Interstitial Fluid and Lymph Formation and Transport: Physiological Regulation and Roles in Inflammation and Cancer

Injectable butyrate-prodrug micelles induce long-acting immune modulation and prevent autoimmune arthritis in mice

Short chain fatty acid (SCFAs), such as butyrate, have shown promising therapeutic potential due to their immunomodulatory effects, particularly in maintaining immune homeostasis. However, the clinical application of SCFAs is limited by the need for frequent and high oral dosages. Rheumatoid arthritis (RA) is characterized by aberrant activation of peripheral T cells and myeloid cells. In this study, we aimed to deliver butyrate directly to the lymphatics using a polymeric micelle-based butyrate prodrug to induce long-lasting immunomodulatory effects. Notably, negatively charged micelles (Neg-ButM) demonstrated superior efficacy in targeting the lymphatics following subcutaneous (s.c.) administration and were retained in the draining lymph nodes, spleen, and liver for over one month. In the collagen antibody-induced arthritis (CAIA) mouse model of RA, only two s.c. injections of Neg-ButM successfully prevented disease onset and promoted tolerogenic phenotypes in T cells and myeloid cells, both locally and systemically. These results underscore the potential of this strategy in managing inflammatory autoimmune diseases by directly modulating immune responses via lymphatic delivery.

Targeting lymphatic function in cardiovascular-kidney-metabolic syndrome: preclinical methods to analyze lymphatic function and therapeutic opportunities

The lymphatic vascular system spans nearly every organ in the body and serves as an important network that maintains fluid, metabolite, and immune cell homeostasis. Recently, there has been a growing interest in the role of lymphatic biology in chronic disorders outside the realm of lymphatic abnormalities, lymphedema, or oncology, such as cardiovascular-kidney-metabolic syndrome (CKM). We propose that enhancing lymphatic function pharmacologically may be a novel and effective way to improve quality of life in patients with CKM syndrome by engaging multiple pathologies at once throughout the body. Several promising therapeutic targets that enhance lymphatic function have already been reported and may have clinical benefit. However, much remains unclear of the discreet ways the lymphatic vasculature interacts with CKM pathogenesis, and translation of these therapeutic targets to clinical development is challenging. Thus, the field must improve characterization of lymphatic function in preclinical mouse models of CKM syndrome to better understand molecular mechanisms of disease and uncover effective therapies.

Prediction of subcutaneous drug absorption - Development of novel simulated interstitial fluid media for predictive subcutaneous in vitro assays

Media that mimic physiological fluids at the site of administration have proven to be valuable in vitro tools for predicting in vivo drug release, particularly for routes of administration where animal studies cannot accurately predict human performance. The objective of the present study was to develop simulated interstitial fluids (SISFs) that mimic the major components and physicochemical properties of subcutaneous interstitial fluids (ISFs) from preclinical species and humans, but that can be easily prepared in the laboratory and used in in vitro experiments to estimate in vivo drug release and absorption of subcutaneously administered formulations. Based on data from a previous characterization study of ISFs from different species, two media were developed: a simulated mouse-rat ISF and a simulated human-monkey ISF. The novel SISFs were used in initial in vitro diffusion studies with a commercial injectable preparation of liraglutide. Although the in vitro model used for this purpose still requires significant refinement, these two new media will undoubtedly contribute to a better understanding of the in vivo performance of subcutaneous injectables in different species and will help to reduce the number of unnecessary in vivo experiments in preclinical species by implementation in predictive in vitro models.

Lymphatic failure and lymphatic interventions: Knowledge gaps and future directions for a new frontier in congenital heart disease

Lymphatic failure is a broad term that describes the lymphatic circulation's inability to adequately transport fluid and solutes out of the interstitium and into the systemic venous circulation, which can result in dysfunction and dysregulation of immune responses, dietary fat absorption, and fluid balance maintenance. Several investigations have recently elucidated the nexus between lymphatic failure and congenital heart disease, and the associated morbidity and mortality is now well-recognized. However, the precise pathophysiology and pathogenesis of lymphatic failure remains poorly understood and relatively understudied, and there are no targeted therapeutics or interventions to reliably prevent its development and progression. Thus, there is growing enthusiasm towards the development and application of novel percutaneous and surgical lymphatic interventions. Moreover, there is consensus that further investigations are needed to delineate the underlying mechanisms of lymphatic failure, which could help identify novel therapeutic targets and develop innovative procedures to improve the overall quality of life and survival of these patients. With these considerations, this review aims to provide an overview of the lymphatic circulation and its vasculature as it relates to current understandings into the pathophysiology and pathogenesis of lymphatic failure in patients with congenital heart disease, while also summarizing strategies for evaluating and managing lymphatic complications, as well as specific areas of interest for future translational and clinical research efforts.

Harnessing the role of microneedles as sensors: current status and future perspectives

In recent years, microneedles (MNs) have been transformed to serve a wide range of applications in the biomedical field. Their role as sensors in wearable devices has provided an alternative to blood-based monitoring of health and diagnostic methods. Hence, they have become a topic of research interest for several scientists working in the biomedical field. These MNs as sensors offer the continuous monitoring of biomarkers like glucose, nucleic acids, proteins, polysaccharides and electrolyte ions, which can therefore screen for and diagnose disease conditions in humans. The present review focuses on types of MN sensors and their applications. Various clinical trials and bottlenecks of MN R&D are also discussed.

Same yet different - how lymph node heterogeneity affects immune responses

Lymph nodes are secondary lymphoid organs in which immune responses of the adaptive immune system are initiated and regulated. Distributed throughout the body and embedded in the lymphatic system, local lymph nodes are continuously informed about the state of the organs owing to a constant drainage of lymph. The tissue-derived lymph carries products of cell metabolism, proteins, carbohydrates, lipids, pathogens and circulating immune cells. Notably, there is a growing body of evidence that individual lymph nodes differ from each other in their capacity to generate immune responses. Here, we review the structure and function of the lymphatic system and then focus on the factors that lead to functional heterogeneity among different lymph nodes. We will discuss how lymph node heterogeneity impacts on cellular and humoral immune responses and the implications for vaccination, tumour development and tumour control by immunotherapy.

Biorelevant subcutaneous in vitro test predicts the release of human and fast acting insulin formulations

The administration of insulins by subcutaneous injection is nowadays widely prevalent. The injection site is located below the dermis and composed of cells and the extracellular matrix formed of a network of macromolecules such as hyaluronic acid and collagen. Following an injection, the insulins from the formulated products are timely released as drug molecules from the injection site into systemic circulation. In this publication, we show the development of an in vitro setup utilizing a hydrogel composed of a special collagen-hyaluronic acid mixture that mimics the extracellular matrix. Another setup was used for differentiation of the commercially available and research insulin formulations by determining the in vitro permeation characteristics with the results that were correlated with the human in vivo data. Significant differentiation was achieved at 90 % confidence level between the permeation curves of insulin glulisine containing formulations (U100 and a concentrated research formulation), while in case of the insulin lispro containing formulations (U100 and U200) the permeation curves showed similarity. These results demonstrated that the in vitro setup may be used as a tool for formulation development and drug candidate profiling as it is able to differentiate or show similarities between the agglomeration states and concentration of the active pharmaceutical ingredients.

Crosstalk between metabolism and cell death in tumorigenesis

It is generally recognized that tumor cells proliferate more rapidly than normal cells. Due to such an abnormally rapid proliferation rate, cancer cells constantly encounter the limits of insufficient oxygen and nutrient supplies. To satisfy their growth needs and resist adverse environmental events, tumor cells modify the metabolic pathways to produce both extra energies and substances required for rapid growth. Realizing the metabolic characters special for tumor cells will be helpful for eliminating them during therapy. Cell death is a hot topic of long-term study and targeting cell death is one of the most effective ways to repress tumor growth. Many studies have successfully demonstrated that metabolism is inextricably linked to cell death of cancer cells. Here we summarize the recently identified metabolic characters that specifically impact on different types of cell deaths and discuss their roles in tumorigenesis.

