Dendritic Cell-Targeted pH-Responsive Extracellular Vesicles for Anticancer Vaccination

Incorporation of recombinant proteins into extracellular vesicles by Lactococcus cremoris

Extracellular vesicles (EVs) are nanosized lipid bilayer particles released by various cellular organisms that carry an array of bioactive molecules. EVs have diagnostic potential, as they play a role in intercellular interspecies communication, and could be applied in drug delivery. In contrast to mammalian cell-derived EVs, the study of EVs from bacteria, particularly Gram-positive bacteria, received less research attention. This study aimed to investigate the production of EVs by lactic acid bacterium Lactococcus cremoris NZ9000 and to examine the impact of recombinant protein expression on their formation and protein content. Four different recombinant proteins were expressed in L. cremoris NZ9000, in different forms of expression and combinations, and the produced EVs were isolated using the standard ultracentrifugation method. The presence of vesicular structures (50-200 nm) in the samples was confirmed by transmission electron microscopy and by flow cytometry using membrane-specific stain. Mass spectrometry analyses confirmed the presence of recombinant proteins in the EVs fraction, with amounts ranging from 13.17 to 100%, highlighting their significant incorporation into the vesicles, together with intrinsic L. cremoris NZ9000 proteins that were either more abundant in the cytoplasm (ribosomal proteins, metabolic enzymes) or present in the membrane. The presence of the most abundant lactococcal proteins in EVs fraction suggests that protein cargo-loading of EVs in L. cremoris NZ9000 is not regulated. However, our data suggests that L. cremoris NZ9000 genetically engineered to express recombinant proteins can produce EVs containing these proteins in scalable manner. As L. cremoris NZ9000 is considered safe bacterium, EVs from L. cremoris NZ9000 could have several advantages over EVs from other bacteria, implying possible biotechnological applications, e.g. in therapeutic protein delivery.

Mesenchymal stem cell‐derived extracellular vesicles: Recent therapeutics and targeted drug delivery advances

The targeted drug delivery field is rapidly advancing, focusing on developing biocompatible nanoparticles that meet rigorous criteria of non‐toxicity, biocompatibility, and efficient release of encapsulated molecules. Conventional synthetic nanoparticles (SNPs) face complications such as elevated immune responses, complex synthesis methods, and toxicity, which restrict their utility in therapeutics and drug delivery. Extracellular vesicles (EVs) have emerged as promising substitutes for SNPs, leveraging their ability to cross biological barriers, biocompatibility, reduced toxicity, and natural origin. Notably, mesenchymal stem cell‐derived EVs (MSC‐EVs) have garnered much curiosity due to their potential in therapeutics and drug delivery. Studies suggest that MSC‐EVs, the central paracrine contributors of MSCs, replicate the therapeutic effects of MSCs. This review explores the characteristics of MSC‐EVs, emphasizing their potential in therapeutics and drug delivery for various diseases, including CRISPR/Cas9 delivery for gene editing. It also delves into the obstacles and challenges of MSC‐EVs in clinical applications and provides insights into strategies to overcome the limitations of biodistribution and target delivery.

Development of 5-Fluorouracil/pH-Responsive Adjuvant-Embedded Extracellular Vesicles for Targeting αvβ3 Integrin Receptors in Tumors

To selectively target and treat murine melanoma B16BL6 tumors expressing αvβ3 integrin receptors, we engineered tumor-specific functional extracellular vesicles (EVs) tailored for the targeted delivery of antitumor drugs. This objective was achieved through the incorporation of a pH-responsive adjuvant, cyclic arginine-glycine-aspartic acid peptide (cRGD, serving as a tumor-targeting ligand), and 5-fluorouracil (5-FU, employed as a model antitumor drug). The pH-responsive adjuvant, essential for modulating drug release, was synthesized by chemically conjugating 3-(diethylamino)propylamine (DEAP) to deoxycholic acid (DOCA, a lipophilic substance capable of integrating into EVs' membranes), denoted as DEAP-DOCA. The DOCA, preactivated using N-(2-aminoethyl)maleimide (AEM), was chemically coupled with the thiol group of the cRGD-DOCA through the thiol-maleimide click reaction, resulting in the formation of cRGD-DOCA. Subsequently, DEAP-DOCA, cRGD-DOCA, and 5-FU were efficiently incorporated into EVs using a sonication method. The resulting tumor-targeting EVs, expressing cRGD ligands, demonstrated enhanced in vitro/in vivo cellular uptake specifically for B16BL6 tumors expressing αvβ3 integrin receptors. The ionization characteristics of the DEAP in DEAP-DOCA induced destabilization of the EVs membrane at pH 6.5 through protonation of the DEAP substance, thereby expediting 5-FU release. Consequently, an improvement in the in vivo antitumor efficacy was observed for B16BL6 tumors. Based on these comprehensive in vitro/in vivo findings, we anticipate that this EV system holds substantial promise as an exceptionally effective platform for antitumor therapeutic delivery.

