Nanoparticle targeting to the endothelium during normothermic machine perfusion of human kidneys

Drug delivery strategies for local immunomodulation in transplantation: Bridging the translational gap

Drug delivery strategies for local immunomodulation hold tremendous promise compared to current clinical gold-standard systemic immunosuppression as they could improve the benefit to risk ratio of life-saving or life-enhancing transplants. Such strategies have facilitated prolonged graft survival in animal models at lower drug doses while minimizing off-target effects. Despite the promising outcomes in preclinical animal studies, progression of these strategies to clinical trials has faced challenges. A comprehensive understanding of the translational barriers is a critical first step towards clinical validation of effective immunomodulatory drug delivery protocols proven for safety and tolerability in pre-clinical animal models. This review overviews the current state-of-the-art in local immunomodulatory strategies for transplantation and outlines the key challenges hindering their clinical translation.

Contrast-enhanced computed tomography for ex vivo assessment of human kidneys: A proof-of-concept study

BACKGROUND

Ex vivo perfusion of transplant-declined human organs has emerged as a promising platform to study the response of an organ to novel therapeutic strategies. However, to fully realize the capability of this platform for performing translational research in human organ pathophysiology, there is a need for robust assays to assess organ function and disease. State-of-the-art research methods rely on analyses of biopsies taken during perfusion, which both damages the organ and only provides localized information. Developing non-invasive, whole organ methods of assessment is critical to the further development of this research platform.

METHODS

We use ex vivo cold infusion scanning (EXCIS) with contrast-enhanced computed tomography (CT) to quantify perfusion in kidneys preserved ex vivo. EXCIS-CT computes three complementary metrics for whole organ assessment: a dynamic assessment of contrast filling, a measure of vascular network anatomical structure, and a static assessment of perfusion heterogeneity.

RESULTS

These metrics were applied to a series of six transplant-declined human kidneys, which demonstrated a range of anatomies and perfusion. Lastly, two transplant-declined human kidneys were imaged before and after a 1-h period of ex vivo normothermic perfusion (NMP). We found variable responses to NMP, with one kidney maintaining the vascular network and hemodynamics and the other showing significant changes in vessel size and spatial perfusion profile.

CONCLUSIONS

EXCIS-CT provides metrics that can be used to characterize whole organ perfusion and vascular function.

Nanotechnology-based Strategies for Molecular Imaging, Diagnosis, and Therapy of Organ Transplantation

Organ transplantation is the preferred paradigm for patients with end-stage organ failures. Despite unprecedented successes, complications such as immune rejection, ischemia-reperfusion injury, and graft dysfunction remain significant barriers to long-term recipient survival after transplantation. Conventional immunosuppressive drugs have limited efficacy because of significant drug toxicities, high systemic immune burden, and emergence of transplant infectious disease, leading to poor quality of life for patients. Nanoparticle-based drug delivery has emerged as a promising medical technology and offers several advantages by enhancing the delivery of drug payloads to their target sites, reducing systemic toxicity, and facilitating patient compliance over free drug administration. In addition, nanotechnology-based imaging approaches provide exciting diagnostic methods for monitoring molecular and cellular changes in transplanted organs, visualizing immune responses, and assessing the severity of rejection. These noninvasive technologies are expected to help enhance the posttransplantation patient survival through real time and early diagnosis of disease progression. Here, we present a comprehensive review of nanotechnology-assisted strategies in various aspects of organ transplantation, including organ protection before transplantation, mitigation of ischemia-reperfusion injury, counteraction of immune rejection, early detection of organ dysfunction posttransplantation, and molecular imaging and diagnosis of immune rejection.

Thermosensitive Hydrogels as Targeted and Controlled Drug Delivery Systems: Potential Applications in Transplantation

Drug delivery in transplantation plays a vital role in promoting graft survival, preventing rejection, managing complications, and contributing to positive patient outcomes. Targeted and controlled drug delivery can minimize systemic effects. Thermosensitive hydrogels, due to their unique sol-gel transition properties triggered by thermo-stimuli, have attracted significant research interest as a potential drug delivery system in transplantation. This review describes the current status, characteristics, and recent applications of thermosensitive hydrogels for drug delivery. Studies aimed at improving allotransplantation outcomes using thermosensitive hydrogels are then elaborated on. Finally, the challenges and opportunities associated with their use are discussed. Understanding the progress of research will serve as a guide for future improvements in their application as a means of targeted and controlled drug delivery in translational therapeutic applications for transplantation.

Application of nanomaterials in heart transplantation: a narrative review

Background and Objective

Heart transplantation (HT) is a therapeutic option for end-stage heart disease. Still, it faces many challenges, especially the shortage of donor sources and the poor durability of grafts, which are the two critical issues. In this review, we generalize the application of existing nanomedicine technologies in donor management as well as prevention and diagnosis of post-transplantation complications, also including the current preclinical studies of nanomaterials in cardiac tissue engineering and gene-editing xeno-donor grafts. Finally, we discuss the remaining problems and future directions of nanomaterials in the field of HT.

Methods

A narrative review using current search of the most recent literature on the topic. The terms "nanomaterials", "nano medicine'', "Heart transplantation (HT)", "Nano-drug delivery system (NDDS)" or their combination were searched in PubMed and Google Scholar. The specified timeframe began from 1990, and we prioritized publications mainly from the last 10 years.

Key Content and Findings

Nano-systems integrating therapeutic and diagnostic functions have been applied to cardiovascular diseases (CVDs) with their unique advantages in multiple fields such as drug delivery, tissue engineering, gene editing, imaging, biomarker editing, and many other aspects. In terms of transplantation, the preservation, transportation, and pretreatment of donor hearts machine perfusion (MP) provide the possibility for nano-systems with unique features, and therapeutic and diagnostic functions to be directly and passively targeted in order to improve the functional status of the transplanted organs or to increase the ability to tolerate the graft of patients. The development of nano-imaging, nanosensor, and nano biomarker technologies are also being applied to monitor the status of transplant recipients for early prevention and treatment of post-transplantation-related complications. Nanomaterials combined with cardiac tissue engineering and gene editing technologies could also expand graft sources and alleviate donor shortages.

Conclusions

Although the overall research on nanomaterial applications in the field of HT is in its infancy, its role in improving the prognosis of transplant recipients and breaking the current dilemma of HT is clear. However, before nanotechnologies can be translated into clinical applications in the future, they must be aimed at ensuring the drug delivery system's safety and pose a challenge in the direction of the ability to intervene with multiple drugs in combination.

Nanosystem Delivers Senescence Activators and Immunomodulators to Combat Liver Cancer

CD47 blockade has emerged as a promising immunotherapy against liver cancer. However, the optimization of its antitumor effectiveness using efficient drug delivery systems or combinations of therapeutic agents remains largely incomplete. Here, patients with liver cancer co-expressing CD47 and CDC7 (cell division cycle 7, a negative senescence-related gene) are found to have the worst prognosis. Moreover, CD47 is highly expressed, and senescence is inhibited after the development of chemoresistance, suggesting that combination therapy targeting CD47 and CDC7 to inhibit CD47 and induce senescence may be a promising strategy for liver cancer. The efficacy of intravenously administered CDC7 and CD47 inhibitors is limited by low uptake and short circulation times. Here, inhibitors are coloaded into a dual-targeted nanosystem. The sequential release of the inhibitors from the nanosystem under acidic conditions first induces cellular senescence and then promotes immune responses. In an in situ liver cancer mouse model and a chemotherapy-resistant mouse model, the nanosystem effectively inhibited tumor growth by 90.33% and 85.15%, respectively. Overall, the nanosystem in this work achieved the sequential release of CDC7 and CD47 inhibitors in situ to trigger senescence and induce immunotherapy, effectively combating liver cancer and overcoming chemoresistance.

