rich cell penetrating peptides

To deliver useful biological payloads into the cytosolic space of cells, cell-penetrating peptides have to cross biological membranes. The molecular features that control or enhance this activity remain unclear. Herein, a dimeric template of the arginine-rich HIV TAT CPP was used to establish the effect of incorporating groups and residues of various chemical structures and properties. A positive correlation is established between the relative hydrophobicity of these additional moieties and the ability of the CPP conjugates to deliver a peptidic probe into live cells. CPP conjugates with low hydrophobicity lead to no detectable delivery activity, while CPPs containing groups of increasing hydrophobicity achieve intracellular delivery at low micromolar concentrations. Notably, the chemical structures of the hydrophobic groups do not appear to play a role in overall cell penetration activity. The cell penetration activity detected is consistent with endosomal escape. Leakage assays with lipid bilayer of endosomal membrane composition also establish a positive correlation between hydrophobicity and membrane permeation. Overall, these results indicate that the presence of a relatively hydrophobic moiety, regardless of structure, is required in a CPP structure to enhance its cell penetration. It also indicates that simple modifications, including fluorophores used for cell imaging or small payloads, modulate the activity of CPPs and that a given CPP-conjugate may be unique in its membrane permeation properties.

mRNA nanomedicine: Design and recent applications

The rational design and application of mRNA-based medicine have recently yielded some key successes in the clinical management of human diseases. mRNA technology allows for the facile and direct production of proteins in vivo, thus circumventing the need for lengthy drug development cycles and complex production workflows. As such, mRNA formulations can significantly improve upon the biological therapies that have become commonplace in modern medicine. Despite its many advantages, mRNA is inherently fragile and has specific delivery requirements. Leveraging the engineering flexibility of nanobiotechnology, mRNA payloads can be incorporated into nanoformulations such that they do not invoke unwanted immune responses, are targeted to tissues of interest, and can be delivered to the cytosol, resulting in improved safety while enhancing bioactivity. With the rapidly evolving landscape of nanomedicine, novel technologies that are under development have the potential to further improve the clinical utility of mRNA medicine. This review covers the design principles relevant to engineering mRNA-based nanomedicine platforms. It also details the current research on mRNA nanoformulations for addressing viral infections, cancers, and genetic diseases. Given the trends in the field, future mRNA-based nanomedicines have the potential to change how many types of diseases are managed in the clinic.

Specific Activation of Photosensitizer with Extrinsic Enzyme for Precisive Photodynamic Therapy

Delivery of functional proteins into the intracellular space has been a challenging task that could lead to a myriad of therapeutic applications. We report herein a novel bioconjugation strategy for enzyme modification and selective delivery into cancer cells for lock-and-key-type activation of photosensitizers. Using a bifunctional linker containing a bis(bromomethyl)phenyl group and an o-phthalaldehyde moiety, it could induce cyclization of the peptide sequence Ac-NH-CRGDfC-CONH₂ through site-specific dibenzylation with the two cysteine residues and further coupling with β-galactosidase via the phthalaldehyde-amine capture reaction. This facile two-step one-pot procedure enabled the preparation of cyclic RGD-modified β-galactosidase readily, which could be internalized selectively into α_vβ₃ integrin-overexpressed cancer cells. Upon encountering an intrinsically quenched distyryl boron dipyrromethene-based photosensitizer conjugated with a galactose moiety through a self-immolative linker inside the cells, the extrinsic enzyme induced specific cleavage of the β-galactosidic bond followed by self-immolation to release an activated derivative, thereby restoring the photodynamic activities and causing cell death effectively. The high specificity of this extrinsic enzyme-activated photosensitizing system was also demonstrated in vivo using nude mice bearing an α_vβ₃ integrin-positive U87-MG tumor. The specific activation at the tumor site resulted in lighting up and complete eradication of the tumor upon laser irradiation, while by using the native β-galactosidase, the effects were largely reduced. In contrast to the conventional activation using intrinsic enzymes, this extrinsic enzyme activatable approach can further minimize the nonspecific activation toward precisive photodynamic therapy.

Transfection of Heat Shock Protein 70 kDa (HSP70)

Heat shock protein 70 kDa (HSP70) is a major protein family in the cell protections against stress-induced denaturation and aggregation and in the folding of nascent proteins. It is a highly conserved protein that can be found in most organisms and is strongly connected to several intracellular pathways such as protein folding and refolding, protein degradation and regulation, and protection against intense stress. Cellular delivery of HSP70 would be of high impact for clarification of its role in these cellular processes.