Recent Findings on Therapeutic Cancer Vaccines: An Updated Review

Cancer remains one of the global leading causes of death and various vaccines have been developed over the years against it, including cell-based, nucleic acid-based, and viral-based cancer vaccines. Although many vaccines have been effective in in vivo and clinical studies and some have been FDA-approved, there are major limitations to overcome: (1) developing one universal vaccine for a specific cancer is difficult, as tumors with different antigens are different for different individuals, (2) the tumor antigens may be similar to the body's own antigens, and (3) there is the possibility of cancer recurrence. Therefore, developing personalized cancer vaccines with the ability to distinguish between the tumor and the body's antigens is indispensable. This paper provides a comprehensive review of different types of cancer vaccines and highlights important factors necessary for developing efficient cancer vaccines. Moreover, the application of other technologies in cancer therapy is discussed. Finally, several insights and conclusions are presented, such as the possibility of using cold plasma and cancer stem cells in developing future cancer vaccines, to tackle the major limitations in the cancer vaccine developmental process.

Defining tropism and activity of natural and engineered extracellular vesicles

Extracellular vesicles (EVs) have important roles as mediators of cell-to-cell communication, with physiological functions demonstrated in various in vivo models. Despite advances in our understanding of the biological function of EVs and their potential for use as therapeutics, there are limitations to the clinical approaches for which EVs would be effective. A primary determinant of the biodistribution of EVs is the profile of proteins and other factors on the surface of EVs that define the tropism of EVs in vivo. For example, proteins displayed on the surface of EVs can vary in composition by cell source of the EVs and the microenvironment into which EVs are delivered. In addition, interactions between EVs and recipient cells that determine uptake and endosomal escape in recipient cells affect overall systemic biodistribution. In this review, we discuss the contribution of the EV donor cell and the role of the microenvironment in determining EV tropism and thereby determining the uptake and biological activity of EVs.

Extracellular vesicles as next generation immunotherapeutics

Extracellular vesicles (EVs) function as a mode of intercellular communication and molecular transfer to elicit diverse biological/functional response. Accumulating evidence has highlighted that EVs from immune, tumour, stromal cells and even bacteria and parasites mediate the communication of various immune cell types to dynamically regulate host immune response. EVs have an innate capacity to evade recognition, transport and transfer functional components to target cells, with subsequent removal by the immune system, where the immunological activities of EVs impact immunoregulation including modulation of antigen presentation and cross-dressing, immune activation, immune suppression, and immune surveillance, impacting the tumour immune microenvironment. In this review, we outline the recent progress of EVs in immunorecognition and therapeutic intervention in cancer, including vaccine and targeted drug delivery and summarise their utility towards clinical translation. We highlight the strategies where EVs (natural and engineered) are being employed as a therapeutic approach for immunogenicity, tumoricidal function, and vaccine development, termed immuno-EVs. With seminal studies providing significant progress in the sequential development of engineered EVs as therapeutic anti-tumour platforms, we now require direct assessment to tune and improve the efficacy of resulting immune responses - essential in their translation into the clinic. We believe such a review could strengthen our understanding of the progress in EV immunobiology and facilitate advances in engineering EVs for the development of novel EV-based immunotherapeutics as a platform for cancer treatment.