Myocardial edema, inflammation, and injury in human heart donated after circulatory death are sensitive to warm ischemia and subsequent cold storage

BACKGROUND

Single-dose del Nido solution was recently used in human donation after circulatory death (DCD) heart procurement. We compared the effect of del Nido cardioplegia on myocardial edema, inflammatory response, and injury in human DCD hearts and human donation after brain death (DBD) hearts with different warm ischemic times (WIT) and subsequent cold saline storage times (CST).

METHODS

A total of 24 human hearts, including 6 in the DBD group and 18 in the DCD group-were procured for the research study. The DCD group was divided into 3 subgroups based on WIT: 20, 40, and ≥60 minutes. All hearts received 1 L of del Nido cardioplegia before being placed in cold saline for 6 hours. Left ventricular biopsies were performed at 0, 2, 4, and 6 hours. Temporal changes in myocardial edema, inflammatory cytokines (TNF-α, IL-6, and IL-1β), and histopathology injury scores were compared between the DBD and DCD groups.

RESULTS

DCD hearts showed more profound changes in myocardial edema, inflammation, and injury than DBD hearts at baseline and subsequent CST. The DCD heart with WIT of 20 and 40 minutes with CST of 4 and 2 hours, respectively, appeared to have limited myocardial edema, inflammation, and injury. DCD hearts with WIT ≥60 minutes showed severe myocardial edema, inflammation, and injury at baseline and subsequent CST.

CONCLUSIONS

Single-dose cold del Nido cardioplegia and subsequent cold normal saline storage can preserve both DCD and DBD hearts. DCD hearts have been shown to be able to tolerate a WIT of 20 minutes and subsequent CST of 4 hours without experiencing significant myocardial edema, inflammation, and injury.

Cell- and Serum-Derived Proteins Act as DAMPs to Activate RAW 264.7 Macrophage-like Cells on Silicone Implants

Protein adsorption after biomaterial implantation is the first stage of the foreign body response (FBR). However, the source(s) of the adsorbed proteins that lead to damaged associated molecular patterns (DAMPs) and induce inflammation have not been fully elucidated. This study examined the effects of different protein sources, cell-derived (from a NIH/3T3 fibroblast cell lysate) and serum-derived (from fetal bovine serum), which were compared to implant-derived proteins (after a 30 min subcutaneous implantation in mice) on activation of RAW 264.7 cells cultured in minimal (serum-free) medium. Both cell-derived and serum-derived protein sources when preadsorbed to either tissue culture polystyrene or medical-grade silicone induced RAW 264.7 cell activation. The combination led to an even higher expression of pro-inflammatory cytokine genes and proteins. Implant-derived proteins on silicone explants induced a rapid inflammatory response that then subsided more quickly and to a greater extent than the studies with in vitro cell-derived or serum-derived protein sources. Proteomic analysis of the implant-derived proteins identified proteins that included cell-derived and serum-derived, but also other proteinaceous sources (e.g., extracellular matrix), suggesting that the latter or nonproteinaceous sources may help to temper the inflammatory response in vivo. These findings indicate that both serum-derived and cell-derived proteins adsorbed to implants can act as DAMPs to drive inflammation in the FBR, but other protein sources may play an important role in controlling inflammation.

Mechanical Ventilation during Bronchiolitis: The Macklin Effect

This is a case of barotrauma imaging (Macklin effect) after invasive mechanical ventilation in a 14-week-old newborn with complicated bronchiolitis. Teaching point: Imaging could help us improve defining the anatomical boundaries of the Macklin effect, an incompletely known anatomo-physiological entity.

Thrombospondins in the tumor microenvironment

Many cancers begin with the formation of a small nest of transformed cells that can remain dormant for years. Thrombospondin-1 (TSP-1) initially promotes dormancy by suppressing angiogenesis, a key early step in tumor progression. Over time, increases in drivers of angiogenesis predominate, and vascular cells, immune cells, and fibroblasts are recruited to the tumor mass forming a complex tissue, designated the tumor microenvironment. Numerous factors, including growth factors, chemokine/cytokine, and extracellular matrix, participate in the desmoplastic response that in many ways mimics wound healing. Vascular and lymphatic endothelial cells, and cancer-associated pericytes, fibroblasts, macrophages and immune cells are recruited to the tumor microenvironment, where multiple members of the TSP gene family promote their proliferation, migration and invasion. The TSPs also affect the immune signature of tumor tissue and the phenotype of tumor-associated macrophages. Consistent with these observations, expression of some TSPs has been established to correlate with poor outcomes in specific types of cancer.

Quantitative analysis of molecular transport in the extracellular space using physics-informed neural network

The brain extracellular space (ECS), an irregular, extremely tortuous nanoscale space located between cells or between cells and blood vessels, is crucial for nerve cell survival. It plays a pivotal role in high-level brain functions such as memory, emotion, and sensation. However, the specific form of molecular transport within the ECS remain elusive. To address this challenge, this paper proposes a novel approach to quantitatively analyze the molecular transport within the ECS by solving an inverse problem derived from the advection-diffusion equation (ADE) using a physics-informed neural network (PINN). PINN provides a streamlined solution to the ADE without the need for intricate mathematical formulations or grid settings. Additionally, the optimization of PINN facilitates the automatic computation of the diffusion coefficient governing long-term molecule transport and the velocity of molecules driven by advection. Consequently, the proposed method allows for the quantitative analysis and identification of the specific pattern of molecular transport within the ECS through the calculation of the Péclet number. Experimental validation on two datasets of magnetic resonance images (MRIs) captured at different time points showcases the effectiveness of the proposed method. Notably, our simulations reveal identical molecular transport patterns between datasets representing rats with tracer injected into the same brain region. These findings highlight the potential of PINN as a promising tool for comprehensively exploring molecular transport within the ECS.

Programmable intratumoral drug delivery to breast cancer using wireless bioelectronic device with electrochemical actuation

OBJECTIVE

Breast cancer is a global health concern that demands attention. In our contribution to addressing this disease, our study focuses on investigating a wireless micro-device for intratumoral drug delivery, utilizing electrochemical actuation. Microdevices have emerged as a promising approach in this field due to their ability to enable controlled injections in various applications.

METHODS

Our study is conducted within a computational framework, employing models that simulate the behavior of the microdevice and drug discharge based on the principles of the ideal gas law. Furthermore, the distribution of the drug within the tissue is simulated, considering both diffusion and convection mechanisms. To predict the therapeutic response, a pharmacodynamic model is utilized, considering the chemotherapeutic effects and cell proliferation.

RESULTS

The findings demonstrate that an effective current of 3 mA, along with an initial gas volume equal to the drug volume in the microdevice, optimizes drug delivery. Microdevices with multiple injection capabilities exhibit enhanced therapeutic efficacy, effectively suppressing cell proliferation. Additionally, tumors with lower microvascular density experience higher drug concentrations in the extracellular space, resulting in significant cell death in hypoxic regions.

CONCLUSIONS

Achieving an efficient therapeutic response involves considering both the characteristics of the tumor microenvironment and the frequency of injections within a specific time frame.

A novel therapy for fracture healing by increasing lymphatic drainage

Background

The musculoskeletal system contains an extensive network of lymphatic vessels. Decreased lymph flow of the draining collecting lymphatics usually occurs in clinic after traumatic fractures. However, whether defects in lymphatic drainage can affect fracture healing is unclear.