PepFect14 is a cell-penetrating peptide known to be able to mediate the transfection of various oligonucleotides to multiple cell lines with a higher efficacy than most commercially available transfection agents and without inducing significant toxic effects.

In this study we demonstrated that PepFect14 was able to form a complex with HSP70 and to deliver it inside cells in the same fashion with oligonucleotide delivery. The delivered HSP70 showed an effect in the cell regulation indicating that the protein was biologically available in the cytoplasm and the interactions with PepFect14 did not impeach its active sites once the plasma barrier crossed.

This study reports the first successful delivery of HSP70 to our knowledge and the first protein transfection mediated by PepFect14. It opens new fields of research for both PepFect14 as a delivery agent and HSP70 as a therapeutic agent; with potential in peptide aggregation caused diseases such as Parkinson’s and Alzheimer’s diseases.

Deep Learning-Assisted Automated Single Cell Electroporation Platform for Effective Genetic Manipulation of Hard-to-Transfect Cells

Genome engineering of cells using CRISPR/Cas systems has opened new avenues for pharmacological screening and investigating the molecular mechanisms of disease. A critical step in many such studies is the intracellular delivery of the gene editing machinery and the subsequent manipulation of cells. However, these workflows often involve processes such as bulk electroporation for intracellular delivery and fluorescence activated cell sorting for cell isolation that can be harsh to sensitive cell types such as human-induced pluripotent stem cells (hiPSCs). This often leads to poor viability and low overall efficacy, requiring the use of large starting samples. In this work, a fully automated version of the nanofountain probe electroporation (NFP-E) system, a nanopipette-based single-cell electroporation method is presented that provides superior cell viability and efficiency compared to traditional methods. The automated system utilizes a deep convolutional network to identify cell locations and a cell-nanopipette contact algorithm to position the nanopipette over each cell for the application of electroporation pulses. The automated NFP-E is combined with microconfinement arrays for cell isolation to demonstrate a workflow that can be used for CRISPR/Cas9 gene editing and cell tracking with potential applications in screening studies and isogenic cell line generation.

Fluorination Promotes the Cytosolic Delivery of Genes, Proteins, and Peptides

The cytosolic delivery of biomolecules such as genes, proteins, and peptides is of great importance for biotherapy but usually limited by multiple barriers during the process. Cell membrane with high hydrophobic character is one of the representative biological barriers for cytosolic delivery. The introduction of hydrophobic ligands such as aliphatic lipids onto materials or biomolecules could improve their membrane permeability. However, these ligands are lipophilic and tend to interact with the phospholipids in the membrane as well as serum proteins, which may hinder efficient intracellular delivery. To solve this issue, our research group proposed the use of fluorous ligands with both hydrophobicity and lipophobicity as ideal alternatives to aliphatic lipids to promote cytosolic delivery.In our first attempt, fluorous ligands were conjugated onto cationic polymers to increase their gene delivery efficacy. The fluorination dramatically increased the gene delivery performance at low polymer doses. In addition, the strategy greatly improved the serum tolerance of cationic polymers, which is critical for efficient gene delivery in vivo. Besides serum tolerance, mechanism studies revealed that fluorination increases multiple steps such as cellular uptake and endosomal escape. Fluorination also allowed the assembly of low-molecular-weight polymers and achieved highly efficient gene delivery with minimal material toxicity. The method showed robust efficiency for polymers, including linear polymers, branched polymers, dendrimers, bola amphiphilies, and dendronized polymers.Besides gene delivery, fluorinated polymers were also used for intracellular protein delivery via a coassembly strategy. For this purpose, two lead fluoropolymers were screened from a library of amphiphilic materials. The fluoropolymers are greatly superior to their nonfluorinated analogues conjugated with aliphatic lipids. The fluorous lipids are beneficial for polymer assembly and protein encapsulation, reduced protein denaturation, facilitated endocytosis, and decreased polymer toxicity compared to nonfluorinated lipids. The materials exhibited potent efficacy in therapeutic protein and peptide delivery to achieve cancer therapy and were able to fabricate a personalized nanovaccine for cancer immunotherapy. Finally, the fluorous lipids were directly conjugated to peptides via a disulfide bond for cytosolic peptide delivery. Fluorous lipids drive the assembly of cargo peptides into uniform nanoparticles with much improved proteolytic stability and promote their delivery into various types of cells. The delivery efficacy of this strategy is greatly superior to traditional techniques such as cell-penetrating peptides both in vitro and in vivo. Overall, the fluorination techniques provide efficient and promising strategies for the cytosolic delivery of biomolecules.

