Exosome Engineering Research Articles

PROteolysis Targeting Chimeras: A new cutting‐edge nanomedicine for colorectal cancer

AbstractColorectal cancer (CRC) is a prevalent malignancy with a high mortality rate, necessitating innovative treatment strategies. PROTACs (PROteolysis Targeting Chimeras) represent a promising therapeutic approach by targeting and degrading oncogenic proteins via the ubiquitin‐proteasome pathway. This study explores the potential of using exosomes as delivery vehicles for PROTACs to enhance treatment efficacy. Exosomes, due to their biocompatibility and inherent targeting capabilities, offer a precise method for delivering PROTACs to CRC cells, potentially overcoming challenges associated with traditional therapies such as drug resistance and off‐target effects. By harnessing the advantages of both exosome‐based delivery and PROTAC technology, this approach aims to improve targeted protein degradation and therapeutic outcomes in CRC treatment. Further research is required to optimize exosome engineering, ensure efficient PROTAC loading, and validate the safety and efficacy of this novel therapeutic strategy through preclinical and clinical trials.

Shape Engineering of Exosomes for Endoplasmic Reticulum-Targeted Delivery and Amplified Anticancer Efficacy

Exosomes are nanoscale extracellular vesicles that have become pivotal in advancing targeted drug delivery strategies for cancer therapy. In this study, we conducted a comparative analysis of the intracellular targeting capabilities of differently shaped exosomes, including milk exosome nanorods (MR), ginger exosome nanorods (GR), and cancer cell exosome nanorods (HR), compared to their spherical counterparts. Our observations revealed that exosome nanorods demonstrated effective and sustained targeting of the endoplasmic reticulum (ER) within cancer cells, while exosome nanospheres were captured within lysosomes. Building on this principle, we chose milk-derived exosomes (mExo) for the in vivo research, engineering the surface of MR with folate to enhance their tumor-targeting efficacy. We demonstrated the effective accumulation of these folate-modified MR (FMR) around the ER in cancer cells, as validated in both orthotopic colorectal cancer (CRC) tissues and human CRC biopsy samples. Furthermore, when loaded with curcumin (Cur), the FMR@Cur exhibited remarkable efficacy in suppressing tumors in orthotopic CRC mouse models. This effect is attributed to the targeted delivery of FMR@Cur to the ER, leading to enhanced ER-stress induced apoptosis. Overall, our study underscores the pivotal role of shape engineering in exosome-mediated drug delivery, offering novel insights and paving the way for innovative strategies to enhance the precision of intracellular drug targeting in cancer therapy.

Innovative Diagnosis and Therapeutic Modalities: Engineered Exosomes in Autoimmune Disease.

Autoimmune diseases refer to a group of conditions where the immune system produces an immune response against self-antigens, resulting in tissue damage. These diseases have profound impacts on the health of patients. In recent years, with the rapid development in the field of biomedicine, engineered exosomes have emerged as a noteworthy class of biogenic nanoparticles. By precisely manipulating the cargo and surface markers of exosomes, engineered exosomes have gained enhanced anti-inflammatory, immunomodulatory, and tissue reparative abilities, providing new prospects for the treatment of autoimmune diseases. Engineered exosomes not only facilitate the efficient delivery of bioactive molecules including nucleic acids, proteins, and cytokines, but also possess the capability to modulate immune cell functions, suppress inflammation, and restore immune homeostasis. This review mainly focuses on the applications of engineered exosomes in several typical autoimmune diseases. Additionally, this article comprehensively summarizes the current approaches for modification and engineering of exosomes and outlines their prospects in clinical applications. In conclusion, engineered exosomes, as an innovative therapeutic approach, hold promise for the management of autoimmune diseases. However, while significant progress has been made, further rigorous research is still needed to address the challenges that engineered exosomes may encounter in the therapeutic intervention process, in order to facilitate their successful translation into clinical practice and ultimately benefit a broader population of patients.