Methods

To investigate the effect of lymphatic dysfunction on fracture healing, we used a selective VEGFR3 tyrosine kinase inhibitor to treat tibial fractured mice for 5 weeks versus a vehicle-treated control. To ensure successfully establishing deceased lymphatic drainage model for fractured mice, we measured lymphatic clearance by near infrared indocyanine green lymphatic imaging (NIR-ICG) and the volume of the draining popliteal lymph nodes (PLNs) by ultrasound at the whole phases of fracture healing. In addition, hindlimb edema from day 0 to day 7 post-fracture, pain sensation by Hargreaves test at day 1 post-fracture, bone histomorphometry by micro-CT and callus composition by Alcian Blue-Hematoxylin/Orange G staining at day 14 post-fracture, and bone quality by biomechanical testing at day 35 post-fracture were applied to evaluate fracture healing. To promote fracture healing via increasing lymphatic drainage, we then treated fractured mice with anti-mouse podoplanin (PDPN) neutralizing antibody or isotype IgG antibody for 1 week to observe lymphatic drainage function and assess bone repair as methods described above.

Results

Compared to vehicle-treated group, SAR-treatment group significantly decreased lymphatic clearance and the volume of draining PLNs. SAR-treatment group significantly increased soft tissue swelling, and reduced bone volume (BV)/tissue volume (TV), trabecular number (Tb.N), woven bone and biomechanical properties of fracture callus. In addition, anti-PDPN treated group significantly reduced the number of CD41+ platelets in PLNs and increased the number of pulsatile lymphatic vessels, lymphatic clearance and the volume of PLNs. Moreover, anti-PDPN treated group significantly reduced hindlimb edema and pain sensation and increased BV/TV, trabecular number (Tb.Th), woven bone and biomechanical properties of fracture callus.

Conclusions

Inhibition of proper lymphatic drainage function delayed fracture healing. Use of a anti-PDPN neutralizing antibody reduced lymphatic platelet thrombosis (LPT), increased lymphatic drainage and improved fracture healing.

The translational potential of this article

(1) We demonstrated lymphatic drainage function is crucial for fracture healing. (2) To unblock the lymphatic drainage and prevent the risk of bleeding and mortality by blood thinner, we demonstrated PDPN neutralizing antibody is a novel and safe way forward in the treatment of bone fracture healing by eliminating LPT and increasing lymphatic drainage.

Tangram of Sodium and Fluid Balance

Homeostasis of fluid and electrolytes is a tightly controlled physiological process. Failure of this process is a hallmark of hypertension, chronic kidney disease, heart failure, and other acute and chronic diseases. While the kidney remains the major player in the control of whole-body fluid and electrolyte homeostasis, recent discoveries point toward more peripheral mechanisms leading to sodium storage in tissues, such as skin and muscle, and a link between this sodium and a range of diseases, including the conditions above. In this review, we describe multiple facets of sodium and fluid balance from traditional concepts to novel discoveries. We examine the differences between acute disruption of sodium balance and the longer term adaptation in chronic disease, highlighting areas that cannot be explained by a kidney-centric model alone. The theoretical and methodological challenges of more recently proposed models are discussed. We acknowledge the different roles of extracellular and intracellular spaces and propose an integrated model that maintains fluid and electrolyte homeostasis and can be distilled into a few elemental players: the microvasculature, the interstitium, and tissue cells. Understanding their interplay will guide a more precise treatment of conditions characterized by sodium excess, for which primary aldosteronism is presented as a prototype.

Developmental progression of lymphatic valve morphology and function

Introduction: The bileaflet valves found in collecting lymphatic vessels and some veins are essential for maintaining a unidirectional flow, which is important for lymphatic and venous function. Under an adverse pressure gradient, the two leaflets tightly overlap to prevent backflow. Valves are proposed to share four main stages of development, based on images obtained from randomly oriented valves in fixed mouse embryos, with the best structural views obtained from larger venous valves. It is not known at what stage lymphatic valves (LVs) become functional (e.g., able to oppose backflow), although a requirement for stage 4 is presumed. Methods: To gain an insight into this sequence of events for LVs, we used Prox1CreER T2 :Foxo1 fl/fl mice and Foxc2CreER T2 :Foxo1 fl/fl mouse models, in which deletion of the valve repressor factor Foxo1 promotes the development of new LVs in adult lymphatic vessels. Both strains also contained a Prox1eGFP reporter to image the lymphatic endothelium. Mesenteric collecting lymphatic vessels were dissected, cannulated, and pressurized for ex vivo tests of valve function. LVs at various stages (1-4 and intermediate) were identified in multi-valve segments, which were subsequently shortened to perform the backleak test on single valves. The GFP signal was then imaged at high magnification using a confocal microscope. Z-stack reconstructions enabled 1:1 comparisons of LV morphology with a quantitative measurement of back leak. Results: As expected, LVs of stages 1-3 were completely leaky in response to outflow pressure elevation. Stage 4 valves were generally not leaky, but valve integrity depended on the Cre line used to induce new valve formation. A high percentage of valves at leaflet an intermediate stage (3.5), in which there was an insertion of a second commissure, but without proper luminal alignment, effectively resisted back leak when the outflow pressure was increased. Discussion: Our findings represent the first 3D images of developing lymphatic valves and indicate that valves become competent between stages 3 and 4 of development.

Local electroneutrality breakdown for electrolytes within varying-section nanopores

We determine the local charge dynamics of a [Formula: see text] electrolyte embedded in a varying-section channel. By means of an expansion based on the length scale separation between the axial and transverse direction of the channel, we derive closed formulas for the local excess charge for both, dielectric and conducting walls, in 2D (planar geometry) as well as in 3D (cylindrical geometry). Our results show that, even at equilibrium, the local charge electroneutrality is broken whenever the section of the channel is not homogeneous for both dielectric and conducting walls as well as for 2D and 3D channels. Interestingly, even within our expansion, the local excess charge in the fluid can be comparable to the net charge on the walls. We critically discuss the onset of such local electroneutrality breakdown in particular with respect to the correction that it induces on the effective free energy profile experienced by tracer ions.

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

Progress and challenges in the translation of cancer nanomedicines

With the booming development of nanotechnology, nanomedicines have made considerable progress in the pharmaceutical field. However, the number of nanodrugs approved for clinical treatment is very limited. The main obstacles stem from the complexity of nanomedicine composition, tumor heterogeneity, complexity and incomplete understanding of nanotumor interactions, uncontrollable scaling, high production costs, and uncertainty of regulations and standards. This review article described the current stage of nanomedicines and highlighted the challenges, strategies, and opportunities for clinical translation of nanomedicines.

Microfluidic-Based Reconstitution of Functional Lymphatic Microvasculature: Elucidating the Role of Lymphatics in Health and Disease

The knowledge of the blood microvasculature and its functional role in health and disease has grown significantly attributable to decades of research and numerous advances in cell biology and tissue engineering; however, the lymphatics (the secondary vascular system) has not garnered similar attention, in part due to a lack of relevant in vitro models that mimic its pathophysiological functions. Here, a microfluidic-based approach is adopted to achieve precise control over the biological transport of growth factors and interstitial flow that drive the in vivo growth of lymphatic capillaries (lymphangiogenesis). The engineered on-chip lymphatics with in vivo-like morphology exhibit tissue-scale functionality with drainage rates of interstitial proteins and molecules comparable to in vivo standards. Computational and scaling analyses of the underlying transport phenomena elucidate the critical role of the three-dimensional geometry and lymphatic endothelium in recapitulating physiological drainage. Finally, the engineered on-chip lymphatics enabled studies of lymphatic-immune interactions that revealed inflammation-driven responses by the lymphatics to recruit immune cells via chemotactic signals similar to in vivo, pathological events. This on-chip lymphatics platform permits the interrogation of various lymphatic biological functions, as well as screening of lymphatic-based therapies such as interstitial absorption of protein therapeutics and lymphatic immunomodulation for cancer therapy.

