Extracellular Vesicle- and Extracellular Vesicle Mimetics-Based Drug Delivery Systems: New Perspectives, Challenges, and Clinical Developments

Advances in extracellular vesicles as mediators of cell-to-cell communication in pregnancy

Cell-to-cell communication mediated by Extracellular Vesicles (EVs) is a novel and emerging area of research, especially during pregnancy, in which placenta derived EVs can facilitate the feto-maternal communication. EVs comprise a heterogeneous group of vesicle sub-populations with diverse physical and biochemical characteristics and originate by specific biogenesis mechanisms. EVs transfer molecular cargo (including proteins, nucleic acids, and lipids) between cells and are critical mediators of cell communication. There is growing interest among researchers to explore into the molecular cargo of EVs and their functions in a physiological and pathological context. For example, inflammatory mediators such as cytokines are shown to be released in EVs and EVs derived from immune cells play key roles in mediating the immune response as well as immunoregulatory pathways. Pregnancy complications such as gestational diabetes mellitus, preeclampsia, intrauterine growth restriction and preterm birth are associated with altered levels of circulating EVs, with differential EV cargo and bioactivity in target cells. This implicates the intriguing roles of EVs in reprogramming the maternal physiology during pregnancy. Moreover, the capacity of EVs to carry bioactive molecules makes them a promising tool for biomarker development and targeted therapies in pregnancy complications. This review summarizes the physiological and pathological roles played by EVs in pregnancy and pregnancy-related disorders and describes the potential of EVs to be translated into clinical applications in the diagnosis and treatment of pregnancy complications.

In vivo production of CAR-T cells using virus-mimetic fusogenic nanovesicles

Engineered T cells expressing chimeric antigen receptor (CAR) exhibit high response rates in B-cell malignancy treatments and possess therapeutic potentials against various diseases. However, the complicated ex vivo production process of CAR-T cells limits their application. Herein, we use virus-mimetic fusogenic nanovesicles (FuNVs) to produce CAR-T cells in vivo via membrane fusion-mediated CAR protein delivery. Briefly, the FuNVs are modified using T-cell fusogen, adapted from measles virus or reovirus fusogens via displaying anti-CD3 single-chain variable fragment. The FuNVs can efficiently fuse with the T-cell membrane in vivo, thereby delivering the loaded anti-CD19 (αCD19) CAR protein onto T-cells to produce αCD19 CAR-T cells. These αCD19 CAR-T cells alone or in combination with anti-OX40 antibodies can treat B-cell lymphoma without inducing cytokine release syndrome. Thus, our strategy provides a novel method for engineering T cells into CAR-T cells in vivo and can further be employed to deliver other therapeutic membrane proteins.

Smart Nanoscale Extracellular Vesicles in the Brain: Unveiling their Biology, Diagnostic Potential, and Therapeutic Applications

Information exchange is essential for the brain, where it communicates the physiological and pathological signals to the periphery and vice versa. Extracellular vesicles (EVs) are a heterogeneous group of membrane-bound cellular informants actively transferring informative calls to and from the brain via lipids, proteins, and nucleic acid cargos. In recent years, EVs have also been widely used to understand brain function, given their "cell-like" properties. On the one hand, the presence of neuron and astrocyte-derived EVs in biological fluids have been exploited as biomarkers to understand the mechanisms and progression of multiple neurological disorders; on the other, EVs have been used in designing targeted therapies due to their potential to cross the blood-brain-barrier (BBB). Despite the expanding literature on EVs in the context of central nervous system (CNS) physiology and related disorders, a comprehensive compilation of the existing knowledge still needs to be made available. In the current review, we provide a detailed insight into the multifaceted role of brain-derived extracellular vesicles (BDEVs) in the intricate regulation of brain physiology. Our focus extends to the significance of these EVs in a spectrum of disorders, including brain tumors, neurodegenerative conditions, neuropsychiatric diseases, autoimmune disorders, and others. Throughout the review, parallels are drawn for using EVs as biomarkers for various disorders, evaluating their utility in early detection and monitoring. Additionally, we discuss the promising prospects of utilizing EVs in targeted therapy while acknowledging the existing limitations and challenges associated with their applications in clinical scenarios. A foundational comprehension of the current state-of-the-art in EV research is essential for informing the design of future studies.

Therapeutic targets and potential delivery systems of melatonin in osteoarthritis

Osteoarthritis (OA) is a highly prevalent age-related musculoskeletal disorder that typically results in chronic pain and disability. OA is a multifactorial disease, with increased oxidative stress, dysregulated inflammatory response, and impaired matrix metabolism contributing to its onset and progression. The neurohormone melatonin, primarily synthesized by the pineal gland, has emerged as a promising therapeutic agent for OA due to its potential to alleviate inflammation, oxidative stress, and chondrocyte death with minimal adverse effects. The present review provides a comprehensive summary of the current understanding regarding melatonin as a promising pharmaceutical agent for the treatment of OA, along with an exploration of various delivery systems that can be utilized for melatonin administration. These findings may provide novel therapeutic strategies and targets for inhibiting the advancement of OA.

Rapid plasma membrane isolation via intracellular polymerization-mediated biomolecular confinement

Plasma membrane isolation is a foundational process in membrane proteomic research, cellular vesicle studies, and biomimetic nanocarrier development, yet separation processes for this outermost layer are cumbersome and susceptible to impurities and low yield. Herein, we demonstrate that cellular cytosol can be chemically polymerized for decoupling and isolation of plasma membrane within minutes. A rapid, non-disruptive in situ polymerization technique is developed with cell membrane-permeable polyethyleneglycol-diacrylate (PEG-DA) and a blue-light-sensitive photoinitiator, lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP). The photopolymerization chemistry allows for precise control of intracellular polymerization and tunable confinement of cytosolic molecules. Upon cytosol solidification, plasma membrane proteins and vesicles are rapidly derived and purified as nucleic acids and intracellular proteins as small as 15 kDa are stably entrapped for removal. The polymerization chemistry and membrane derivation technique are broadly applicable to primary and fragile cell types, enabling facile membrane vesicle extraction from shorted-lived neutrophils and human primary CD8 T cells. The study demonstrates tunable intracellular polymerization via optimized live cell chemistry, offers a robust membrane isolation methodology with broad biomedical utility, and reveals insights on molecular crowding and confinement in polymerized cells. STATEMENT OF SIGNIFICANCE: Isolating the minute fraction of plasma membrane proteins and vesicles requires extended density gradient ultracentrifugation processes, which are susceptible to low yield and impurities. The present work demonstrates that the membrane isolation process can be vastly accelerated via a rapid, non-disruptive intracellular polymerization approach that decouples cellular cytosols from the plasma membrane. Following intracellular polymerization, high-yield plasma membrane proteins and vesicles can be derived from lysis buffer and sonication treatment, respectively. And the intracellular content entrapped within the polymerized hydrogel is readily removed within minutes. The technique has broad utility in membrane proteomic research, cellular vesicle studies, and biomimetic materials development, and the work offers insights on intracellular hydrogel-mediated molecular confinement.

