Delivery of Therapeutic RNA to the Bone Marrow in Multiple Myeloma Using CD38-Targeted Lipid Nanoparticles

More than a delivery system: the evolving role of lipid-based nanoparticles

Lipid-based nanoparticles, including liposomes and lipid nanoparticles (LNPs), make up an important class of drug delivery systems. Their modularity enables encapsulation of a wide range of therapeutic cargoes, their ease of functionalization allows for incorporation of targeting motifs and anti-fouling coatings, and their scalability facilitates rapid translation to the clinic. While the discovery and early understanding of lipid-based nanoparticles is heavily rooted in biology, formulation development has largely focused on materials properties, such as how liposome and lipid nanoparticle composition can be altered to maximize drug loading, stability and circulation. To achieve targeted delivery and enable improved accumulation of therapeutics at target tissues or disease sites, emphasis is typically placed on the use of external modifications, such as peptide, protein, and polymer motifs. However, these approaches can increase the complexity of the nanocarrier and complicate scale up. In this review, we focus on how our understanding of lipid structure and function in biological contexts can be used to design intrinsically functional and targeted nanocarriers. We highlight formulation-based strategies, such as the incorporation of bioactive lipids, that have been used to modulate liposome and lipid nanoparticle properties and improve their functionality while retaining simple nanocarrier designs. We also highlight classes of naturally occurring lipids, their functions, and how they have been incorporated into lipid-based nanoparticles. We will additionally position these approaches into the historical context of both liposome and LNP development.

Targeting capacity, safety and efficacy of engineered extracellular vesicles delivered by transdermal microneedles to treat plasmacytoma in mice

BACKGROUND

Engineered extracellular vesicles (EVs) are emerging as a highly potential platform for targeted drug delivery in cancer therapy. Although intravenous injection is commonly used in EV treatment, there is growing interest in using microneedles (MNs) for transdermal EV delivery; however, comprehensive studies comparing the tissue distribution, safety and antitumour efficacy of these two approaches for delivering engineered EVs remain scarce.

METHODS

We used EVs derived from umbilical cord mesenchymal stem cells, modified with phospholipid‒polyethylene glycol‒N-hydroxysuccinimide and conjugated with CD38 peptides (CD38-EVs), to target myeloma cells that highly express CD38 antigen, and tested their safety and antitumour efficacy in mice with subcutaneous plasmacytoma, administrated via dissolvable transdermal MNs or intravenous injection. Flow cytometry, immunofluorescence and fluorescence molecular projection imaging analysis were employed to evaluate the distribution of CD38-EVs at the cellular level and within living systems. Additionally, histopathological analysis and biochemical analyses were conducted to assess the antitumour effects and safety of CD38-EVs loaded with doxorubicin (CD38-EVs-Dox).

RESULTS

Compared to standard EVs, CD38-EVs exhibited enhanced uptake by CD38high tumour cells and reduced uptake by CD38-negative non-tumour cells in vitro. In plasmacytoma NOD/SCID mouse models, CD38-EVs encapsulated within MNs (CD38-EVsMNs) effectively targeted the tumour cells much more than the standard EVs encapsulated within MNs (EVsMNs) and CD38-EVs intravenously administrated (CD38-EVsi.v), with reduced distribution to the lungs and spleen. Additionally, CD38-EVs-Dox induced significantly greater cytotoxicity against the tumour cells than EVs-Dox in vitro, and CD38-EVs-DoxMNs significantly reduced tumour burden compared to both EVs-DoxMNs and CD38-EVs-Doxi.v, while maintaining favourable safety profiles.

CONCLUSIONS

CD38-EVs-DoxMNs have superior efficacy and safety in treating plasmacytoma mice, compared to CD38-EVs-Doxi.v, providing novel insights into the potential of MNs as a platform for delivering targeted engineered EVs in tumour therapy.

HIGHLIGHTS

Enhanced tumor targeting: CD38-modified EVs (CD38-EVs) showed increased uptake by CD38high tumor cells while reducing uptake by CD38-negative non-tumor cells. Optimized delivery: MN-loaded CD38-EVs targeted tumors more effectively than MN-loaded EVs and intravenously injected CD38-EVs, with lower lung and spleen accumulation. Superior antitumor efficacy: MN-delivered CD38-EVs-Dox significantly suppressed tumor growth, outperforming intravenous CD38-EVs-Dox and MN-delivered EVs-Dox.