Advances in biomedical systems based on microneedles: design, fabrication, and application

Wearable devices have become prevalent in biomedical studies due to their convenient portability and potential utility in biomarker monitoring for healthcare. Accessing interstitial fluid (ISF) across the skin barrier, microneedle (MN) is a promising minimally invasive wearable technology for transdermal sensing and drug delivery. MN has the potential to overcome the limitations of conventional transdermal drug administration, making it another prospective mode of drug delivery after oral and injectable. Subsequently, combining MN with multiple sensing approaches has led to its extensive application to detect biomarkers in ISF. In this context, employing MN platforms and control schemes to merge diagnostic and therapeutic capabilities into theranostic systems will facilitate on-demand therapy and point-of-care diagnostics, paving the way for future MN technologies. A comprehensive analysis of the growing advances of microneedles in biomedical systems is presented in this review to summarize the latest studies for academics in the field and to offer for reference the issues that need to be addressed in MN application for healthcare. Covering an array of novel studies, we discuss the following main topics: classification of microneedles in the biomedical field, considerations of MN design, current applications of microneedles in diagnosis and therapy, and the regulatory landscape and prospects of microneedles for biomedical applications. This review sheds light on the significance of microneedle-based innovations, presenting an analysis of their potential implications and contributions to the community of wearable healthcare technologies. The review provides a comprehensive understanding of the field's current state and potential, making it a valuable resource for academics and clinicians seeking to harness the full potential of MN applications.

3D-printed, aptamer-based microneedle sensor arrays using magnetic placement on live rats for pharmacokinetic measurements in interstitial fluid

Molecular monitoring in the dermal interstitial fluid (ISF) is an attractive approach to painlessly screen markers of health and disease status on the go. One promising strategy for accessing ISF involves the use of wearable patches containing microneedle sensor arrays. To date, such microneedle sensors have been fabricated via various manufacturing strategies based on injection molding, machining, and advanced lithography to name a few. Our groups previously reported 3D-printed microneedles as a convenient and scalable approach to sensor fabrication that, when combined with aptamer-based molecular measurements, can support continuous molecular monitoring in ISF. However, the original platform suffered from poor patch stability when deployed on the skin of rodents in vivo. We identified that this problem was due to the rheological properties of the rodent skin, which can contract post microneedle placement, physically pushing the microneedles out of the skin. This sensor retraction caused a loss of electrical contact between working and reference needles, irreversibly damaging the sensors. To address this problem, we report here an innovative approach that allows magnetic placement of microneedle sensor arrays on the skin of live rodents, affixing the patches under light pressure that prevents needle retraction. Using this strategy, we achieved sensor signaling baselines that drift at rates comparable to those seen with other in vivo deployments of electrochemical, aptamer-based sensors. We illustrate real-time pharmacokinetic measurements in live Sprague-Dawley rats using SLA-printed, aptamer-functionalized microneedles and demonstrate their ability to support drift correction via kinetic differential measurements. We also discuss future prospects and challenges.

Myocardial Oedema as a Consequence of Viral Infection and Persistence-A Narrative Review with Focus on COVID-19 and Post COVID Sequelae

Microvascular integrity is a critical factor in myocardial fluid homeostasis. The subtle equilibrium between capillary filtration and lymphatic fluid removal is disturbed during pathological processes leading to inflammation, but also in hypoxia or due to alterations in vascular perfusion and coagulability. The degradation of the glycocalyx as the main component of the endothelial filtration barrier as well as pericyte disintegration results in the accumulation of interstitial and intracellular water. Moreover, lymphatic dysfunction evokes an increase in metabolic waste products, cytokines and inflammatory cells in the interstitial space contributing to myocardial oedema formation. This leads to myocardial stiffness and impaired contractility, eventually resulting in cardiomyocyte apoptosis, myocardial remodelling and fibrosis. The following article reviews pathophysiological inflammatory processes leading to myocardial oedema including myocarditis, ischaemia-reperfusion injury and viral infections with a special focus on the pathomechanisms evoked by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In addition, clinical implications including potential long-term effects due to viral persistence (long COVID), as well as treatment options, are discussed.

Regulation of antioxidants in cancer

Scientists in this field often joke, "If you don't have a mechanism, say it's ROS." Seemingly connected to every biological process ever described, reactive oxygen species (ROS) have numerous pleiotropic roles in physiology and disease. In some contexts, ROS act as secondary messengers, controlling a variety of signaling cascades. In other scenarios, they initiate damage to macromolecules. Finally, in their worst form, ROS are deadly to cells and surrounding tissues. A set of molecules with detoxifying abilities, termed antioxidants, is the direct counterpart to ROS. Notably, antioxidants exist in the public domain, touted as a "cure-all" for diseases. Research has disproved many of these claims and, in some cases, shown the opposite. Of all the diseases, cancer stands out in its paradoxical relationship with antioxidants. Although the field has made numerous strides in understanding the roles of antioxidants in cancer, many questions remain.

Integrated PK/PD Modeling Relates Smoothened Inhibitor Biomarkers to The Heterogeneous Intratumor Disposition of Cetuximab in Pancreatic Cancer Tumor Models

Therapeutic antibodies have shown little efficacy in the treatment of pancreatic ductal adenocarcinomas (PDAC). Tumor desmoplasia, hypovascularity, and poor perfusion result in insufficient tumor cell exposure, contributing to treatment failure. Smoothened inhibitors of hedgehog signaling (sHHi) increase PDAC tumor permeability, perfusion, and drug delivery, and provide a tool to develop a quantitative, mechanistic understanding as to how the temporal dynamics of tumor priming can impact intratumor distribution of monoclonal antibodies (mAb). A linked pharmacokinetic (PK)/pharmacodynamic (PD) model was developed to integrate the plasma and tumor PK of a sHHi priming agent with its effects upon downstream stromal biomarkers Gli1, hyaluronic acid, and interstitial fluid pressure in PDAC patient-derived xenograft (PDX) tumors. In parallel, in situ tumor concentrations of cetuximab (CTX: anti-epidermal growth factor receptor; EGFR) were quantified as a marker for tumor delivery of mAb or antibody-drug conjugates. A minimal, physiologically-based pharmacokinetic (mPBPK) model was constructed to link sHHi effects upon mechanistic effectors of tumor barrier compromise with the intratumor distribution of CTX, and CTX occupancy of EGFR in tumors. Integration of the mPBPK model of mAb deposition and intratumor distribution with the PK/PD model of tumor responses to priming not only identified physiological parameters that are critical for tumor antibody distribution, but also provides insight into dosing regimens that could achieve maximal tumor disposition of therapeutic antibodies under conditions of transient PDAC tumor permeability barrier compromise that mechanistically-diverse tumor priming strategies may achieve.

Application of quantitative protein mass spectrometric data in the early predictive analysis of membrane-bound target engagement by monoclonal antibodies

Model-informed drug discovery advocates the use of mathematical modeling and simulation for improved efficacy in drug discovery. In the case of monoclonal antibodies (mAbs) against cell membrane antigens, this requires quantitative insight into the target tissue concentration levels. Protein mass spectrometry data are often available but the values are expressed in relative, rather than in molar concentration units that are easier to incorporate into pharmacokinetic models. Here, we present an empirical correlation that converts the parts per million (ppm) concentrations in the PaxDb database to their molar equivalents that are more suitable for pharmacokinetic modeling. We evaluate the insight afforded to target tissue distribution by analyzing the likely tumor-targeting accuracy of mAbs recognizing either epidermal growth factor receptor or its homolog HER2. Surprisingly, the predicted tissue concentrations of both these targets exceed the Kd values of their respective therapeutic mAbs. Physiologically based pharmacokinetic (PBPK) modeling indicates that in these conditions only about 0.05% of the dosed mAb is likely to reach the solid tumor target cells. The rest of the dose is eliminated in healthy tissues via both nonspecific and target-mediated processes. The presented approach allows evaluation of the interplay between the target expression level in different tissues that determines the overall pharmacokinetic properties of the drug and the fraction that reaches the cells of interest. This methodology can help to evaluate the efficacy and safety properties of novel drugs, especially if the off-target cell degradation has cytotoxic outcomes, as in the case of antibody-drug conjugates.