Harnessing Engineered Immune Cells and Bacteria as Drug Carriers for Cancer Immunotherapy

Immunotherapy continues to be in the spotlight of oncology therapy research in the past few years and has been proven to be a promising option to modulate one's innate and adaptive immune systems for cancer treatment. However, the poor delivery efficiency of immune agents, potential off-target toxicity, and nonimmunogenic tumors significantly limit its effectiveness and extensive application. Recently, emerging biomaterial-based drug carriers, including but not limited to immune cells and bacteria, are expected to be potential candidates to break the dilemma of immunotherapy, with their excellent natures of intrinsic tumor tropism and immunomodulatory activity. More than that, the tiny vesicles and physiological components derived from them have similar functions with their source cells due to the inheritance of various surface signal molecules and proteins. Herein, we presented representative examples about the latest advances of biomaterial-based delivery systems employed in cancer immunotherapy, including immune cells, bacteria, and their derivatives. Simultaneously, opportunities and challenges of immune cells and bacteria-based carriers are discussed to provide reference for their future application in cancer immunotherapy.

Extracellular vesicles in pancreatic cancer immune escape: Emerging roles and mechanisms

Pancreatic cancer (PC) is the most lethal malignancy worldwide due to its delayed diagnosis and limited treatment options. Despite great progress in clinical trials of immunotherapies for various cancers, their effectiveness in PC is very low, indicating that immune evasion is still a major obstacle to immunotherapy in PC. However, the mechanism of immune escape in PC is not fully understood, which substantially restricts the development of immunotherapy. As an important component of intercellular communication networks, extracellular vesicles (EVs) have attracted increasing attention in relation to immune escape. This review aims to provide a better understanding of the roles of EVs in tumor immune escape and the potential to expand their application in cancer immunotherapy. The relationship between PC and the tumor immune microenvironment is briefly introduced. Then, the mechanism by which EVs are involved in immune regulation is summarized, and the latest progress in determining the role of EVs in regulating PC immune escape is highlighted.

Direct Modification of Extracellular Vesicles and Its Applications for Cancer Therapy: A Mini-Review

Extracellular vesicles (EVs) are a class of lipid membrane-bound vesicles released by various cells and mediate cell-to-cell communication. By reason of their high physiochemical stability and biocompatibility, EVs are considered as novel drug delivery system. An increasing number of studies have indicated that EVs can be modified to enhance their loading efficiency, targeting ability and therapeutic capabilities for cancer therapy. Compared with the tedious process of gene engineering approaches, direct modification of EVs is easier, faster and versatile. This mini review will summarize the prevailing approaches for direct modification of EVs. Additionally, the potential applications of modified EVs in cancer therapy are also discussed, which will help readers gain a better understanding of the technologies and applications in this field.

The Current Landscape of mRNA Vaccines Against Viruses and Cancer-A Mini Review

Both infectious viral diseases and cancer have historically been some of the most common causes of death worldwide. The COVID-19 pandemic is a decidedly relevant example of the former. Despite progress having been made over past decades, new and improved techniques are still needed to address the limitations faced by current treatment standards, with mRNA-based therapy emerging as a promising solution. Highly flexible, scalable and cost-effective, mRNA therapy is proving to be a compelling vaccine platform against viruses. Likewise, mRNA vaccines show similar promise against cancer as a platform capable of encoding multiple antigens for a diverse array of cancers, including those that are patient specific as a novel form of personalized medicine. In this review, the molecular mechanisms, biotechnological aspects, and clinical developments of mRNA vaccines against viral infections and cancer are discussed to provide an informative update on the current state of mRNA therapy research.

New Advances in Exosome-based Targeted Drug Delivery Systems

In recent years, various drug nano-delivery platforms have emerged to enhance drug effectiveness in cancer treatment. However, their successful translation to clinics have been hampered by unwanted side effects, as well as associated toxicity. Therefore, there is an imperative need for drug delivery vehicles capable of surpassing cellular barriers and also efficiently transfer therapeutic payloads to tumor cells. Exosomes, a class of small extracellular vesicles naturally released from all cells, have been exploited as a favorable delivery vehicle due to their natural role in intracellular communication and biocompatibility. In this review, information on exosome biogenesis, contents, forms of isolation and their natural functions is discussed, further complemented with the various successful methodologies for therapeutic payloads encapsulation, including distinct loading approaches. In addition, grafting of molecules to improve pharmacokinetics, tumor homing-ligands, as well as stimuli-responsive elements to enhance cell specificity are also debated. In the end, the current status of clinical-grade exosome-based therapies is outlined.