Nature-inspired platform nanotechnology for RNA delivery to myeloid cells and their bone marrow progenitors

Nucleic acid therapeutics are used for silencing, expressing or editing genes in vivo. However, their systemic stability and targeted delivery to bone marrow resident cells remains a challenge. In this study we present a nanotechnology platform based on natural lipoproteins, designed for delivering small interfering RNA (siRNA), antisense oligonucleotides and messenger RNA to myeloid cells and haematopoietic stem and progenitor cells in the bone marrow. We developed a prototype apolipoprotein nanoparticle (aNP) that stably incorporates siRNA into its core. We then created a comprehensive library of aNP formulations and extensively characterized their physicochemical properties and in vitro performance. From this library, we selected eight representative aNP-siRNA formulations and evaluated their ability to silence lysosomal-associated membrane protein 1 (Lamp1) expression in immune cell subsets in mice after intravenous administration. Using the most effective aNP identified from the screening process, we tested the platform's potential for therapeutic gene silencing in a syngeneic murine tumour model. We also demonstrated the aNP platform's suitability for splice-switching with antisense oligonucleotides and for protein production with messenger RNA by myeloid progenitor cells in the bone marrow. Our data indicate that the aNP platform holds translational potential for delivering various types of nucleic acid therapeutics to myeloid cells and their progenitors.

Modular Design of Lipopeptide-Based Organ-Specific Targeting (POST) Lipid Nanoparticles for Highly Efficient RNA Delivery

Lipid nanoparticles (LNPs) with highly efficient and specific extrahepatic targeting abilities are promising in gene delivery, and the lipopeptides (LPs) with excellent designability and functionality are expected to empower the construction of functional LNPs. This study aims to develop highly efficient ionizable components that accurately match different targeting lipid systems through the modular design of LPs. Based on this, a lipopeptide-based organ-specific targeting (POST) LNP screening strategy is constructed, in which lysine-histidine-based lipopeptides (KH-LPs) are designed as highly efficient ionizable components. The optimal KH-LP LNP screened in vitro shows excellent siRNA/mRNA transfecting ability in various hard-to-transfect cell lines. Compared to the classic LNPs, the POST LNPs screened in vivo achieve even higher (or at least comparable) efficiency and specificity in delivering mRNA and siRNA to the lung, liver, and spleen, respectively. The structure-activity relationship (SAR) proves that the modular regulation of LP structures can accurately provide the optimal ionizable components for different targeting lipid systems, demonstrating the potential of this strategy in developing efficient and selective targeting systems, which is expected to open up more possibilities for gene therapy.

Ionizable Lipids with Optimized Linkers Enable Lung-Specific, Lipid Nanoparticle-Mediated mRNA Delivery for Treatment of Metastatic Lung Tumors

Lipid nanoparticles (LNPs) have emerged as a groundbreaking delivery system for vaccines and therapeutic mRNAs. Ionizable lipids are the most pivotal component of LNPs due to their ability to electrostatically interact with mRNA, allowing its encapsulation while concurrently enabling its endosomal escape following cellular internalization. Thus, extensive research has been performed to optimize the ionizable lipid structure and to develop formulations that are well tolerated and allow efficient targeting of different organs that result in a high and sustained mRNA expression. However, one facet of the ionizable lipids' structure has been mostly overlooked: the linker segment between the ionizable headgroup and their tails. Here, we screened a rationally designed library of ionizable lipids with different biodegradable linkers. We extensively characterized LNPs formulated using these ionizable lipids and elucidated how these minor structural changes in the ionizable lipids structure radically influenced the LNPs' biodistribution in vivo. We showed how the use of amide and urea linkers can modulate the LNPs' pKa, resulting in an improved specificity for lung transfection. Finally, we demonstrated how one of these lipids (lipid 35) that form LNPs entrapping a bacterial toxin [pseudomonas exotoxin A (mmPE)] in the form of an mRNA reduced tumor burden and significantly increased the survival of mice with lung metastasis.