Capillary leak and endothelial permeability in critically ill patients: a current overview

Capillary leak syndrome (CLS) represents a phenotype of increased fluid extravasation, resulting in intravascular hypovolemia, extravascular edema formation and ultimately hypoperfusion. While endothelial permeability is an evolutionary preserved physiological process needed to sustain life, excessive fluid leak-often caused by systemic inflammation-can have detrimental effects on patients' outcomes. This article delves into the current understanding of CLS pathophysiology, diagnosis and potential treatments. Systemic inflammation leading to a compromise of endothelial cell interactions through various signaling cues (e.g., the angiopoietin-Tie2 pathway), and shedding of the glycocalyx collectively contribute to the manifestation of CLS. Capillary permeability subsequently leads to the seepage of protein-rich fluid into the interstitial space. Recent insights into the importance of the sub-glycocalyx space and preserving lymphatic flow are highlighted for an in-depth understanding. While no established diagnostic criteria exist and CLS is frequently diagnosed by clinical characteristics only, we highlight more objective serological and (non)-invasive measurements that hint towards a CLS phenotype. While currently available treatment options are limited, we further review understanding of fluid resuscitation and experimental approaches to target endothelial permeability. Despite the improved understanding of CLS pathophysiology, efforts are needed to develop uniform diagnostic criteria, associate clinical consequences to these criteria, and delineate treatment options.

Multiphysics-Informed Pharmacokinetic Modeling of Systemic Exposure of Intramuscularly Injected LNPs

Lipid nanoparticle (LNP) constructs have been widely developed for gene therapy delivery. Understanding local absorption and presystemic clearance kinetics of LNPs, however, remains limited. This subsequently restrains the prediction and assessment of the systemic exposure of locally injected LNPs. As such, a multiscale computational approach was developed by integrating multiphysics simulation of intramuscular absorption kinetics of LNPs with whole-body pharmacokinetics modeling, bridged by a presystemic lymphatic kinetic model. The overall framework was enabled by utilizing physiological parameters obtained from the literature and drug-related parameters derived from experiments. The multiscale modeling and simulation approach predicted the systemic exposure of LNPs administered intramuscularly, with a high degree of agreement between the predicted and the experimental data. Sensitivity analyses revealed that the local absorption rate, pinocytosis presystemic clearance rate, and lymph flow rate of the presystemic lymphatic compartment had the most significant impacts on Cmax. The study yielded refreshing perspectives on estimating systemic exposures of locally injected LNPs and their safety and effectiveness.

Opportunities and challenges in the diagnostic utility of dermal interstitial fluid

The volume of interstitial fluid (ISF) in the human body is three times that of blood. Yet, collecting diagnostically useful ISF is more challenging than collecting blood because the extraction of dermal ISF disrupts the delicate balance of pressure between ISF, blood and lymph, and because the triggered local inflammation further skews the concentrations of many analytes in the extracted fluid. In this Perspective, we overview the most meaningful differences in the make-up of ISF and blood, and discuss why ISF cannot be viewed generally as a diagnostically useful proxy for blood. We also argue that continuous sensing of small-molecule analytes in dermal ISF via rapid assays compatible with nanolitre sample volumes or via miniaturized sensors inserted into the dermis can offer clinically advantageous utility, particularly for the monitoring of therapeutic drugs and of the status of the immune system.

MPET2: a multi-network poroelastic and transport theory for predicting absorption of monoclonal antibodies delivered by subcutaneous injection

Subcutaneous injection of monoclonal antibodies (mAbs) has attracted much attention in the pharmaceutical industry. During the injection, the drug is delivered into the tissue producing strong fluid flow and tissue deformation. While data indicate that the drug is initially uptaken by the lymphatic system due to the large size of mAbs, many of the critical absorption processes that occur at the injection site remain poorly understood. Here, we propose the MPET² approach, a multi-network poroelastic and transport model to predict the absorption of mAbs during and after subcutaneous injection. Our model is based on physical principles of tissue biomechanics and fluid dynamics. The subcutaneous tissue is modeled as a mixture of three compartments, i.e., interstitial tissue, blood vessels, and lymphatic vessels, with each compartment modeled as a porous medium. The proposed biomechanical model describes tissue deformation, fluid flow in each compartment, the fluid exchanges between compartments, the absorption of mAbs in blood vessels and lymphatic vessels, as well as the transport of mAbs in each compartment. We used our model to perform a high-fidelity simulation of an injection of mAbs in subcutaneous tissue and evaluated the long-term drug absorption. Our model results show good agreement with experimental data in depot clearance tests.

Outsmarting trogocytosis to boost CAR NK/T cell therapy

Chimeric antigen receptor (CAR) NK and T cell therapy are promising immunotherapeutic approaches for the treatment of cancer. However, the efficacy of CAR NK/T cell therapy is often hindered by various factors, including the phenomenon of trogocytosis, which involves the bidirectional exchange of membrane fragments between cells. In this review, we explore the role of trogocytosis in CAR NK/T cell therapy and highlight potential strategies for its modulation to improve therapeutic efficacy. We provide an in-depth analysis of trogocytosis as it relates to the fate and function of NK and T cells, focusing on its effects on cell activation, cytotoxicity, and antigen presentation. We discuss how trogocytosis can mediate transient antigen loss on cancer cells, thereby negatively affecting the effector function of CAR NK/T cells. Additionally, we address the phenomenon of fratricide and trogocytosis-associated exhaustion, which can limit the persistence and effectiveness of CAR-expressing cells. Furthermore, we explore how trogocytosis can impact CAR NK/T cell functionality, including the acquisition of target molecules and the modulation of signaling pathways. To overcome the negative effects of trogocytosis on cellular immunotherapy, we propose innovative approaches to modulate trogocytosis and augment CAR NK/T cell therapy. These strategies encompass targeting trogocytosis-related molecules, engineering CAR NK/T cells to resist trogocytosis-induced exhaustion and leveraging trogocytosis to enhance the function of CAR-expressing cells. By overcoming the limitations imposed by trogocytosis, it may be possible to unleash the full potential of CAR NK/T therapy against cancer. The knowledge and strategies presented in this review will guide future research and development, leading to improved therapeutic outcomes in the field of immunotherapy.

The lymphatic system favours survival of a unique T. brucei population

Trypanosoma brucei colonise and multiply in the blood vasculature, as well as in various organs of the host's body. Lymph nodes have been previously shown to harbour large numbers of parasites, and the lymphatic system has been proposed as a key site that allows T. brucei distribution through, and colonization of the mammalian body. However, visualization of host-pathogen interactions in the lymphatic system has never captured dynamic events with high spatial and temporal resolution throughout infection. In our work, we used a mixture of tools including intravital microscopy and ex vivo imaging to study T. brucei distribution in 20 sets of lymph nodes. We demonstrate that lymph node colonization by T. brucei is different across lymph node sets, with the most heavily colonised being the draining lymph nodes of main tissue reservoirs: the gonadal white adipose tissue and pancreas. Moreover, we show that the lymphatic vasculature is a pivotal site for parasite dispersal, and altering this colonization by blocking LYVE-1 is detrimental for parasite survival. Additionally, parasites within the lymphatic vasculature have unique morphological and behavioural characteristics, different to those found in the blood, demonstrating that across both types of vasculature, these environments are physically separated. Finally, we demonstrate that the lymph nodes and the lymphatic vasculature undergo significant alterations during T. brucei infection, resulting in oedema throughout the host's body.

