Efficient intracellular and in vivo delivery of toxin proteins by a ROS-responsive polymer for cancer therapy

Fluoroalkane Engineered Magnetic Vectors Unlock the Potential of Gasdermin in Vivo Delivery for Pyroptosis Induced Cancer Therapy

Pyroptosis, a programmed necrotic cell death mediated by gasdermin, can activate strong immune responses and serve as a potential target for cancer therapy. Nevertheless, the relatively large molecular size and negative surface charge of gasdermin impede them from effectively intracellular delivery and directly inducing pyroptosis. Here, a cytosolic protein delivery system, fluorinated iron oxide nanoparticles (FIONPs) is reported, which can self-assemble with active gasdermin A3 protein (GSDMA3) via noncovalent interactions and effectively trigger pyroptosis in 4T1 cells. It is proved that the delivery system is versatile for various cargo proteins (ribonuclease A, saporin, β-galactosidase, and bovine serum albumin) with different isoelectric points and molecular weights, without compromising their biological activity in vitro. What's more, under magnetic drive, FIONPs facilitate active transport of GSDMA3 in vivo, further augmenting tumor suppression and immune response. Overall, magnetic-driven FIONPs provide an effective delivery system for intracellular protein transductions, and the application of the delivery system reveals that direct delivery of GSDMA3 significantly elicits robust antitumor immunity via the induction of pyroptosis.

ROS-Responsive Cationic Polymers with Intrinsic Anti-Inflammatory Activity for Intracellular Protein Delivery

The intracellular delivery of protein drugs via nanocarriers offers significant potential for expanding their therapeutic applications. However, the unintended activation of innate immune responses and inflammation triggered by the carriers presents a major challenge, often compromising therapeutic efficacy. Here, we present oligoethylenimine-thioketal (OEI-TK), a reactive oxygen species-responsive cationic polymer with intrinsic anti-inflammatory properties, to overcome this challenge. OEI-TK self-assembles electrostatically with bovine serum albumin (BSA) to form stable nanoparticles (OTB NPs) with excellent encapsulation efficiency. In vitro studies confirmed that OTB NPs retained OEI-TK's antioxidant and anti-inflammatory properties, enhanced biocompatibility, and efficiently delivered BSA into cells. Furthermore, OEI-TK facilitated the intracellular delivery of β-galactosidase while preserving its enzymatic activity, demonstrating its potential for functional protein transport. These findings highlight OEI-TK as a promising platform with dual benefits of inflammation modulation and intracellular protein delivery, holding potential for the synergistic treatment of inflammation-related diseases.

Tumor Microenvironment-Responsive Polymer Delivery Platforms for Cancer Therapy

Most chemotherapeutic and bioimaging agents struggle with inadequate bioavailability, primarily due to their limited biocompatibility and lack of specificity in targeting, leading to low or decreased anticancer efficacy and inaccurate imaging. To surmount these obstacles, the development of stimuli-responsive polymer delivery platforms, predominantly leveraging the tumor microenvironment (TME), has emerged as a promising strategy. Therapeutic and diagnostic agents can be released controllably at the tumor site by virtue of the bond cleavage or hydrophobic to hydrophilic transformation of TME-sensitive linkages in TME-responsive systems, thus augmenting cancer treatment and imaging precision, while simultaneously attenuating the damage to healthy tissues and false imaging signals caused by non-specific drug leakage. In this comprehensive review, we scrutinize recent studies of TME-responsive polymer delivery platforms, encompassing pH-, ROS-, GSH-, enzyme-, and hypoxia-responsive vectors, significantly from the perspective of their molecular design and responsive mechanism, and further summarizing their bio-application in drug delivery and diagnostic imaging. Moreover, this review encapsulates the critical challenges and offers an insightful perspective on the future prospects of TME-responsive polymer delivery platforms in terms of molecular and vector design.

