Physiological models for in vivo imaging and targeting the lymphatic system: Nanoparticles and extracellular vesicles

Lymphangiogenesis orchestrating tumor microenvironment: Face changing in immunotherapy

In the era of immunotherapy, the lymphatic system has garnered significant attention from researchers. Increasing evidence highlights the complex regulation of lymphatic vessels (LVs) within the tumor microenvironment, unveiling a paradox in tumor progression: while LVs enhance immune surveillance, they simultaneously foster immune suppression. This review summarizes the regulatory factors of lymphangiogenesis, discusses the intricate effects of LVs on immunotherapy, and emphasizes the potential connection between lymphangiogenesis and tertiary lymphoid structure. Additionally, current therapeutic strategies targeting lymphangiogenesis are critically evaluated, with a forward-looking perspective on future research directions and regulatory approaches to achieve precise targeting and optimize immunotherapy paradigms.

IGF2BP3 Triggers STAT3 Pathway by Stabilizing SRC RNA in an m6A-Dependent Manner to Promote Lymphatic Metastasis in LUAD

Lymph node metastasis significantly affects the NSCLC patients' staging, treatment strategy, and prognosis. Studies have shown that IGF2BP3, an oncofetal protein and an m6A reader, overexpresses and correlates to lymph node metastasis and worse overall survival in histopathological studies including NSCLC, but its mechanism needs further study. This study explored IGF2BP3's function and mechanism in LUAD lymphatic metastasis using public databases, a human LUAD tissue microarray, human LUAD cells, and a lymphatic metastasis model in male BALB/c nude mice. Firstly, we proved that IGF2BP3 overexpression was positively correlated to patients' lymph node metastasis and worse overall survival in bioinformatics and a human LUAD tissue microarray analysis. IGF2BP3 was knocked out or overexpressed in human LUAD cell lines. Functionally, IGF2BP3 facilitated NCI-H1299, NCI-H358, and A549 cell growth, migration, invasion, and EMT in vitro, and promoted tumorigenesis, lymphangiogenesis, and lymphatic metastasis of NCI-H1299 cells in BALB/c nude mice. Mechanically, RIP, RNA pull-down assay, MeRIP, mRNA stability assays, rescue experiments, and immunohistochemical assays were conducted. IGF2BP3 was demonstrated to bind to the m6A site of the 3'UTR region of SRC, stabilizing its mRNA and activating the downstream STAT3 signaling pathway and lymphatic growth factors such as VEGF-C, therefore affecting lymphatic metastasis. The cell migration and EMT function of IGF2BP3 were partially rescued by utilizing SRC siRNA or AZD0530, an SRC inhibitor. This study demonstrated that IGF2BP3 promotes lymphatic metastasis in LUAD via activating the m6A-SRC-STAT3-VEGFC signaling axis, indicating that IGF2BP3 is a potential therapeutic target to overcome metastasis in LUAD patients.

An Update on the Role of Lymphatic Function in Skin Inflammatory Disorders: A Scoping Review

The lymphatic system is essential in maintaining skin health through coordinated immunological actions. This review explores the relationship between lymphatic function and skin health, as well as the impact of lymphatic dysfunction in the development and progression of inflammatory skin disorders. A systemic search was conducted in the Web of Science, Embase, and Ovid MEDLINE databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. Included studies were peer-reviewed human or animal research published in English from 2014 to 2024, focusing on inflammatory skin disorders, including skin cancer, autoimmune skin diseases, and infectious skin diseases. A total of 1232 citations were identified, with 37 studies meeting the eligibility criteria after assessment and critical appraisal. The review's findings highlight the essential role of lymphatics in maintaining skin health, mitigating inflammatory, infectious, and skin cancer-related processes, and delaying the effects of skin aging. The mechanisms underlying lymphatic function in these processes are complex, with some aspects needing further investigation. However, the evidence indicates that a well-functioning skin lymphatic system, supported by various cytokines, aids in reducing the inflammatory state, reduces inflammation, alleviates lymphedema, and prevents lymphatic stasis, which can increase infection risk. Several studies demonstrated that restoring lymphatic function through improved neutrophil migration and cytokine responses reduces the spread of infectious diseases.