Engineering extracellular vesicles mimetics for targeted chemotherapy of drug-resistant ovary cancer

Aim: To develop nanocarriers for targeting the delivery of chemotherapeutics to overcome multidrug-resistant ovarian cancer. Materials & methods: Doxorubicin-loaded nanovesicles were obtained through serial extrusion, followed by loading of P-glycoprotein siRNA and folic acid. The targeting ability and anticancer efficacy of the nanovesicles were evaluated. Results: The doxorubicin-loaded nanovesicles showed a high production yield. The presence of P-glycoprotein siRNA and folic acid resulted in reversed drug resistance and tumor targeting. This nanoplatform tremendously inhibited the viability of multidrug-resistant ovarian cancer cells, which was able to target tumor tissue and suppress tumor growth without adverse effects. Conclusion: These bioengineered nanovesicles could serve as novel extracellular vesicles mimetics for chemotherapeutics delivery to overcome multidrug resistance.

Thinking small to win big? A critical review on the potential application of extracellular vesicles for biomarker discovery and new therapeutic approaches in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an extremely deadly form of cancer, with limited progress in 5-year survival rates despite significant research efforts. The main challenges in treating PDAC include difficulties in early detection, and resistance to current therapeutic approaches due to aggressive molecular and microenvironment features. These challenges emphasize the importance of identifying clinically validated biomarkers for early detection and clinical management. Extracellular vesicles (EVs), particularly exosomes, have emerged as crucial mediators of intercellular communication by transporting molecular cargo. Recent research has unveiled their role in initiation, metastasis, and chemoresistance of PDAC. Consequently, utilizing EVs in liquid biopsies holds promise for the identification of biomarkers for early detection, prognosis, and monitoring of drug efficacy. However, numerous limitations, including challenges in isolation and characterization of homogeneous EVs populations, as well as the absence of standardized protocols, can affect the reliability of studies involving EVs as biomarkers, underscoring the necessity for a prudent approach. EVs have also garnered considerable attention as a promising drug delivery system and novel therapy for tumors. The loading of biomolecules or chemical drugs into exosomes and their subsequent delivery to target cells can effectively impede tumor progression. Nevertheless, there are obstacles that must be overcome to ensure the accuracy and efficacy of therapies relying on EVs for the treatment of tumors. In this review, we examine both recent advancements and remaining obstacles, exploring the potential of utilizing EVs in biomarker discovery as well as for the development of drug delivery vehicles.

Cellular organelles as drug carriers for disease treatment

Organelles not only constitute the basic structure of the cell but also are important in maintaining the normal physiological activities of the cell. With the development of biomimetic nanoscience, researchers have developed technologies to use organelles as drug carriers for disease treatment. Compared with traditional drug carriers, organelle drug carriers have the advantages of good biocompatibility, high drug loading efficiency, and modifiability, and the surface biomarkers of organelles can also participate in intracellular signal transduction to enhance intracellular and intercellular communication, and assist in enhancing the therapeutic effect of drugs. Among different types of organelles, extracellular vesicles, lipid droplets, lysosomes, and mitochondria have been used as drug carriers. This review briefly reviews the biogenesis, isolation methods, and drug-loading methods of four types of organelles, and systematically summarizes the research progress in using organelles as drug-delivery systems for disease treatment. Finally, the challenges faced by organelle-based drug delivery systems are discussed. Although the organelle-based drug delivery systems still face challenges before they can achieve clinical translation, they offer a new direction and vision for the development of next-generation drug carriers.

Targeting the central nervous system: From synthetic nanoparticles to extracellular vesicles-Focus on Alzheimer's and Parkinson's disease

Neurodegenerative diseases (NDs) such as Alzheimer's disease (AD) and Parkinson's disease (PD) are an accelerating global health problem as life expectancy rises worldwide. Despite their significant burden in public health systems to date, the existing treatments only manage the symptoms without slowing down disease progression. Thus, the ongoing neurodegenerative process remains untreated. Moreover, the stronghold of the brain-the blood-brain barrier (BBB)-prevents drug penetrance and dwindles effective treatments. In the last years, nanotechnology-based drug delivery systems (DDS) have become a promising approach to target and treat these disorders related to the central nervous system (CNS). PLGA based nanoparticles (NPs) were the first employed DDS for effective drug delivery. However, the poor drug loading capacity and localized immunogenicity prompted the scientific community to move to another DDS such as lipid-based NPs. Despite the lipid NPs' safety and effectiveness, their off-target accumulation together with the denominated CARPA (complement activation-related pseudo allergy) reaction has limited their complete clinical translation. Recently, biological NPs naturally secreted by cells, termed as extracellular vesicles (EVs) have emerged as promising more complex biocompatible DDS. In addition, EVs act as dual players in NDs treatment, as a "cell free" therapy themselves, as well as new biological NPs with numerous characteristics that qualify them as promising carriers over synthetic DDS. The present review aims to display advantages, drawbacks, current limitations and future prospective of the previously cited synthetic and biological DDS to enter the brain and treat one of 21st century most challenging diseases, NDs. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Extracellular vesicle-mediated targeting strategies for long-term health benefits in gestational diabetes

Extracellular vesicles (EVs) are critical mediators of cell communication, playing important roles in regulating molecular cross-talk between different metabolic tissues and influencing insulin sensitivity in both healthy and gestational diabetes mellitus (GDM) pregnancies. The ability of EVs to transfer molecular cargo between cells imbues them with potential as therapeutic agents. During pregnancy, the placenta assumes a vital role in metabolic regulation, with multiple mechanisms of placenta-mediated EV cross-talk serving as central components in GDM pathophysiology. This review focuses on the role of the placenta in the pathophysiology of GDM and explores the possibilities and prospects of targeting the placenta to address insulin resistance and placental dysfunction in GDM. Additionally, we propose the use of EVs as a novel method for targeted therapeutics in treating the dysfunctional placenta. The primary aim of this review is to comprehend the current status of EV targeting approaches and assess the potential application of these strategies in placental therapeutics, thereby delivering molecular cargo and improving maternal and fetal outcomes in GDM. We propose that EVs have the potential to revolutionize GDM management, offering hope for enhanced maternal-fetal health outcomes and more effective treatments.

Recent Trends in the Use of Small Extracellular Vesicles as Optimal Drug Delivery Vehicles in Oncology

Small extracellular vesicles (sEVs) are produced by most cells and play an important role in cell-to-cell communication and maintaining cellular homeostasis. Their ability to transfer biological cargo to target cells makes them a promising tool for cancer drug delivery. Advances in sEV engineering, EV mimetics, and ligand-directed targeting have improved the efficacy of anticancer drug delivery and functionality. EV-based RNA interference and hybrid miRNA transfer have also been extensively used in various preclinical cancer models. Despite these developments, gaps still exist in our understanding of using sEVs to treat solid tumor malignancies effectively. This article provides an overview of the last five years of sEV research and its current status for the efficient and targeted elimination of cancer cells, which could advance cancer research and bring sEV formulations into clinical use.

Bio-Inspired Nanocarriers Derived from Stem Cells and Their Extracellular Vesicles for Targeted Drug Delivery

With their seemingly limitless capacity for self-improvement, stem cells have a wide range of potential uses in the medical field. Stem-cell-secreted extracellular vesicles (EVs), as paracrine components of stem cells, are natural nanoscale particles that transport a variety of biological molecules and facilitate cell-to-cell communication which have been also widely used for targeted drug delivery. These nanocarriers exhibit inherent advantages, such as strong cell or tissue targeting and low immunogenicity, which synthetic nanocarriers lack. However, despite the tremendous therapeutic potential of stem cells and EVs, their further clinical application is still limited by low yield and a lack of standardized isolation and purification protocols. In recent years, inspired by the concept of biomimetics, a new approach to biomimetic nanocarriers for drug delivery has been developed through combining nanotechnology and bioengineering. This article reviews the application of biomimetic nanocarriers derived from stem cells and their EVs in targeted drug delivery and discusses their advantages and challenges in order to stimulate future research.

