Spatiotemporal Delivery of CRISPR/Cas9 Genome Editing Machinery Using Stimuli-Responsive Vehicles

Precisely Targeted Nanoparticles for CRISPR-Cas9 Delivery in Clinical Applications

Clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR-Cas9), an emerging gene-editing technology, has recently gained rapidly increasing attention. However, the lack of efficient delivery vectors to deliver CRISPR-Cas9 to specific cells or tissues has hindered the translation of this biotechnology into clinical applications. Chemically synthesized nanoparticles (NPs), as attractive non-viral delivery platforms for CRISPR-Cas9, have been extensively investigated because of their unique characteristics, such as controllable size, high stability, multi-functionality, bio-responsive behavior, biocompatibility, and versatility in chemistry. In this review, the key considerations for the precise design of chemically synthesized-based nanoparticles include efficient encapsulation, cellular uptake, the targeting of specific tissues and cells, endosomal escape, and controlled release. We discuss cutting-edge strategies to integrate chemical modifications into non-viral nanoparticles that guide the CRISPR-Cas9 genome-editing machinery to specific edits. We also highlighted the rationale of intelligent nanoparticle design. In particular, we have summarized promising functional groups and molecules that can effectively optimize carrier function. In addition, this review focuses on advances in the widespread application of NPs delivery in the biomedical fields to promote the development of safe, specific, and efficient NPs for delivering CRISPR-Cas9 systems, providing references for accelerating their clinical translational applications.

Polyamine-Depleting Hydrogen-Bond Organic Frameworks Unleash Dendritic Cell and T Cell Vigor for Targeted CRISPR/Cas-Assisted Cancer Immunotherapy

Polyamines have tantalized cancer researchers as a potential means to rein in the rampant growth of cancer cells. However, clinical trials in recent decades have disappointed in delivering notable progress. Herein, a microfluidic-assisted synthetic hydrogen-bond organic framework (HOF) as a polyamine-depleting nanoplatforms designed to unleash the vigor of both dendritic cells (DCs) and T cells for precision cancer immunotherapy is reported. Upon internalization by tumor cells, the loaded plasma amine oxidase (PAO) in HOF efficiently depletes polyamines, remolding the tumor microenvironment and alleviating T-cell immunosuppression. This process also generates acrolein and H2O2, triggering CRISPR-assisted neoantigen generation. Specifically, Acrolein induces carbonyl stress, increasing mutational burdens. Simultaneously, HOF leverages the energy from the bis[2,4,5-trichloro-6-(pentyloxycarbonyl)phenyl] oxalate (CPPO)-H2O2 reaction for CRET-triggered singlet oxygen production, leading to thioether bond cleavage and release CRISPR-Cas9. Once released, CRISPR-Cas9 knocks out the DNA mismatch repair (MMR)-related MLH1 gene, further elevating mutational burdens and generating neoantigens, ideal targets for DCs. This dual-action strategy not only corrects T-cell immunosuppression but also enhances DC efficacy, presenting a powerful approach for tumor immunotherapy.

PAM-Independent CRISPR-Cas12a System for Specific Assays of Single Nucleotide Variants

The CRISPR-Cas12a system has been extensively utilized in nucleic acid detection owing to its remarkable sensitivity and specificity. Nonetheless, its strict dependency on the presence of a protospacer adjacent motif (PAM) within double-stranded DNA (dsDNA) introduces considerable limitations, thereby constraining its applicability, flexibility, and broader accessibility in molecular diagnostics. Here, we communicate a universal, robust, and high-fidelity method for a PAM-independent nucleic acid assay based on the CRISPR-Cas12a system, named TRACER (mutant target-recognized PAM-independent CRISPR-Cas12a enzyme reporting system). TRACER can effectively distinguish target nucleic acids at concentrations as low as 0.5 aM, thereby enabling it to identify the presence of a 0.1% single nucleotide variant (SNV)-included mutant-type gene in heterozygotes. Thus, TRACER exhibits comparable sensitivity, specificity, and accuracy to Sanger sequencing in analyzing the SNV-related clinical tumor samples. Overall, TRACER introduces a brand-new perspective for SNV assays by eliminating the dependency on PAM sites and significantly expands the application range of the CRISPR-Cas12a system, thus holding immense potential for clinical diagnostics, biomedical research, and drug discovery.

Remotely Sequential Activation of Biofunctional MXenes for Spatiotemporally Controlled Photothermal Cancer Therapy Integrated with Multimodal Imaging

Spatiotemporally controlled cancer therapy may offer great advantages in precision medicine, but still remains some challenges in programmed sequential release and co-localization of components at target sites. Herein, a MXene-based nanoprobe (TCC@M) is meticulously designed by engineering of photodynamically activated CRISPR-Cas9 and cancer cell membrane-camouflaged Ti3C2 MXenes for targeting delivery and spatiotemporally controlled gene regulation followed by enhanced photothermal therapy (PTT) via two near-infrared irradiations. The first irradiation can activate the photosensitizer bound in cancer cells internalized TCC@M to release Cas9 ribonucleoprotein (RNP) by photodynamic effect. The released Cas9 RNP then enters the nuclei directed by the fused nuclear localization sequence in Cas9 to cleave the heat shock protein (HSP) 90α gene, which greatly reduces the expression of HSP90α protein and thus effectively sensitizes cancer cells to heat, leading to enhanced PTT at a mild temperature (<45 °C) risen by Ti₃C₂ MXenes under the second irradiation. Simultaneously, TCC@M can produce fluorescence, photoacoustic, and thermal imaging signals to guide the optimal irradiation timing. The in vivo studies have demonstrated the spatiotemporally selective therapeutic efficacy of the designed TCC@M. This innovative approach presents an effective integration of gene regulation and enhanced PTT, exemplifying a precise cancer treatment strategy.