The Lymphatic Vascular System in Extracellular Vesicle-Mediated Tumor Progression

Tumor growth and progression require molecular interactions between malignant and host cells. In recent years, extracellular vesicles (EVs) emerged as an important pillar of such interactions, carrying molecular information from their donor cells to distant recipient cells. Thereby, the phenotype and function of the recipient cells are altered, which may facilitate tumor immune escape and tumor metastasis to other organs through the formation of pre-metastatic niches. A prerequisite for these effects of tumor cell-derived EVs is an efficient transport system from the site of origin to the body periphery. Here, we highlight the role of the lymphatic vascular system in the distribution and progression-promoting functions of tumor cell-derived EVs. Importantly, the lymphatic vascular system is the primary drainage system for interstitial fluid and its soluble, particulate, and cellular contents, and therefore represents the principal route for regional (i.e., to tumor-draining lymph nodes) and systemic distribution of EVs derived from solid tumors. Furthermore, recent studies highlighted the tumor-draining lymph node as a crucial site where tumor-derived EVs exert their effects. A deeper mechanistic understanding of how EVs gain access to the lymphatic vasculature, how they interact with their recipient cells in tumor-draining lymph nodes and beyond, and how they induce phenotypic and functional maladaptation will be instrumental to identify new molecular targets and conceive innovative approaches for cancer therapy.

Mechanisms of lymph node metastasis: An extracellular vesicle perspective

In several solid tumors such as breast cancer, prostate cancer, colorectal cancer or melanoma, tumor draining lymph nodes are the earliest tissues where colonization by tumor cells is detected. Lymph nodes act as sentinels of metastatic dissemination, the deadliest phase of tumor progression. Besides hematogenous dissemination, lymphatic spread of tumor cells has been demonstrated, adding more complexity to the mechanisms involved in metastasis. A network of blood and lymphatic vessels surrounds tumors providing routes for tumor soluble factors to mediate regional and long-distance effects. Additionally, extracellular vesicles (EVs), particularly small EVs/exosomes, have been shown to circulate through the blood and lymph, favoring the formation of pre-metastatic niches in the tumor-draining lymph nodes (TDLNs) and distant organs. In this review, we present an overview of the relevance of lymph node metastasis, the structural and immune changes occurring in TDLNs during tumor progression, and how extracellular vesicles contribute to modulating some of these alterations while promoting the formation of lymph node pre-metastatic niches.

Interactions between nanoparticles and lymphatic systems: Mechanisms and applications in drug delivery

The lymphatic system has garnered significant attention in drug delivery research due to the advantages it offers, such as enhancing systemic exposure and enabling lymph node targeting for nanomedicines via the lymphatic delivery route. The journey of drug carriers involves transport from the administration site to the lymphatic vessels, traversing the lymph before entering the bloodstream or targeting specific lymph nodes. However, the anatomical and physiological barriers of the lymphatic system play a pivotal role in influencing the behavior and efficiency of carriers. To expedite research and subsequent clinical translation, this review begins by introducing the composition and classification of the lymphatic system. Subsequently, we explore the routes and mechanisms through which nanoparticles enter lymphatic vessels and lymph nodes. The review further delves into the interactions between nanomedicine and body fluids at the administration site or within lymphatic vessels. Finally, we provide a comprehensive overview of recent advancements in lymphatic delivery systems, addressing the challenges and opportunities inherent in current systems for delivering macromolecules and vaccines.