A Dynamic Deferoxamine Polymer with Exceptional Performance in Mitochondrial Iron Depletion and Cytosolic Protein Delivery

Deferoxamine (DFO) is an FDA-approved naturally occurring iron chelator commonly used to treat transfusion-induced iron overload. The abundant and flexible hydroxamic acid groups in DFO enable exceptional iron binding capacity and high protein binding via hydrogen bonding interactions. However, the applications of DFO to sequester intracellular iron and to deliver proteins inside cells are limited due to poor membrane-permeability. Herein, the fabrication of a dynamic DFO polymer is proposed to achieve robust intracellular protein delivery and efficient mitochondrial iron depletion. Specifically, DFO is grafted onto a polycatechol scaffold via dynamic catechol-boronate chemistry. The obtained DFO polymer shows robust protein binding capacity, and the formed protein complexes show high resistance toward serum proteins. It effectively delivers various cargo proteins into cytosol of treated cells with maintained bioactivity. In addition, the polymer delivers DFO inside cells, and the released DFO efficiently depletes mitochondrial iron, which significantly inhibits mitochondrial oxidative phosphorylation and glycolysis. Remarkable synergistic cytotoxic effects are achieved when the DFO polymer is loaded with toxic proteins. This study provides a general strategy for facile preparation of bioactive polymer toward robust protein delivery, and the designed polymer can be a promising carrier for the delivery of protein therapeutics to treat cancer.

Bone-Targeted Fluoropeptide Nanoparticle Inhibits NF-κB Signaling to Treat Osteosarcoma and Tumor-Induced Bone Destruction

Osteosarcoma is a malignant bone cancer usually characterized by symptoms of bone loss due to pathologically enhanced osteoclast activity. Activated osteoclasts enhance bone resorption and promote osteosarcoma cell progression by secreting various cytokines. Intercepting the detrimental interplay between osteoclasts and osteosarcoma cells is considered as an option for osteosarcoma treatment. Here, a bone-targeted fluoropeptide nanoparticle that can inhibit the nuclear factor kappa B (NF-κB) signaling in both osteoclasts and osteosarcoma to address the above issue is developed. The NF-κB essential modulator binding domain (NBD) peptide is conjugated with a fluorous tag to improve its proteolytic stability and intracellular penetration. The NBD peptide is efficiently delivered into cells after fluorination to induce apoptosis of osteocarcoma cells, and inhibits osteoclasts differentiation. The fluorous-tagged NBD peptide is further co-assembled with an oligo (aspartic acid) terminated fluoropeptide to form bone-targeted peptide nanoparticles for osteosarcoma treatment. The targeted nanoparticles efficiently inhibited tumor progression and osteosarcoma-induced bone destruction in vivo. This co-assembled fluoropeptide nanoplatform proposed in this study offers a promising approach for targeted and intracellular delivery of peptide therapeutics in the treatment of various diseases.

Rational design of diblock copolymer enables efficient cytosolic protein delivery

Polymer-mediated cytosolic protein delivery demonstrates a promising strategy for the development of protein therapeutics. Here, we propose a new designed diblock copolymer which realizes efficient cytosolic protein delivery both in vitro and in vivo. The polymer contains one protein-binding block composed of phenylboronic acid (PBA) and N-(3-dimethylaminopropyl) (DMAP) pendant units for protein binding and endosomal escape, respectively, followed by the response to ATP enriched in the cytosol which triggers the protein release. The other block is PEG designed to improve particle size control and circulation in vivo. By optimizing the block composition, sequence and length of the copolymer, the optimal one (BP20) was identified with the binding block containing 20 units of both PBA and DMAP, randomly distributed along the chain. When mixed with proteins, the BP20 forms stable nanoparticles and mediates efficient cytosolic delivery of a wide range of proteins including enzymes, toxic proteins and CRISPR/Cas9 ribonucleoproteins (RNP), to various cell lines. The PEG block, especially when further modified with folic acid (FA), enables tumor-targeted delivery of Saporin in vivo, which significantly suppresses the tumor growth. Our results shall inspire the design of novel polymeric vehicles with robust capability for cytosolic protein delivery, which holds great potential for both biological research and therapeutic applications.