Synthetic hyaluronic acid coating preserves the phenotypes of lymphatic endothelial cells

Lymphatic endothelial cells (LECs) play a critical role in the formation and maintenance of the lymphatic vasculature, which is essential for the immune system, fluid balance, and tissue repair. However, LECs are often difficult to study in vivo and in vitro models that accurately mimic their behaviors and phenotypes are limited. In particular, LECs have been shown to lose their lymphatic markers over time while being cultured in vitro, which reflect their plasticity and heterogeneity in vivo. Since LECs uniquely express lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1), we hypothesized that surface coating with hyaluronic acid (HA) can preserve LEC phenotypes and functionalities. Dopamine conjugated hyaluronic acid (HA-DP) was synthesized with 42% degree of substitution to enable surface modification and conjugation onto standard tissue culture plates. Compared to fibronectin coating and tissue culture plate controls, surface coating with HA-DP was able to preserve lymphatic markers, such as prospero homeobox protein 1 (Prox1), podoplanin (PDPN), and LYVE-1 over several passages in vitro. LECs cultured on HA-DP expressed lower levels of focal adhesion kinase (FAK) and YAP/TAZ, which may be responsible for the maintenance of the lymphatic characteristics. Collectively, the HA-DP coating may provide a novel method for culturing human LECs in vitro toward more representative studies in basic lymphatic biology and lymphatic regeneration.

The exercise IL-6 enigma in cancer

Interleukin (IL)-6 elicits both anticancer and procancer effects depending on the context, which we have termed the 'exercise IL-6 enigma'. IL-6 is released from skeletal muscles during exercise to regulate short-term energy availability. Exercise-induced IL-6 provokes biological effects that may protect against cancer by improving insulin sensitivity, stimulating the production of anti-inflammatory cytokines, mobilising immune cells, and reducing DNA damage in early malignant cells. By contrast, IL-6 continuously produced by leukocytes in inflammatory sites drives tumorigenesis by promoting chronic inflammation and activating tumour-promoting signalling pathways. How can a molecule have such opposing effects on cancer? Here, we review the roles of IL-6 in chronic inflammation, tumorigenesis, and exercise-associated cancer prevention and define the factors that underpin the exercise IL-6 enigma.

Epithelial Transport in Disease: An Overview of Pathophysiology and Treatment

Epithelial transport is a multifaceted process crucial for maintaining normal physiological functions in the human body. This comprehensive review delves into the pathophysiological mechanisms underlying epithelial transport and its significance in disease pathogenesis. Beginning with an introduction to epithelial transport, it covers various forms, including ion, water, and nutrient transfer, followed by an exploration of the processes governing ion transport and hormonal regulation. The review then addresses genetic disorders, like cystic fibrosis and Bartter syndrome, that affect epithelial transport. Furthermore, it investigates the involvement of epithelial transport in the pathophysiology of conditions such as diarrhea, hypertension, and edema. Finally, the review analyzes the impact of renal disease on epithelial transport and highlights the potential for future research to uncover novel therapeutic interventions for conditions like cystic fibrosis, hypertension, and renal failure.

Role of the interstitium during septic shock: a key to the understanding of fluid dynamics?

BACKGROUND

While not traditionally included in the conceptual understanding of circulation, the interstitium plays a critical role in maintaining fluid homeostasis. Fluid balance regulation is a critical aspect of septic shock, with a well-known association between fluid balance and outcome. The regulation of transcapillary flow is the first key to understand fluid homeostasis during sepsis.

MAIN TEXT

Capillary permeability is increased during sepsis, and was classically considered to be necessary and sufficient to explain the increase of capillary filtration during inflammation. However, on the other side of the endothelial wall, the interstitium may play an even greater role to drive capillary leak. Indeed, the interstitial extracellular matrix forms a complex gel-like structure embedded in a collagen skeleton, and has the ability to directly attract intravascular fluid by decreasing its hydrostatic pressure. Thus, interstitium is not a mere passive reservoir, as was long thought, but is probably major determinant of fluid balance regulation during sepsis. Up to this date though, the role of the interstitium during sepsis and septic shock has been largely overlooked. A comprehensive vision of the interstitium may enlight our understanding of septic shock pathophysiology. Overall, we have identified five potential intersections between septic shock pathophysiology and the interstitium: 1. increase of oedema formation, interacting with organ function and metabolites diffusion; 2. interstitial pressure regulation, increasing transcapillary flow; 3. alteration of the extracellular matrix; 4. interstitial secretion of inflammatory mediators; 5. decrease of lymphatic outflow.

CONCLUSIONS

We aimed at reviewing the literature and summarizing the current knowledge along these specific axes, as well as methodological aspects related to interstitium exploration.

Numerical studies of the lymphatic uptake rate

Lymphatic uptake is essential for transporting nutrients, wastes, immune cells, and therapeutic proteins. Despite its importance, the literature lacks a quantitative analysis of the factors that affect lymphatic uptake, including interstitial pressure, downstream pressure, and tissue deformation. In this paper, we present a coupled model of a poroelastic tissue with initial lymphatics and quantify the impact of these factors on the rate of lymphatic uptake. Our results indicate that the lymphatic uptake increases with the amplitude of the oscillating downstream pressure when the amplitude exceeds a threshold. Additionally, the cross-sectional area of initial lymphatics increases with the volumetric strain of the tissue, while the interstitial pressure increases when the strain rate becomes negative. Therefore, the lymphatic uptake reaches its maximum when the tissue has positive volumetric strain while being compressed. We have also investigated the effect of intersection angles and positions of two initial lymphatics and concluded that they have minor impacts on lymphatic uptake. However, the lymphatic uptake per unit length of initial lymphatics decreases with their total length. These findings advance our understanding of lymphatic uptake and can guide the development of strategies to accelerate the transport of therapeutics.

Tumor interstitial fluid analysis enables the study of microenvironment-cell interactions in cancers

The tumor microenvironment (TME) plays a crucial role in regulating the state and function of all cell types residing in the tumor and thus impacts many aspects of tumor biology. The importance of the TME has led to an interest in characterizing the composition of the TME and how TME components regulate cancer and stromal cell biology. Tumor interstitial fluid (TIF) is the local perfusate of the TME that carries metabolites, electrolytes, and soluble macromolecules to tumor-resident cells. Recently, techniques to isolate TIF have been coupled with analytical techniques to interrogate the composition of TIF, providing new insight into TME composition. In this review, we will discuss what TIF studies indicate about TME composition and new avenues TIF analysis provides to delineate how the TME regulates tumor biology.

Prognostic Implication of Focal Breast Edema on Preoperative Breast Magnetic Resonance Imaging in Breast Cancer Patients

PURPOSE

In this study, we investigated the prognostic implications of focal breast edema on preoperative breast magnetic resonance imaging (MRI) in patients with breast cancer.

METHODS

Data of 899 patients with breast cancer at a single institution were retrospectively analyzed. The patients were divided into an edema-positive group (EPG) and an edema-negative group (ENG) based on the presence of peritumoral, prepectoral, or subcutaneous edema. Two radiologists evaluated the presence or absence of focal edema and its subtypes on preoperative breast MRI. Clinicopathologic characteristics and survival outcomes were compared between the two groups and among the three subtypes using Pearson's χ² test, Kaplan-Meier estimator, and Cox proportional hazards model.