Nanoparticle-assisted Targeting Delivery Technologies for Preventing Organ Rejection

Although organ transplantation is a life-saving medical procedure, the challenge of posttransplant rejection necessitates safe and effective immune modulation strategies. Nanodelivery approaches may have the potential to overcome the limitations of small-molecule immunosuppressive drugs, achieving efficacious treatment options for transplant tolerance without compromising overall host immunity. This review highlights recent advances in biomaterial-assisted formulations and technologies for targeted nanodrug delivery with transplant organ- or immune cell-level precision for treating graft rejection after transplantation. We provide an overview of the mechanism of transplantation rejection, current clinically approved immunosuppressive drugs, and their relevant limitations. Finally, we discuss the targeting principles and advantages of organ- and immune cell-specific delivery technologies. The development of biomaterial-assisted novel therapeutic strategies holds considerable promise for treating organ rejection and clinical translation.

The application of nanotechnology in kidney transplantation

Kidney transplantation is a crucial treatment option for end-stage renal disease patients, but challenges related to graft function, rejection and immunosuppressant side effects persist. This review highlights the potential of nanotechnology in addressing these challenges. Nanotechnology offers innovative solutions to enhance organ preservation, evaluate graft function, mitigate ischemia-reperfusion injury and improve drug delivery for immunosuppressants. The integration of nanotechnology holds promise for improving outcomes in kidney transplantation.

Nanoparticle-based T cell immunoimaging and immunomodulatory for diagnosing and treating transplant rejection

T cells serve a pivotal role in the rejection of transplants, both by directly attacking the graft and by recruiting other immune cells, which intensifies the rejection process. Therefore, monitoring T cells becomes crucial for early detection of transplant rejection, while targeted drug delivery specifically to T cells can significantly enhance the effectiveness of rejection therapy. However, regulating the activity of T cells within transplanted organs is challenging, and the prolonged use of immunosuppressive drugs is associated with notable side effects and complications. Functionalized nanoparticles offer a potential solution by targeting T cells within transplants or lymph nodes, thereby reducing the off-target effects and improving the long-term survival of the graft. In this review, we will provide an overview of recent advancements in T cell-targeted imaging molecular probes for diagnosing transplant rejection and the progress of T cell-regulating nanomedicines for treating transplant rejection. Additionally, we will discuss future directions and the challenges in clinical translation.

H2O2-stimulated Janus-shaped self-propelled nanomotors as an active treatment for acute renal injury

As emerging nanosystems, nanomotors have been applied in the active treatment of many diseases. In this paper, Pt@chitosan-loaded melatonin asymmetrical nanomaterials embedded with L-serine (S, kidney injury molecule 1-targeting agent) were constructed to alleviate acute kidney injury (AKI). The Janus nanocarriers arrived at the renal injury site via the bloodstream and exhibited high permeability. Because of melatonin distribution in the kidneys combined with H2O2-stimulated O2 release, the administration of the Janus nanosystem resulted in active treatment through the motion of nanomotors by asymmetrical O2 release.

Perfusate Proteomes Provide Biological Insight Into Oxygenated Versus Standard Hypothermic Machine Perfusion in Kidney Transplantation

OBJECTIVE

To provide mechanistic insight into key biological alterations in donation after circulatory death kidneys during continuous pefusion we performed mass spectrometry profiling of perfusate samples collected during a phase 3 randomized double-blind paired clinical trial of hypothermic machine perfusion with and without oxygen (COMPARE).

BACKGROUND

Despite the clinical benefits of novel perfusion technologies aiming to better preserve donor organs, biological processes that may be altered during perfusion have remained largely unexplored. The collection of serial perfusate samples during the COMPARE clinical trial provided a unique resource to study perfusate proteomic profiles, with the hypothesis that in-depth profiling may reveal biologically meaningful information on how donor kidneys benefit from this intervention.

METHODS

Multiplexed liquid chromatography-tandem mass spectrometry was used to obtain a proteome profile of 210 perfusate samples. Partial least squares discriminant analysis and multivariate analysis involving clinical and perfusion parameters were used to identify associations between profiles and clinical outcomes.

RESULTS

Identification and quantitation of 1716 proteins indicated that proteins released during perfusion originate from the kidney tissue and blood, with blood-based proteins being the majority. Data show that the overall hypothermic machine perfusion duration is associated with increasing levels of a subgroup of proteins. Notably, high-density lipoprotein and complement cascade proteins are associated with 12-month outcomes, and blood-derived proteins are enriched in the perfusate of kidneys that developed acute rejection.

CONCLUSIONS

Perfusate profiling by mass spectrometry was informative and revealed proteomic changes that are biologically meaningful and, in part, explain the clinical observations of the COMPARE trial.

Pushing the boundaries of innovation: the potential of ex vivo organ perfusion from an interdisciplinary point of view

Ex vivo machine perfusion (EVMP) is an emerging technique for preserving explanted solid organs with primary application in allogeneic organ transplantation. EVMP has been established as an alternative to the standard of care static-cold preservation, allowing for prolonged preservation and real-time monitoring of organ quality while reducing/preventing ischemia-reperfusion injury. Moreover, it has paved the way to involve expanded criteria donors, e.g., after circulatory death, thus expanding the donor organ pool. Ongoing improvements in EVMP protocols, especially expanding the duration of preservation, paved the way for its broader application, in particular for reconditioning and modification of diseased organs and tumor and infection therapies and regenerative approaches. Moreover, implementing EVMP for in vivo-like preclinical studies improving disease modeling raises significant interest, while providing an ideal interface for bioengineering and genetic manipulation. These approaches can be applied not only in an allogeneic and xenogeneic transplant setting but also in an autologous setting, where patients can be on temporary organ support while the diseased organs are treated ex vivo, followed by reimplantation of the cured organ. This review provides a comprehensive overview of the differences and similarities in abdominal (kidney and liver) and thoracic (lung and heart) EVMP, focusing on the organ-specific components and preservation techniques, specifically on the composition of perfusion solutions and their supplements and perfusion temperatures and flow conditions. Novel treatment opportunities beyond organ transplantation and limitations of abdominal and thoracic EVMP are delineated to identify complementary interdisciplinary approaches for the application and development of this technique.

Transformative Materials for Interfacial Drug Delivery

Drug delivery systems (DDS) are designed to temporally and spatially control drug availability and activity. They assist in improving the balance between on-target therapeutic efficacy and off-target toxic side effects. DDS aid in overcoming biological barriers encountered by drug molecules upon applying them via various routes of administration. They are furthermore increasingly explored for modulating the interface between implanted (bio)medical materials and host tissue. Herein, an overview of the biological barriers and host-material interfaces encountered by DDS upon oral, intravenous, and local administration is provided, and material engineering advances at different time and space scales to exemplify how current and future DDS can contribute to improved disease treatment are highlighted.