Protein transfection via spherical nucleic acids

The efficient transfection of functional proteins into cells can serve as a means for regulating cellular processes toward solving fundamental challenges in biology and medicine. However, the use of proteins as effective intracellular agents is hindered by their low cellular uptake and susceptibility to degradation. Over the past 15 years, our group has been developing spherical nucleic acids (SNAs), nanoparticles functionalized with a dense radially oriented shell of nucleic acids. These structures actively enter cells and have opened new frontiers in chemical sensing, biodiagnostics and therapeutics. Recently, we have shown that proteins can be used as structurally precise and homogeneous nanoparticle cores in SNAs. The resultant protein SNAs (ProSNAs) allow previously cell-impermeable proteins to actively enter cells, exhibit high degrees of stability and activity both in cell culture and in vivo, and show enhanced pharmacokinetics. Consequently, these modular structures constitute a plug-and-play platform in which the protein core and nucleic acid shell can be independently varied to achieve a desired function. Here, we describe the synthesis of ProSNAs through the chemical modification of solvent-accessible surface residues (3-5 d). We also discuss design considerations, strategies for characterization, and applications of ProSNAs in cellular transfection, biological sensing and functional enzyme delivery in vivo.

Molecularly engineered tumor acidity-responsive plant toxin gelonin for safe and efficient cancer therapy

Due to the unsatisfactory therapeutic efficacy and inexorable side effects of small molecule antineoplastic agents, extensive efforts have been devoted to the development of more potent macromolecular agents with high specificity. Gelonin is a plant-derived protein toxin that exhibits robust antitumor effect via inactivating ribosomes and inhibiting protein synthesis. Nonetheless, its poor internalization ability to tumor cells has compromised the therapeutic promise of gelonin. In this study, a tumor acidity-responsive intracellular protein delivery system ─ functional gelonin (Trx-pHLIP-Gelonin, TpG) composed of a thioredoxin (Trx) tag, a pH low insertion peptide (pHLIP) and gelonin, was designed and obtained by genetic recombination technique for the first time. TpG could effectively enter into tumor cells under weakly acidic conditions and markedly suppress tumor cell proliferation via triggering cell apoptosis and inhibiting protein synthesis. Most importantly, treatment by intravenous injection into subcutaneous SKOV3 solid tumors in a mouse model showed that TpG was much more effective than gelonin in curtailing tumor growth rates with negligible toxicity. Collectively, our present work suggests that the tumor acidity-targeted delivery manner endowed by pHLIP offers a new avenue for efficient delivery of other bioactive substances to acidic diseased tissues.

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A pH-responsive gelonin delivery platform — TpG was molecularly engineered.

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TpG exhibited good thermal stability and excellent serum stability.

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TpG enabled an efficient intracellular translocation of gelonin at pH 6.5.

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TpG exerted pronounced anti-proliferative effect via inducing massive apoptosis.

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TpG significantly delayed tumor growth with favorable in vivo biosafety profile.

Easy preparation of a liposome-mediated protein delivery system by freeze-thawing a liposome–protein complex

Homeostasis can be achieved by adding a protein supplement; however, an appropriate vector is required to deliver the protein into the cell because of the low stability of proteins in...

Tetraphenylethylene-Featured Fluorescent Supramolecular Nanoparticles for Intracellular Trafficking of Protein Delivery and Neuroprotection

The delivery of protein into mammalian cells enables the dissection and manipulation of biological processes; however, this potency is challenged by the lack of an efficient protein delivery tool and a means to monitor its intracellular trafficking. Herein, we report that the hierarchical self-assembly of tetraphenylethylene (TPE)-featured metal-organic cages (MOCs) and β-cyclodextrin-conjugated polyethylenimine can generate fluorescent supramolecular nanoparticles (FSNPs) to deliver protein into neural cells, a cell line that is hard to transfect using conventional strategy. Further, the aggregation-induced emission (AIE) of TPE enabled the fluorescent monitoring of cytosolic protein release. It is found that FSNPs can deliver and release protein into cytosol for subcellular targeting as fast as 18 h post-delivery. Moreover, the delivery of molecular chaperone DJ-1 using FSNPs activates MAPK/ERK signaling of neural cells to protect cells from oxidative stress.