An update on stem cell and stem cell-derived extracellular vesicle-based therapy in the management of Alzheimer's disease

Globally, neurological diseases pose a major burden to healthcare professionals in terms of the management and prevention of the disorder. Among neurological diseases, Alzheimer's disease (AD) accounts for 50%-70% of dementia and is the fifth leading cause of mortality worldwide. AD is a progressive, degenerative neurological disease, with the loss of neurons and synapses in the cerebral cortex and subcortical regions. The management of AD remains a debate among physicians as no standard and specific "disease-modifying" modality is available. The concept of 'Regenerative Medicine' is aimed at regenerating the degenerated neural tissues to reverse the pathology in AD. Genetically modified engineered stem cells modify the course of AD after transplantation into the brain. Extracellular vesicles (EVs) are an emerging new approach in cell communication that involves the transfer of cellular materials from parental cells to recipient cells, resulting in changes at the molecular and signaling levels in the recipient cells. EVs are a type of vesicle that can be transported between cells. Many have proposed that EVs produced from mesenchymal stem cells (MSCs) may have therapeutic promise in the treatment of AD. The biology of AD, as well as the potential applications of stem cells and their derived EVs-based therapy, were explored in this paper.

Intrathecal Injection of Autologous Mesenchymal Stem-Cell-Derived Extracellular Vesicles in Spinal Cord Injury: A Feasibility Study in Pigs

Spinal cord injury (SCI) remains one of the current medical and social problems, as it causes deep disability in patients. The use of mesenchymal stem cell (MSC)-derived extracellular vesicles (EVs) is one strategy for stimulating the post-traumatic recovery of the structure and function of the spinal cord. Here, we chose an optimal method for obtaining cytochalasin B-induced EVs, including steps with active vortex mixing for 60 s and subsequent filtration to remove nuclei and disorganized inclusions. The therapeutic potential of repeated intrathecal injection of autologous MSC-derived EVs in the subacute period of pig contused SCI was also evaluated for the first time. In this study, we observed the partial restoration of locomotor activity by stimulating the remyelination of axons and timely reperfusion of nervous tissue.

Bioengineered exosomal-membrane-camouflaged abiotic nanocarriers: neurodegenerative diseases, tissue engineering and regenerative medicine

A bio-inspired strategy has recently been developed for camouflaging nanocarriers with biomembranes, such as natural cell membranes or subcellular structure-derived membranes. This strategy endows cloaked nanomaterials with improved interfacial properties, superior cell targeting, immune evasion potential, and prolonged duration of systemic circulation. Here, we summarize recent advances in the production and application of exosomal membrane-coated nanomaterials. The structure, properties, and manner in which exosomes communicate with cells are first reviewed. This is followed by a discussion of the types of exosomes and their fabrication methods. We then discuss the applications of biomimetic exosomes and membrane-cloaked nanocarriers in tissue engineering, regenerative medicine, imaging, and the treatment of neurodegenerative diseases. Finally, we appraise the current challenges associated with the clinical translation of biomimetic exosomal membrane-surface-engineered nanovehicles and evaluate the future of this technology.

Fluorescence, ultrasonic and photoacoustic imaging for analysis and diagnosis of diseases

Biomedical imaging technology, which allows us to peer deeply within living subjects and visually explore the delivery and distribution of agents in living things, is producing tremendous opportunities for the early diagnosis and precise therapy of diseases. In this feature article, based on reviewing the latest representative examples of progress together with our recent efforts in the bioimaging field, we intend to introduce three typical kinds of non-invasive imaging technologies, i.e., fluorescence, ultrasonic and photoacoustic imaging, in which optical and/or acoustic signals are employed for analyzing various diseases. In particular, fluorescence imaging possesses a series of outstanding advantages, such as high temporal resolution, as well as rapid and sensitive feedback. Hence, in the first section, we will introduce the latest studies on developing novel fluorescence imaging methods for imaging bacterial infections, cancer and lymph node metastasis in a long-term and real-time manner. However, the issues of imaging penetration depth induced by photon scattering and light attenuation of biological tissue limit their widespread in vivo imaging applications. Taking advantage of the excellect penetration depth of acoustic signals, ultrasonic imaging has been widely applied for determining the location, size and shape of organs, identifying normal and abnormal tissues, as well as confirming the edges of lesions in hospitals. Thus, in the second section, we will briefly summarize recent advances in ultrasonic imaging techniques for diagnosing diseases in deep tissues. Nevertheless, the absence of lesion targeting and dependency on a professional technician may lead to the possibility of false-positive diagnosis. By combining the merits of both optical and acoustic signals, newly-developed photoacoustic imaging, simultaneously featuring higher temporal and spatial resolution with good sensitivity, as well as deeper penetration depth, is discussed in the third secretion. In the final part, we further discuss the major challenges and prospects for developing imaging technology for accurate disease diagnosis. We believe that these non-invasive imaging technologies will introduce a new perspective for the precise diagnosis of various diseases in the future.

Autologous platelet-rich plasma in the delayed union of long bone fractures - A quasi experimental study

Introduction

Fractures of long bones unite without any complication except for 2%-10% which may lead to delayed or non-union of the fracture. Management of delayed union of fractures poses a great challenge for orthopaedic surgeons. Platelet-rich plasma (PRP) is an autologous blood-derived biological agent, which delivers growth factors, cytokines, and bio-micro molecules at supraphysiologic concentrations at the site of tissue injury, thus potentiating the body's healing efforts. Various studies and research have proved the osteogenic activity of PRP. The growth factors present in the PRP induce the locally available resilient progenitor or stem cells and convert the atrophic environment into a trophic environment.

Materials and methods

We investigated the safety and efficacy of autologous PRP injection in the delayed union of long bone fractures. A total of 25 cases of delayed union of long bone fractures were augmented with 3 doses of autologous PRP at 3 weekly intervals and were followed up for 12 months. All the cases were documented with pre-and post-procedural and 12th -month visual analog score (VAS) and Warden's score.

Results

Out of 25 cases, 21 (84.00%) cases showed good union of fracture with adequate callus formation by 10-12 weeks with 3 doses of autologous PRP injections. The mean pre-procedural VAS and Warden's score at the final follow-up showed statistically significant results (p < 0.05). No other complications were noted due to autologous PRP application among the study participants during the study period except for 3 cases (2 cases of non-union, and 1 case of implant failure).

Conclusion

Results of the current study suggest that autologous injection of PRP might be a safe and effective therapeutic tool for the management of delayed union of long bone fractures.

Nanomaterial-mediated photoporation for intracellular delivery

Translocation of extrinsic molecules into living cells is becoming increasingly crucial in biological studies ranging from cell engineering to biomedical applications. The concerns regarding biosafety and immunogenicity for conventional vectors and physical methods yet challenge effective intracellular delivery. Here, we begin with an overview of approaches for trans-membrane delivery up to now. These methods are featured with a relatively mature application but usually encounter low cell survival. Our review then proposes an advanced application for nanomaterial-sensitized photoporation triggered with a laser. We cover the mechanisms, procedures, and outcomes of photoporation-induced intracellular delivery with a highlight on its versatility to different living cells. We hope the review discussed here encourages researchers to further improvement and applications for photoporation-induced intracellular delivery. STATEMENT OF SIGNIFICANCE.