Rational nanoparticle design: Optimization using insights from experiments and mathematical models

Polymeric nanoparticles are highly tunable drug delivery systems that show promise in targeting therapeutics to specific sites within the body. Rational nanoparticle design can make use of mathematical models to organize and extend experimental data, allowing for optimization of nanoparticles for particular drug delivery applications. While rational nanoparticle design is attractive from the standpoint of improving therapy and reducing unnecessary experiments, it has yet to be fully realized. The difficulty lies in the complexity of nanoparticle structure and behavior, which is added to the complexity of the physiological mechanisms involved in nanoparticle distribution throughout the body. In this review, we discuss the most important aspects of rational design of polymeric nanoparticles. Ultimately, we conclude that many experimental datasets are required to fully model polymeric nanoparticle behavior at multiple scales. Further, we suggest ways to consider the limitations and uncertainty of experimental data in creating nanoparticle design optimization schema, which we call quantitative nanoparticle design frameworks.

Machine perfusion of the liver and bioengineering

With the increasing number of accepted candidates on waiting lists worldwide, there is an urgent need to expand the number and the quality of donor livers. Dynamic preservation approaches have demonstrated various benefits, including improving liver function and graft survival, and reducing liver injury and post-transplant complications. Consequently, organ perfusion techniques are being used in clinical practice in many countries. Despite this success, a proportion of livers do not meet current viability tests required for transplantation, even with the use of modern perfusion techniques. Therefore, devices are needed to further optimise machine liver perfusion - one promising option is to prolong machine liver perfusion for several days, with ex situ treatment of perfused livers. For example, stem cells, senolytics, or molecules targeting mitochondria or downstream signalling can be administered during long-term liver perfusion to modulate repair mechanisms and regeneration. Besides, today's perfusion equipment is also designed to enable the use of various liver bioengineering techniques, to develop scaffolds or for their re-cellularisation. Cells or entire livers can also undergo gene modulation to modify animal livers for xenotransplantation, to directly treat injured organs or to repopulate such scaffolds with "repaired" autologous cells. This review first discusses current strategies to improve the quality of donor livers, and secondly reports on bioengineering techniques to design optimised organs during machine perfusion. Current practice, as well as the benefits and challenges associated with these different perfusion strategies are discussed.

Targeted nanotherapy for kidney diseases: a comprehensive review

Kidney diseases represent a major public health problem, affecting millions of people worldwide. Moreover, the treatment of kidney diseases is burdened by the problematic effects of conventional drug delivery, such as systemic drug toxicity, rapid drug clearance, and the absence of precise targeting of the kidney. Although the use of nanotechnology in medicine is in its early stage and lacks robust translational studies, nanomedicines have already shown great promise as novel drug-delivery systems for the treatment of kidney disease. On the basis of our current knowledge of renal anatomy and physiology, pathophysiology of kidney diseases, and physicochemical characteristics of nanoparticles, an expansive repertoire and wide use of nanomedicines could be developed for kidney diseases in the near future. Some limitations have slowed the transition of these agents from preclinical studies to clinical trials, however. In this review, we summarize the current knowledge on renal drug-delivery systems and recent advances in renal cell targeting; we also demonstrate their important potential as future paradigm-shifting therapies for kidney diseases.

Current Evidence and Future Perspectives to Implement Continuous and End-Ischemic Use of Normothermic and Oxygenated Hypothermic Machine Perfusion in Clinical Practice

The use of high-risk renal grafts for transplantation requires the optimization of pretransplant assessment and preservation reconditioning strategies to decrease the organ discard rate and to improve short- and long-term clinical outcomes. Active oxygenation is increasingly recognized to play a central role in dynamic preservation strategies, independent of preservation temperature, to recondition mitochondria and to restore the cellular energy profile. The oxygen-related decrease in mitochondrial succinate accumulation ameliorates the harmful effects of ischemia-reperfusion injury. The differences between normothermic and hypothermic machine perfusion with regard to organ assessment, preservation, and reconditioning, as well as the logistic and economic implications, are factors to take into consideration for implementation at a local level. Therefore, these different techniques should be considered complementary to the perfusion strategy selected depending on functional intention and resource availability. This review provides an overview of the current clinical evidence of normothermic and oxygenated hypothermic machine perfusion, either as a continuous or end-ischemic preservation strategy, and future perspectives.

Preliminary observations of an ex vivo normothermic whole blood machine perfusion in an experimental liver transplant porcine model

BACKGROUND

Even though transplantation is an essential treatment with no viable alternatives, a significant worldwide donor shortage persists. In this study, we assessed the metabolism of livers that underwent extended periods of circulatory death and subsequently conducted functional validation through transplantation to explore the feasibility of using livers from an uncontrolled donor after circulatory death (u-DCD).

METHODS

A donor model simulating u-DCD was constructed using pigs. The prolonged warm ischemia time (WIT) was set to 60, 120, and 180 minutes, and the liver function was evaluated after 24 hours of perfusion using an originally developed normothermic perfusion system. Based on the results, functional confirmation by transplantation was performed on the 2 groups with prolonged WIT of 60 and 180 minutes.

RESULTS

Based on the 24-hour perfusion of the liver alone, we evaluated the function by transplanting the WI 60-minute model and 180-minute model (N = 3 each). Warm ischemia was 73.5 ± 3.7 minutes and 188 ± 3 minutes in the 60-minute model and 180-minute model, respectively. In the model with 60 minutes of WI, one case survived until the endpoint, and 2 cases survived between 8 and 12 hours, whereas, in the model with 180 minutes of WI, they died within 6 hours.

CONCLUSION

We constructed a completely uncontrolled circulatory arrest model without anticoagulation and showed the possibility of using u-DCD livers by ex vivo machine perfusion and transplantation.

Nanoparticle-Based Interventions for Liver Transplantation

Liver transplantation is the only treatment for hepatic insufficiency as a result of acute and chronic liver injuries/pathologies that fail to recover. Unfortunately, there remains an enormous and growing gap between organ supply and demand. Although recipients on the liver transplantation waitlist have significantly higher mortality, livers are often not allocated because they are (i) classified as extended criteria or marginal livers and (ii) subjected to longer cold preservation time (>6 h) with a direct correlation of poor outcomes with longer cold ischemia. Downregulating the recipient's innate immune response to successfully tolerate a graft having longer cold ischemia times or ischemia-reperfusion injury through induction of immune tolerance in the graft and the host would significantly improve organ utilization and post-transplant outcomes. Broadly, technologies proposed for development aim to extend the life of the transplanted liver through post-transplant or recipient conditioning. In this review, we focus on the potential benefits of nanotechnology to provide unique pre-transplant grafting and recipient conditioning of extended criteria donor livers using immune tolerance induction and hyperthermic pre-conditioning.