RESULTS

There were 399 (44.4%) and 500 (55.6%) patients in the EPG and ENG, respectively. The EPG showed significantly higher rates of axillary lymph node metastasis (55.6% vs. 19.2%, p < 0.001) and lymphovascular invasion (LVI) (57.9% vs. 12.6%, p < 0.001) than the ENG. Patients in the EPG showed significantly worse overall survival (OS) rate (log-rank p < 0.001; hazard ratio [HR], 4.83; 95% confidence interval [CI], 2.56-9.11) and recurrence-free survival rate (log-rank p < 0.001; HR, 3.00; 95% CI, 1.94-4.63) than those in the ENG. After adjusting for other variables, focal breast edema remained a significant factor affecting the OS rate, regardless of the edema type. Specifically, the presence of subcutaneous edema emerged as the strongest predictor for OS with the highest HR (p < 0.001; HR, 9.10; 95% CI, 3.05-27.15).

CONCLUSION

Focal breast edema on preoperative breast MRI implies a higher possibility of LVI and axillary lymph node metastasis, which can lead to a poor prognosis. A detailed description of focal breast edema, especially subcutaneous edema, on preoperative breast MRI may provide prognostic predictions. More intensive surveillance is required for patients with breast cancer and focal preoperative breast edema.

Physiomimetic biocompatibility evaluation of directly printed degradable porous iron implants using various cell types

Additively manufactured (AM) degradable porous metallic biomaterials offer unique opportunities for satisfying the design requirements of an ideal bone substitute. Among the currently available biodegradable metals, iron has the highest elastic modulus, meaning that it would benefit the most from porous design. Given the successful preclinical applications of such biomaterials for the treatment of cardiovascular diseases, the moderate compatibility of AM porous iron with osteoblast-like cells, reported in earlier studies, has been surprising. This may be because, as opposed to static in vitro conditions, the biodegradation products of iron in vivo are transported away and excreted. To better mimic the in situ situations of biodegradable biomaterials after implantation, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static conditions to the conditions with dynamic in situ-like fluid flow perfusion in a bioreactor. Furthermore, the compatibility of these scaffolds with four different cell types was evaluated to better understand the implications of these implants for the complex process of natural wound healing. These included endothelial cells, L929 fibroblasts, RAW264.7 macrophage-like cells, and osteoblastic MG-63 cells. The biodegradation rate of the scaffolds was significantly increased in the perfusion bioreactor as compared to static immersion. Under either condition, the compatibility with L929 cells was the best. Moreover, the compatibility with all the cell types was much enhanced under physiomimetic dynamic flow conditions as compared to static biodegradation. Our study highlights the importance of physiomimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro. STATEMENT OF SIGNIFICANCE: Additively manufactured (AM) degradable porous metals offer unique opportunities for the treatment of large bony defects. Despite the successful preclinical applications of biodegradable iron in the cardiovascular field, the moderate compatibility of AM porous iron with osteoblast-like cells was reported. To better mimic the in vivo condition, we compared the biodegradation behavior and cytocompatibility of AM porous iron under static condition to dynamic perfusion. Furthermore, the compatibility of these scaffolds with various cell types was evaluated to better simulate the process of natural wound healing. Our study suggests that AM porous iron holds great promise for orthopedic applications, while also highlighting the importance of physio-mimetic culture conditions and cell type selection when evaluating the cytocompatibility of degradable biomaterials in vitro.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

A facile fluid pressure system reveals differential cellular response to interstitial pressure gradients and flow

Interstitial fluid pressure gradients and interstitial flow have been shown to drive morphogenic processes that shape tissues and influence progression of diseases including cancer. The advent of porous media microfluidic approaches has enabled investigation of the cellular response to interstitial flow, but questions remain as to the critical biophysical and biochemical signals imparted by interstitial fluid pressure gradients and resulting flow on resident cells and extracellular matrix (ECM). Here, we introduce a low-cost method to maintain physiological interstitial fluid pressures that is built from commonly accessible laboratory equipment, including a laser pointer, camera, Arduino board, and a commercially available linear actuator. We demonstrate that when the system is connected to a microfluidic device containing a 3D porous hydrogel, physiologic pressure is maintained with sub-Pascal resolution and when basic feedback control is directed using an Arduino, constant pressure and pressure gradient can be maintained even as cells remodel and degrade the ECM hydrogel over time. Using this model, we characterized breast cancer cell growth and ECM changes to ECM fibril structure and porosity in response to constant interstitial fluid pressure or constant interstitial flow. We observe increased collagen fibril bundling and the formation of porous structures in the vicinity of cancer cells in response to constant interstitial fluid pressure as compared to constant interstitial flow. Collectively, these results further define interstitial fluid pressure as a driver of key pathogenic responses in cells, and the systems and methods developed here will allow for future mechanistic work investigating mechanotransduction of interstitial fluid pressures and flows.

Sodium accumulation in the skin is associated with higher density of skin lymphatic vessels in patients with arterial hypertension

PURPOSE

Recent studies, conducted mainly on the rodent model, have demonstrated that regulatory pathway in the skin provided by glycosaminoglycans, nuclear factor of activated T cells 5 (NFAT5), vascular endothelial growth factor C (VEGF-C) and process of lymphangiogenesis may play an important role in extrarenal regulation of sodium (Na+) balance, body water volume, and blood pressure. We aimed to investigate the concentrations and relations among the main factors of this pathway in human skin to confirm that this regulatory axis also exists in humans.

PATIENTS AND METHODS

Skin specimens from patients diagnosed with arterial hypertension and from control group were histologically and molecularly examined.

RESULTS

The primary hypertensive and control groups did not differ in Na+ ​concentrations in the skin. However, the patients with hypertension and higher skin Na+ concentration had significantly greater density of skin lymphatic vessels. Higher skin Na+concentration was associated with higher skin water content. In turn, skin water content correlated with factors associated with lymphangiogenesis, i.e. NFAT5, VEGF-C, and podoplanin (PDPN) mRNA expression in the skin. The strong mutual pairwise correlations of the expressions of NFAT5, VEGF-C, vascular endothelial growth factor D (VEGF-D) and PDPN mRNA were noted in the skin in all of the studied groups.

CONCLUSIONS

Our study confirms that skin interstitium and the lymphatic system may be important players in the pathophysiology of arterial hypertension in humans. Based on the results of our study and existing literature in this field, we propose the hypothetical model which might explain the phenomenon of salt-sensitivity.

SubQ-Sim: A Subcutaneous Physiologically Based Biopharmaceutics Model. Part 1: The Injection and System Parameters

PURPOSE

To construct a detailed mechanistic and physiologically based biopharmaceutics model capable of predicting 1) device-formulation-tissue interaction during the injection process and 2) binding, degradation, local distribution, diffusion, and drug absorption, following subcutaneous injection. This paper is part of a series and focusses on the first aspect.

METHODS

A mathematical model, SubQ-Sim, was developed incorporating the details of the various substructures within the subcutaneous environment together with the calculation of dynamic drug disposition towards the lymph ducts and venous capillaries. Literature was searched to derive key model parameters in healthy and diseased subjects. External factors such as body temperature, exercise, body position, food or stress provide a means to calculate the impact of "life events" on the pharmacokinetics of subcutaneously administered drugs.

RESULTS

The model predicts the tissue backpressure time profile during the injection as a function of injection rate, volume injected, solution viscosity, and interstitial fluid viscosity. The shape of the depot and the concentrations of the formulation and proteins in the depot are described. The model enables prediction of formulation backflow following premature needle removal and the resulting formulation losses. Finally, the effect of disease (type 2 diabetes) or the presence of recombinant human hyaluronidase in the formulation on the injection pressure, are explored.

CONCLUSIONS

This novel model can successfully predict tissue back pressure, depot dimensions, drug and protein concentration and formulation losses due to incorrect injection, which are all important starting conditions for predicting drug absorption from a subcutaneous dose. The next article will describe the absorption model and validation against clinical data.