Genetic and Covalent Protein Modification Strategies to Facilitate Intracellular Delivery

Protein-based therapeutics represent a rapidly growing segment of approved disease treatments. Successful intracellular delivery of proteins is an important precondition for expanded in vivo and in vitro applications of protein therapeutics. Direct modification of proteins and peptides for improved cytosolic translocation are a promising method of increasing delivery efficiency and expanding the viability of intracellular protein therapeutics. In this Review, we present recent advances in both synthetic and genetic protein modifications for intracellular delivery. Active endocytosis-based and passive internalization pathways are discussed, followed by a review of modification methods for improved cytosolic delivery. After establishing how proteins can be modified, general strategies for facilitating intracellular delivery, such as chemical supercharging or inclusion of cell-penetrating motifs, are covered. We then outline protein modifications that promote endosomal escape. We finally examine the delivery of two potential classes of therapeutic proteins, antibodies and associated antibody fragments, and gene editing proteins, such as cas9.

Engineered variants of the Ras effector protein RASSF5 (NORE1A) promote anticancer activities in lung adenocarcinoma

Within the superfamily of small GTPases, Ras appears to be the master regulator of such processes as cell cycle progression, cell division, and apoptosis. Several oncogenic Ras mutations at amino acid positions 12, 13, and 61 have been identified that lose their ability to hydrolyze GTP, giving rise to constitutive signaling and eventually development of cancer. While disruption of the Ras/effector interface is an attractive strategy for drug design to prevent this constitutive activity, inhibition of this interaction using small molecules is impractical due to the absence of a cavity to which such molecules could bind. However, proteins and especially natural Ras effectors that bind to the Ras/effector interface with high affinity could disrupt Ras/effector interactions and abolish procancer pathways initiated by Ras oncogene. Using a combination of computational design and in vitro evolution, we engineered high-affinity Ras-binding proteins starting from a natural Ras effector, RASSF5 (NORE1A), which is encoded by a tumor suppressor gene. Unlike previously reported Ras oncogene inhibitors, the proteins we designed not only inhibit Ras-regulated procancer pathways, but also stimulate anticancer pathways initiated by RASSF5. We show that upon introduction into A549 lung carcinoma cells, the engineered RASSF5 mutants decreased cell viability and mobility to a significantly greater extent than WT RASSF5. In addition, these mutant proteins induce cellular senescence by increasing acetylation and decreasing phosphorylation of p53. In conclusion, engineered RASSF5 variants provide an attractive therapeutic strategy able to oppose cancer development by means of inhibiting of procancer pathways and stimulating anticancer processes.

Targeting the Inside of Cells with Biologicals: Chemicals as a Delivery Strategy

Delivering macromolecules into the cytosol or nucleus is possible in vitro for DNA, RNA and proteins, but translation for clinical use has been limited. Therapeutic delivery of macromolecules into cells requires overcoming substantially higher barriers compared to the use of small molecule drugs or proteins in the extracellular space. Breakthroughs like DNA delivery for approved gene therapies and RNA delivery for silencing of genes (patisiran, ONPATTRO^®, Alnylam Pharmaceuticals, Cambridge, MA, USA) or for vaccination such as the RNA-based coronavirus disease 2019 (COVID-19) vaccines demonstrated the feasibility of using macromolecules inside cells for therapy. Chemical carriers are part of the reason why these novel RNA-based therapeutics possess sufficient efficacy for their clinical application. A clear advantage of synthetic chemicals as carriers for macromolecule delivery is their favourable properties with respect to production and storage compared to more bioinspired vehicles like viral vectors or more complex drugs like cellular therapies. If biologicals can be applied to intracellular targets, the druggable space is substantially broadened by circumventing the limited utility of small molecules for blocking protein–protein interactions and the limitation of protein-based drugs to the extracellular space. An in depth understanding of the macromolecular cargo types, carrier types and the cell biology of delivery is crucial for optimal application and further development of biologicals inside cells. Basic mechanistic principles of the molecular and cell biological aspects of cytosolic/nuclear delivery of macromolecules, with particular consideration of protein delivery, are reviewed here. The efficiency of macromolecule delivery and applications in research and therapy are highlighted.