Sterile Pancreas Inflammation during Preservation and after Transplantation

The pancreas is very susceptible to ischemia-reperfusion injury. Early graft losses due to pancreatitis and thrombosis represent a major issue after pancreas transplantation. Sterile inflammation during organ procurement (during brain death and ischemia-reperfusion) and after transplantation affects organ outcomes. Sterile inflammation of the pancreas linked to ischemia-reperfusion injury involves the activation of innate immune cell subsets such as macrophages and neutrophils, following tissue damage and release of damage-associated molecular patterns and pro-inflammatory cytokines. Macrophages and neutrophils favor tissue invasion by other immune cells, have deleterious effects or functions, and promote tissue fibrosis. However, some innate cell subsets may promote tissue repair. This outburst of sterile inflammation promotes adaptive immunity activation via antigen exposure and activation of antigen-presenting cells. Better controlling sterile inflammation during pancreas preservation and after transplantation is of utmost interest in order to decrease early allograft loss (in particular thrombosis) and increase long-term allograft survival. In this regard, perfusion techniques that are currently being implemented represent a promising tool to decrease global inflammation and modulate the immune response.

How to Best Protect Kidneys for Transplantation-Mechanistic Target

The increasing number of patients on the kidney transplant waiting list underlines the need to expand the donor pool and improve kidney graft utilization. By protecting kidney grafts adequately from the initial ischemic and subsequent reperfusion injury occurring during transplantation, both the number and quality of kidney grafts could be improved. The last few years have seen the emergence of many new technologies to abrogate ischemia-reperfusion (I/R) injury, including dynamic organ preservation through machine perfusion and organ reconditioning therapies. Although machine perfusion is gradually making the transition to clinical practice, reconditioning therapies have not yet progressed from the experimental setting, pointing towards a translational gap. In this review, we discuss the current knowledge on the biological processes implicated in I/R injury and explore the strategies and interventions that are being proposed to either prevent I/R injury, treat its deleterious consequences, or support the reparative response of the kidney. Prospects to improve the clinical translation of these therapies are discussed with a particular focus on the need to address multiple aspects of I/R injury to achieve robust and long-lasting protective effects on the kidney graft.

Honoring the gift: The transformative potential of transplant-declined human organs

For decades, transplantation has been a life-saving treatment for those fortunate enough to gain access. Nevertheless, many patients die waiting for an organ and countless more never make it onto the waitlist because of a shortage of donor organs. Concurrently, thousands of donated organs are declined for transplant each year because of concerns about poor outcomes post-transplant. The decline of any donated organ-even if medically justified-is tragic for both the donor family and potential recipients. In this Personal Viewpoint, we discuss the need for a new mindset in how we honor the gift of organ donation. We believe that the use of transplant-declined human organs in translational research has the potential to hasten breakthrough discoveries in a multitude of scientific and medical areas. More importantly, such breakthroughs will allow us to properly value every donated organ. We further discuss the many practical challenges that such research presents and offer some possible solutions based on experiences in our own research laboratories. Finally, we share our perspective on what we believe are the necessary next steps to ensure a future where every donated organ realizes its full potential to impact the lives of current and future patients.

Oridonin inhibits inflammation of epithelial cells via dual-targeting of CD31 Keap1 to ameliorate acute lung injury

Introdcution

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are major causes of COVID-19 mortality. However, drug delivery to lung tissues is impeded by endothelial cell barriers, limiting the efficacy of existing treatments. A prompt and aggressive treatment strategy is therefore necessary.

Methods

We assessed the ability of anti-CD31-ORI-NPs to penetrate endothelial cell barriers and specifically accumulate in lung tissues using an animal model. We also compared the efficacy of anti-CD31-ORI-NPs to that of free oridonin in ameliorating acute lung injury and evaluated the cytotoxicity of both treatments on endothelial cells.

Results

Compared to free ORI, the amount of anti-CD31-ORI-NPs accumulated in lung tissues increase at least three times. Accordingly, anti-CD31-ORI-NPs improve the efficacy three times on suppressing IL-6 and TNF-a secretion, ROS production, eventually ameliorating acute lung injury in animal model. Importantly, anti-CD31-ORI-NPs significantly decrease the cytotoxicity at least two times than free oridonin on endothelial cells.

Discussion

Our results from this study will not only offer a novel therapeutic strategy with high efficacy and low toxicity, but also provide the rational design of nanomaterials of a potential drug for acute lung injury therapy.

Nucleic Acid Delivery to the Vascular Endothelium

This Review examines the state-of-the-art in the delivery of nucleic acid therapies that are directed to the vascular endothelium. First, we review the most important homeostatic functions and properties of the vascular endothelium and summarize the nucleic acid tools that are currently available for gene therapy and nucleic acid delivery. Second, we consider the opportunities available with the endothelium as a therapeutic target and the experimental models that exist to evaluate the potential of those opportunities. Finally, we review the progress to date from investigations that are directly targeting the vascular endothelium: for vascular disease, for peri-transplant therapy, for angiogenic therapies, for pulmonary endothelial disease, and for the blood-brain barrier, ending with a summary of the future outlook in this field.

Modelling acute antibody-mediated rejection of human kidney transplants using ex-vivo warm machine perfusion

BACKGROUND

Transplant rejection is a major cause of graft loss and morbidity. Currently, no human models of antibody-mediated rejection (AMR) exist, limiting mechanistic investigation and organ-specific targeted therapy. Here, using 12 human kidneys and ex-vivo normothermic machine perfusion, we demonstrate phenotypes of AMR after addition of antibodies against either human HLA class I or blood group antigens (A, B), thus modelling clinical AMR that can follow HLA incompatible (HLAi) or blood group incompatible (ABOi) transplantation.

METHODS

Discarded human kidneys with wide ranging demographics and cold ischaemia times (11-54 h) were perfused with red blood cells and fresh frozen plasma (FFP) as a source of complement/coagulation factors. For the HLAi model, 600 μg of W6/32 anti-class 1 HLA antibody was added to the circuit (time '0'). For the ABOi model, high titre FFP of the relevant blood group antibody was added. Renal blood flow index (RBFi, mL/min/100 g), C3 desArg, prothrombin fragments 1 + 2 and histology were determined. Our endpoints included haemodynamic changes, thrombosis, and biopsy proven complement deposition.

FINDINGS

Compared to control kidneys perfused without anti-donor antibodies, both models demonstrated haemodynamic collapse after antibody perfusion with only the HLAi model showing glomerular C4d deposition.

INTERPRETATION

We show that a clinically relevant human kidney model of AMR is feasible, and anticipate that these models, with refinements, could provide a basis to test different strategies to prevent AMR.

FUNDING

The Rosetrees and Stonygate Trust, The Royal College of Surgeons of England Fellowship Grant, NIHR Biomedical Research Centre/KCL Early Career Grant, Kidney Research U.K.