Surface functionalization of exosomes for chondrocyte-targeted siRNA delivery and cartilage regeneration

Osteoarthritis (OA) is the most prevalent degenerative cartilage disease, but no effective treatment is currently available to ameliorate the dysregulation of cartilage catabolism. Cartilage degeneration is closely related to the change in the physiology of chondrocytes: for example, chondrocytes of the OA patients overexpress matrix metallopeptidase 13 (MMP13), a.k.a. collagenase 3, which damages the extracellular matrix (ECM) of the cartilage and deteriorate the disease progression. Inhibiting MMP13 has shown to be beneficial for OA treatments, but delivering therapeutics to the chondrocytes embedded in the dense cartilage is a challenge. Here, we engineered the exosome surface with the cartilage affinity peptide (CAP) through lipid insertion to give chondrocyte-targeting exosomes, CAP-Exo, which was then loaded with siRNA against MMP13 (siMMP13) in the interior to give CAP-Exo/siMMP13. Intra-articular administration of CAP-Exo/siMMP13 reduced the MMP13 level and increased collagen COL2A1 and proteoglycan in cartilage in a rat model of anterior cruciate ligament transection (ACLT)-induced OA. Proteomic analysis showed that CAP-Exo/siMMP13 treatment restored the altered protein levels in the IL-1β-treated chondrocytes. Taken together, a facile exosome engineering method enabled targeted delivery of siRNA to chondrocytes and chondrocyte-specific silencing of MMP13 to attenuate cartilage degeneration.

Engineering exosomes to reshape the immune microenvironment in breast cancer: Molecular insights and therapeutic opportunities.

Breast cancer remains a global health challenge, necessitating innovative therapeutic approaches. Immunomodulation and immunotherapy have emerged as promising strategies for breast cancer treatment. Engineered exosomes are the sort of exosomes modified with surface decoration and internal therapeutic molecules. Through suitable modifications, engineered exosomes exhibit the capability to overcome the limitations associated with traditional therapeutic approaches. This ability opens up novel avenues for the development of more effective, personalized, and minimally invasive interventions. In this comprehensive review, we explore the molecular insights and therapeutic potential of engineered exosomes in breast cancer. We discuss the strategies employed for exosome engineering and delve into their molecular mechanisms in reshaping the immune microenvironment of breast cancer. By elucidating the contribution of engineered exosomes to breast cancer immunomodulation, this review underscores the transformative potential of this emerging field for improving breast cancer therapy. Surface modification of exosomes can improve the targeting specificity. The engineered exosome-loaded immunomodulatory cargo regulates the tumour immune microenvironment. Engineered exosomes are involved in the immune regulation of breast cancer.

Abstract 5815: Next-generation RNAi therapeutics: siRNA-loaded exosomes targeting KRAS G12C in non-small cell lung cancer (NSCLC)

Abstract Background: NSCLC represents the predominant subtype of lung cancer, boasting an overall 5-year survival rate of 26%, a figure that fluctuates based on the disease stage. Within NSCLC, certain cancer gene mutations, notably KRAS G12C, are currently classified as 'undruggable targets,' creating hurdles in achieving effective treatment. The development of innovative anticancer drugs aimed at these challenging targets is expected to present a viable solution to these difficulties. Methods: Exosomes have garnered attention as an inventive drug delivery system for in vivo gene delivery through systemic injection. We used a new post-loading approach by actively loading KRAS G12C siRNA into exosomes using the shock waves (SWEET: shock wave exosome engineering technology ) in this study. The effect of in vitro and in vivo were tested in NCI-H358 (KRAS G12C mt NSCLC) cells and its xenograft mouse model. The tumor size and weight were measured twice a week. Results: We developed an exosome-based therapeutic using siRNA to effectively inhibit KRAS G12C, targeting NSCLC. The SWEET platform's post-loading method showed a high efficiency in loading KRAS G12C siRNA into exosomes. The KRAS G12C siRNA-loaded exosomes effectively silenced oncogenic KRAS G12C expression in cancer cells; they inhibited tumor growth when administered intravenously in a NSCLC xenograft mouse model. Remarkably, the anticancer effect of KRAS G12C-loaded exosome was similar to that of Sotorasib, a KRAS G12C mutation targeting anti-cancer drug. Conclusion: Our study showed KRAS G12C siRNA loaded exosomes were effectively delivered to NSCLC tumor tissue via intravenous (IV) administration. And its anti-cancer effects were very similar to sotorasib, showing potential as a treatment for KRAS G12C mutation-expressing cancer. The effective delivery of siRNA to tumor tissues through exosomes highlights the potential of this technology as a promising approach for developing new RNAi therapeutics for cancer. Citation Format: Hyo Kyeong Kim, Yujeong Choi, Kyoung Hwa Kim, Yeongju Byun, Tae Hee Kim, Jae Hwan Kim, Shung Hyun An, DaeHo Bae, MyeongKwan Choi, Jihwa Chung, Kihwan Kwon. Next-generation RNAi therapeutics: siRNA-loaded exosomes targeting KRAS G12C in non-small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5815.