Interest of extracellular vesicles in regards to lipid nanoparticle based systems for intracellular protein delivery

Compared to chemicals that continue to dominate the overall pharmaceutical market, protein therapeutics offer the advantages of higher specificity, greater activity, and reduced toxicity. While nearly all existing therapeutic proteins were developed against soluble or extracellular targets, the ability for proteins to enter cells and target intracellular compartments can significantly broaden their utility for a myriad of exiting targets. Given their physical, chemical, biological instability that could induce adverse effects, and their limited ability to cross cell membranes, delivery systems are required to fully reveal their biological potential. In this context, as natural protein nanocarriers, extracellular vesicles (EVs) hold great promise. Nevertheless, if not present naturally, bringing an interest protein into EV is not an easy task. In this review, we will explore methods used to load extrinsic protein into EVs and compare these natural vectors to their close synthetic counterparts, liposomes/lipid nanoparticles, to induce intracellular protein delivery.

Antibody Nanocarriers for Cancer Management

Antibodies are extremely valuable tools in modern medicine due to their ability to target diseased cells through selective antigen binding and thereby regulate cellular signaling or inhibit cell-cell interactions with high specificity. However, the therapeutic utility of freely delivered antibodies is limited by high production costs, low efficacy, dose-limiting toxicities, and inability to cross the cellular membrane (which hinders antibodies against intracellular targets). To overcome these limitations, researchers have begun to develop nanocarriers that can improve antibodies' delivery efficiency, safety profile, and clinical potential. This review summarizes recent advances in the design and implementation of nanocarriers for extracellular or intracellular antibody delivery, emphasizing important design considerations, and points to future directions for the field.

Rapid protein delivery to living cells for biomolecular investigation

The lack of a simple, fast and efficient method for protein delivery is limiting the widespread application of in-cell experiments, which are crucial for understanding the cellular function. We present here an innovative strategy to deliver proteins into both prokaryotic and eukaryotic cells, exploiting thermal vesiculation. This method allows to internalize substantial amounts of proteins, with different molecular weight and conformation, without compromising the structural properties and cell viability. Characterizing proteins in a physiological environment is essential as the environment can dramatically affect the conformation and dynamics of biomolecules as shown by in-cell EPR spectra vs those acquired in buffer solution. Considering its versatility, this method opens the possibility to scientists to study proteins directly in living cells through a wide range of techniques.

Advances in the Structural Design of Polyelectrolyte Complex Micelles

Polyelectrolyte complex micelles (PCMs) are a unique class of self-assembled nanoparticles that form with a core of associated polycations and polyanions, microphase-separated from neutral, hydrophilic coronas in aqueous solution. The hydrated nature and structural and chemical versatility make PCMs an attractive system for delivery and for fundamental polymer physics research. By leveraging block copolymer design with controlled self-assembly, fundamental structure-property relationships can be established to tune the size, morphology, and stability of PCMs precisely in pursuit of tailored nanocarriers, ultimately offering storage, protection, transport, and delivery of active ingredients. This perspective highlights recent advances in predictive PCM design, focusing on (i) structure-property relationships to target specific nanoscale dimensions and shapes and (ii) characterization of PCM dynamics primarily using time-resolved scattering techniques. We present several vignettes from these two emerging areas of PCM research and discuss key opportunities for PCM design to advance precision medicine.

A Novel Cell-Based Intracellular Protein-Protein Interaction Detection Platform (SOLIS) for Multimodality Screening

Intervention in protein-protein interactions (PPIs) has tremendous effects in the molecular therapy of many diseases. To fulfill the requirements for targeting intracellular proteins, here we develop SOS-localization-based interaction screening (SOLIS), which elaborately mimics signaling via the Ras-mitogen-activated protein kinase pathway. SOLIS employs two chimeric proteins in which a membrane localization motif (CaaX) is fused at the C-terminus of a protein of interest and the catalytic domain of SOS is fused at the C-terminus of another protein of interest. Interaction between the two proteins of interest induces membrane localization of the SOS chimera and cell proliferation. Thus, the SOLIS system enables enrichment of superior binders based on cell proliferation in an intracellular PPI-dependent manner. This was verified by three major modalities against intracellular PPIs (small molecules, peptide aptamers, and intrabodies). The system worked over a broad range of affinities (K_D = 0.32-140 nM). In a screening of a site-directed randomized library, novel intrabody clones were selected on the basis of the potency of cell proliferation. Three other PPI detection methods (NanoBiT, SPR, and pull-down assays) were employed to characterize the SOLIS system, and several intrabody clones were judged as false negatives in these assays. SOLIS signals would be less sensitive to the orientation/conformation of the chimeric proteins, and this feature emerges as the advantage of SOLIS as a mammalian cytosolic PPI detection system with few false negatives.