Peptide-Functionalized Lipid Nanoparticles for Targeted Systemic mRNA Delivery to the Brain

Systemic delivery of large nucleic acids, such as mRNA, to the brain remains challenging in part due to the blood-brain barrier (BBB) and the tendency of delivery vehicles to accumulate in the liver. Here, we design a peptide-functionalized lipid nanoparticle (LNP) platform for targeted mRNA delivery to the brain. We utilize click chemistry to functionalize LNPs with peptides that target receptors overexpressed on brain endothelial cells and neurons, namely the RVG29, T7, AP2, and mApoE peptides. We evaluate the effect of LNP targeting on brain endothelial and neuronal cell transfection in vitro, investigating factors such as serum protein adsorption, intracellular trafficking, endothelial transcytosis, and exosome secretion. Finally, we show that LNP peptide functionalization enhances mRNA transfection in the mouse brain and reduces hepatic delivery after systemic administration. Specifically, RVG29 LNPs improved neuronal transfection in vivo, establishing its potential as a nonviral platform for delivering mRNA to the brain.

Lipid Nanoparticles With Fine-Tuned Composition Show Enhanced Colon Targeting as a Platform for mRNA Therapeutics

Lipid Nanoparticles (LNPs) recently emerged as an invaluable RNA delivery platform. With many LNP-based therapeutics in the pre-clinical and clinical pipelines, there is extensive research dedicated to improving LNPs. These efforts focus mainly on the tolerability and transfectability of new ionizable lipids and RNAs, or modulating LNPs biodistribution with active targeting strategies. However, most formulations follow the well-established lipid proportions used in clinically approved products. Nevertheless, investigating the effects of LNPs composition on their biodistribution can expand the toolbox for particle design, leading to improved delivery strategies. Herein, a new LNPs (30-n-LNPs) formulation with increasing amounts of phospholipids is investigated as a possible mRNA delivery system for treating Inflammatory Bowel Diseases. Compared to LNPs with benchmark composition (b-LNPs), n-LNPs containing 30% distearoylphosphatidylcholine (DSPC) are well tolerated following intravenous administration and display natural targeting toward the inflamed colon in dextran sodium sulfate (DSS)-colitis bearing mice, while de-targeting clearing organs such as the liver and spleen. Using interleukin-10-encoding mRNA as therapeutic cargo, n-LNPs demonstrated a reduction of pathological burden in colitis-bearing mice. n-LNPs represent a starting point to further investigate the influence of LNPs composition on systemic biodistribution, ultimately opening new therapeutic modalities in different pathologies.

Bispecific antibody targeting of lipid nanoparticles

Lipid nanoparticles (LNP) are the most clinically advanced non-viral gene delivery system. While progress has been made for enhancing delivery, cell specific targeting remains a challenge. Targeting moieties such as antibodies can be chemically-conjugated to LNPs however, this approach is complex and has challenges for scaling up. Here, we developed an approach to generate antibody-conjugated LNPs that utilizes a bispecific antibody (bsAb) as the targeting bridge. As a docking site for the bsAb, we generated LNPs with a short epitope, derived from hemagglutinin antigen (HA), embedded in the PEG component of the particle (LNPHA). We generated bsAb in which one domain binds HA and the other binds different cell surface proteins, including PD-L1, CD4, CD5, and SunTag. Non-chemical conjugation of the bsAb and LNP resulted in a major increase in the efficiency and specificity of transfecting cells expressing the cognate target. LNP/bsAb mediated a 4-fold increase in in vivo transfection of PD-L1 expressing cancer cells, and a 26-fold increase in ex vivo transfection of quiescent primary human T cells. Additionally, we created a universal bsAb recognizing HA and anti-rat IgG2, enabling LNP tethering to off-the-shelf antibodies such as CD4, CD8, CD20, CD45, and CD3. By utilizing a molecular dock and bsAb technology, these studies demonstrate a simple and effective strategy to generate antibody-conjugated LNPs, enabling precise and efficient mRNA delivery.