Improved Neural Inductivity of Size-Controlled 3D Human Embryonic Stem Cells Using Magnetic Nanoparticles

Background: To improve the efficiency of neural development from human embryonic stem cells, human embryoid body (hEB) generation is vital through 3-dimensional formation. However, conventional approaches still have limitations: long-term cultivation and laborious steps for lineage determination. Methods: In this study, we controlled the size of hEBs for ectodermal lineage specification using cell-penetrating magnetic nanoparticles (MNPs), which resulted in reduced time required for initial neural induction. The magnetized cells were applied to concentrated magnetic force for magnet-derived multicellular organization. The uniformly sized hEBs were differentiated in neural induction medium (NIM) and suspended condition. This neurally induced MNP-hEBs were compared with other groups. Results: As a result, the uniformly sized MNP-hEBs in NIM showed significantly improved neural inductivity through morphological analysis and expression of neural markers. Signaling pathways of the accelerated neural induction were detected via expression of representative proteins; Wnt signaling, dopaminergic neuronal pathway, intercellular communications, and mechanotransduction. Consequently, we could shorten the time necessary for early neurogenesis, thereby enhancing the neural induction efficiency. Conclusion: Overall, this study suggests not only the importance of size regulation of hEBs at initial differentiation stage but also the efficacy of MNP-based neural induction method and stimulations for enhanced neural tissue regeneration.

Potential applications of using tissue-specific EVs in targeted therapy and vaccinology

Many cell types secrete spherical membrane bodies classified as extracellular vesicles (EVs). EVs participate in intercellular communication and are present in body fluids, including blood, lymph, and cerebrospinal fluid. The time of EVs survival in the body varies depending on the body's localisation. Once the EVs reach cells, they trigger a cellular response. Three main modes of direct interaction of EVs with a target cell were described: receptor-ligand interaction mode, a direct fusion of EVs with the cellular membrane and EVs internalisation. Studies focused on the medical application of EVs. Medical application of EVs may require modification of their surface and interior. EVs surface was modified by affecting the parental cells or by the direct amendment of isolated EVs. The interior modification involved introducing materials into the cells or direct administrating isolated EVs. EVs carry proteins, lipids, fragments of DNA, mRNA, microRNA (miRNA) and long non-coding RNA. Because of EVs availability in liquid biopsy, they are potential diagnostic markers. Modified EVs could enhance the treatment of diseases such as colorectal cancer, Parkinson's disease, leukaemia or liver fibrosis. EVs have specific tissue tropisms, which makes them convenient organ-directed carriers of nucleic acids, drugs and vaccines. In conclusion, recently published works have shown that EVs could become biomarkers and modern vehicles of advanced drug forms.

NIR-II Fluorescence Imaging for the Detection and Resection of Cancerous Foci and Lymph Nodes in Early-Stage Orthotopic and Advanced-Stage Metastatic Ovarian Cancer Models

The high mortality rate of ovarian cancer can be primarily attributed to late diagnosis and early lymph node (LN) metastasis. The anatomically deep-located ovaries own intricate anatomical structures and lymphatic drainages that compromise the resolution and sensitivity of near-infrared first-window (NIR-I) fluorescence imaging. Reported NIR-II imaging studies of ovarian cancer focused on late-stage metastasis detection via the intraperitoneal xenograft model. However, given the significant improvement in patient survival associated with early-stage cancer detection, locating tumors that are restricted within the ovary is equally crucial. We obtained the polymer nanoparticles with bright near-infrared-II fluorescence (NIR-II NPs) by nanoprecipitation of DSPE-PEG, one of the ingredients of FDA-approved nanoparticle products, and benzobisthiadiazole, an organic NIR-II dye. The one-step synthesis and safe component lay the groundwork for its clinical translation. Benefiting from the NIR-II emission (∼1060 nm), NIR-II NPs enabled a high signal-to-noise (S/N) ratio (13.4) visualization of early-stage orthotopic ovarian tumors with NIR-II fluorescence imaging for the first time. Imaging with orthotopic xenograft allows a more accurate mimic of human ovarian cancer origin, thereby addressing the dilemma of translating existing nanoprobe preclinical research by providing the nano-bio interactions with early local tumor environments. After PEGylation, the desirable-sized probe (∼80 nm) exhibited high lymphophilicity and relatively extended circulation. NIR-II NPs maintained their accurate detection of orthotopic tumors, tumor-regional LNs, and minuscule (<1 mm) disseminated peritoneal metastases simultaneously (with S/N ratios all above 5) in mice with advanced-stage cancer in real time ∼36 h after systematic delivery. With NIR-II fluorescence guidance, we achieved accurate surgical staging in tumor-bearing mice and complete tumor removal comparable to clinical practice, which provides preclinical data for translating NIR-II fluorescence image-guided surgery.