Nanogene editing drug delivery systems in the treatment of liver fibrosis

Liver fibrosis is a group of diseases that seriously affect the health of the world's population. Despite significant progress in understanding the mechanisms of liver fibrogenesis, the technologies and drugs used to treat liver fibrosis have limited efficacy. As a revolutionary genetic tool, gene editing technology brings new hope for treating liver fibrosis. Combining nano-delivery systems with gene editing tools to achieve precise delivery and efficient expression of gene editing tools that can be used to treat liver fibrosis has become a rapidly developing field. This review provides a comprehensive overview of the principles and methods of gene editing technology and commonly used gene editing targets for liver fibrosis. We also discuss recent advances in common gene editing delivery vehicles and nano-delivery formulations in liver fibrosis research. Although gene editing technology has potential advantages in liver fibrosis, it still faces some challenges regarding delivery efficiency, specificity, and safety. Future studies need to address these issues further to explore the potential and application of liver fibrosis technologies in treating liver fibrosis.

Perspectives on CRISPR Genome Editing to Prevent Prion Diseases in High-Risk Individuals

Prion diseases are neurodegenerative disorders caused by misfolded prion proteins. Although rare, the said diseases are always fatal; they commonly cause death within months of developing clinical symptoms, and their diagnosis is exceptionally difficult pre-mortem. There are no known cures or treatments other than symptomatic care. Given the aggressiveness of prion diseases on onset, therapies after disease onset could be challenging. Prevention to reduce the incidence or to delay the disease onset has been suggested to be a more feasible approach. In this perspective article, we summarize our current understandings of the origin, risk factors, and clinical manifestations of prion diseases. We propose a PCR testing of the blood to identify PRNP gene polymorphisms at codons 129 and 127 in individuals with familial PRNP mutations to assess the risk. We further present the CRISPR/Cas9 gene editing strategy as a perspective preventative approach for these high-risk individuals to induce a polymorphic change at codon 127 of the PRNP gene, granting immunity to prion diseases in selected high-risk individuals, in particular, in individuals with familial PRNP mutations.

A Guanidinobenzol-Rich Polymer Overcoming Cascade Delivery Barriers for CRISPR-Cas9 Genome Editing

The efficient cytosolic delivery of the CRISPR-Cas9 machinery remains a challenge for genome editing. Herein, we performed ligand screening and identified a guanidinobenzol-rich polymer to overcome the cascade delivery barriers of CRISPR-Cas9 ribonucleoproteins (RNPs) for genome editing. RNPs were stably loaded into the polymeric nanoparticles (PGBA NPs) by their inherent affinity. The polymer facilitated rapid endosomal escape of RNPs via a dynamic multiple-step cascade process. Importantly, the incorporation of fluorescence in the polymer helps to identify the correlation between cellular uptake and editing efficiency, increasing the efficiency up to 70% from the initial 30% for the enrichment of edited cells. The PGBA NPs efficiently deliver RNPs for in vivo gene editing via both local and systemic injections and dramatically reduce PCSK9 level. These results indicate that PGBA NPs enable the cascade delivery of RNPs for genome editing, showing great promise in broadening the therapeutic potential of the CRISPR-Cas9 technique.

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.

Protein-Integrated Hydrogen-Bonded Organic Frameworks: Chemistry and Biomedical Applications

Hydrogen-bonded organic frameworks (HOFs) are porous nanomaterials that offer exceptional biocompatibility and versatility for integrating proteins for biomedical applications. This minireview concisely discusses recent advancements in the chemistry and functionality of protein-HOF interfaces. It particularly focuses on strategic methodologies, such as the careful selection of building blocks and the genetic engineering of proteins, to facilitate protein-HOF interactions. We examine the role of enzyme encapsulation within HOFs, highlighting its capability to preserve enzyme function, a crucial aspect for applications in biosensing and disease diagnosis. Moreover, we discuss the emerging utility of nanoscale HOFs for intracellular protein delivery, illustrating their applicability as nanoreactors for intracellular catalysis and neuroprotective biorthogonal catalysis within cellular compartments. We highlight the significant advancement of designing biodegradable HOFs tailored for cytosolic protein delivery, underscoring their promising application in targeted cancer therapies. Finally, we provide a perspective viewpoint on the design of biocompatible protein-HOF assemblies, underlining their promising prospects in drug delivery, disease diagnosis, and broader biomedical applications.

Near-Infrared Light Activated Formulation for the Spatially Controlled Release of CRISPR-Cas9 Ribonucleoprotein for Brain Gene Editing

The CRISPR/Cas9 system has emerged as a promising platform for gene editing; however, the lack of an efficient and safe delivery system to introduce it into cells continues to hinder clinical translation. Here, we report a rationally designed gene-editing nanoparticle (NP) formulation for brain applications: an sgRNA:Cas9 ribonucleoprotein complex is immobilized on the NP surface by oligonucleotides that are complementary to the sgRNA. Irradiation of the formulation with a near-infrared (NIR) laser generates heat in the NP, leading to the release of the ribonucleoprotein complex. The gene-editing potential of the formulation was demonstrated in vitro at the single-cell level. The safety and gene editing of the formulation were also demonstrated in the brains of reporter mice, specifically in the subventricular zone after intracerebral administration and in the olfactory bulb after intranasal administration. The formulation presented here offers a new strategy for the spatially controlled delivery of the CRISPR system to the brain.