Delivery Aspects for Implementing siRNA Therapeutics for Blood Diseases

Hematological disorders result in significant health consequences, and traditional therapies frequently entail adverse reactions without addressing the root cause. A potential solution for hematological disorders characterized by gain-of-function mutations lies in the emergence of small interfering RNA (siRNA) molecules as a therapeutic option. siRNAs are a class of RNA molecules composed of double-stranded RNAs that can degrade specific mRNAs, thereby inhibiting the synthesis of underlying disease proteins. Therapeutic interventions utilizing siRNA can be tailored to selectively target genes implicated in diverse hematological disorders, including sickle cell anemia, β-thalassemia, and malignancies such as lymphoma, myeloma, and leukemia. The development of efficient siRNA silencers necessitates meticulous contemplation of variables such as the RNA backbone, stability, and specificity. Transportation of siRNA to specific cells poses a significant hurdle, prompting investigations of diverse delivery approaches, including chemically modified forms of siRNA and nanoparticle formulations with various biocompatible carriers. This review delves into the crucial role of siRNA technology in targeting and treating hematological malignancies and disorders. It sheds light on the latest research, development, and clinical trials, detailing how various pharmaceutical approaches leverage siRNA against blood disorders, mainly concentrating on cancers. It outlines the preferred molecular targets and physiological barriers to delivery while emphasizing the growing potential of various therapeutic delivery methods. The need for further research is articulated in the context of overcoming the shortcomings of siRNA in order to enrich discussions around siRNA's role in managing blood disorders and aiding the scientific community in advancing more targeted and effective treatments.

Recent advances in targeted drug delivery systems for multiple myeloma

Despite significant therapeutic advances, multiple myeloma (MM) remains a challenging, incurable, hematological malignancy. The efficacy of traditional chemotherapy and currently available anti-MM agents is in part limited by their adverse effects, which restrict their therapeutic potential. Nanotherapeutics is an emerging field of cancer therapy that can overcome the biological and chemical barriers of existing anticancer drugs. This review presents an overview of recent advancements in nanoparticle- and immunotherapy-based drug delivery systems for MM treatment. It further delves into the targeting strategies, mechanism of controlled drug release, and challenges associated with the development of drug delivery systems for the treatment of MM.

RNA-loaded nanoparticles for the treatment of hematological cancers

Hematological cancers encompass a diverse group of malignancies affecting the blood, bone marrow, lymph nodes, and spleen. These disorders present unique challenges due to their complex etiology and varied clinical manifestations. Despite significant advancements in understanding and treating hematological malignancies, innovative therapeutic approaches are continually sought to enhance patient outcomes. This review highlights the application of RNA nanoparticles (RNA-NPs) in the treatment of hematological cancers. We delve into detailed discussions on in vitro and preclinical studies involving RNA-NPs for adult patients, as well as the application of RNA-NPs in pediatric hematological cancer. The review also addresses ongoing clinical trials involving RNA-NPs and explores the emerging field of CAR-T therapy engineered by RNA-NPs. Finally, we discuss the challenges still faced in translating RNA-NP research to clinics.

Lipid nanoparticles-based RNA therapies for breast cancer treatment

Breast cancer (BC) prevails as a major burden on global healthcare, being the most prevalent form of cancer among women. BC is a complex and heterogeneous disease, and current therapies, such as chemotherapy and radiotherapy, frequently fall short in providing effective solutions. These treatments fail to mitigate the risk of cancer recurrence and cause severe side effects that, in turn, compromise therapeutic responses in patients. Over the last decade, several strategies have been proposed to overcome these limitations. Among them, RNA-based technologies have demonstrated their potential across various clinical applications, notably in cancer therapy. However, RNA therapies are still limited by a series of critical issues like off-target effect and poor stability in circulation. Thus, novel approaches have been investigated to improve the targeting and bioavailability of RNA-based formulations to achieve an appropriate therapeutic outcome. Lipid nanoparticles (LNPs) have been largely proven to be an advantageous carrier for nucleic acids and RNA. This perspective explores the most recent advances on RNA-based technology with an emphasis on LNPs' utilization as effective nanocarriers in BC therapy and most recent progresses in their clinical applications.

Delivery of nucleic acid based genome editing platforms via lipid nanoparticles: Clinical applications

CRISPR/Cas technology presents a promising approach for treating a wide range of diseases, including cancer and genetic disorders. Despite its potential, the translation of CRISPR/Cas into effective in-vivo gene therapy encounters challenges, primarily due to the need for safe and efficient delivery mechanisms. Lipid nanoparticles (LNPs), FDA-approved for RNA delivery, show potential for delivering also CRISPR/Cas, offering the capability to efficiently encapsulate large mRNA molecules with single guide RNAs. However, achieving precise targeting in-vivo remains a significant obstacle, necessitating further research into optimizing LNP formulations. Strategies to enhance specificity, such as modifying LNP structures and incorporating targeting ligands, are explored to improve organ and cell type targeting. Furthermore, the development of base and prime editing technology presents a potential breakthrough, offering precise modifications without generating double-strand breaks (DSBs). Prime editing, particularly when delivered via targeted LNPs, holds promise for treating diverse diseases safely and precisely. This review assesses both the progress made and the persistent challenges faced in using LNP-encapsulated CRISPR-based technologies for therapeutic purposes, with a particular focus on clinical translation.