Extracellular vesicles in malaria: an agglomeration of two decades of research

Malaria is a complex parasitic disease, caused by Plasmodium spp. More than a century after the discovery of malaria parasites, this disease continues to pose a global public health problem and the pathogenesis of the severe forms of malaria remains incompletely understood. Extracellular vesicles (EVs), including exosomes and microvesicles, have been increasingly researched in the field of malaria in a bid to fill these knowledge gaps. EVs released from Plasmodium-infected red blood cells and other host cells during malaria infection are now believed to play key roles in disease pathogenesis and are suggested as vital components of the biology of Plasmodium spp. Malaria-derived EVs have been identified as potential disease biomarkers and therapeutic tools. In this review, key findings of malaria EV studies over the last 20 years are summarized and critically analysed. Outstanding areas of research into EV biology are identified. Unexplored EV research foci for the future that will contribute to consolidating the potential for EVs as agents in malaria prevention and control are proposed.

Recent Advances in Exosome-Based Drug Delivery for Cancer Therapy

Simple Summary

Exosomes derived from various sources can deliver therapeutic agents such as small molecule drugs, nucleic acids, and proteins to cancer cells by passive or active targeting. These exosomes can encapsulate drugs inside the exosomes, extending drug half-life and increasing drug release stability. In addition, exosomes are highly biocompatible due to their endogenous origin and can be used as nanocarriers for tissue-specific targeted delivery. This review discusses recent advances in exosome-based drug delivery for cancer therapy.

Abstract

Exosomes are a class of extracellular vesicles, with a size of about 100 nm, secreted by most cells and carrying various bioactive molecules such as nucleic acids, proteins, and lipids, and reflect the biological status of parent cells. Exosomes have natural advantages such as high biocompatibility and low immunogenicity for efficient delivery of therapeutic agents such as chemotherapeutic drugs, nucleic acids, and proteins. In this review, we introduce the latest explorations of exosome-based drug delivery systems for cancer therapy, with particular focus on the targeted delivery of various types of cargoes.

From Exosome Glycobiology to Exosome Glycotechnology, the Role of Natural Occurring Polysaccharides

Exosomes (EXOs) are nano-sized informative shuttles acting as endogenous mediators of cell-to-cell communication. Their innate ability to target specific cells and deliver functional cargo is recently claimed as a promising theranostic strategy. The glycan profile, actively involved in the EXO biogenesis, release, sorting and function, is highly cell type-specific and frequently altered in pathological conditions. Therefore, the modulation of EXO glyco-composition has recently been considered an attractive tool in the design of novel therapeutics. In addition to the available approaches involving conventional glyco-engineering, soft technology is becoming more and more attractive for better exploiting EXO glycan tasks and optimizing EXO delivery platforms. This review, first, explores the main functions of EXO glycans and associates the potential implications of the reported new findings across the nanomedicine applications. The state-of-the-art of the last decade concerning the role of natural polysaccharides—as targeting molecules and in 3D soft structure manufacture matrices—is then analysed and highlighted, as an advancing EXO biofunction toolkit. The promising results, integrating the biopolymers area to the EXO-based bio-nanofabrication and bio-nanotechnology field, lay the foundation for further investigation and offer a new perspective in drug delivery and personalized medicine progress.

Clinical applications for exosomes: Are we there yet?

Exosomes are a subset of extracellular vesicles essential for cell-cell communication in health and disease with the ability to transport nucleic acids, functional proteins and other metabolites. Their clinical use as diagnostic biomarkers and therapeutic carriers has become a major field of research over recent years, generating rapidly expanding scientific interest and financial investment. Their reduced immunogenicity compared to liposomes or viral vectors and their ability to cross major physiological barriers like the blood-brain barrier make them an appealing and innovative option as biomarkers and therapeutic agents. Here, we review the latest clinical developments of exosome biotechnology for diagnostic and therapeutic purposes, including the most recent COVID-19-related exosome-based clinical trials. We present current exosome engineering strategies for optimal clinical safety and efficacy, and assess the technology developed for good manufacturing practice compliant scaling up and storage approaches along with their limitations in pharmaceutical industry.