Communication molecules (ncRNAs) mediate tumor-associated macrophage polarization and tumor progression.

Non-coding RNAs play important roles in tumor cells and macrophages and participate in their communication as messengers. Non-coding RNAs have an impact in tumor cell proliferation, migration, and apoptosis, and they also regulate the differentiation and regulation of immune cells. In macrophages, they stimulate the polarization of macrophages into M1 or M2 by regulating proteins related to signaling pathways; in tumor cells, non-coding RNAs can enter macrophages through exosomes and affect the latter polarization. The polarization of macrophages further regulates the biological functions of cancer cells. The direction of macrophage polarization determines tumor progression, angiogenesis and drug resistance. This often creates a feedback loop. Non-coding RNAs act as bridges between tumor cells and macrophages to regulate the balance of the tumor microenvironment. We reviewed the signaling pathways related to macrophage polarization and the regulatory mechanisms of non-coding RNA in tumor-associated macrophages M1 and M2, and discussed the potential applications and prospects of exosome engineering.

Exosome-Mediated Antigen Delivery: Unveiling Novel Strategies in Viral Infection Control and Vaccine Design.

Exosomes are small subtypes of extracellular vesicles (EVs) naturally released by different types of cells into their environment. Their physiological roles appear to be multiple, yet many aspects of their biological activities remain to be understood. These vesicles can transport and deliver a variety of cargoes and may serve as unconventional secretory vesicles. Thus, they play a crucial role as important vectors for intercellular communication and the maintenance of homeostasis. Exosome production and content can vary under several stresses or modifications in the cell microenvironment, influencing cellular responses and stimulating immunity. During infectious processes, exosomes are described as double-edged swords, displaying both beneficial and detrimental effects. Owing to their tractability, the analysis of EVs from multiple biofluids has become a booming tool for monitoring various pathologies, from infectious to cancerous origins. In this review, we present an overview of exosome features and discuss their particular and ambiguous functions in infectious contexts. We then focus on their properties as diagnostic or therapeutic tools. In this regard, we explore the capacity of exosomes to vectorize immunogenic viral antigens and their function in mounting adaptive immune responses. As exosomes provide interesting platforms for antigen presentation, we further review the available data on exosome engineering, which enables peptides of interest to be exposed at their surface. In the light of all these data, exosomes are emerging as promising avenues for vaccine strategies.

A novel exosome based therapeutic intervention against neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) is a highly lethal variant of castration-resistant prostate cancer (CRPC) with poor survival rates. Current treatment options for NEPC are limited to highly toxic platinum drugs highlighting the urgent need for new therapies. This study aimed to develop a novel therapeutic approach using engineered exosomes against NEPC. Exosomes were modified to target CEACAM5, an NEPC surface antigen, by attaching CEACAM5 antibodies to HEK293T exosomes. These exosomes were loaded with drugs inhibiting EZH2 and the androgen receptor (AR) as recent research shows a persistent role of AR in NEPC wherein it plays a concerted role with EZH2 in driving neuronal gene programs. In vitro experiments with NEPC cell lines demonstrated that CEACAM5-targeted exosomes were specifically taken up by NEPC cells, leading to reduced cellular viability and decreased expression of neuronal markers. Further in vivo tests using a NEPC patient-derived xenograft model (LuCaP145.1) showed significant tumor regression in mice treated with engineered exosomes compared to control mice receiving IgG-labeled exosomes. These results suggest that CEACAM5-engineered exosomes hold promise as a targeted therapy for NEPC. Importantly, our exosome engineering strategy is versatile and can be adapted to target various surface antigens in prostate cancer and other diseases.

A comprehensive review of engineered exosomes from the preparation strategy to therapeutic applications.

Exosomes exhibit high bioavailability, biological stability, targeted specificity, low toxicity, and low immunogenicity in shuttling various bioactive molecules such as proteins, lipids, RNA, and DNA. Natural exosomes, however, have limited production, targeting abilities, and therapeutic efficacy in clinical trials. On the other hand, engineered exosomes have demonstrated long-term circulation, high stability, targeted delivery, and efficient intracellular drug release, garnering significant attention. The engineered exosomes bring new insights into developing next-generation drug delivery systems and show enormous potential in therapeutic applications, such as tumor therapies, diabetes management, cardiovascular disease, and tissue regeneration and repair. In this review, we provide an overview of recent advancements associated with engineered exosomes by focusing on the state-of-the-art strategies for cell engineering and exosome engineering. Exosome isolation methods, including traditional and emerging approaches, are systematically compared along with advancements in characterization methods. Current challenges and future opportunities are further discussed in terms of the preparation and application of engineered exosomes.