Polyphenol-Assisted Biomineralization of Metal-Organic Framework Nanoparticles for Precision Delivery of Therapeutic Proteins to Cancer Cells

The delivery of proteins into the cytosol holds great promise for cell signaling manipulation and the development of precision medicine. However, this potency is challenged by achieving targeted and controlled delivery, specifically within diseased cells. In this study, we introduce a versatile and effective method for the precision delivery of therapeutic proteins to cancer cells by designing polyphenol-assisted biomineralization of zeolite imidazole framework-8 (ZIF-8). We demonstrate that by leveraging the strong noncovalent binding affinity of epigallocatechin gallate (EGCG) with both proteins and ZIF-8, our approach significantly enhances the biomineralization of ZIF-8, which in turn improves the efficiency of protein encapsulation and intracellular delivery. Moreover, the incorporation of EGCG within ZIF-8 enables controlled degradation of the nanoparticles and the selective release of the encapsulated proteins in cancer cells. This selective release is triggered by the oxidation of EGCG in response to the high levels of reactive oxygen species (ROS) found within cancer cells that destabilize the EGCG/ZIF-8 nanoparticles. We have further demonstrated the ability of EGCG/ZIF-8 to deliver a wide range of proteins into cancer cells, including bacterial virulence protein, to rewire cell signaling and prohibit tumor cell growth in a mouse xenograft model. Our strategy and findings underscore the potential of designing the EGCG/ZIF-8 interface for specific and controlled protein delivery for targeted cancer therapy.

Dual-responsive nanocarriers for efficient cytosolic protein delivery and CRISPR-Cas9 gene therapy of inflammatory skin disorders

Developing protein drugs that can target intracellular sites remains a challenge due to their inadequate membrane permeability. Efficient carriers for cytosolic protein delivery are required for protein-based drugs, cancer vaccines, and CRISPR-Cas9 gene therapies. Here, we report a screening process to identify highly efficient materials for cytosolic protein delivery from a library of dual-functionalized polymers bearing both boronate and lipoic acid moieties. Both ligands were found to be crucial for protein binding, endosomal escape, and intracellular protein release. Polymers with higher grafting ratios exhibit remarkable efficacies in cytosolic protein delivery including enzymes, monoclonal antibodies, and Cas9 ribonucleoprotein while preserving their activity. Optimal polymer successfully delivered Cas9 ribonucleoprotein targeting NLRP3 to disrupt NLRP3 inflammasomes in vivo and ameliorate inflammation in a mouse model of psoriasis. Our study presents a promising option for the discovery of highly efficient materials tailored for cytosolic delivery of specific proteins and complexes such as Cas9 ribonucleoprotein.

Engineering Anti-CRISPR Proteins to Create CRISPR-Cas Protein Switches for Activatable Genome Editing and Viral Protease Detection

Proteins capable of switching between distinct active states in response to biochemical cues are ideal for sensing and controlling biological processes. Activatable CRISPR-Cas systems are significant in precise genetic manipulation and sensitive molecular diagnostics, yet directly controlling Cas protein function remains challenging. Herein, we explore anti-CRISPR (Acr) proteins as modules to create synthetic Cas protein switches (CasPSs) based on computational chemistry-directed rational protein interface engineering. Guided by molecular fingerprint analysis, electrostatic potential mapping, and binding free energy calculations, we rationally engineer the molecular interaction interface between Cas12a and its cognate Acr proteins (AcrVA4 and AcrVA5) to generate a series of orthogonal protease-responsive CasPSs. These CasPSs enable the conversion of specific proteolytic events into activation of Cas12a function with high switching ratios (up to 34.3-fold). These advancements enable specific proteolysis-inducible genome editing in mammalian cells and sensitive detection of viral protease activities during virus infection. This work provides a promising strategy for developing CRISPR-Cas tools for controllable gene manipulation and regulation and clinical diagnostics.

A quaternary ammonium-based nanosystem enables delivery of CRISPR/Cas9 for cancer therapy

Genome editing mediated by CRISPR/Cas9 is an attractive weapon for cancer therapy. However, in vivo delivery of CRISPR/Cas9 components to achieve therapeutic efficiency is still challenging. Herein, a quaternary ammonium-functionalized poly(L-lysine) and a cholesterol-modified PEG (QNP) were self-assembled with a negatively charged CRISPR Cas9/sgRNA ribonucleoprotein (RNP) to form a ternary complex (QNP/RNP). Such a delivery system of QNP exhibited multiplex genome editing capabilities in vitro (e.g., the GFP gene and the PLK1 gene). In addition, QNP/RNPPLK1 containing PLK1 sgRNA led to 30.99% of genome editing efficiency in MCF-7 cells with negligible cytotoxicity of the carrier. QNP/RNPPLK1, which was capable of simultaneously inhibiting cell proliferation, mediating cell cycle arrest and downregulating expression of PLK1, held great in vitro therapeutic efficiency. Moreover, QNP/RNPPLK1 exhibited outstanding accumulation in tumors and high biocompatibility in vivo. In an MCF-7 xenograft animal model, QNP/RNPPLK1 showed excellent anti-tumor efficacy and achieved 17.75% indels ratio. This work showcases the successful delivery of CRISPR Cas9/sgRNA RNP with enhanced genome editing efficiency and provides a potential on-demand strategy for cancer therapy.