Monobody adapter for functional antibody display on nanoparticles for adaptable targeted delivery applications

Vascular endothelial cells (ECs) play a central role in the pathophysiology of many diseases. The use of targeted nanoparticles (NPs) to deliver therapeutics to ECs could dramatically improve efficacy by providing elevated and sustained intracellular drug levels. However, achieving sufficient levels of NP targeting in human settings remains elusive. Here, we overcome this barrier by engineering a monobody adapter that presents antibodies on the NP surface in a manner that fully preserves their antigen-binding function. This system improves targeting efficacy in cultured ECs under flow by >1000-fold over conventional antibody immobilization using amine coupling and enables robust delivery of NPs to the ECs of human kidneys undergoing ex vivo perfusion, a clinical setting used for organ transplant. Our monobody adapter also enables a simple plug-and-play capacity that facilitates the evaluation of a diverse array of targeted NPs. This technology has the potential to simplify and possibly accelerate both the development and clinical translation of EC-targeted nanomedicines.

Protection of transplants against antibody-mediated injuries: from xenotransplantation to allogeneic transplantation, mechanisms and therapeutic insights

Long-term allograft survival in allotransplantation, especially in kidney and heart transplantation, is mainly limited by the occurrence of antibody-mediated rejection due to anti-Human Leukocyte Antigen antibodies. These types of rejection are difficult to handle and chronic endothelial damages are often irreversible. In the settings of ABO-incompatible transplantation and xenotransplantation, the presence of antibodies targeting graft antigens is not always associated with rejection. This resistance to antibodies toxicity seems to associate changes in endothelial cells phenotype and modification of the immune response. We describe here these mechanisms with a special focus on endothelial cells resistance to antibodies. Endothelial protection against anti-HLA antibodies has been described in vitro and in animal models, but do not seem to be a common feature in immunized allograft recipients. Complement regulation and anti-apoptotic molecules expression appear to be common features in all these settings. Lastly, pharmacological interventions that may promote endothelial cell protection against donor specific antibodies will be described.

Wanted: An endothelial cell targeting atlas for nanotherapeutic delivery in allograft organs

Despite the profound shortage of organs available for transplant in the U.S., over 5,000 donated organs were declined for use in 2020. Many of these organs were declined due to donor comorbidities or preservation injuries that predispose grafts to rejection and loss. The risks of these poor outcomes can potentially be reduced by pre-transplant application of normothermic machine perfusion (NMP). To date, the clinical use of NMP has focused on extending preservation and improving organ assessment, but the opportunity for ex situ therapeutic delivery may be the most transformative aspect of this technology. In this Personal Viewpoint, we argue that the endothelial cells (ECs) that line the graft vasculature are an accessible, under-exploited, and attractive target for transplant therapeutics delivered during NMP. We further contend that molecularly targeted nanoparticles (NPs) represent a promising therapeutic vehicle particularly well-suited to NMP. However, to achieve this potential, we need to answer the following three key questions: (1) What EC sub-populations exist within an organ? (2) How can these cells be accessed? (3) And most important, how can preferential retention of NPs by the cells of interest be maximized? Here we argue for creating an EC-targeting atlas as a body of knowledge that answers these questions.

Cerium oxide nanoparticles administration during machine perfusion of discarded human livers: A pilot study

The combined approach of ex situ normothermic machine perfusion (NMP) and nanotechnology represents a strategy to mitigate ischemia/reperfusion injury in liver transplantation (LT). We evaluated the uptake, distribution, and efficacy of antioxidant cerium oxide nanoparticles (nanoceria) during normothermic perfusion of discarded human livers. A total of 9 discarded human liver grafts were randomized in 2 groups and underwent 4 h of NMP: 5 grafts were treated with nanoceria conjugated with albumin (Alb-NC; 50 µg/ml) and compared with 4 untreated grafts. The intracellular uptake of nanoceria was analyzed by electron microscopy (EM) and inductively coupled plasma-mass spectrometry (ICP-MS). The antioxidant activity of Alb-NC was assayed in liver biopsies by glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) assay, telomere length, and 4977-bp common mitochondrial DNA deletion (mtDNA⁴⁹⁷⁷ deletion). The cytokine profile was evaluated in perfusate samples. EM and ICP-MS confirmed Alb-NC internalization, rescue of mitochondrial phenotype, decrease of lipid droplet peroxidation, and lipofuscin granules in the treated grafts. Alb-NC exerted an antioxidant activity by increasing GSH levels (percentage change: +94% ± 25%; p = 0.01), SOD (+17% ± 4%; p = 0.02), and CAT activity (51% ± 23%; p = 0.03), reducing the occurrence of mtDNA⁴⁹⁷⁷ deletion (-67.2% ± 11%; p = 0.03), but did not affect cytokine release. Alb-NC during ex situ perfusion decreased oxidative stress, upregulating graft antioxidant defense. They could be a tool to improve quality grafts during NMP and represent an antioxidant strategy aimed at protecting the graft against reperfusion injury during LT.

Nanotherapeutics in transplantation: How do we get to clinical implementation?

Patients undergoing organ transplantation transition from one life-altering issue (organ dysfunction) to a lifelong commitment-immunosuppression. Regimens of immunosuppressive agents (ISAs) come with significant side effects and comorbidities. Recently, the use of nanoparticles (NPs) as a solution to the problems associated with the long-term and systemic use of ISAs in transplantation has emerged. This minireview describes the role of NPs in organ transplantation and discusses obstacles to clinical implementation and pathways to clinical translation.

Targeting vascular inflammation through emerging methods and drug carriers

Acute inflammation is a common dangerous component of pathogenesis of many prevalent conditions with high morbidity and mortality including sepsis, thrombosis, acute respiratory distress syndrome (ARDS), COVID-19, myocardial and cerebral ischemia-reperfusion, infection, and trauma. Inflammatory changes of the vasculature and blood mediate the course and outcome of the pathology in the tissue site of insult, remote organs and systemically. Endothelial cells lining the luminal surface of the vasculature play the key regulatory functions in the body, distinct under normal vs. pathological conditions. In theory, pharmacological interventions in the endothelial cells might enable therapeutic correction of the overzealous damaging pro-inflammatory and pro-thrombotic changes in the vasculature. However, current agents and drug delivery systems (DDS) have inadequate pharmacokinetics and lack the spatiotemporal precision of vascular delivery in the context of acute inflammation. To attain this level of precision, many groups design DDS targeted to specific endothelial surface determinants. These DDS are able to provide specificity for desired tissues, organs, cells, and sub-cellular compartments needed for a particular intervention. We provide a brief overview of endothelial determinants, design of DDS targeted to these molecules, their performance in experimental models with focus on animal studies and appraisal of emerging new approaches. Particular attention is paid to challenges and perspectives of targeted therapeutics and nanomedicine for advanced management of acute inflammation.

Nanotechnology in Kidney and Islet Transplantation: An Ongoing, Promising Field

Organ transplantation has evolved rapidly in recent years as a reliable option for patients with end-stage organ failure. However, organ shortage, surgical risks, acute and chronic rejection reactions and long-term immunosuppressive drug applications and their inevitable side effects remain extremely challenging problems. The application of nanotechnology in medicine has proven highly successful and has unique advantages for diagnosing and treating diseases compared to conventional methods. The combination of nanotechnology and transplantation brings a new direction of thinking to transplantation medicine. In this article, we provide an overview of the application and progress of nanotechnology in kidney and islet transplantation, including nanotechnology for renal pre-transplantation preservation, artificial biological islets, organ imaging and drug delivery.