Non-invasive molecular imaging for precision diagnosis of metastatic lymph nodes: opportunities from preclinical to clinical applications

Lymph node metastasis is an indicator of the invasiveness and aggressiveness of cancer. It is a vital prognostic factor in clinical staging of the disease and therapeutic decision-making. Patients with positive metastatic lymph nodes are likely to develop recurrent disease, distant metastasis, and succumb to death in the coming few years. Lymph node dissection and histological analysis are needed to detect whether regional lymph nodes have been infiltrated by cancer cells and determine the likely outcome of treatment and the patient's chances of survival. However, these procedures are invasive, and tissue biopsies are prone to sampling error. In recent years, advanced molecular imaging with novel imaging probes has provided new technologies that are contributing to comprehensive management of cancer, including non-invasive investigation of lymphatic drainage from tumors, identifying metastatic lymph nodes, and guiding surgeons to operate efficiently in patients with complex lesions. In this review, first, we outline the current status of different molecular imaging modalities applied for lymph node metastasis management. Second, we summarize the multi-functional imaging probes applied with the different imaging modalities as well as applications of cancer lymph node metastasis from preclinical studies to clinical translations. Third, we describe the limitations that must be considered in the field of molecular imaging for improved detection of lymph node metastasis. Finally, we propose future directions for molecular imaging technology that will allow more personalized treatment plans for patients with lymph node metastasis.

Extracellular vesicles and melanoma: New perspectives on tumor microenvironment and metastasis

Secreted extracellular vesicles (EVs) are lipid bilayer particles without functional nucleus naturally released from cells which constitute an intercellular communication system. There is a broad spectrum of vesicles shed by cells based on their physical properties such as size (small EVs and large EVs), biogenesis, cargo and functions, which provide an increasingly heterogenous landscape. In addition, they are involved in multiple physiological and pathological processes. In cancer, EV release is opted by tumor cells as a beneficial process for tumor progression. Cutaneous melanoma is a cancer that originates from the melanocyte lineage and shows a favorable prognosis at early stages. However, when melanoma cells acquire invasive capacity, it constitutes the most aggressive and deadly skin cancer. In this context, extracellular vesicles have been shown their relevance in facilitating melanoma progression through the modulation of the microenvironment and metastatic spreading. In agreement with the melanosome secretory capacity of melanocytes, melanoma cells display an enhanced EV shedding activity that has contributed to the utility of melanoma models for unravelling EV cargo and functions within a cancer scenario. In this review, we provide an in-depth overview of the characteristics of melanoma-derived EVs and their role in melanoma progression highlighting key advances and remaining open questions in the field.

Biological Features of Extracellular Vesicles and Challenges

Extracellular vesicles (EVs) are vesicles with a lipid bilayer membrane on the outside, which are widely found in various body fluids and contain biological macromolecules such as DNA, RNA, lipids and proteins on the inside. EVs were once thought to be vesicles for the removal of waste materials, but are now known to be involved in a variety of pathophysiological processes in many diseases. This study examines the advantage of EVs and the challenges associated with their application. A more rational use of the advantageous properties of EVs such as composition specificity, specific targeting, circulatory stability, active penetration of biological barriers, high efficient drug delivery vehicles and anticancer vaccines, oxidative phosphorylation activity and enzymatic activity, and the resolution of shortcomings such as isolation and purification methods, storage conditions and pharmacokinetics and biodistribution patterns during drug delivery will facilitate the clinical application of EVs.