Polymer-Protein Assemblies with Tunable Vesicular and Hierarchical Nanostructures

The construction of variable structured multi-protein nano-assemblies is of great interest for the development of protein-based therapeutic systems. This study showcases the synthesis of polymer-protein assemblies with tunable structure like single- and multi-layer polymer-crosslinked protein vesicles, Janus protein vesicles and other hierarchical-structured assemblies by utilizing a dynamic template-assistant intermittent-assembly approach. The generalization of the methodology helps the protein assemblies to gain notable functional complexity. And we demonstrate compelling evidence highlighting the substantial impact of the topological morphology of protein nanoaggregates on their cellular uptake capacity.

Modulating the tumoral SPARC content to enhance albumin-based drug delivery for cancer therapy

Insufficient delivery of therapeutic agents into solid tumors by systemic administration remains a major challenge in cancer treatment. Secreted protein acidic and rich in cysteine (SPARC) has high binding affinity to albumin and has been shown to enhance the penetration and uptake of albumin-based drug carriers in tumors. Here, we developed a strategy to alter the tumor microenvironment (TME) by upregulating SPARC to enhance the delivery efficiency of albumin-based drug carriers into tumors. We prepared albumin nanoparticles encapsulating an NF-κB controllable CRISPR activation system (SP-NPs). SP-NPs achieved tumor-selective SPARC upregulation by responding to the highly activated NF-κB in tumor cells. Whereas a single dose of SP-NPs only modestly upregulated SPARC expression, serial administration of SP-NPs created a positive feedback loop that induced progressive increases in SPARC expression as well as tumor cell uptake and tumor penetration of the nanoparticles in vitro, in organoids, and in subcutaneous tumors in vivo. Additionally, pre-treatment with SP-NPs significantly enhanced the anti-tumor efficacy of Abraxane, a commercialized albumin-bound paclitaxel nanoformulation. Our data provide evidence that modulating SPARC in the TME can enhance the efficiency of albumin-based drug delivery to solid tumors, which may result in new strategies to increase the efficacy of nanoparticle-based cancer drugs.

Unleashing the Power of Proenzyme Delivery for Targeted Therapeutic Applications Using Biodegradable Lipid Nanoparticles

Proenzymes, functioning as inactive precursor forms of enzymes, hold significant promise for regulating essential biological processes. Their inherent property of latency, remaining inert until they arrive at the intended site of action, positions them as particularly promising candidates for the development of targeted therapeutics. Despite this potential, the therapeutic potential of proenzymes is challenged by designing proenzymes with excellent selectivity for disease cells. This limitation is further exacerbated by the inability of proenzymes to spontaneously cross the cell membrane, a biological barrier that impedes the cellular internalization of exogenous macromolecules. Therefore, efficacious intracellular delivery is paramount to unlocking the full therapeutic potency of proenzymes.In this Account, we first elucidate our recent advancements made in designing biodegradable lipid nanoparticles (LNPs) for the cell-specific delivery of biomacromolecules, including proteins and nucleic acids. Using a strategy of parallel synthesis, we have constructed an extensive library of ionizable lipids, each integrated with different biodegradable moieties. This combinatorial approach has led to the identification of LNPs that are particularly efficacious for the delivery of biomacromolecules specifically to tumor cells. This innovation capitalizes on the unique intracellular environment of cancer cells to control the degradation of LNPs, thereby ensuring the targeted release of therapeutics within tumor cells. Additionally, we discuss the structure-activity relationship governing the delivery efficacy of these LNPs and their applicability in regulating tumor cell signaling, specifically through the delivery of bacterial effector proteins.In the second segment, we aim to provide an overview of our recent contributions to the field of proenzyme design, where we have chemically tailored proteins to render them responsive to the unique milieu of tumor cells. Specifically, we elaborate on the chemical principles employed to modify proteins and DNAzymes, thereby priming them for activation in the presence of NAD(P)H:quinone oxidoreductase 1 (NQO1), an enzyme that is prevalently upregulated within tumor cells. We summarize the methodologies for intracellular delivery of these proenzymes using biodegradable LNPs, both in vitro and in vivo. The concomitant intracellular delivery and activation of proenzymes are examined in the context of enhanced therapeutic outcomes and targeted CRISPR/Cas9 genome editing.In conclusion, we offer a perspective on the chemical principles that could be leveraged to optimize LNPs for tissue-specific delivery of proenzymes. We also explore chemical strategies for the irreversible modulation of proenzyme activity within living cells and in vivo. Through this discussion, we provide insights into potential avenues for overcoming existing limitations and enhancing the delivery of proenzymes using LNPs, particularly for developing tumor-targeted therapies and genome editing applications.

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.

A DNA Origami-Based Gene Editing System for Efficient Gene Therapy in Vivo

DNA nanostructures have played an important role in the development of novel drug delivery systems. Herein, we report a DNA origami-based CRISPR/Cas9 gene editing system for efficient gene therapy in vivo. In our design, a PAM-rich region precisely organized on the surface of DNA origami can easily recruit and load sgRNA/Cas9 complex by PAM-guided assembly and pre-designed DNA/RNA hybridization. After loading the sgRNA/Cas9 complex, the DNA origami can be further rolled up by the locking strands with a disulfide bond. With the incorporation of DNA aptamer and influenza hemagglutinin (HA) peptide, the cargo-loaded DNA origami can realize the targeted delivery and effective endosomal escape. After reduction by GSH, the opened DNA origami can release the sgRNA/Cas9 complex by RNase H cleavage to achieve a pronounced gene editing of a tumor-associated gene for gene therapy in vivo. This rationally developed DNA origami-based gene editing system presents a new avenue for the development of gene therapy.