Cytoskeleton-modulating nanomaterials and their therapeutic potentials

The cytoskeleton, an intricate network of protein fibers within cells, plays a pivotal role in maintaining cell shape, enabling movement, and facilitating intracellular transport. Its involvement in various pathological states, ranging from cancer proliferation and metastasis to the progression of neurodegenerative disorders, underscores its potential as a target for therapeutic intervention. The exploration of nanotechnology in this realm, particularly the use of nanomaterials for cytoskeletal modulation, represents a cutting-edge approach with the promise of novel treatments. Inorganic nanomaterials, including those derived from gold, metal oxides, carbon, and black phosphorus, alongside organic variants such as peptides and proteins, are at the forefront of this research. These materials offer diverse mechanisms of action, either by directly interacting with cytoskeletal components or by influencing cellular signaling pathways that, in turn, modulate the cytoskeleton. Recent advancements have introduced magnetic field-responsive and light-responsive nanomaterials, which allow for targeted and controlled manipulation of the cytoskeleton. Such precision is crucial in minimizing off-target effects and enhancing therapeutic efficacy. This review explores the importance of research into cytoskeleton-targeting nanomaterials for developing therapeutic interventions for a range of diseases. It also addresses the progress made in this field, the challenges encountered, and future directions for using nanomaterials to modulate the cytoskeleton. The continued exploration of nanomaterials for cytoskeleton modulation holds great promise for advancing therapeutic strategies against a broad spectrum of diseases, marking a significant step forward in the intersection of nanotechnology and medicine.

Substituting Poly(ethylene glycol) Lipids with Poly(2-ethyl-2-oxazoline) Lipids Improves Lipid Nanoparticle Repeat Dosing

Poly(ethylene glycol) (PEG)-lipids are used in Food-and-Drug-Administration-approved lipid nanoparticle (LNP)-RNA drugs, which are safe and effective. However, it is reported that PEG-lipids may also contribute to accelerated blood clearance and rare cases of hypersensitivity; this highlights the utility of exploring PEG-lipid alternatives. Here, it is shown that LNPs containing poly(2-ethyl-2-oxazoline) (PEOZ)-lipids can deliver messenger RNA (mRNA) to multiple cell types in mice inside and outside the liver. In addition, it is reported that LNPs formulated with PEOZ-lipids show reduced clearance from the bloodstream and lower levels of antistealth lipid immunoglobulin Ms than LNPs formulated with PEG-lipids. These data justify further exploration of PEOZ-lipids as alternatives to PEG-lipids in LNP-RNA formulations.

Dynamic carriers for therapeutic RNA delivery

Carriers for RNA delivery must be dynamic, first stabilizing and protecting therapeutic RNA during delivery to the target tissue and across cellular membrane barriers and then releasing the cargo in bioactive form. The chemical space of carriers ranges from small cationic lipids applied in lipoplexes and lipid nanoparticles, over medium-sized sequence-defined xenopeptides, to macromolecular polycations applied in polyplexes and polymer micelles. This perspective highlights the discovery of distinct virus-inspired dynamic processes that capitalize on mutual nanoparticle-host interactions to achieve potent RNA delivery. From the host side, subtle alterations of pH, ion concentration, redox potential, presence of specific proteins, receptors, or enzymes are cues, which must be recognized by the RNA nanocarrier via dynamic chemical designs including cleavable bonds, alterable physicochemical properties, and supramolecular assembly-disassembly processes to respond to changing biological microenvironment during delivery.

Cationic cholesterol-dependent LNP delivery to lung stem cells, the liver, and heart

Adding a cationic helper lipid to a lipid nanoparticle (LNP) can increase lung delivery and decrease liver delivery. However, it remains unclear whether charge-dependent tropism is universal or, alternatively, whether it depends on the component that is charged. Here, we report evidence that cationic cholesterol-dependent tropism can differ from cationic helper lipid-dependent tropism. By testing how 196 LNPs delivered mRNA to 22 cell types, we found that charged cholesterols led to a different lung:liver delivery ratio than charged helper lipids. We also found that combining cationic cholesterol with a cationic helper lipid led to mRNA delivery in the heart as well as several lung cell types, including stem cell-like populations. These data highlight the utility of exploring charge-dependent LNP tropism.