New approaches in extracellular vesicle engineering for improving the efficacy of anti-cancer therapies

Cancer is a disease that evolves continuously with unpredictable outcomes. Although conventional chemotherapy can display significant antitumor effects, the lack of specificity and poor bioavailability remain major concerns in cancer therapy. Moreover, with the advent of novel anti-cancer gene therapies, there is an urgent need for drug delivery vectors capable of bypassing cellular barriers and efficiently transferring therapeutic cargo to recipient cells. A number of drug delivery systems have been proposed to overcome these limitations, but their successful clinical translation has been hampered by the onset of unexpected side effects and associated toxicities. The application of extracellular vesicles (EVs), a class of naturally released, cell-derived particles, as drug delivery vectors presents a breakthrough in nanomedicine, taking into account their biocompatibility and natural role in intercellular communication. Combining the advantageous intrinsic properties of EVs with surface functionalization and the encapsulation of drugs allows for a new class of engineered EVs that serve as effective therapeutic carriers. Here, we describe the various successful approaches involving the application of engineered EVs as bio-derived drug delivery vectors in cancer therapy. The latest and most effective strategies of engineering EVs to improve drug loading, stealth properties and tumour targeting capabilities of EVs are debated. Finally, current obstacles and future perspectives of smart engineered EVs are discussed.

Membrane Microvesicles as Potential Vaccine Candidates

The prevention and control of infectious diseases is crucial to the maintenance and protection of social and public healthcare. The global impact of SARS-CoV-2 has demonstrated how outbreaks of emerging and re-emerging infections can lead to pandemics of significant public health and socio-economic burden. Vaccination is one of the most effective approaches to protect against infectious diseases, and to date, multiple vaccines have been successfully used to protect against and eradicate both viral and bacterial pathogens. The main criterion of vaccine efficacy is the induction of specific humoral and cellular immune responses, and it is well established that immunogenicity depends on the type of vaccine as well as the route of delivery. In addition, antigen delivery to immune organs and the site of injection can potentiate efficacy of the vaccine. In light of this, microvesicles have been suggested as potential vehicles for antigen delivery as they can carry various immunogenic molecules including proteins, nucleic acids and polysaccharides directly to target cells. In this review, we focus on the mechanisms of microvesicle biogenesis and the role of microvesicles in infectious diseases. Further, we discuss the application of microvesicles as a novel and effective vaccine delivery system.

Drug delivery systems based on CD44-targeted glycosaminoglycans for cancer therapy

The polysaccharide-based biomaterials hyaluronic acid (HA) and chondroitin sulfate (CS) have aroused great interest for use in drug delivery systems for tumor therapy, as they have outstanding biocompatibility and great targeting ability for cluster determinant 44 (CD44). In addition, modified HA and CS can self-assemble into micelles or micellar nanoparticles (NPs) for targeted drug delivery. This review discusses the formation of HA- and CS-based NPs, and various types of CS-based NPs including CS-drug conjugates, CS-polymer NPs, CS-small molecule NPs, polyelectrolyte nanocomplexes (PECs), CS-metal NPs, and nanogels. We then focus on the applications of HA- and CS-based NPs in tumor chemotherapy, gene therapy, photothermal therapy (PTT), photodynamic therapy (PDT), sonodynamic therapy (SDT), and immunotherapy. Finally, this review is expected to provide guidelines for the development of various HA- and CS-based NPs used in multiple cancer therapies.

Chemical Strategies to Boost Cancer Vaccines

Personalized cancer vaccines (PCVs) are reinvigorating vaccine strategies in cancer immunotherapy. In contrast to adoptive T-cell therapy and checkpoint blockade, the PCV strategy modulates the innate and adaptive immune systems with broader activation to redeploy antitumor immunity with individualized tumor-specific antigens (neoantigens). Following a sequential scheme of tumor biopsy, mutation analysis, and epitope prediction, the administration of neoantigens with synthetic long peptide (SLP) or mRNA formulations dramatically improves the population and activity of antigen-specific CD4+ and CD8+ T cells. Despite the promising prospect of PCVs, there is still great potential for optimizing prevaccination procedures and vaccine potency. In particular, the arduous development of tumor-associated antigen (TAA)-based vaccines provides valuable experience and rational principles for augmenting vaccine potency which is expected to advance PCV through the design of adjuvants, delivery systems, and immunosuppressive tumor microenvironment (TME) reversion since current personalized vaccination simply admixes antigens with adjuvants. Considering the broader application of TAA-based vaccine design, these two strategies complement each other and can lead to both personalized and universal therapeutic methods. Chemical strategies provide vast opportunities for (1) exploring novel adjuvants, including synthetic molecules and materials with optimizable activity, (2) constructing efficient and precise delivery systems to avoid systemic diffusion, improve biosafety, target secondary lymphoid organs, and enhance antigen presentation, and (3) combining bioengineering methods to innovate improvements in conventional vaccination, "smartly" re-educate the TME, and modulate antitumor immunity. As chemical strategies have proven versatility, reliability, and universality in the design of T cell- and B cell-based antitumor vaccines, the union of such numerous chemical methods in vaccine construction is expected to provide new vigor and vitality in cancer treatment.