The emerging role of exosomes in innate immunity, diagnosis and therapy

Exosomes, which are nano-sized transport bio-vehicles, play a pivotal role in maintaining homeostasis by exchanging genetic or metabolic information between different cells. Exosomes can also play a vital role in transferring virulent factors between the host and parasite, thereby regulating host gene expression and the immune interphase. The association of inflammation with disease development and the potential of exosomes to enhance or mitigate inflammatory pathways support the notion that exosomes have the potential to alter the course of a disease. Clinical trials exploring the role of exosomes in cancer, osteoporosis, and renal, neurological, and pulmonary disorders are currently underway. Notably, the information available on the signatory efficacy of exosomes in immune-related disorders remains elusive and sporadic. In this review, we discuss immune cell-derived exosomes and their application in immunotherapy, including those against autoimmune connective tissue diseases. Further, we have elucidated our views on the major issues in immune-related pathophysiological processes. Therefore, the information presented in this review highlights the role of exosomes as promising strategies and clinical tools for immune regulation.

Hybrid exosomes, exosome-like nanovesicles and engineered exosomes for therapeutic applications

Exosomes are endosome-derived nanovesicles involved in cellular communication. They are natural nanocarriers secreted by various cells, making them suitable candidates for diverse drug delivery and therapeutic applications from a material standpoint. They have a phospholipid bilayer decorated with functional molecules and an enclosed parental matrix, which has attracted interest in developing designer/hybrid engineered exosome nanocarriers. The structural versatility of exosomes allows the modification of their original configuration using various methods, including genetic engineering, chemical procedures, physical techniques, and microfluidic technology, to load exosomes with additional cargo for expanded biomedical applications. Exosomes show enormous potential for overcoming the limitations of conventional nanoparticle-based techniques in targeted therapy. This review highlights the exosome sources, characteristics, state of the art in the field of hybrid exosomes, exosome-like nanovesicles and engineered exosomes as potential cargo delivery vehicles for therapeutic applications.

Engineered Nanovesicles from Fibroblasts Modulate Dermal Papillae Cells In Vitro and Promote Human Hair Follicle Growth Ex Vivo

Alopecia is a common medical condition affecting both sexes. Dermal papilla (DP) cells are the primary source of hair regeneration in alopecia patients. Therapeutic applications of extracellular vesicles (EVs) are restricted by low yields, high costs, and their time-consuming collection process. Thus, engineered nanovesicles (eNVs) have emerged as suitable therapeutic biomaterials in translational medicine. We isolated eNVs by the serial extrusion of fibroblasts (FBs) using polycarbonate membrane filters and serial and ultracentrifugation. We studied the internalization, proliferation, and migration of human DP cells in the presence and absence of FB-eNVs. The therapeutic potential of FB-eNVs was studied on ex vivo organ cultures of human hair follicles (HFs) from three human participants. FB-eNVs (2.5, 5, 7.5, and 10 µg/mL) significantly enhanced DP cell proliferation, with the maximum effect observed at 7.5 µg/mL. FB-eNVs (5 and 10 µg/mL) significantly enhanced the migration of DP cells at 36 h. Western blotting results suggested that FB-eNVs contain vascular endothelial growth factor (VEGF)-a. FB-eNV treatment increased the levels of PCNA, pAKT, pERK, and VEGF-receptor-2 (VEGFR2) in DP cells. Moreover, FB-eNVs increased the human HF shaft size in a short duration ex vivo. Altogether, FB-eNVs are promising therapeutic candidates for alopecia.

Reprogramming of T cell-derived small extracellular vesicles using IL2 surface engineering induces potent anti-cancer effects through miRNA delivery

T cell-derived small extracellular vesicles (sEVs) exhibit anti-cancer effects. However, their anti-cancer potential should be reinforced to enhance clinical applicability. Herein, we generated interleukin-2-tethered sEVs (IL2-sEVs) from engineered Jurkat T cells expressing IL2 at the plasma membrane via a flexible linker to induce an autocrine effect. IL2-sEVs increased the anti-cancer ability of CD8+ T cells without affecting regulatory T (Treg ) cells and down-regulated cellular and exosomal PD-L1 expression in melanoma cells, causing their increased sensitivity to CD8+ T cell-mediated cytotoxicity. Its effect on CD8+ T and melanoma cells was mediated by several IL2-sEV-resident microRNAs (miRNAs), whose expressions were upregulated by the autocrine effects of IL2. Among the miRNAs, miR-181a-3p and miR-223-3p notably reduced the PD-L1 protein levels in melanoma cells. Interestingly, miR-181a-3p increased the activity of CD8+ T cells while suppressing Treg cell activity. IL2-sEVs inhibited tumour progression in melanoma-bearing immunocompetent mice, but not in immunodeficient mice. The combination of IL2-sEVs and existing anti-cancer drugs significantly improved anti-cancer efficacy by decreasing PD-L1 expression in vivo. Thus, IL2-sEVs are potential cancer immunotherapeutic agents that regulate both immune and cancer cells by reprogramming miRNA levels.

Stimuli-responsive and biomimetic delivery systems for sepsis and related complications

Sepsis, a consequence of an imbalanced immune response to infection, is currently one of the leading causes of death globally. Despite advances in the discoveries of potential targets and nanotechnology, sepsis still lacks effective drug delivery systems for optimal treatment. Stimuli-responsive and biomimetic nano delivery systems, specifically, are emerging as advanced bio-inspired nanocarriers for enhancing the treatment of sepsis. Herein, we present a critical review of different stimuli-responsive systems, including pH-; enzyme-; ROS- and toxin-responsive nanocarriers, reported in the delivery of therapeutics for sepsis. Biomimetic nanocarriers, utilizing natural pathways in the inflammatory cascade to optimize sepsis therapy, are also reviewed, in addition to smart, multifunctional vehicles. The review highlights the nanomaterials designed for constructing these systems; their physicochemical properties; the mechanisms of drug release; and their potential for enhancing the therapeutic efficacy of their cargo. Current challenges are identified and future avenues for research into the optimization of bio-inspired nano delivery systems for sepsis are also proposed. This review confirms the potential of stimuli-responsive and biomimetic nanocarriers for enhanced therapy against sepsis and related complications.

Focus on organoids: cooperation and interconnection with extracellular vesicles - Is this the future of in vitro modeling?

Organoids are simplified in vitro model systems of organs that are used for modeling tissue development and disease, drug screening, cell therapy, and personalized medicine. Despite considerable success in the design of organoids, challenges remain in achieving real-life applications. Organoids serve as unique and organized groups of micro physiological systems that are capable of self-renewal and self-organization. Moreover, they exhibit similar organ functionality(ies) as that of tissue(s) of origin. Organoids can be designed from adult stem cells, induced pluripotent stem cells, or embryonic stem cells. They consist of most of the important cell types of the desired tissue/organ along with the topology and cell-cell interactions that are highly similar to those of an in vivo tissue/organ. Organoids have gained interest in human biomedical research, as they demonstrate high promise for use in basic, translational, and applied research. As in vitro models, organoids offer significant opportunities for reducing the reliance and use of experimental animals. In this review, we will provide an overview of organoids, as well as those intercellular communications mediated by extracellular vesicles (EVs), and discuss the importance of organoids in modeling a tumor immune microenvironment (TIME). Organoids can also be exploited to develop a better understanding of intercellular communications mediated by EVs. Also, organoids are useful in mimicking TIME, thereby offering a better-controlled environment for studying various associated biological processes and immune cell types involved in tumor immunity, such as T-cells, macrophages, dendritic cells, and myeloid-derived suppressor cells, among others.