Histidine-Rich Protein Accelerates the Biomineralization of Zeolitic Imidazolate Frameworks for In Vivo Protein Delivery

Biomineralization of metal-organic frameworks (MOFs) provides a powerful approach for intracellular protein delivery, enabling the study of biological function and therapeutic potential of proteins. However, the potency of this approach is largely challenged by the low efficiency of current strategies for interfacing proteins with MOFs for biomineralization and intracellular delivery. Here, we report a versatile and convenient biomineralization strategy for the rapid encapsulation and enhanced delivery of proteins using MOFs, accelerated by histidine-rich proteins. We demonstrate that the histidine-rich green fluorescent protein (H39GFP) can accelerate the biomineralization of MOFs by promoting the coordination between proteins and metal ions, leading to enhanced protein delivery efficiency up to 15-fold. Moreover, we show that the delivery of H39GFP-fused cytotoxic ribonuclease and bacterial-derived RAS protease can effectively inhibit tumor cell growth. The strategy of promoting the biomineralization of MOFs via histidine-rich proteins for enhanced intracellular delivery could be expanded to other biomacromolecules, advancing their therapeutic potential and the biomedical scope of MOFs.

CRISPR/Cas9 systems: Delivery technologies and biomedical applications

The emergence of the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) genome-editing system has brought about a significant revolution in the realm of managing human diseases, establishing animal models, and so on. To fully harness the potential of this potent gene-editing tool, ensuring efficient and secure delivery to the target site is paramount. Consequently, developing effective delivery methods for the CRISPR/Cas9 system has become a critical area of research. In this review, we present a comprehensive outline of delivery strategies and discuss their biomedical applications in the CRISPR/Cas9 system. We also provide an in-depth analysis of physical, viral vector, and non-viral vector delivery strategies, including plasmid-, mRNA- and protein-based approach. In addition, we illustrate the biomedical applications of the CRISPR/Cas9 system. This review highlights the key factors affecting the delivery process and the current challenges facing the CRISPR/Cas9 system, while also delineating future directions and prospects that could inspire innovative delivery strategies. This review aims to provide new insights and ideas for advancing CRISPR/Cas9-based delivery strategies and to facilitate breakthroughs in biomedical research and therapeutic applications.

One-pot synthesis of dynamically cross-linked polymers for serum-resistant nucleic acid delivery

Cationic polymers used for nucleic acid delivery often suffer from complicated syntheses, undesired intracellular cargo release and low serum stability. Herein, a series of ternary polymers were synthesized via facile green chemistry to achieve efficient plasmid DNA and mRNA delivery in serum. During the one-pot synthesis of the ternary polymer, acetylphenylboric acid (APBA), polyphenol and low-molecular weight polyethyleneimine (PEI 1.8k) were dynamically cross-linked with each other due to formation of an imine between PEI 1.8k and APBA and formation of a boronate ester between APBA and polyphenol. Series of polyphenols, including ellagic acid (EA), epigallocatechin gallate (EGCG), nordihydroguaiaretic acid (NDGA), rutin (RT) and rosmarinic acid (RA), and APBA molecules, including 2-acetylphenylboric acid (2-APBA), 3-acetylphenylboric acid (3-APBA) and 4-acetylphenylboric acid (4-APBA), were screened and the best-performing ternary polymer, 2-PEI-RT, constructed from RT and 2-APBA, was identified. The ternary polymer featured efficient DNA condensation to favor cellular internalization, and the acidic environment in endolysosomes triggered effective degradation of the polymer to promote cargo release. Thus, 2-PEI-RT showed robust plasmid DNA transfection efficiencies in various tumor cells in serum, outperforming the commercial reagent PEI 25k by 1-3 orders of magnitude. Moreover, 2-PEI-RT mediated efficient cytosolic delivery of Cas9-mRNA/sgRNA to enable pronounced CRISPR-Cas9 genome editing in vitro. Such a facile and robust platform holds great potential for non-viral nucleic acid delivery and gene therapy.

Targeting telomerase utilizing zeolitic imidazole frameworks as non-viral gene delivery agents across different cancer cell types

Telomerase, a ribonucleoprotein coded by the hTERT gene, plays an important role in cellular immortalization and carcinogenesis. hTERT is a suitable target for cancer therapeutics as its activity is highly upregulated in most of cancer cells but absent in normal somatic cells. Here, by employing the two Metal-Organic Frameworks (MOFs), viz. ZIF-C and ZIF-8, based biomineralization we encapsulate Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 plasmid system that targets hTERT gene (CrhTERT) in cancer cells. When comparing the two biocomposites, ZIF-C shows the better loading capacity and cell viability. The loaded plasmid in ZIF-C is highly protected against enzymatic degradation. CrhTERT@ZIF-C is efficiently endocytosed by cancer cells and the subcellular release of CrhTERT leads to telomerase knockdown. The resultant inhibition of hTERT expression decreases cellular proliferation and causing cancer cell death. Furthermore, hTERT knockdown shows a significant reduction in tumour metastasis and alters protein expression. Collectively we show the high potential of ZIF-C-based biocomposites as a promising general tool for gene therapy of different types of cancers.