Perspectives in Manipulating EVs for Therapeutic Applications: Focus on Cancer Treatment

Extracellular vesicles (EVs) receive special attention from oncologists due to their assumed usefulness as prognostic markers, vaccines to induce anti-cancer immune response, and physiological delivery tools. The latter application, which supports the reduction of side effects of treatment, is still fraught with many challenges, including established methods for loading EVs with selected cargo and directing them towards target cells. EVs could be loaded with selected cargo either in vitro using several physicochemical techniques, or in vivo by modification of parental cell, which may have an advantage over in vitro procedures, since some of them significantly influence EVs’ properties. Otherwise, our research findings suggest that EVs could be passively supplemented with micro RNAs (miRNAs) or miRNA antagonists to induce expected biological effect. Furthermore, our observations imply that antigen-specific antibody light chains could coat the surface of EVs to increase the specificity of cell targeting. Finally, the route of EVs’ administration also determines their bioavailability and eventually induced therapeutic effect. Besides, EV membrane lipids may possibly possess immune adjuvant activity. The review summarizes the current knowledge on the possibilities to manipulate EVs to use them as a delivery tool, with the special emphasis on anti-cancer therapy.

Cyclic RGD-Conjugated Hyaluronate Dot Bearing Cleavable Doxorubicin for Multivalent Tumor Targeting

In this study, we developed an extremely small-sized water-soluble hyaluronate dot (dHA) conjugated with cyclic RGD (cRGD) and cleavable doxorubicin (DOX, as a model antitumor drug), named cRGD@dHA-c-DOX. This dot with HA moieties (as specific ligands to tumor CD44 receptors) and cRGD moieties (as specific ligands to tumor integrin α_vβ₃) was designed to enable multivalent tumor targeting. In particular, the imine bonds, linking the DOX and dHA, can exhibit cleavage performance at endosomal pH, resulting in pH-triggered DOX release from cRGD@dHA-c-DOX. We demonstrated that cRGD@dHA-c-DOX resulted in highly improved cellular uptake and cell death in MDA-MB-231 tumor cells (CD44+, integrin α_vβ₃+) compared to those in Huh7 tumor cells (CD44-, integrin α_vβ₃-). In vivo studies using MDA-MB-231 tumor-bearing mice revealed that cRGD@dHA-c-DOX enhanced the tumor inhibition efficacy. These results suggest that cRGD@dHA-c-DOX can be utilized as a promising multivalent tumor-targeting drug carrier for highly efficient tumor treatment.

Tumor-Homing pH-Sensitive Extracellular Vesicles for Targeting Heterogeneous Tumors

In this study, we fabricated tumor-homing pH-sensitive extracellular vesicles for efficient tumor treatment. These vesicles were prepared using extracellular vesicles (EVs; BTEVs extracted from BT-474 tumor cells or SKEVs extracted from SK-N-MC tumor cells), hyaluronic acid grafted with 3-(diethylamino)propylamine (HDEA), and doxorubicin (DOX, as a model antitumor drug). Consequently, HDEA/DOX anchored EVs (HDEA@EVs) can interact with origin tumor cells owing to EVs’ homing ability to origin cells. Therefore, EV blends of HDEA@BTEVs and HDEA@SKEVs demonstrate highly increased cellular uptake in both BT-474 and SK-N-MC cells: HDEA@BTEVs for BT-474 tumor cells and HDEA@SKEVs for SK-N-MC tumor cells. Furthermore, the hydrophobic HDEA present in HDEA@EVs at pH 7.4 can switch to hydrophilic HDEA at pH 6.5 as a result of acidic pH-induced protonation of 3-(diethylamino)propylamine (DEAP) moieties, resulting in an acidic pH-activated EVs’ disruption, accelerated release of encapsulated DOX molecules, and highly increased cell cytotoxicity. However, EV blends containing pH-insensitive HA grafted with deoxycholic acid (HDOC) (HDOC@BTEVs and HDOC@SKEVs) showed less cell cytotoxicity for both BT-474 and SK-N-MC tumor cells, because they did not act on EVs’ disruption and the resulting DOX release. Consequently, the use of these tumor-homing pH-sensitive EV blends may result in effective targeted therapies for various tumor cells.