Organically derived exosomes as carriers of anticancer drugs and imaging agents for cancer treatment

Extracellular vesicles (EVs), is the umbrella term used for different types of vesicles produced by the cells, among which exosomes form the largest group. Exosomes perform intercellular communication by carrying several biologics from donor or parental cells and delivering them to recipient cells. Their unique cargo-carrying capacity has recently been explored for use as delivery vehicles of anticancer drugs and imaging agents. Being naturally produced, exosomes have many advantages over synthetic lipid-based nanoparticles currently being used clinically to treat cancer and other diseases. The finding of the role of exosomes in human diseases has led to numerous preclinical and clinical studies exploring their use as an amenable drug delivery vehicle and a theranostic in cancer diagnosis and treatment. However, there are certain limitations associated with exosomes, with the most important being the selection of the biological source for producing highly biocompatible exosomes on a large scale. This review article explores the various sources from which therapeutically viable exosomes can be isolated for use as drug carriers for cancer treatment. The methods of exosome isolation and the process of loading them with cancer therapeutics and imaging agents are also discussed in the follow-up sections. Finally, the article concludes with future directions for exosome-based applications in cancer diagnosis and treatment.

Recent advances in surface modification of micro- and nano-scale biomaterials with biological membranes and biomolecules

Surface modification of biomaterial can improve its biocompatibility and add new biofunctions, such as targeting specific tissues, communication with cells, and modulation of intracellular trafficking. Here, we summarize the use of various natural materials, namely, cell membrane, exosomes, proteins, peptides, lipids, fatty acids, and polysaccharides as coating materials on micron- and nano-sized particles and droplets with the functions imparted by coating with different materials. We discuss the applicability, operational parameters, and limitation of different coating techniques, from the more conventional approaches such as extrusion and sonication to the latest innovation seen on the microfluidics platform. Methods commonly used in the field to examine the coating, including its composition, physical dimension, stability, fluidity, permeability, and biological functions, are reviewed.

Bench to Bedside: New Therapeutic Approaches with Extracellular Vesicles and Engineered Biomaterials for Targeting Therapeutic Resistance of Cancer Stem Cells

Cancer has recently been the second leading cause of death worldwide, trailing only cardiovascular disease. Cancer stem cells (CSCs), represented as tumor-initiating cells (TICs), are mainly liable for chemoresistance and disease relapse due to their self-renewal capability and differentiating capacity into different types of tumor cells. The intricate molecular mechanism is necessary to elucidate CSC's chemoresistance properties and cancer recurrence. Establishing efficient strategies for CSC maintenance and enrichment is essential to elucidate the mechanisms and properties of CSCs and CSC-related therapeutic measures. Current approaches are insufficient to mimic the in vivo chemical and physical conditions for the maintenance and growth of CSC and yield unreliable research results. Biomaterials are now widely used for simulating the bone marrow microenvironment. Biomaterial-based three-dimensional (3D) approaches for the enrichment of CSC provide an excellent promise for future drug discovery and elucidation of molecular mechanisms. In the future, the biomaterial-based model will contribute to a more operative and predictive CSC model for cancer therapy. Design strategies for materials, physicochemical cues, and morphology will offer a new direction for future modification and new methods for studying the CSC microenvironment and its chemoresistance property. This review highlights the critical roles of the microenvironmental cues that regulate CSC function and endow them with drug resistance properties. This review also explores the latest advancement and challenges in biomaterial-based scaffold structure for therapeutic approaches against CSC chemoresistance. Since the recent entry of extracellular vesicles (EVs), cell-derived nanostructures, have opened new avenues of investigation into this field, which, together with other more conventionally studied signaling pathways, play an important role in cell-to-cell communication. Thus, this review further explores the subject of EVs in-depth. This review also discusses possible future biomaterial and biomaterial-EV-based models that could be used to study the tumor microenvironment (TME) and will provide possible therapeutic approaches. Finally, this review concludes with potential perspectives and conclusions in this area.

Bioengineering Extracellular Vesicles for the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVD) remain one of the leading causes of mortality worldwide. Despite recent advances in diagnosis and interventions, there is still a crucial need for new multifaceted therapeutics that can address the complicated pathophysiological mechanisms driving CVD. Extracellular vesicles (EVs) are nanovesicles that are secreted by all types of cells to transport molecular cargo and regulate intracellular communication. EVs represent a growing field of nanotheranostics that can be leveraged as diagnostic biomarkers for the early detection of CVD and as targeted drug delivery vesicles to promote cardiovascular repair and recovery. Though a promising tool for CVD therapy, the clinical application of EVs is limited by the inherent challenges in EV isolation, standardization, and delivery. Hence, this review will present the therapeutic potential of EVs and introduce bioengineering strategies that augment their natural functions in CVD.

Current understanding of MSC-derived exosomes in the management of knee osteoarthritis

Mesenchymal stem cell-derived exosomes (MSC-Exos) have been utilized as medicinal agents or as delivery vehicles in cartilage injuries and cartilage-based diseases. Given the ongoing emergence of evidence on the effector mechanisms and methods of the utility of the MSC-Exos in knee osteoarthritis, a comprehensive review of the current evidence is the need of the hour. Hence, in this article, we review the current understanding of the role of MSC-Exos in the management of knee osteoarthritis in view of their classification, characterization, biogenesis, mechanism of action, pathways involved in their therapeutic action, in-vitro evidence on cartilage regeneration, in-vivo evidence in OA knee models and recent advances in using MSC-Exos to better streamline future research from bench to bedside for OA knee.

Hybrid extracellular vesicles-liposome incorporated advanced bioink to deliver microRNA

In additive manufacturing, bioink formulations govern strategies to engineer 3D living tissues that mimic the complex architectures and functions of native tissues for successful tissue regeneration. Conventional 3D-printed tissues are limited in their ability to alter the fate of laden cells. Specifically, the efficient delivery of gene expression regulators (i.e. microRNAs (miRNAs)) to cells in bioprinted tissues has remained largely elusive. In this study, we explored the inclusion of extracellular vesicles (EVs), naturally occurring nanovesicles (NVs), into bioinks to resolve this challenge. EVs show excellent biocompatibility, rapid endocytosis, and low immunogenicity, which lead to the efficient delivery of miRNAs without measurable cytotoxicity. EVs were fused with liposomes to prolong and control their release by altering their physical interaction with the bioink. Hybrid EVs-liposome (hEL) NVs were embedded in gelatin-based hydrogels to create bioinks that could efficiently encapsulate and deliver miRNAs at the target site in a controlled and sustained manner. The regulation of cells' gene expression in a 3D bioprinted matrix was achieved using the hELs-laden bioink as a precursor for excellent shape fidelity and high cell viability constructs. Novel regulatory factors-loaded bioinks will expedite the translation of new bioprinting applications in the tissue engineering field.

Application of Cell-Derived Extracellular Vesicles and Engineered Nanovesicles for Hair Growth: From Mechanisms to Therapeutics

Hair loss is one of the most common disorders that affect both male and female patients. Cell-derived nanovesicles (CDVs) are natural extracellular vesicles and engineered nanovesicles that can carry various biologicals materials such as proteins, lipids, mRNA, miRNA, and DNA. These vesicles can communicate with local or distant cells and are capable of delivering endogenous materials and exogenous drugs for regenerative therapies. Recent studies revealed that CDVs can serve as new treatment strategies for hair growth. Herein, we review current knowledge on the role of CDVs in applications to hair growth. The in-depth understanding of the mechanisms by which CDVs enable therapeutic effects for hair growth may accelerate successful clinical translation of these vesicles for treating hair loss.