Controlled siRNA Release of Nanopolyplex for Effective Targeted Anticancer Therapy in Animal Model

Introduction

Spatiotemporally controlled release of siRNA for anti-tumor therapy poses significant challenges. Near-infrared (NIR) light, known for its exceptional tissue penetration and minimal tissue invasiveness, holds promise as a viable exogenous stimulus for inducing controlled siRNA release in vivo. However, the majority of light-responsive chemical bonds exhibit absorption wavelengths in the ultraviolet (UV) or short-wavelength visible light range.

Methods

To achieve NIR-controlled siRNA release, the study synthesized a UV-sensitive triblock copolymer cRGD-poly(ethylene glycol)-b-poly(aspartic acid ester-5-(2'-(dimethylamino)ethoxy)-2-nitrobenzyl alcohol)-b-polyphenylalanine, abbreviated as cRGD-PEG-PAsp(EDONB)-PPHE. This copolymer is composed of a cRGD-capped PEG block (cRGD-PEG), a poly(aspartate) block modified with cationic moieties through UV-cleavable 2-nitrobenzyl ester bonds [PAsp(EDONB)], and a hydrophobic polyphenylalanine block (PPHE). The cationic amphiphilic polymer cRGD-PEG-PAsp(EDONB)-PPHE can assemble with hydrophobic upconversion nanoparticles (UCNPs) to form a cationic micelle designated as T-UCNP, which subsequently complexes with siRNA to create the final nanopolyplex T-si/UCNP. siRNA-PLK1 was employed to prepare T-PLK1/UCNP nanopolyplex for anti-tumor therapy.

Results

T-PLK1/UCNP not only exhibited outstanding tumor cell targeting through cRGD modification but also achieved 980 nm NIR-controlled PLK1 gene silencing. This was achieved by utilizing the encapsulated UCNPs to convert NIR into UV light, facilitating the cleavage of 2-nitrobenzyl ester bonds. As a result, there was a significant suppression of tumor growth.

Conclusion

The UCNPs-encapsulated nanopolyplex T-si/UCNP, capable of co-delivering siRNA and UCNPs, enables precise NIR-controlled release of siRNA at the tumor site for cancer RNAi therapy. This nanopolyplex can enhance the controllability and safety of RNAi therapy for tumors, and it also holds the potential to serve as a platform for achieving controlled release and activation of other drugs, such as mRNA and DNA.

Lymphatic vessel: origin, heterogeneity, biological functions, and therapeutic targets

Lymphatic vessels, comprising the secondary circulatory system in human body, play a multifaceted role in maintaining homeostasis among various tissues and organs. They are tasked with a serious of responsibilities, including the regulation of lymph absorption and transport, the orchestration of immune surveillance and responses. Lymphatic vessel development undergoes a series of sophisticated regulatory signaling pathways governing heterogeneous-origin cell populations stepwise to assemble into the highly specialized lymphatic vessel networks. Lymphangiogenesis, as defined by new lymphatic vessels sprouting from preexisting lymphatic vessels/embryonic veins, is the main developmental mechanism underlying the formation and expansion of lymphatic vessel networks in an embryo. However, abnormal lymphangiogenesis could be observed in many pathological conditions and has a close relationship with the development and progression of various diseases. Mechanistic studies have revealed a set of lymphangiogenic factors and cascades that may serve as the potential targets for regulating abnormal lymphangiogenesis, to further modulate the progression of diseases. Actually, an increasing number of clinical trials have demonstrated the promising interventions and showed the feasibility of currently available treatments for future clinical translation. Targeting lymphangiogenic promoters or inhibitors not only directly regulates abnormal lymphangiogenesis, but improves the efficacy of diverse treatments. In conclusion, we present a comprehensive overview of lymphatic vessel development and physiological functions, and describe the critical involvement of abnormal lymphangiogenesis in multiple diseases. Moreover, we summarize the targeting therapeutic values of abnormal lymphangiogenesis, providing novel perspectives for treatment strategy of multiple human diseases.