Honeycomb-like pH-responsive γ-cyclodextrin electrospun particles for highly efficient tumor therapy

We report here the tumor-implantable microparticles with a honeycomb-like porous structure. These microparticles were prepared by electrospinning using γ-cyclodextrin (γ-CD) conjugated with 3-(diethylamino)propylamine (DEAP, as a pH-responsive moiety), named γ-CD-DEAP. The resulting microparticles had pore channels (constructed using γ-CD-DEAP) extending into the deep compartment of the microparticles and allowing efficient paclitaxel (PTX, as a chemotherapeutic model drug) entrapment by a simple hole-filling encapsulation process. Importantly, the hydrophobic DEAP (at pH 7.4) in the γ-CD-DEAP microparticles changed to hydrophilic DEAP (at pH 6.8) because of its acidic pH-induced protonation. This phenomenon resulted in an acidic pH-activated particle destruction by a charge-charge repulsion between the protonated DEAP moieties and allowed a pH-triggered release of the encapsulated PTX from the collapsed microparticles. Consequently, γ-CD-DEAP microparticles implanted at the tumor site caused a significant enhancement of the in vitro/in vivo tumor cell ablation, suggesting their significant potential as a chemotherapeutic implant for tumor therapy.

Extracellular vesicle-based drug delivery systems for cancer treatment

Extracellular vesicles (EVs) are naturally occurring cell-secreted nanoparticles that play important roles in many physiological and pathological processes. EVs enable intercellular communication by serving as delivery vehicles for a wide range of endogenous cargo molecules, such as RNAs, proteins, carbohydrates, and lipids. EVs have also been found to display tissue tropism mediated by surface molecules, such as integrins and glycans, making them promising for drug delivery applications. Various methods can be used to load therapeutic agents into EVs, and additional modification strategies have been employed to prolong circulation and improve targeting. This review gives an overview of EV-based drug delivery strategies in cancer therapy.

A Valid Bisphosphonate Modified Calcium Phosphate-Based Gene Delivery System: Increased Stability and Enhanced Transfection Efficiency In Vitro and In Vivo

Calcium phosphate (CaP) nanoparticles, as a promising vehicle for gene delivery, have been widely used owing to their biocompatibility, biodegradability and adsorptive capacity for nucleic acids. Unfortunately, their utility in vivo has been profoundly restricted due to numerous technical barriers such as the lack of tissue specificity and limited transfection efficiency, as well as uncontrollable aggregation over time. To address these issues, an effective conjugate folate-polyethylene glycol-pamidronate (shortened as FA-PEG-Pam) was designed and coated on the surface of CaP/NLS/pDNA (CaP/NDs), forming a versatile gene carrier FA-PEG-Pam/CaP/NDs. Inclusion of FA-PEG-Pam significantly reduced the size of CaP nanoparticles, thus inhibiting the aggregation of CaP nanoparticles. FA-PEG-Pam/CaP/NDs showed better cellular uptake than mPEG-Pam/CaP/NDs, which could be attributed to the high-affinity interactions between FA and highly expressed FR. Meanwhile, FA-PEG-Pam/CaP/NDs had low cytotoxicity and desired effect on inducing apoptosis (71.1%). Furthermore, FA-PEG-Pam/CaP/NDs showed admirable transfection efficiency (63.5%) due to the presence of NLS peptides. What’s more, in vivo studies revealed that the hybrid nanoparticles had supreme antitumor activity (IR% = 58.7%) among the whole preparations. Altogether, FA-PEG-Pam/CaP/NDs was expected to be a hopeful strategy for gene delivery.