Lymphatic targeting for therapeutic application using nanoparticulate systems

The lymphatic system has grasped attention of researchers to a greater extent. The conventional methods of lymphatic delivery are now being modified to include nanotechnology to enhance the targeting of the drug at the specific pathological site. Scientists have worked successfully on different drug loaded nanocarriers that are modulated for the lymphatic system targeting for the treatment of various fatal diseases. Huge strides have been made in methods of delivery of these drugs either individually or in combination along with nanoparticles, therapeutic genes, and vaccines. However, the products introduced for commercial use are almost near nil. Altogether, there are challenges that need to be resolved and studies that are meant to be done for further improvements. The current review focuses on the understanding and pathophysiology of the lymphatic system and changes that occur during disease, drug characteristics, and physicochemical parameters that influence the lymphatic uptake of drugs and different nanocarriers. We further highlight different potential results obtained over the years with nanocarriers and other delivery methods to effectively target the lymphatic system for their therapeutic application. The challenges and drawbacks governing the lack of products available clinically have also been discussed.

Imaging of fluorescent polymer dots in relation to channels and immune cells in the lymphatic system

Polymer dots (Pdots) have been applied to imaging lymph nodes (LNs) and lymphatic vessels (LVs) in living mice and rats. However, the mechanism of absorption, distribution, metabolism, and excretion of Pdots in LNs and LVs is still unclear. Therefore, the relationship between Pdots and immune cells, LVs and collagen fibers in lymphatics was studied by multiple in vivo and ex vivo microscopic imaging methods and detection techniques. Flow cytometry showed that Pdots could be phagocytosed by macrophages and monocytes, and had no relationship with B cells, T cells and dendric cells in LNs. Silver staining, immunofluorescence and two-photon microscope showed that Pdots gathered in collagen fibers and LVs of LNs. Furthermore, immunofluorescence imaging results verified that Pdots were distributed in the extracellular space of collecting LVs endothelial cells. In addition, Pdots in the collecting LVs were basically cleared by leaking into the surrounding tissue or draining LNs after 21 days of injection. During the long-time observation, Pdots also helped monitor the contraction frequency and variation range of LV. Our study lays a foundation on the research of Pdots as the carrier to study lymphatic structure and function in the future.

Near-Infrared-II Quantum Dots for In Vivo Imaging and Cancer Therapy

In vivo fluorescence imaging can perform real-time, noninvasive, and high spatiotemporal resolution imaging to accurately obtain the dynamic biological information in vivo, which plays significant roles in the early diagnosis and treatment of cancer. However, traditional in vivo fluorescence imaging usually operates in the visible and near-infrared (NIR)-I windows, which are severely interfered by the strong tissue absorption, tissue scattering, and autofluorescence. The emergence of NIR-II imaging at 1000-1700 nm significantly breaks through the imaging limitations in deep tissues, due to less tissue scattering and absorption. Benefiting from the outstanding optical properties of NIR-II quantum dots (QDs), such as high brightness and good photostability, in vivo fluorescence imaging exhibits excellent temporal-spatial resolution and large penetration depth, and QDs have become a kind of promising fluorescent biomarkers in the field of in vivo fluorescence imaging. Herein, the authors review NIR-II QDs from preparation to modification, and summarize recent applications of NIR-II QDs, including in vivo imaging and imaging-guided therapies. Finally, they discuss the special concerns when NIR-II QDs are shifted from in vivo imaging applications to further in-depth applications.

Multifunctional Nanosystems with Enhanced Cellular Uptake for Tumor Therapy

Rapid development of nanotechnology provides promising strategies in biomedicine, especially in tumor therapy. In particular, the cellular uptake of nanosystems is not only a basic premise to realize various biomedical applications, but also a fatal factor for determining the final therapeutic effect. Thus, a systematic and comprehensive summary is necessary to overview the recent research progress on the improvement of nanosystem cellular uptake for cancer treatment. According to the process of nanosystems entering the body, they can be classified into three categories. The first segment is to enhance the accumulation and permeation of nanosystems to tumor cells through extracellular microenvironment stimulation. The second segment is to improve cellular internalization from extracellular to intracellular via active targeting. The third segment is to enhance the intracellular retention of therapeutics by subcellular localization. The major factors in the delivery can be utilized to develop multifunctional nanosystems for strengthening the tumor therapy. Ultimately, the key challenges and prospective in the emerging research frontier are thoroughly outlined. This review is expected to provide inspiring ideas, promising strategies and potential pathways for developing advanced anticancer nanosystems in clinical practice.