Surface conjugation of antibodies improves nanoparticle uptake in bronchial epithelial cells

BACKGROUND

Advances in Molecular Therapy have made gene editing through systemic or topical administration of reagents a feasible strategy to treat genetic diseases in a rational manner. Encapsulation of therapeutic agents in nanoparticles can improve intracellular delivery of therapeutic agents, provided that the nanoparticles are efficiently taken up within the target cells. In prior work we had established proof-of-principle that nanoparticles carrying gene editing reagents can mediate site-specific gene editing in fetal and adult animals in vivo that results in functional disease improvement in rodent models of β-thalassemia and cystic fibrosis. Modification of the surface of nanoparticles to include targeting molecules (e.g. antibodies) holds the promise of improving cellular uptake and specific cellular binding.

METHODS AND FINDINGS

To improve particle uptake for diseases of the airway, like cystic fibrosis, our group tested the impact of nanoparticle surface modification with cell surface marker antibodies on uptake in human bronchial epithelial cells in vitro. Binding kinetics of antibodies (Podoplanin, Muc 1, Surfactant Protein C, and Intracellular Adhesion Molecule-1 (ICAM)) were determined to select appropriate antibodies for cellular targeting. The best target-specific antibody among those screened was ICAM antibody. Surface conjugation of nanoparticles with antibodies against ICAM improved cellular uptake in bronchial epithelial cells up to 24-fold.

CONCLUSIONS

This is a first demonstration of improved nanoparticle uptake in epithelial cells using conjugation of target specific antibodies. Improved binding, uptake or specificity of particles delivered systemically or to the luminal surface of the airway would potentially improve efficacy, reduce the necessary dose and thus safety of administered therapeutic agents. Incremental improvement in the efficacy and safety of particle-based therapeutic strategies may allow genetic diseases such as cystic fibrosis to be cured on a fundamental genetic level before birth or shortly after birth.

rhADAMTS13 reduces oxidative stress by cleaving VWF in ischaemia/reperfusion-induced acute kidney injury

AIMS

Acute kidney injury (AKI), a major health burden, lacks effective therapy. Anti-inflammatory actions of a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13 (ADAMTS13) may provide a new treatment option for AKI. Along with inflammation, oxidative stress is critical for AKI development, yet the impact of ADAMTS13 on oxidative stress in AKI remains to be fully elucidated.

METHODS

We assess recombinant human ADAMTS13 (rhADAMTS13) actions on oxidative stress in a murine ischaemia/reperfusion (IR) model. Antioxidant stress-enzyme activities, renal morphology, kidney function markers and vascular function of isolated afferent arterioles are quantified.

RESULTS

rhADAMTS13 provided after IR, reduces blood urea nitrogen (BUN) by 33% and serum creatinine (Scr) by 73% in 24 hours post-IR. rhADAMTS13 reduces BUN (40.03 ± 20.34 mmol/L vs 72.35 ± 18.74 mmol/L, P < .01), Scr (75.67 ± 51.19 μmol/L vs 176.17 ± 55.38 μmol/L, P < .01) and proteinuria by 41% in 48 hours post-IR as well. Moreover, rhADAMTS13 administration decreases malondialdehyde (MDA) and increases the activity of antioxidant stress enzymes, and attenuates reactive oxygen species production. rhADAMTS13 also upregulates nuclear factor-erythroid-2-related factor 2/haem oxygenase-1, enhances antioxidant enzymes activity and alleviates endothelial dysfunction. Finally, treatment with rhADAMTS13 mitigates severe functional and morphological injury present in IR mice. Extracellular signal-regulated kinase (ERK) phosphorylation is limited by rhADAMTS13 and PPARγ expression is partly restored in ischaemic kidneys. Co-administration of von Willebrand factor (VWF) impairs rhADAMTS13's antioxidant capacity and its protective role in IR.

CONCLUSION

rhADAMTS13 alleviates renal IR injury through antioxidant effects by cleaving VWF.

Renal Normothermic Machine Perfusion: The Road Toward Clinical Implementation of a Promising Pretransplant Organ Assessment Tool

The increased utilization of high-risk renal grafts for transplantation requires optimization of pretransplant organ assessment strategies. Current decision-making methods to accept an organ for transplantation lack overall predictive power and always contain an element of subjectivity. Normothermic machine perfusion (NMP) creates near-physiological conditions, which might facilitate a more objective assessment of organ quality before transplantation. NMP is rapidly gaining popularity, with various transplant centers developing their own NMP protocols and renal viability criteria. However, to date, no validated sets of on-pump viability markers exist nor are there unified NMP protocols. This review provides a critical overview of the fundamentals of current renal NMP protocols and proposes a framework to approach further development of ex vivo organ evaluation. We also comment on the potential logistical implications of routine clinical use of NMP, which is a more complex procedure compared with static cold storage or even hypothermic machine perfusion.

Strategies to deliver RNA by nanoparticles for therapeutic potential

The use of a variety of RNA molecules, including messenger RNA, small interfering RNA, and microRNA, has shown great potential for prevention and therapy of many pathologies. However, this therapeutic promise has historically been limited by short in vivo half-life, lack of targeted delivery, and safety issues. Nanoparticle (NP)-mediated delivery has been a successful platform to overcome these limitations, with multiple formulations already in clinical trials and approved by the FDA. Although there is a diversity of NPs in terms of material formulation, size, shape, and charge that have been proposed for biomedical applications, specific modifications are required to facilitate sufficient RNA delivery and adequate therapeutic effect. This includes optimization of (i) RNA incorporation into NPs, (ii) specific cell targeting, (iii) cellular uptake and (iv) endosomal escape ability. In this review, we summarize the methods by which NPs can be modified for RNA delivery to achieve optimal therapeutic effects.

Ex-vivo Kidney Machine Perfusion: Therapeutic Potential

Kidney transplantation remains the gold standard treatment for patients suffering from end-stage kidney disease. To meet the constantly growing organ demands grafts donated after circulatory death (DCD) or retrieved from extended criteria donors (ECD) are increasingly utilized. Not surprisingly, usage of those organs is challenging due to their susceptibility to ischemia-reperfusion injury, high immunogenicity, and demanding immune regulation after implantation. Lately, a lot of effort has been put into improvement of kidney preservation strategies. After demonstrating a definite advantage over static cold storage in reduction of delayed graft function rates in randomized-controlled clinical trials, hypothermic machine perfusion has already found its place in clinical practice of kidney transplantation. Nevertheless, an active investigation of perfusion variables, such as temperature (normothermic or subnormothermic), oxygen supply and perfusate composition, is already bringing evidence that ex-vivo machine perfusion has a potential not only to maintain kidney viability, but also serve as a platform for organ conditioning, targeted treatment and even improve its quality. Many different therapies, including pharmacological agents, gene therapy, mesenchymal stromal cells, or nanoparticles (NPs), have been successfully delivered directly to the kidney during ex-vivo machine perfusion in experimental models, making a big step toward achievement of two main goals in transplant surgery: minimization of graft ischemia-reperfusion injury and reduction of immunogenicity (or even reaching tolerance). In this comprehensive review current state of evidence regarding ex-vivo kidney machine perfusion and its capacity in kidney graft treatment is presented. Moreover, challenges in application of these novel techniques in clinical practice are discussed.