Small extracellular vesicles encapsulating lefty1 mRNA inhibit hepatic fibrosis

Liver fibrosis is the deposition of extracellular matrix (ECM) in the liver caused by persistent chronic injury, which can lead to more serious diseases such as cirrhosis or cancer. Blocking the effect of transforming growth factor β1 (TGF-β1), one of the most important cytokines in liver fibrosis, may be one of the effective ways to inhibit liver fibrosis. As a kind of natural nano-scale vesicles, small extracellular vesicles (sEvs) have displayed excellent delivery vehicle properties. Herein, we prepared hepatic stellate cell (HSC)-derived sEvs loading left-right determination factor 1 (lefty1) mRNA (sEvLs) and we wanted to verify whether they can inhibit fibrosis by blocking the TGF-β1 signaling pathway. The results showed that sEvLs had effective cell uptake and reduced activation of HSCs. Rats that were injected with CCl₄ by intraperitoneal injection for 6 weeks exhibited obvious symptoms of liver fibrosis and were treated with systemically administered sEvLs and free sEvs for 4 weeks. Rats injected with olive oil alone served as sham controls. Administration of sEvLs significantly reduced the area of fibrosis compared with free sEvs. We demonstrated that sEvLs inhibited HSCs activation and ECM production, and promote ECM degradation by downregulating α-smooth muscle actin (α-SMA), collagen I, tissue inhibitor of metalloproteinase (TIMP) -1 and upregulating matrix metalloprotease (MMP) -1. In summary, as an endogenous delivery vehicle, sEvs could deliver mRNA to attenuate hepatic fibrosis by blocking the TGF-β/Smad signaling pathway.

Drug Delivery Systems with a “Tumor-Triggered” Targeting or Intracellular Drug Release Property Based on DePEGylation

Coating nanosized anticancer drug delivery systems (DDSs) with poly(ethylene glycol) (PEG), the so-called PEGylation, has been proven an effective method to enhance hydrophilicity, aqueous dispersivity, and stability of DDSs. What is more, as PEG has the lowest level of protein absorption of any known polymer, PEGylation can reduce the clearance of DDSs by the mononuclear phagocyte system (MPS) and prolong their blood circulation time in vivo. However, the “stealthy” characteristic of PEG also diminishes the uptake of DDSs by cancer cells, which may reduce drug utilization. Therefore, dynamic protection strategies have been widely researched in the past years. Coating DDSs with PEG through dynamic covalent or noncovalent bonds that are stable in blood and normal tissues, but can be broken in the tumor microenvironment (TME), can achieve a DePEGylation-based “tumor-triggered” targeting or intracellular drug release, which can effectively improve the utilization of drugs and reduce their side effects. In this review, the stimuli and methods of “tumor-triggered” targeting or intracellular drug release, based on DePEGylation, are summarized. Additionally, the targeting and intracellular controlled release behaviors of the DDSs are briefly introduced.

CAR T-Cell-Based gene therapy for cancers: new perspectives, challenges, and clinical developments

Chimeric antigen receptor (CAR)-T cell therapy is a progressive new pillar in immune cell therapy for cancer. It has yielded remarkable clinical responses in patients with B-cell leukemia or lymphoma. Unfortunately, many challenges remain to be addressed to overcome its ineffectiveness in the treatment of other hematological and solidtumor malignancies. The major hurdles of CAR T-cell therapy are the associated severe life-threatening toxicities such as cytokine release syndrome and limited anti-tumor efficacy. In this review, we briefly discuss cancer immunotherapy and the genetic engineering of T cells and, In detail, the current innovations in CAR T-cell strategies to improve efficacy in treating solid tumors and hematologic malignancies. Furthermore, we also discuss the current challenges in CAR T-cell therapy and new CAR T-cell-derived nanovesicle therapy. Finally, strategies to overcome the current clinical challenges associated with CAR T-cell therapy are included as well.

Biodistribution, pharmacokinetics and excretion studies of intravenously injected nanoparticles and extracellular vesicles: Possibilities and challenges

There is a large interest in developing nanoparticles and extracellular vesicles for delivery of therapeutics or imaging agents. Regulatory approval of such products requires knowledge about their biodistribution, metabolism and excretion. We here discuss possibilities and challenges of methods used for such studies, which most often are performed after labelling with radioactive isotopes or fluorescent molecules. It is important to evaluate if the labelled and unlabeled products can be expected to behave similarly in the body. Furthermore, one needs to critically consider whether the labels are still associated with the product at the time of analyses. We discuss advantages and disadvantages of different imaging modalities such as PET, SPECT, MRI, CT, ultrasound and optical imaging for whole-body biodistribution, and describe how to estimate the amount of labelled product in harvested organs and tissue. Microscopy of cells and tissues and various mass spectrometry methods are also discussed in this review.

Convalescent serum-derived exosomes: Attractive niche as COVID-19 diagnostic tool and vehicle for mRNA delivery

The spread of SARS-CoV-2 over the entire world is more commonly known as COVID-19. COVID-19 has impacted society in every aspect of routine life. SARS-CoV-2 infection is often misdiagnosed as influenza or seasonal upper respiratory tract viral infections. General diagnostic tools can detect the viral antigen or isotypes of antibodies. However, inter- and intraindividual variations in antibody levels can cause false negatives in antibody immunoassays. On the contrary, the false-positive test results can also occur due to either cross-reactivity of the viral antigens or some other patient-related autoimmune factors. There is need for a cogent diagnostic tool with more specificity, selectivity, and reliability. Here, we have described the potential of convalescent serum-derived exosome as a diagnostic tool for the detection of SARS-CoV-2, even in asymptomatic patients, which is a limitation for currently practiced diagnostic tests throughout the globe. In addition, its potential as a vehicle for messenger RNA (mRNA) delivery is also emphasized.

Identification of Angiogenic Cargoes in Human Fibroblasts-Derived Extracellular Vesicles and Induction of Wound Healing

A complete redevelopment of the skin remains a challenge in the management of acute and chronic wounds. Recently, the application of extracellular vesicles (EVs) for soft tissue wound healing has received much attention. As fibroblasts are fundamental cells for soft tissues and skin, we investigate the proangiogenic factors in human normal fibroblast-derived EVs (hNF-EVs) and their effects on wound healing. Normal fibroblasts were isolated from human skin tissues and characterized by immunofluorescence (IF) and Western blotting (WB). hNF-EVs were isolated by ultracentrifugation and characterized using transmission electron microscopy and WB. The proangiogenic cargos in hNF-EVs were identified by a TaqMan assay and a protein array. Other in vitro assays, including internalization assays, cell counting kit-8 analysis, scratch wound assays, WBs, and tube formation assays were conducted to assess the effects of hNF-EVs on fibroblasts and endothelial cells. A novel scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue was applied onto full-thickness skin wounds in mice. The wound healing therapeutical effect of hNF-EVs was assessed by calculating the rate of wound closure and through histological analysis. Isolated hNF was confirmed by verifying the expression of the fibroblast markers vimentin, αSMA, Hsp70, and S100A4. Isolated hNF-EVs showed intact EVs with round morphology, enriched in CD81 and CD63, and devoid of the cell markers GM130, Calnexin, and Cytochrome C. Our TaqMan assay showed that hNF-EVs were enriched in miR130a and miR210, and protein arrays showed enriched levels of the proangiogenic proteins’ vascular endothelial growth factor (VEGF)-D and CXCL8. Next, we found that the internalization of hNF-EVs into hNF increased the proliferation and migration of hNF, in addition to increasing the expression of bFGF, MMP2, and αSMA. The internalization of hNF-EVs into the endothelial cells increased their proliferation and tube formation. A scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue accelerated the wound healing rate in full-thickness skin wounds in mice, and the treatments increased the cellular density, deposition, and maturation of collagens in the wounds. Moreover, the scaffold-free noninvasive delivery of hNF-EVs with or without fibrin glue increased the VEGF and CD31 expression in the wounds, indicating that hNF-EVs have an angiogenic ability to achieve complete skin regeneration. These findings open up for new treatment strategies to be developed for wound healing. Further, we offer a new approach to the efficient, scaffold-free noninvasive delivery of hNF-EVs to wounds.