MnO2-mineralized milk exosomes as a novel nanoplatform for glutathione detection.

Exosomes have garnered significant attention in the realms of disease diagnosis and therapeutics, owing to their remarkable biocompatibility. While engineered exosomes have the potential to augment delivery efficiency, targeting specificity, and circulation longevity, the intricacies of sample preparation have often hindered their broader application. In this pioneering study, we introduce a novel nanoplatform by leveraging surface manganese dioxide (MnO2) mineralization of milk exosomes. This innovative technique not only amplifies the inherent properties of exosomes but also endows them with additional functionalities, transforming them into a multifaceted tool for disease detection and therapeutic intervention. To expand the application of MnO2@milk exosomes, milk exosomes were stained with lipophilic molecules (curcumin) to prepare MnO2@mEVs-curcumin (MEC). The prepared nanocomposite was employed to detect GSH in cancer cells. By integrating exosome engineering with surface mineralization, we have paved the way for the creation of advanced biomaterials.

Engineered exosomes as a prospective therapy for diabetic foot ulcers.

Diabetic foot ulcer (DFU), characterized by high recurrence rate, amputations and mortality, poses a significant challenge in diabetes management. The complex pathology involves dysregulated glucose homeostasis leading to systemic and local microenvironmental complications, including peripheral neuropathy, micro- and macro-angiopathy, recurrent infection, persistent inflammation and dysregulated re-epithelialization. Novel approaches to accelerate DFU healing are actively pursued, with a focus on utilizing exosomes. Exosomes are natural nanovesicles mediating cellular communication and containing diverse functional molecular cargos, including DNA, mRNA, microRNA (miRNA), lncRNA, proteins, lipids and metabolites. While some exosomes show promise in modulating cellular function and promoting ulcer healing, their efficacy is limited by low yield, impurities, low loading content and inadequate targeting. Engineering exosomes to enhance their curative activity represents a potentially more efficient approach for DFUs. This could facilitate focused repair and regeneration of nerves, blood vessels and soft tissue after ulcer development. This review provides an overview of DFU pathogenesis, strategies for exosome engineering and the targeted therapeutic application of engineered exosomes in addressing critical pathological changes associated with DFUs.

Engineered Exosome for Drug Delivery: Recent Development and Clinical Applications.

Exosomes are nano-sized membrane vesicles that transfer bioactive molecules between cells and modulate various biological processes under physiological and pathological conditions. By applying bioengineering technologies, exosomes can be modified to express specific markers or carry therapeutic cargo and emerge as novel platforms for the treatment of cancer, neurological, cardiovascular, immune, and infectious diseases. However, there are many challenges and uncertainties in the clinical translation of exosomes. This review aims to provide an overview of the recent advances and challenges in the translation of engineered exosomes, with a special focus on the methods and strategies for loading drugs into exosomes, the pros and cons of different loading methods, and the optimization of exosome production based on the drugs to be encapsulated. Moreover, we also summarize the current clinical applications and prospects of engineered exosomes, as well as the potential risks and limitations that need to be addressed in exosome engineering, including the standardization of exosome preparation and engineering protocols, the quality and quantity of exosomes, the control of drug release, and the immunogenicity and cytotoxicity of exosomes. Overall, engineered exosomes represent an exciting frontier in nanomedicine, but they still face challenges in large-scale production, the maintenance of storage stability, and clinical translation. With continuous advances in this field, exosome-based drug formulation could offer great promise for the targeted treatment of human diseases.

Engineered exosomes: a promising vehicle in cancer therapy.

During the past few decades, researchers have attempted to discover an effective treatment for cancer. Exosomes are natural nanovesicles released by various cells and play a role in communication between cells. While natural exosomes have high clinical potential, their inherent limitations have prompted researchers to design exosomes with improved therapeutic properties. To achieve this purpose, researchers have undertaken exosome engineering to modify the surface properties or internal composition of exosomes. After these modifications, engineered exosomes can be used as carriers for delivery of chemotherapeutic agents, targeted drug delivery or development of cancer vaccines. The present study provides an overview of exosomes, including their biogenesis, biological functions, isolation techniques, engineering methods, and potential applications in cancer therapy.