Shifting Paradigms for Suppressing Fibrosis in Kidney Transplants: Supplementing Perfusion Solutions With Anti-fibrotic Drugs

Great efforts have been made toward addressing the demand for donor kidneys. One of the most promising approaches is to use kidneys from donation after circulatory death donors. These kidneys, however, suffer from more severe ischemia and reperfusion injury than those obtained via donation after brain death and are thus more prone to develop interstitial fibrosis and tubular atrophy. Even though machine perfusion is increasingly used to reduce ischemia and reperfusion injury, there are no effective treatments available to ameliorate interstitial fibrosis and tubular atrophy, forcing patients to resume dialysis, undergo re-transplantation, or suffer from premature death. Safe and effective anti-fibrotic therapies are therefore greatly desired. We propose a new therapeutic approach in which machine perfusion solutions are supplemented with anti-fibrotic compounds. This allows the use of higher concentrations than those used in humans whilst eliminating side effects in other organs. To the authors' knowledge, no one has reviewed whether such an approach could reduce interstitial fibrosis and tubular atrophy; we therefore set out to explore its merit. In this review, we first provide background information on ischemia and reperfusion injury as well as interstitial fibrosis and tubular atrophy, after which we describe currently available approaches for preserving donor kidneys. We then present an evaluation of selected compounds. To identify promising compounds, we analyzed publications describing the effects of anti-fibrotic molecules in precision-cut kidneys slices, which are viable explants that can be cultured ex vivo for up to a few days whilst retaining functional and structural features. LY2109761, galunisertib, imatinib, nintedanib, and butaprost were shown to exert anti-fibrotic effects in slices within a relatively short timeframe (<48 h) and are therefore considered to be excellent candidates for follow-up ex vivo machine perfusion studies.

A digital pathology tool for quantification of color features in histologic specimens

In preclinical research, histological analysis of tissue samples is often limited to qualitative or semiquantitative scoring assessments. The reliability of this analysis can be impaired by the subjectivity of these approaches, even when read by experienced pathologists. Furthermore, the laborious nature of manual image assessments often leads to the analysis being restricted to a relatively small number of images that may not accurately represent the whole sample. Thus, there is a clear need for automated image analysis tools that can provide robust and rapid quantification of histologic samples from paraffin-embedded or cryopreserved tissues. To address this need, we have developed a color image analysis algorithm (DigiPath) to quantify distinct color features in histologic sections. We demonstrate the utility of this tool across multiple types of tissue samples and pathologic features, and compare results from our program to other quantitative approaches such as color thresholding and hand tracing. We believe this tool will enable more thorough and reliable characterization of histological samples to facilitate better rigor and reproducibility in tissue-based analyses.

The Application of Nanoparticles in Diagnosis and Treatment of Kidney Diseases

Nanomedicine is currently showing great promise for new methods of diagnosing and treating many diseases, particularly in kidney disease and transplantation. The unique properties of nanoparticles arise from the diversity of size effects, used to design targeted nanoparticles for specific cells or tissues, taking renal clearance and tubular secretion mechanisms into account. The design of surface particles on nanoparticles offers a wide range of possibilities, among which antibodies play an important role. Nanoparticles find applications in encapsulated drug delivery systems containing immunosuppressants and other drugs, in imaging, gene therapies and many other branches of medicine. They have the potential to revolutionize kidney transplantation by reducing and preventing ischemia-reperfusion injury, more efficiently delivering drugs to the graft site while avoiding systemic effects, accurately localizing and visualising the diseased site and enabling continuous monitoring of graft function. So far, there are known nanoparticles with no toxic effects on human tissue, although further studies are still needed to confirm their safety.

Intra-Organ Delivery of Nanotherapeutics for Organ Transplantation

Targeted delivery of therapeutics through the use of nanoparticles (NPs) has emerged as a promising method that increases their efficacy and reduces their side effects. NPs can be tailored to localize to selective tissues through conjugation to ligands that bind cell-specific receptors. Although the vast majority of nanodelivery platforms have focused on cancer therapy, efforts have begun to introduce nanotherapeutics to the fields of immunology as well as transplantation. In this review, we provide an overview from a clinician's perspective of current nanotherapeutic strategies to treat solid organ transplants with NPs during the time interval between organ harvest from the donor and placement into the recipient, an innovative technology that can provide major benefits to transplant patients. The use of ex vivo normothermic machine perfusion (NMP), which is associated with preserving the function of the organ following transplantation, also provides an ideal opportunity for a localized, sustained, and controlled delivery of nanotherapeutics to the organ during this critical time period. Here, we summarize previous endeavors to improve transplantation outcomes by treating the organ with NPs prior to placement in the recipient. Investigations in this burgeoning field of research are promising, but more extensive studies are needed to overcome the physiological challenges to achieving effective nanotherapeutic delivery to transplanted organs discussed in this review.

Microvascular fluid flow in ex vivo and engineered lungs

In recent years, it has become common to experiment with ex vivo perfused lungs for organ transplantation and to attempt regenerative pulmonary engineering using decellularized lung matrices. However, our understanding of the physiology of ex vivo organ perfusion is imperfect; it is not currently well understood how decreasing microvascular barrier affects the perfusion of pulmonary parenchyma. In addition, protocols for lung perfusion and organ culture fluid-handling are far from standardized, with widespread variation on both basic methods and on ideally controlled parameters. To address both of these deficits, a robust, noninvasive, and mechanistic model is needed which is able to predict microvascular resistance and permeability in perfused lungs while providing insight into capillary recruitment. Although validated mathematical models exist for fluid flow in native pulmonary tissue, previous models generally assume minimal intravascular leak from artery to vein and do not assess capillary bed recruitment. Such models are difficult to apply to both ex vivo lung perfusions, in which edema can develop over time and microvessels can become blocked, and to decellularized ex vivo organomimetic cultures, in which microvascular recruitment is variable and arterially perfused fluid enters into the alveolar space. Here, we develop a mathematical model of pulmonary microvascular fluid flow which is applicable in both instances, and we apply our model to data from native, decellularized, and regenerating lungs under ex vivo perfusion. The results provide substantial insight into microvascular pressure-flow mechanics, while producing previously unknown output values for tissue-specific capillary-alveolar hydraulic conductivity, microvascular recruitment, and total organ barrier resistance.NEW & NOTEWORTHY We present a validated model of pulmonary microvascular fluid mechanics and apply this model to study the effects of increased capillary permeability in decellularized and regenerating lungs. We find that decellularization alters microvascular steady-state mechanics and that re-endothelialization partially rescues key biologic parameters. The described model provides powerful insight into intraorgan microvascular dynamics and may be used to guide regenerative engineering experiments. We include all data and derivations necessary to replicate this work.