Structural and Molecular Fusion MRI Nanoprobe for Differential Diagnosis of Malignant Tumors and Follow-Up Chemodynamic Therapy

Enhanced imaging techniques using contrast agents enable high-resolution structural imaging to reveal space-occupying lesions but rarely provide detailed molecular information. To this end, we report a structural and molecular fusion magnetic resonance imaging (MRI) nanoprobe for differential diagnosis between benign and malignant tumors. This fusion nanoprobe, termed FFT NPs, follows a working mechanism involving a T₁-/T₂-weighted magnetic resonance tuning effect (MRET) between a magnetic Fe₃O₄ core and a paramagnetic Fe-tannic acid (Fe-TA) shell. The FFT NPs with an "always-on" inert T₂ signal provide structural MRI (sMRI) contrast of tumors while affording an activated T₁ signal in the presence of ATP, which is overproduced during the rapid growth of malignant tumors to enable molecular MRI (mMRI) of tumor lesions. We propose the use of the ratiometric mMRI:sMRI intensity to assist in the differential diagnosis of malignant 4T1 tumors from benign L929 fibroblast tumors. Furthermore, the dissociated FFT NPs were found to be able to catalyze H₂O₂ conversion in 4T1 tumors to generate excess reactive oxygen species (ROS) for chemodynamic therapy. The described fusion nanoprobe strategy enables the differential diagnosis of tumors from a combined spatial and molecular perspective with one-stop MRI imaging with potential applications in precision intervention.

Lipid-based nanocarrier mediated CRISPR/Cas9 delivery for cancer therapy

CRISPR/Cas mediated gene-editing has opened new avenues for therapies that show great potential for treating or curing cancers, genetic disorders, and microbial infections such as HIV. CRISPR/Cas9 tool is highly efficacious in revolutionizing the advent of genome editing; however, its efficient and safe delivery is a major hurdle due to its cellular impermeability and instability. Nano vectors could be explored to scale up the safe and effective delivery of CRISPR/Cas9. This review highlights the importance of CRISPR/Cas9 genome editing system in cancer treatment along with the effect of lipid-based nanoparticles in its safe delivery to cancer cells. The solid-lipid nanoparticles, nanostructured lipid carrier, lipid nanoparticles and niosomes have shown great effect in the delivery of CRISPR compounds to the cancer cells. The design and genome editing application in cancer therapy has been discussed along with the future concern and prospects of lipid nanoparticle based CRISPR/Cas9 has been focused toward the end.

CRISPR/Cas9 therapeutics: progress and prospects

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) gene-editing technology is the ideal tool of the future for treating diseases by permanently correcting deleterious base mutations or disrupting disease-causing genes with great precision and efficiency. A variety of efficient Cas9 variants and derivatives have been developed to cope with the complex genomic changes that occur during diseases. However, strategies to effectively deliver the CRISPR system to diseased cells in vivo are currently lacking, and nonviral vectors with target recognition functions may be the focus of future research. Pathological and physiological changes resulting from disease onset are expected to serve as identifying factors for targeted delivery or targets for gene editing. Diseases are both varied and complex, and the choice of appropriate gene-editing methods and delivery vectors for different diseases is important. Meanwhile, there are still many potential challenges identified when targeting delivery of CRISPR/Cas9 technology for disease treatment. This paper reviews the current developments in three aspects, namely, gene-editing type, delivery vector, and disease characteristics. Additionally, this paper summarizes successful examples of clinical trials and finally describes possible problems associated with current CRISPR applications.

Orthogonal Chemical Activation of Enzyme-Inducible CRISPR/Cas9 for Cell-Selective Genome Editing

The precision and therapeutic potential of CRISPR/Cas9 genome editing are greatly challenged by the less control over Cas9-mediated DNA cleavage. Herein, we introduce a conditional and cell-selective genome editing system controlled by disease-associated enzymes, termed enzyme-inducible CRISPR (eiCRISPR). eiCRISPR comprises Cas9 protein, a self-blocked inactive single-guide RNA (bsgRNA), and a chemically caged deoxyribozyme (DNAzyme) that activates bsgRNA and eiCRISPR in a controllable manner. We design chemical modifications of DNAzyme to suppress its ability to cleave the blocking region of bsgRNA, while the decaging of DNAzyme triggered by the tumor cell-overexpressed enzyme, for instance, NAD(P)H:quinone oxidoreductase (NQO1), restores the activity of bsgRNA and switches on eiCRISPR selectively for genome editing in cancer cells. Moreover, using a biodegradable lipid nanoparticle to deliver eiCRISPR in a tumor-bearing xenograft, we show that the in vivo activation of eiCRISPR enables the editing of human papillomavirus 18 E6 for potential cancer therapy. The strategy of postsynthetic and site-specific modification of DNAzyme is compatible with endogenous chemistries for regulating eiCRISPR for cell-selective genome editing and targeted gene therapy.

Multidrug-Resistant Microbial Therapy Using Antimicrobial Peptides and the CRISPR/Cas9 System

The emergence and spread of multidrug-resistant microbes become a serious threat to animal and human health globally because of their less responsiveness to conventional antimicrobial therapy. Multidrug-resistant microbial infection poses higher morbidity and mortality rate with significant economic losses. Currently, antimicrobial peptides and the CRISPR/Cas9 system are explored as alternative therapy to circumvent the challenges of multidrug-resistant organisms. Antimicrobial peptides are small molecular weight, cationic peptides extracted from all living organisms. It is a promising drug candidate for the treatment of multidrug-resistant microbes by direct microbial killing or indirectly modulating the innate immune system. The CRISPR/Cas9 system is another novel antimicrobial alternative used to manage multidrug-resistant microbial infection. It is a versatile gene-editing tool that uses engineered single guide RNA for targeted gene recognition and the Cas9 enzyme for the destruction of target nucleic acids. Both the CRISPR/Cas9 system and antimicrobial peptides were used to successfully treat nosocomial infections caused by ESKAPE pathogens, which developed resistance to various antimicrobials. Despite, their valuable roles in multidrug-resistant microbial treatments, both the antimicrobial peptides and the CRISPR/Cas systems have various limitations like toxicity, instability, and incurring high manufacturing costs. Thus, this review paper gives detailed explanations of the roles of the CRISPR/Cas9 system and antimicrobial peptides in circumventing the challenges of multidrug-resistant microbial infections, its limitation and prospects in clinical applications.