Effective Attenuation of Arteriosclerosis Following Lymphatic-Targeted Delivery of Hyaluronic Acid-Decorated Rapamycin Liposomes

Background

The activation of lymphatic vessel function is the crux to resolving atherosclerosis (AS), a chronic inflammatory disease. Rapamycin (RAPA) recently has attracted considerable attention as a potent drug to induce atherosclerotic plaque attenuation. The objective of this work was to develop a ligand-decorated, RAPA-loaded liposome for lymphatic-targeted delivery of drugs to improve abnormal lymphatic structure and function, resulting in highly effective regression of atherosclerotic plaques.

Methods

Hyaluronic acid-decorated, RAPA-loaded liposomes (HA-RL) were fabricated by emulsion-solvent evaporation. The average size, zeta potential, entrapment efficiency were characterized, and the stability and drug release in vitro were investigated. Furthermore, the in vitro and in vivo lymphatic targeting ability were evaluated on lymphatic endothelial cells and LDLR-/- mice, and the efficiency of this nano-system in inducing the attenuation of atherosclerotic plaques was confirmed.

Results

HA-RL had a size of 100 nm, over 90% drug encapsulation efficiency, the storage stability was distinguished, demonstrating a slow release from the lipid nano-carriers. The mean retention time (MRT) and elimination half-life (t1/2β) achieved from HA-RL were 100.27±73.08 h and 70.74±50.80 h, respectively. HA-RL acquired the most prominent efficacy of lymphatic-targeted delivery and atherosclerotic plaques attenuation, implying the successful implementation of this novel drug delivery system in vivo.

Conclusion

HA-RL exhibited the most appreciable lymphatic targeting ability and best atherosclerotic plaques attenuation efficiency, opening a new paradigm and promising perspective for the treatment of arteriosclerosis.

Advanced subunit vaccine delivery technologies: From vaccine cascade obstacles to design strategies

Designing and manufacturing safe and effective vaccines is a crucial challenge for human health worldwide. Research on adjuvant-based subunit vaccines is increasingly being explored to meet clinical needs. Nevertheless, the adaptive immune responses of subunit vaccines are still unfavorable, which may partially be attributed to the immune cascade obstacles and unsatisfactory vaccine design. An extended understanding of the crosstalk between vaccine delivery strategies and immunological mechanisms could provide scientific insight to optimize antigen delivery and improve vaccination efficacy. In this review, we summarized the advanced subunit vaccine delivery technologies from the perspective of vaccine cascade obstacles after administration. The engineered subunit vaccines with lymph node and specific cell targeting ability, antigen cross-presentation, T cell activation properties, and tailorable antigen release patterns may achieve effective immune protection with high precision, efficiency, and stability. We hope this review can provide rational design principles and inspire the exploitation of future subunit vaccines.

Laboratory scoring system to predict hepatic indocyanine green clearance ability during fluorescence imaging-guided laparoscopic hepatectomy

BACKGROUND

Indocyanine green (ICG) fluorescence played an important role in tumor localization and margin delineation in hepatobiliary surgery. However, the preoperative regimen of ICG administration was still controversial. Factors associated with tumor fluorescence staining effect were unclear.

AIM

To investigate the preoperative laboratory indexes corelated with ICG fluorescence staining effect and establish a novel laboratory scoring system to screen specifical patients who need ICG dose adjustment.

METHODS

To investigate the predictive indicators of ICG fluorescence characteristics in patients undergoing laparoscopic hepatectomy from January 2018 to January 2021 were included. Blood laboratory tests were completed within 1 wk before surgery. All patients received 5 mg ICG injection 24 h before surgery for preliminary tumor imaging. ImageJ software was used to measure the fluorescence intensity values of regions of interest. Correlation analysis was used to identify risk factors. A laboratory risk model was established to identify individuals at high risk for high liver background fluorescence.

RESULTS

There were 110 patients who were enrolled in this study from January 2019 to January 2021. The mean values of fluorescence intensity of liver background (FI-LB), fluorescence intensity of gallbladder, and fluorescence intensity of target area were 18.87 ± 17.06, 54.84 ± 33.29, and 68.56 ± 36.11, respectively. The receiver operating characteristic (ROC) curve showed that FI-LB was a good indicator for liver clearance ability [area under the ROC curve (AUC) = 0.984]. Correlation analysis found pre-operative aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, adenosine deaminase, and lactate dehydrogenase were positively associated with FI-LB and red blood cell, cholinesterase, and were negatively associated with FI-LB. Total laboratory risk score (TLRS) was calculated according to ROC curve (AUC = 0.848, sensitivity = 0.773, specificity = 0.885). When TLRS was greater than 6.5, the liver clearance ability of ICG was considered as poor.

CONCLUSION

Preoperative laboratory blood indicators can predict hepatic ICG clearance ability. Surgeons can adjust the dose and timing of ICG preoperatively to achieve better liver fluorescent staining.

Nanovaccine-based strategies for lymph node targeted delivery and imaging in tumor immunotherapy

Therapeutic tumor vaccines have attracted considerable attention in the past decade; they can induce tumor regression, eradicate minimal residual disease, establish lasting immune memory and avoid non-specific and adverse side effects. However, the challenge in the field of therapeutic tumor vaccines is ensuring the delivery of immune components to the lymph nodes (LNs) to activate immune cells. The clinical response rate of traditional therapeutic tumor vaccines falls short of expectations due to inadequate lymph node delivery. With the rapid development of nanotechnology, a large number of nanoplatform-based LN-targeting nanovaccines have been exploited for optimizing tumor immunotherapies. In addition, some nanovaccines possess non-invasive visualization performance, which is benefit for understanding the kinetics of nanovaccine exposure in LNs. Herein, we present the parameters of nanoplatforms, such as size, surface modification, shape, and deformability, which affect the LN-targeting functions of nanovaccines. The recent advances in nanoplatforms with different components promoting LN-targeting are also summarized. Furthermore, emerging LNs-targeting nanoplatform-mediated imaging strategies to both improve targeting performance and enhance the quality of LN imaging are discussed. Finally, we summarize the prospects and challenges of nanoplatform-based LN-targeting and /or imaging strategies, which optimize the clinical efficacy of nanovaccines in tumor immunotherapies.

Fluid Osmolarity Modulates the Rate of Spontaneous Contraction of Lymphatic Vessels and Lymph Flow by Means of a Cooperation between TRPV and VRAC Channels

Lymphatic vessels are capable of sustaining lymph formation and propulsion via an intrinsic mechanism based on the spontaneous contraction of the lymphatic muscle in the wall of lymphatic collectors. Exposure to a hyper- or hypo-osmolar environment can deeply affect the intrinsic contraction rate and therefore alter lymph flow. In this work, we aimed at defining the putative receptors underlying such a response. Functional experiments were conducted in ex vivo rat diaphragmatic specimens containing spontaneously contracting lymphatic vessels that were exposed to either hyper- or hypo-osmolar solutions. Lymphatics were challenged with blockers to TRPV4, TRPV1, and VRAC channels, known to respond to changes in osmolarity and/or cell swelling and expressed by lymphatic vessels. Results show that the normal response to a hyperosmolar environment is a steady decrease in the contraction rate and lymph flow and can be prevented by blocking TRPV1 channels with capsazepine. The response to a hyposmolar environment consists of an early phase of an increase in the contraction rate, followed by a decrease. The early phase is abolished by blocking VRACs with DCPIB, while blocking TRPV4 mainly resulted in a delay of the early response. Overall, our data suggest that the cooperation of the three channels can shape the response of lymphatic vessels in terms of contraction frequency and lymph flow, with a prominent role of TRPV1 and VRACs.