ROS-responsive hydrogels: from design and additive manufacturing to biomedical applications

Hydrogels with intricate 3D networks and high hydrophilicity have qualities resembling those of biological tissues, making them ideal candidates for use as smart biomedical materials. Reactive oxygen species (ROS) responsive hydrogels are an innovative class of smart hydrogels, and are cross-linked by ROS-responsive modules through covalent interactions, coordination interactions, or supramolecular interactions. Due to the introduction of ROS response modules, this class of hydrogels exhibits a sensitive response to the oxidative stress microenvironment existing in organisms. Simultaneously, due to the modularity of the ROS-responsive structure, ROS-responsive hydrogels can be manufactured on a large scale through additive manufacturing. This review will delve into the design, fabrication, and applications of ROS-responsive hydrogels. The main goal is to clarify the chemical principles that govern the response mechanism of these hydrogels, further providing new perspectives and methods for designing responsive hydrogel materials.

Targeted protein delivery based on stimuli-triggered nanomedicine

Protein-based drugs have shown unique advantages to treat various diseases in recent years. However, most protein therapeutics in clinical use are limited to extracellular targets with low delivery efficiency. To realize targeted protein delivery, a series of stimuli-triggered nanoparticle formulations have been developed to improve delivery efficiency and reduce off-target release. These smart nanoparticles are designed to release cargo proteins in response to either internal or external stimuli at pathological tissues. In this way, varieties of protein-based drugs including antibodies, enzymes, and pro-apoptotic proteins can be effectively delivered to desired sites for the treatment of cancer, inflammation, metabolic diseases, and so on with minimal side effects. In this review, recent advances in the design of stimuli-triggered nanomedicine for targeted protein delivery in different biomedical applications will be discussed. A deeper understanding of these emerging strategies helps develop more efficient protein delivery systems for clinical use in the future.

Intracellular Protein Delivery: Approaches, Challenges, and Clinical Applications

Protein biologics are powerful therapeutic agents with diverse inhibitory and enzymatic functions. However, their clinical use has been limited to extracellular applications due to their inability to cross plasma membranes. Overcoming this physiological barrier would unlock the potential of protein drugs for the treatment of many intractable diseases. In this review, we highlight progress made toward achieving cytosolic delivery of recombinant proteins. We start by first considering intracellular protein delivery as a drug modality compared to existing Food and Drug Administration-approved drug modalities. Then, we summarize strategies that have been reported to achieve protein internalization. These techniques can be broadly classified into 3 categories: physical methods, direct protein engineering, and nanocarrier-mediated delivery. Finally, we highlight existing challenges for cytosolic protein delivery and offer an outlook for future advances.

Responsive Microneedles as a New Platform for Precision Immunotherapy

Microneedles are a well-known transdermal or transdermal drug delivery system. Different from intramuscular injection, intravenous injection, etc., the microneedle delivery system provides unique characteristics for immunotherapy administration. Microneedles can deliver immunotherapeutic agents to the epidermis and dermis, where immune cells are abundant, unlike conventional vaccine systems. Furthermore, microneedle devices can be designed to respond to certain endogenous or exogenous stimuli including pH, reactive oxygen species (ROS), enzyme, light, temperature, or mechanical force, thereby allowing controlled release of active compounds in the epidermis and dermis. In this way, multifunctional or stimuli-responsive microneedles for immunotherapy could enhance the efficacy of immune responses to prevent or mitigate disease progression and lessen systemic adverse effects on healthy tissues and organs. Since microneedles are a promising drug delivery system for accurate delivery and controlled drug release, this review focuses on the progress of using reactive microneedles for immunotherapy, especially for tumors. Limitations of current microneedle system are summarized, and the controllable administration and targeting of reactive microneedle systems are examined.