Extracellular Vesicles as Novel Drug-Delivery Systems through Intracellular Communications

Since it has been reported that extracellular vesicles (EVs) carry cargo using cell-to-cell comminication according to various in vivo situations, they are exprected to be applied as new drug-delivery systems (DDSs). In addition, non-coding RNAs, such as microRNAs (miRNAs), have attracted much attention as potential biomarkers in the encapsulated extracellular-vesicle (EV) form. EVs are bilayer-based lipids with heterogeneous populations of varying sizes and compositions. The EV-mediated transport of contents, which includes proteins, lipids, and nucleic acids, has attracted attention as a DDS through intracellular communication. Many reports have been made on the development of methods for introducing molecules into EVs and efficient methods for introducing them into target vesicles. In this review, we outline the possible molecular mechanisms by which miRNAs in exosomes participate in the post-transcriptional regulation of signaling pathways via cell–cell communication as novel DDSs, especially small EVs.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Biological Carriers for Drug Delivery in Cancer Therapy

Cancer is the second leading cause of death worldwide, with 10.0 million cancer deaths in 2020. Despite advances in targeted therapies, some pharmacological drawbacks associated with anticancer chemo and immunotherapeutic agents include high toxicities, low bioavailability, and drug resistance. In recent years, extracellular vesicles emerged as a new promising platform for drug delivery, with the advantage of their inherent biocompatibility and specific targeting compared to artificial nanocarriers, such as liposomes. Particularly, mesenchymal stem/stromal cells were proposed as a source of extracellular vesicles for cancer therapy because of their intrinsic properties: high in vitro self-renewal and proliferation, regenerative and immunomodulatory capacities, and secretion of extracellular vesicles that mediate most of their paracrine functions. Moreover, extracellular vesicles are static and safer in comparison with mesenchymal stem/stromal cells, which can undergo genetic/epigenetic or phenotypic changes after their administration to patients. In this review, we summarize currently reported information regarding mesenchymal stem/stromal cell-derived extracellular vesicles, their proper isolation and purification techniques - from either naive or engineered mesenchymal stem/stromal cells - for their application in cancer therapy, as well as available downstream modification methods to improve their therapeutic properties. Additionally, we discuss the challenges associated with extracellular vesicles for cancer therapy, and we review some preclinical and clinical data available in the literature.

The Relation Between Extracellular Vesicles Released From Red Blood Cells, Their Cargo, and the Clearance by Macrophages

Extracellular vesicles (EVs) are cell-derived membrane particles that include exosomes, ectosomes, microvesicles, microparticles, apoptotic bodies, and other EV subsets. EVs are involved in intercellular communication and the transport of macromolecules between cells. Here, we propose and test the ability of red blood cell (RBC)-derived EVs (RBC-EVs) as putative drug carriers. EVs were produced by treating RBCs with Phorbol-12-myristate-13-acetate (PMA) and separating from the cells by differential centrifugation steps. RBC-EVs were characterized by size determination, flow cytometry, and scanning electron microscopy (SEM). EVs were loaded with DNA plasmids coding for the green fluorescent protein (GFP) by electroporation. The DNA-loaded EVs (DNA-EVs) were used to transfect THP-1-derived macrophages and analyzed by fluorescence microscopy and flow cytometry. The results showed that RBC-EVs had an almost spherical shape and a polydispersity in their size with an average of 197 ± 44 nm and with a zeta potential of −36 ± 8 mV. RBC-EVs were successfully loaded with DNA but associated with an increase of the polydispersity index (PdI) and showed a positive signal with Picogreen. DNA-EVs were almost completely taken up by macrophages within 24 h, however, resulting in the expression of the GFP in a subpopulation of macrophages. As the way, we designed that RBC-EVs could be potential nucleic acid carriers when the immune system was addressed. This study may contribute to the understanding of the role of EVs in the development of microvesicle-based vehicles.

Extracellular Vesicles Mediate the Intercellular Exchange of Nanoparticles

To exert their therapeutic effects, nanoparticles (NPs) often need to travel into the tissues composed of multilayered cells. Accumulative evidence has revealed the crucial role of transcellular transport route (entry into one cell, exocytosis, and re-entry into another) in this process. While NP endocytosis and subcellular transport are intensively characterized, the exocytosis and re-entry steps are poorly understood, which becomes a barrier for NP delivery into complex tissues. Here, the authors term the exocytosis and re-entry steps together as intercellular exchange. A collagen-based three-dimension assay is developed to specifically quantify the intercellular exchange of NPs, and distinguish the contributions of several potential mechanisms. The authors show that NPs can be exocytosed freely or enclosed inside extracellular vesicles (EVs) for re-entry, while direct cell-cell contact is hardly involved. EVs account for a significant fraction of NP intercellular exchange, and its importance in NP transport is demonstrated in vitro and in vivo. While freely released NPs engage with the same receptors for re-entry, EV-enclosed ones bypass this dependence. These studies provide an easy and precise system to investigate the intercellular exchange stage of NP delivery, and shed the first light in the importance of EVs in NP transport between cells and into complex tissues.

Exosomes in Parkinson: Revisiting Their Pathologic Role and Potential Applications

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by bradykinesia, rigidity, and tremor. Considerable progress has been made to understand the exact mechanism leading to this disease. Most of what is known comes from the evidence of PD brains' autopsies showing a deposition of Lewy bodies-containing a protein called α-synuclein (α-syn)-as the pathological determinant of PD. α-syn predisposes neurons to neurotoxicity and cell death, while the other associated mechanisms are mitochondrial dysfunction and oxidative stress, which are underlying precursors to the death of dopaminergic neurons at the substantia nigra pars compacta leading to disease progression. Several mechanisms have been proposed to unravel the pathological cascade of these diseases; most of them share a particular similarity: cell-to-cell communication through exosomes (EXOs). EXOs are intracellular membrane-based vesicles with diverse compositions involved in biological and pathological processes, which their secretion is driven by the NLR family pyrin domain-containing three proteins (NLRP3) inflammasome. Toxic biological fibrils are transferred to recipient cells, and the disposal of damaged organelles through generating mitochondrial-derived vesicles are suggested mechanisms for developing PD. EXOs carry various biomarkers; thus, they are promising to diagnose different neurological disorders, including neurodegenerative diseases (NDDs). As nanovesicles, the applications of EXOs are not only restricted as diagnostics but also expanded to treat NDDs as therapeutic carriers and nano-scavengers. Herein, the aim is to highlight the potential incrimination of EXOs in the pathological cascade and progression of PD and their role as biomarkers and therapeutic carriers for diagnosing and treating this neuro-debilitating disorder.