Advancements in engineered exosomes for wound repair: current research and future perspectives.

Wound healing is a complex and prolonged process that remains a significant challenge in clinical practice. Exosomes, a type of nanoscale extracellular vesicles naturally secreted by cells, are endowed with numerous advantageous attributes, including superior biocompatibility, minimal toxicity, and non-specific immunogenicity. These properties render them an exceptionally promising candidate for bioengineering applications. Recent advances have illustrated the potential of exosome therapy in promoting tissue repair. To further augment their therapeutic efficacy, the concept of engineered exosomes has been proposed. These are designed and functionally modifiable exosomes that have been tailored on the attributes of natural exosomes. This comprehensive review delineates various strategies for exosome engineering, placing specific emphasis on studies exploring the application of engineered exosomes for precision therapy in wound healing. Furthermore, this review sheds light on strategies for integrating exosomes with biomaterials to enhance delivery effectiveness. The insights presented herein provide novel perspectives and lay a robust foundation for forthcoming research in the realm of cutaneous wound repair therapies.

Exosomes Highlight Future Directions in the Treatment of Acute Kidney Injury

Acute kidney injury (AKI) is a severe health problem associated with high morbidity and mortality rates. It currently lacks specific therapeutic strategies. This review focuses on the mechanisms underlying the actions of exosomes derived from different cell sources, including red blood cells, macrophages, monocytes, mesenchymal stem cells, and renal tubular cells, in AKI. We also investigate the effects of various exosome contents (such as miRNA, lncRNA, circRNA, mRNA, and proteins) in promoting renal tubular cell regeneration and angiogenesis, regulating autophagy, suppressing inflammatory responses and oxidative stress, and preventing fibrosis to facilitate AKI repair. Moreover, we highlight the interactions between macrophages and renal tubular cells through exosomes, which contribute to the progression of AKI. Additionally, exosomes and their contents show promise as potential biomarkers for diagnosing AKI. The engineering of exosomes has improved their clinical potential by enhancing isolation and enrichment, target delivery to injured renal tissues, and incorporating small molecular modifications for clinical use. However, further research is needed to better understand the specific mechanisms underlying exosome actions, their delivery pathways to renal tubular cells, and the application of multi-omics research in studying AKI.

Potential in exosome-based targeted nano-drugs and delivery vehicles for posterior ocular disease treatment: from barriers to therapeutic application.

Posterior ocular disease, a disease that accounts for 55% of all ocular diseases, can contribute to permanent vision loss if left without treatment. Due to the special structure of the eye, various obstacles make it difficult for drugs to reach lesions in the posterior ocular segment. Therefore, the development of highly permeable targeted drugs and delivery systems is particularly important. Exosomes are a class of extracellular vesicles at 30-150nm, which are secreted by various cells, tissues, and body fluids. They carry various signaling molecules, thus endowing them with certain physiological functions. In this review, we describe the ocular barriers and the biogenesis, isolation, and engineering of exosomes, as exosomes not only have pharmacological effects but also are good nanocarriers with targeted properties. Moreover, their biocompatibility and immunogenicity are better than synthetic nanocarriers. Most importantly, they may have the ability to pass through the blood-eye barrier. Thus, they may be developed as both targeted nano-drugs and nano-delivery vehicles for the treatment of posterior ocular diseases. We focus on the current status and potential application of exosomes as targeted nano-drugs and nano-delivery vehicles in posterior ocular diseases.

Exosomes in brain diseases: Pathogenesis and therapeutic targets.

Exosomes are extracellular vesicles with diameters of about 100nm that are naturally secreted by cells into body fluids. They are derived from endosomes and are wrapped in lipid membranes. Exosomes are involved in intracellular metabolism and intercellular communication. They contain nucleic acids, proteins, lipids, and metabolites from the cell microenvironment and cytoplasm. The contents of exosomes can reflect their cells' origin and allow the observation of tissue changes and cell states under disease conditions. Naturally derived exosomes have specific biomolecules that act as the "fingerprint" of the parent cells, and the contents changed under pathological conditions can be used as biomarkers for disease diagnosis. Exosomes have low immunogenicity, are small in size, and can cross the blood-brain barrier. These characteristics make exosomes unique as engineering carriers. They can incorporate therapeutic drugs and achieve targeted drug delivery. Exosomes as carriers for targeted disease therapy are still in their infancy, but exosome engineering provides a new perspective for cell-free disease therapy. This review discussed exosomes and their relationship with the occurrence and treatment of some neuropsychiatric diseases. In addition, future applications of exosomes in the diagnosis and treatment of neuropsychiatric disorders were evaluated in this review.