A zwitterionic polymer-inspired material mediated efficient CRISPR-Cas9 gene editing

The type II prokaryotic CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR/Cas9) adaptive immune system is a cutting-edge genome-editing toolbox. However, its applications are still limited by its inefficient transduction. Herein, we present a novel gene vector, the zwitterionic polymer-inspired material with branched structure (ZEBRA) for efficient CRISPR/Cas9 delivery. Polo-like kinase 1 (PLK1) acts as a master regulator of mitosis and overexpresses in multiple tumor cells. The Cas9 and single guide sgRNA (sgRNA)-encoded plasmid was transduced to knockout Plk1 gene, which was expected to inhibit the expression of PLK1. Our studies demonstrated that ZEBRA enabled to transduce the CRISPR/Cas9 system with large size into the cells efficiently. The transduction with ZEBRA was cell line dependent, which showed ∼10-fold higher in CD44-positive cancer cell lines compared with CD44-negative ones. Furthermore, ZEBRA induced high-level expression of Cas9 proteins by the delivery of CRISPR/Cas9 and efficient gene editing of Plk1 gene, and inhibited the tumor cell growth significantly. This zwitterionic polymer-inspired material is an effective and targeted gene delivery vector and further studies are required to explore its potential in gene delivery applications.

Progress of delivery methods for CRISPR-Cas9

INTRODUCTION

Gene therapy is becoming increasingly common in clinical practice, giving hope for the correction of a wide range of human diseases and defects. The CRISPR/Cas9 system, consisting of the Cas9 nuclease and single-guide RNA (sgRNA), has revolutionized the field of gene editing. However, efficiently delivering the CRISPR-Cas9 to the target organ or cell remains a significant challenge. In recent years, with rapid advances in nanoscience, materials science, and medicine, researchers have developed various technologies that can deliver CRISPR-Cas9 in different forms for in vitro and in vivo gene editing. Here, we review the development of the CRISPR-Cas9 and describe the delivery forms and the vectors that have emerged in CRISPR-Cas9 delivery, summarizing the key barriers and the promising strategies that vectors currently face in delivering the CRISPR-Cas9.

AREAS COVERED

With the rapid development of CRISPR-Cas9, delivery methods are becoming increasingly important in the in vivo delivery of CRISPR-Cas9.

EXPERT OPINION

CRISPR-Cas9 is becoming increasingly common in clinical trials. However, the complex nuclease and protease environment is a tremendous challenge for in vivo clinical applications. Therefore, the development of delivery methods is highly likely to take the application of CRISPR-Cas9 technology to another level.

Nanoparticle-based non-viral CRISPR delivery for enhanced immunotherapy

The CRISPR Cas9 system has received considerable attention due to its simplicity, efficiency, and high precision for gene editing. The development of various therapeutic applications of the CRISPR system is under active research. In particular, its proven effects and promise in immunotherapy are of note. CRISPR/Cas9 components can be transported in various forms, such as plasmid DNA, mRNA of the Cas9 protein with gRNA, or a ribonucleoprotein complex. Even with its proven gene editing superiority, there are limitations in delivering the CRISPR system to target cells. CRISPR systems can be delivered via physical methods, viral vectors, or non-viral carriers. The development of diverse types of nanoparticles that could be used as non-viral carriers could overcome the disadvantages of physical techniques and viral vectors such as low cell viability, induction of immune response, limited loading capacity, and lack of targeting ability. Herein, we review the recent developments in applications of CRISPR system-mediated non-viral carriers in immunotherapy, depending on the targeting cell types, and discuss future research directions.

One-shot dual gene editing for drug-resistant pancreatic cancer therapy

It is challenging to diagnose patients with pancreatic ductal adenocarcinoma (PDAC) early on, and their treatment is often complex. Gemcitabine (GEM) is the first-line treatment for PDAC, but its efficacy is limited in most patients due to the GEM resistance from KRAS and P53 gene mutations. We describe the correction of a double gene mutation and therapeutic effect for the GEM resistant PDAC. Bio-available nanoliposomes (NL) possessing Cas9-ribonucleoproteins and adenine-base editors were developed to conduct KRAS and P53 mutation gene editing directly. NLs were conjugated with EGFR antibodies to tumor-specific delivery, and the anti-cancer effect was verified in vitro and in vivo Model. Our GEM-combinatorial therapeutic strategies using double gene editing systems with one-shot may be a potent therapy for PDAC, overcoming chemoresistance.

Sono-Controllable and ROS-Sensitive CRISPR-Cas9 Genome Editing for Augmented/Synergistic Ultrasound Tumor Nanotherapy

The potential of the cluster regularly interspaced short palindromic repeat (CRISPR)-associated protein 9 (Cas9)-based therapeutic genome editing is severely hampered by the difficulties in precise regulation of the in vivo activity of the CRISPR-Cas9 system. Herein, sono-controllable and reactive oxygen species (ROS)-sensitive sonosensitizer-integrated metal-organic frameworks (MOFs), denoted as P/M@CasMTH1, are developed for augmented sonodynamic therapy (SDT) efficacy using the genome-editing technology. P/M@CasMTH1 nanoparticles comprise singlet oxygen (1 O2 )-generating MOF structures anchored with CRISPR-Cas9 systems via 1 O2 -cleavable linkers, which serve not only as a delivery vector of CRISPR-Cas9 targeting MTH1, but also as a sonoregulator to spatiotemporally activate the genome editing. P/M@CasMTH1 escapes from the lysosomes, harvests the ultrasound (US) energy and converts it into abundant 1 O2 to induce SDT. The generated ROS subsequently trigger cleavage of ROS-responsive thioether bonds, thus inducing controllable release of the CRISPR-Cas9 system and initiation of genome editing. The genomic disruption of MTH1 conspicuously augments the therapeutic efficacy of SDT by destroying the self-defense system in tumor cells, thereby causing cellular apoptosis and tumor suppression. This therapeutic strategy for synergistic MTH1 disruption and abundant 1 O2 generation provides a paradigm for augmenting SDT efficacy based on the emerging nanomedicine-enabled genome-editing technology.