Surface modification of lipid nanoparticles for gene therapy

Gene therapies have the potential to target and effectively treat a variety of diseases including cancer as well as genetic, neurological, and autoimmune disorders. Although we have made significant advances in identifying non-viral strategies to deliver genetic cargo, certain limitations remain. In general, gene delivery is challenging for several reasons including the instabilities of nucleic acids to enzymatic and chemical degradation and the presence of restrictive biological barriers such as cell, endosomal and nuclear membranes. The emergence of lipid nanoparticles (LNPs) helped overcome many of these challenges. Despite its success, further optimization is required for LNPs to yield efficient gene delivery to extrahepatic tissues, as LNPs favor accumulation in the liver after systemic administration. In this mini-review, we provide an overview of current preclinical approaches in that LNP surface modification was leveraged for cell and tissue targeting by conjugating aptamers, antibodies, and peptides among others. In addition to their cell uptake and efficiency-enhancing effects, we outline the (dis-)advantages of the different targeting moieties and commonly used conjugation strategies.

Nanomedicine - Immune System Interactions: Limitations and Opportunities for the Treatment of Cancer

Nanoparticles interact with immune cells in many different ways. These interactions are crucially important for determining nanoparticles' ability to be used for cancer therapy. Traditionally, strategies such as PEGylation have been employed to reduce (the kinetics of) nanoparticle uptake by immune cells, to endow them with long circulation properties, and to enable them to exploit the Enhanced Permeability and Retention (EPR) effect to accumulate in tumors. More recently, with immunotherapy becoming an increasingly important cornerstone in the clinical management of cancer, ever more research efforts in academia and industry are focusing on specifically targeting immune cells with nanoparticles. In this chapter, we describe the barriers and opportunities of immune cell targeting with nanoparticles, and we discuss how nanoparticle-based drug delivery to specific immune cell populations in tumors as well as in secondary myeloid and lymphoid organs (such as bone marrow, lymph nodes, and spleen) can be leveraged to boost the efficacy of cancer immunotherapy.

Brain-Targeted Liposomes Loaded with Monoclonal Antibodies Reduce Alpha-Synuclein Aggregation and Improve Behavioral Symptoms in Parkinson's Disease

Monoclonal antibodies (mAbs) hold promise in treating Parkinson's disease (PD), although poor delivery to the brain hinders their therapeutic application. In the current study, it is demonstrated that brain-targeted liposomes (BTL) enhance the delivery of mAbs across the blood-brain-barrier (BBB) and into neurons, thereby allowing the intracellular and extracellular treatment of the PD brain. BTL are decorated with transferrin to improve brain targeting through overexpressed transferrin-receptors on the BBB during PD. BTL are loaded with SynO4, a mAb that inhibits alpha-synuclein (AS) aggregation, a pathological hallmark of PD. It is shown that 100-nm BTL cross human BBB models intact and are taken up by primary neurons. Within neurons, SynO4 is released from the nanoparticles and bound to its target, thereby reducing AS aggregation, and enhancing neuronal viability. In vivo, intravenous BTL administration results in a sevenfold increase in mAbs in brain cells, decreasing AS aggregation and neuroinflammation. Treatment with BTL also improve behavioral motor function and learning ability in mice, with a favorable safety profile. Accordingly, targeted nanotechnologies offer a valuable platform for drug delivery to treat brain neurodegeneration.

Surface engineering of lipid nanoparticles: targeted nucleic acid delivery and beyond

Harnessing surface engineering strategies to functionalize nucleic acid-lipid nanoparticles (LNPs) for improved performance has been a hot research topic since the approval of the first siRNA drug, patisiran, and two mRNA-based COVID-19 vaccines, BNT162b2 and mRNA-1273. Currently, efforts have been mainly made to construct targeted LNPs for organ- or cell-type-specific delivery of nucleic acid drugs by conjugation with various types of ligands. In this review, we describe the surface engineering strategies for nucleic acid-LNPs, considering ligand types, conjugation chemistries, and incorporation methods. We then outline the general purification and characterization techniques that are frequently used following the engineering step and emphasize the specific techniques for certain types of ligands. Next, we comprehensively summarize the currently accessible organs and cell types, as well as the other applications of the engineered LNPs. Finally, we provide considerations for formulating targeted LNPs and discuss the challenges of successfully translating the "proof of concept" from the laboratory into the clinic. We believe that addressing these challenges could accelerate the development of surface-engineered LNPs for targeted nucleic acid delivery and beyond.