Abstract 5492: Determining effects of the CD206 positive M2 macrophage depleting engineered exosome in combination with anti PD1 therapy in breast tumor

Abstract Introduction: Triple negative breast cancer (TNBC) subtype of breast cancer, which lacks molecular markers such as HER2 and estrogen/progesterone receptors, has limited treatment options. Exosomes are nano-sized (30-150 nm) spherical vesicles, derived from the endosomal system for intercellular communications, can be engineered to express targeting peptides to target specifically CD206 positive M2 macrophage. Investigators have used either synthetic nanoparticles or fusion protein to deliver Fc-IgG2b to initiate Antibody dependent cellular cytotoxicity (ADCC) but reports are showing a lack of ADCC following tagging with gold nanoparticles. To overcome this, in our lab, we developed engineered exosomes in non-tumorous cells, HEK293, to carry therapeutic Fc-mIgG2b to enhance ADCC and to carry peptide to deplete CD206+ M2 macrophages. We investigated the effectiveness of engineered therapeutic exosomes to target and deplete immunosuppressive CD206+ M2 macrophages in TNBC in combination with anti PD-1. Methods: In this study, we developed syngeneic metastatic TBNC model (luciferase + 4T1 cells in Balb/c) by implantation of 50K 4T1-luci cells in fat pad. On day 1 of tumor implantation, animals were treated with vehicle, engineered exosomes, anti-PD1 plus engineered exosomes, 2 dose/week for 3 weeks. They were euthanized 1 day after the last dose of treatment. Single-cell suspension was made from the primary TME, lung, and spleen. Using flow cytometry surfaces markers were investigated to determine different T-cell and myeloid cell populations. Results: We observed very surprising results following three weeks of therapies. Although the number of cytotoxic T-cells was significantly higher in the primary and metastatic TME in exosome-treated animals, there was also an increased number of proliferative T reg cells. The number of CD8+ cells was decreased following concurrent therapy with an anti-PD1 antibody. Most interestingly, lung tissue macrophages (CD11c) showed significantly increased PD-L1 expression following exosomes and anti PD1 with engineered exosomes therapies. Conclusion: This study demonstrates that treatment with engineered therapeutic exosome targeting M2 macrophages with anti PD-1 could be utilized effectively. This study will also make a greater impact in exosome engineering based targeted therapy and will open new arena to target and deplete pathogenic cell in different tumors using engineered exosome. Citation Format: Mahrima Parvin, Mohammad H. Rashid, Ahmet Alptekin, Ali S. Arbab. Determining effects of the CD206 positive M2 macrophage depleting engineered exosome in combination with anti PD1 therapy in breast tumor. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5492.

Targeted delivery of RNAi to cancer cells using RNA-ligand displaying exosome.

Exosome is an excellent vesicle for invivo delivery of therapeutics, including RNAi and chemical drugs. The extremely high efficiency in cancer regression can partly be attributed to its fusion mechanism in delivering therapeutics to cytosol without endosome trapping. However, being composed of a lipid-bilayer membrane without specific recognition capacity for aimed-cells, the entry into nonspecific cells can lead to potential side-effects and toxicity. Applying engineering approaches for targeting-capacity to deliver therapeutics to specific cells is desirable. Techniques with chemical modification invitro and genetic engineering in cells have been reported to decorate exosomes with targeting ligands. RNA nanoparticles have been used to harbor tumor-specific ligands displayed on exosome surface. The negative charge reduces nonspecific binding to vital cells with negatively charged lipid-membrane due to the electrostatic repulsion, thus lowering the side-effect and toxicity. In this review, we focus on the uniqueness of RNA nanoparticles for exosome surface display of chemical ligands, small peptides or RNA aptamers, for specific cancer targeting to deliver anticancer therapeutics, highlighting recent advances in targeted delivery of siRNA and miRNA that overcomes the previous RNAi delivery roadblocks. Proper understanding of exosome engineering with RNA nanotechnology promises efficient therapies for a wide range of cancer subtypes.