Eleutheroside B-loaded poly (lactic-co-glycolic acid) nanoparticles protect against renal fibrosis via Smad3-dependent mechanism

Although renal fibrosis is a common complication of chronic kidney disease (CKD), effective options for its treatment are currently limited. In this study, we evaluated the renal protective effect and possible mechanism of eleutheroside B. In order to solve the allergic reactions, side effects, and low oral bioavailability of eleutheroside B, we successfully prepared PLGA (poly [lactic-co-glycolic acid])-eleutheroside B nanoparticles (NPs) with the diameter of about 128 nm. In vitro and in vivo results showed that eleutheroside B could inhibit expression levels of α-smooth muscle actin (α-SMA) and collagen I. Molecular docking results showed that eleutheroside B bound to Smad3 and significantly decreased the expression of phospho-Smad3 (p-Smad3). Silencing Smad3 reversed the fibrotic protective effect of eleutheroside B in HK2 cells. Furthermore, small animal imaging showed that NPs can selectively accumulate in the UUO kidneys of mice, and retention time reached as long as 7 days. In conclusion, our results suggested that eleutheroside B is a potential drug to protect renal fibrosis and PLGA-eleutheroside B NPs could facilitate specific targeted therapy for renal fibrosis.

Aggravation of fibrin deposition and microthrombus formation within the graft during kidney transplantation

In kidney transplantation, microthrombi and fibrin deposition may lead to local perfusion disorders and subsequently poor initial graft function. Microthrombi are often regarded as donor-derived. However, the incidence, time of development, and potential difference between living donor kidneys (LDK) and deceased donor kidneys(DDK), remains unclear. Two open-needle biopsies, taken at preimplantation and after reperfusion, were obtained from 17 LDK and 28 DDK transplanted between 2005 and 2008. Paraffin-embedded sections were immunohistochemically stained with anti-fibrinogen antibody. Fibrin deposition intensity in peritubular capillaries(PTC) and glomeruli was categorized as negative, weak, moderate or strong and the number of microthrombi/mm² was quantified. Reperfusion biopsies showed more fibrin deposition (20% to 100% moderate/strong, p < 0.001) and more microthrombi/mm² (0.97 ± 1.12 vs. 0.28 ± 0.53, p < 0.01) than preimplantation biopsies. In addition, more microthrombi/mm² (0.38 ± 0.61 vs. 0.09 ± 0.22, p = 0.02) and stronger fibrin intensity in glomeruli (28% vs. 0%, p < 0.01) and PTC (14% vs. 0%, p = 0.02) were observed in preimplantation DDK than LDK biopsies. After reperfusion, microthrombi/mm² were comparable (p = 0.23) for LDK (0.09 ± 0.22 to 0.76 ± 0.49, p = 0.03) and DDK (0.38 ± 0.61 to 0.90 ± 1.11, p = 0.07). Upon reperfusion, there is an aggravation of microthrombus formation and fibrin deposition within the graft. The prominent increase of microthrombi in LDK indicates that they are not merely donor-derived.

Extended criteria grafts and emerging therapeutics strategy in liver transplantation. The unstable balance between damage and repair

Due to increasing demand for donor organs, "extended criteria" donors are increasingly considered for liver transplantation, including elderly donors and donors after cardiac death. The grafts of this subgroup of donors share a major risk to develop significant features of ischemia reperfusion injury, that may eventually lead to graft failure. Ex-situ machine perfusion technology has gained much interest in liver transplantation, because represents both a useful tool for improving graft quality before transplantation and a platform for the delivery of therapeutics directly to the organ. In this review, we survey ongoing clinical evidences supporting the use of elderly and DCD donors in liver transplantation, and the underlying mechanistic aspects of liver aging and ischemia reperfusion injury that influence graft quality and transplant outcome. Finally, we highlight evidences in the field of new therapeutics to test in MP in the context of recent findings of basic and translational research.

Asynchronous blockade of PD-L1 and CD155 by polymeric nanoparticles inhibits triple-negative breast cancer progression and metastasis

PD-L1/PD-1 blockade therapy shows durable responses to triple-negative breast cancer (TNBC), but the response rate is low. CD155 promotes tumor metastasis intrinsically and modulates the immune response extrinsically as the ligand of DNAM-1 (costimulatory receptor) and TIGIT/CD96 (coinhibitory receptors). Herein, we verified that TNBC cells coexpressed PD-L1 and CD155. By examining the receptors of PD-L1 and CD155 on TNBC tumor-infiltrating lymphocytes (TILs) over time, we observed that PD-1 and DNAM-1 were upregulated early, whereas CD96 and TIGIT were upregulated late in CD8⁺ TILs. Based on these findings, we developed CD155 siRNA (siCD155)-loaded mPEG-PLGA-PLL (PEAL) nanoparticles (NPs) coated with PD-L1 blocking antibodies (P/PEAL_siCD155) to asynchronously block PD-L1 and CD155 in a spatiotemporal manner. P/PEAL_siCD155 maximized early-stage CD8⁺ T cell immune surveillance against 4T1 tumor, whereas reversed inhibition status of the late stage CD8⁺ T cells to prevent 4T1 tumor immune escape. In addition, the combination of P/PEAL_siCD155 and tumor-specific CD8 T cells induced immunogenic cell death (ICD) of 4T1 cells to further boost immune checkpoint therapy. Most importantly, P/PEAL_siCD155 displayed excellent TNBC targeting and induced CD8⁺ TILs-dominant intratumor antitumor immunity to efficiently inhibit TNBC progression and metastasis with excellent safety in a syngeneic 4T1 orthotopic TNBC tumor model.

Regulatory T cells and transplantation tolerance: Emerging from the darkness?

The field of tissue transplantation has revolutionized the treatment of patients with failing organs. Its success, thus far, has depended on combinations of immunosuppressive drugs that damp host immunity, while also imposing numerous unwanted side-effects. There is a longstanding recognition that better treatment outcomes, will come from replacing these drugs, fully or in part, by taking advantage of tractable physiological mechanisms of self-tolerance. The past 50 years have seen many advances in the field of self-tolerance, but perhaps, the most tractable of these has been the more recent discovery of a subset T-cells (Treg) whose role is to regulate or damp immunity. This article is intended to first provide the reader with some historical background to explain why we have been slow to identify these cells, despite numerous clues to their existence, and also to indicate how little we know about how they achieve their regulatory function in averting transplant rejection. However, as is often the case in immunology, the therapeutic needs often dictate that our advances move to translation even before detailed explanations of the science are available. The final part of the article will briefly summarize how Treg are being harnessed as agents to interface with or perhaps, replace current drug combinations.

Improving kidney targeting: The influence of nanoparticle physicochemical properties on kidney interactions

Kidney-targeted nanoparticles have become of recent interest due to their potential to deliver drugs directly to diseased tissue, decrease off-target adverse effects, and increase overall tolerability to patients with chronic kidney disease that require lifelong drug exposure. Given the physicochemical properties of nanoparticles can drastically affect their ability to extravasate past cellular and biological barriers and access the kidneys, we surveyed the literature from the past decade and analyzed how nanoparticle size, charge, shape, and material density affects passage and interaction with the kidneys. Specifically, we found that nanoparticle size impacted the mechanism of nanoparticle entry into the kidneys such as glomerular filtration or tubular secretion. In addition, we found charge, aspect ratio, and material density influences nanoparticle renal retention and provide insights for designing nanoparticles for passive kidney targeting. Finally, we conclude by highlighting active targeting strategies that bolster kidney retention and discuss the clinical status of nanomedicine for kidney diseases.