Nanoscale metal-organic frameworks for the intracellular delivery of CRISPR/Cas9 genome editing machinery

The discovery of CRISPR/Cas9 genome-editing technology enables the precise manipulation of mammalian DNA sequences for treating genetic disorders. Despite its high efficiency for genome editing, the introduction of CRISPR/Cas9 machinery, which is composed of Cas9 nuclease protein and guide RNA, into cells challenges its clinical translation potential. Therefore, the intracellular delivery of genome-editing machinery determines the efficacy of gene manipulation via the CRISPR/Cas9 technology. Recently, metallosupramolecules including metal-organic frameworks (MOFs) and metal-organic cages (MOCs) have been designed to selfassemble with Cas9 nuclease and guide RNA for CRISPR/Cas9 delivery and genome editing. Herein, we review the most recent advances and strategies of constructing metallosupramolecules for CRISPR/Cas9 delivery. In particular, we discuss nanoscale MOFs and MOCs that could be assembled and regulated by the intracellular environment for the spatiotemporal delivery of genome editing machinery. We also provide a perspective view of the future development of metallosupramolecules for genome editing and gene therapy in vivo.

External stimuli-responsive nanoparticles for spatially and temporally controlled delivery of CRISPR-Cas genome editors

The CRISPR-Cas9 system is a powerful tool for genome editing, which can potentially lead to new therapies for genetic diseases. To date, various viral and non-viral delivery systems have been developed for the delivery of CRISPR-Cas9 in vivo. However, spatially and temporally controlled genome editing is needed to enhance the specificity in organs/tissues and minimize the off-target effects of editing. In this review, we summarize the state-of-the-art non-viral vectors that exploit external stimuli (i.e., light, magnetic field, and ultrasound) for spatially and temporally controlled genome editing and their in vitro and in vivo applications.

In vivo delivery of CRISPR-Cas9 therapeutics: Progress and challenges

Within less than a decade since its inception, CRISPR-Cas9-based genome editing has been rapidly advanced to human clinical trials in multiple disease areas. Although it is highly anticipated that this revolutionary technology will bring novel therapeutic modalities to many diseases by precisely manipulating cellular DNA sequences, the low efficiency of in vivo delivery must be enhanced before its therapeutic potential can be fully realized. Here we discuss the most recent progress of in vivo delivery of CRISPR-Cas9 systems, highlight innovative viral and non-viral delivery technologies, emphasize outstanding delivery challenges, and provide the most updated perspectives.

In vivo targeted delivery of nucleic acids and CRISPR genome editors enabled by GSH-responsive silica nanoparticles

The rapid development of gene therapy and genome editing techniques brings up an urgent need to develop safe and efficient nanoplatforms for nucleic acids and CRISPR genome editors. Herein we report a stimulus-responsive silica nanoparticle (SNP) capable of encapsulating biomacromolecules in their active forms with a high loading content and loading efficiency as well as a well-controlled nanoparticle size (~50 nm). A disulfide crosslinker was integrated into the silica network, endowing SNP with glutathione (GSH)-responsive cargo release capability when internalized by target cells. An imidazole-containing component was incorporated into the SNP to enhance the endosomal escape capability. The SNP can deliver various cargos, including nucleic acids (e.g., DNA and mRNA) and CRISPR genome editors (e.g., Cas9/sgRNA ribonucleoprotein (RNP), and RNP with donor DNA) with excellent efficiency and biocompatibility. The SNP surface can be PEGylated and functionalized with different targeting ligands. In vivo studies showed that subretinally injected SNP conjugated with all-trans-retinoic acid (ATRA) and intravenously injected SNP conjugated with GalNAc can effectively deliver mRNA and RNP to murine retinal pigment epithelium (RPE) cells and liver cells, respectively, leading to efficient genome editing. Overall, the SNP is a promising nanoplatform for various applications including gene therapy and genome editing.

Spatiotemporal control of CRISPR/Cas9 gene editing

The clustered regularly interspaced short palindromic repeats (CRISPR)/associated protein 9 (CRISPR/Cas9) gene editing technology, as a revolutionary breakthrough in genetic engineering, offers a promising platform to improve the treatment of various genetic and infectious diseases because of its simple design and powerful ability to edit different loci simultaneously. However, failure to conduct precise gene editing in specific tissues or cells within a certain time may result in undesirable consequences, such as serious off-target effects, representing a critical challenge for the clinical translation of the technology. Recently, some emerging strategies using genetic regulation, chemical and physical strategies to regulate the activity of CRISPR/Cas9 have shown promising results in the improvement of spatiotemporal controllability. Herein, in this review, we first summarize the latest progress of these advanced strategies involving cell-specific promoters, small-molecule activation and inhibition, bioresponsive delivery carriers, and optical/thermal/ultrasonic/magnetic activation. Next, we highlight the advantages and disadvantages of various strategies and discuss their obstacles and limitations in clinical translation. Finally, we propose viewpoints on directions that can be explored to further improve the spatiotemporal operability of CRISPR/Cas9.