Cytochalasin B Treatment and Osmotic Pressure Enhance the Production of Extracellular Vesicles (EVs) with Improved Drug Loading Capacity

Extracellular vesicles (EVs) have been highlighted as novel drug carriers due to their unique structural properties and intrinsic features, including high stability, biocompatibility, and cell-targeting properties. Although many efforts have been made to harness these features to develop a clinically effective EV-based therapeutic system, the clinical translation of EV-based nano-drugs is hindered by their low yield and loading capacity. Herein, we present an engineering strategy that enables upscaled EV production with increased loading capacity through the secretion of EVs from cells via cytochalasin-B (CB) treatment and reduction of EV intravesicular contents through hypo-osmotic stimulation. CB (10 µg/mL) promotes cells to extrude EVs, producing ~three-fold more particles than through natural EV secretion. When CB is induced in hypotonic conditions (223 mOsm/kg), the produced EVs (hypo-CIMVs) exhibit ~68% less intravesicular protein, giving 3.4-fold enhanced drug loading capacity compared to naturally secreted EVs. By loading doxorubicin (DOX) into hypo-CIMVs, we found that hypo-CIMVs efficiently deliver their drug cargos to their target and induce up to ~1.5-fold more cell death than the free DOX. Thus, our EV engineering offers the potential for leveraging EVs as an effective drug delivery vehicle for cancer treatment.

Transformable vesicles for cancer immunotherapy

Immunotherapy that utilizes the human immune system to fight cancer represents a revolutionary method for cancer treatment. Immunotherapeutic agents that trigger the immune response should be carefully delivered to the desired site to maximize immunotherapy effectiveness and minimize side effects. Vesicles offer the possibility of encapsulating both hydrophilic and hydrophobic drugs and thus serve as a promising delivery tool. As multiple irreconcilable requirements exist at different transport stages, developing vesicles transformable in response to given stimuli is of great significance. In this review, we first introduced various vesicle types used for immunotherapy. Furthermore, the typical stimuli that trigger vesicle transformation and the usually generated transformation styles were described. Focusing on three aspects of antigen-presenting cell (APC)/T cell activation, tumor microenvironment (TME) amelioration, and immunogenic cell death (ICD)-induced immunotherapy, we reviewed recently reported transformable vesicles for tumor treatment. Finally, we put forward possible directions for future research and clinical translation.

Topical Administration of Melatonin-Loaded Extracellular Vesicle-Mimetic Nanovesicles Improves 2,4-Dinitrofluorobenzene-Induced Atopic Dermatitis

Atopic dermatitis (AD) is caused by multiple factors that trigger chronic skin inflammation, including a defective skin barrier, immune cell activation, and microbial exposure. Although melatonin has an excellent biosafety profile and a potential to treat AD, there is limited clinical evidence from controlled trials that support the use of melatonin as an AD treatment. The delivery of melatonin via the transdermal delivery system is also a challenge in designing melatonin-based AD treatments. In this study, we generated melatonin-loaded extracellular vesicle-mimetic nanoparticles (MelaNVs) to improve the transdermal delivery of melatonin and to evaluate their therapeutic potential in AD. The MelaNVs were spherical nanoparticles with an average size of 100 nm, which is the optimal size for the transdermal delivery of drugs. MelaNVs showed anti-inflammatory effects by suppressing the release of TNF-α and β-hexosaminidase in LPS-treated RAW264.7 cells and compound 48/80-treated RBL-2H3 cells, respectively. MelaNVs showed a superior suppressive effect compared to an equivalent concentration of free melatonin. Treating a 2,4-dinitrofluorobenzene (DNCB)-induced AD-like mouse model with MelaNVs improved AD by suppressing local inflammation, mast cell infiltration, and fibrosis. In addition, MelaNVs effectively suppressed serum IgE levels and regulated serum IFN-γ and IL-4 levels. Taken together, these results suggest that MelaNVs are novel and efficient transdermal delivery systems of melatonin and that MelaNVs can be used as a treatment to improve AD.

Extracellular Vesicles as Therapeutic Tools for the Treatment of Chronic Wounds

Chronic wounds develop when the orderly process of cutaneous wound healing is delayed or disrupted. Development of a chronic wound is associated with significant morbidity and financial burden to the individual and health-care system. Therefore, new therapeutic modalities are needed to address this serious condition. Mesenchymal stem cells (MSCs) promote skin repair, but their clinical use has been limited due to technical challenges. Extracellular vesicles (EVs) are particles released by cells that carry bioactive molecules (lipids, proteins, and nucleic acids) and regulate intercellular communication. EVs (exosomes, microvesicles, and apoptotic bodies) mediate key therapeutic effects of MSCs. In this review we examine the experimental data establishing a role for EVs in wound healing. Then, we explore techniques for designing EVs to function as a targeted drug delivery system and how EVs can be incorporated into biomaterials to produce a personalized wound dressing. Finally, we discuss the status of clinically deploying EVs as a therapeutic agent in wound care.

Development of Extracellular Vesicle Therapeutics: Challenges, Considerations, and Opportunities

Extracellular vesicles (EVs) hold great promise as therapeutic modalities due to their endogenous characteristics, however, further bioengineering refinement is required to address clinical and commercial limitations. Clinical applications of EV-based therapeutics are being trialed in immunomodulation, tissue regeneration and recovery, and as delivery vectors for combination therapies. Native/biological EVs possess diverse endogenous properties that offer stability and facilitate crossing of biological barriers for delivery of molecular cargo to cells, acting as a form of intercellular communication to regulate function and phenotype. Moreover, EVs are important components of paracrine signaling in stem/progenitor cell-based therapies, are employed as standalone therapies, and can be used as a drug delivery system. Despite remarkable utility of native/biological EVs, they can be improved using bio/engineering approaches to further therapeutic potential. EVs can be engineered to harbor specific pharmaceutical content, enhance their stability, and modify surface epitopes for improved tropism and targeting to cells and tissues in vivo. Limitations currently challenging the full realization of their therapeutic utility include scalability and standardization of generation, molecular characterization for design and regulation, therapeutic potency assessment, and targeted delivery. The fields' utilization of advanced technologies (imaging, quantitative analyses, multi-omics, labeling/live-cell reporters), and utility of biocompatible natural sources for producing EVs (plants, bacteria, milk) will play an important role in overcoming these limitations. Advancements in EV engineering methodologies and design will facilitate the development of EV-based therapeutics, revolutionizing the current pharmaceutical landscape.

Overview of the Therapeutic Applications of Stem Cell-Derived Exosomes: A Research and Commercial Perspective

Progress in extracellular vesicle (EV) research over the past two decades has generated significant interest in using EVs in the biomedical field. Exosomes are a subgroup of EVs that comprise endocytic membrane-bound nanovesicles of 40 to 160 nm diameter. These vesicles have been shown to facilitate intercellular communication via the delivery of cellular molecules. There are currently several exciting applications for exosomes being developed in therapeutics, diagnostics, drug delivery, and cellular reprogramming. Stem cell-derived exosomes present the opportunity to harness the power of stem cells while circumventing several of the risks associated with their use. This review summarizes the recent developments in exosome technology and lends a prospective view to the future of exosome use and application in research and medicine. Through a review of relevant patent filings, recent literature, and ongoing clinical trials, a valuable overview of the field of exosomes is provided. © 2021 Wiley Periodicals LLC.