Cyclodextrin curcumin formulation improves outcome in a preclinical pig model of marginal kidney transplantation

Effects of Cyclodextrin Curcumin Formulation on Ischemia-Reperfusion Injury in Porcine DCD Liver Transplantation

BACKGROUND

Curcumin is a pleiotropic antioxidant polyphenol, which has proven to be highly protective in various models of liver injury and inflammation. We hypothesized that adding a stable aqueous curcumin formulation which comprises a water-soluble cyclodextrin curcumin formulation (CDC) complex of the water-insoluble curcumin molecule (Novobion, Espoo, Finland) to preservation solution during liver procurement may reduce ischemia-reperfusion injury and improve graft function after liver transplantation using donation after circulatory death (DCD).

METHODS

In a preclinical pig model of DCD-liver transplantation, livers exposed to 15' of warm ischemia were either modulated (N = 6) with a flush of preservation solution (histidine-tryptophan-ketoglutarate) containing CDC (60 µmol/L) through the vena porta and the aorta, or not (controls, N = 6) before 4 h of cold storage. Area under the curve of log serum aspartate aminotransferase, markers of graft function (lactate, glycemia, prothrombin time, and bile production), inflammation (tumor necrosis factor-alpha), and survival were monitored.

RESULTS

Area under the curve of log serum aspartate aminotransferase were similar between curcumin and control groups (22.12 [20.87-24.88] versus 25.08 [22.1-26.55]; P = 0.28). No difference in the liver function markers were observed between groups except a lower serum lactate level 3-h post-reperfusion in the curcumin group (3 [1.95-6.07] versus 8.2 [4.85-13.45] mmol/L; P = 0.05). Serum tumor necrosis factor-alpha levels were similar in each group. Recipient survival rates were found similar.

CONCLUSIONS

CDC added to the preservation solution in DCD liver pig model did not improve ischemia-reperfusion injury severity, liver function, or survival. Further efforts are needed to explore this strategy, particularly with dynamic preservation, which finds its way into clinical practice.

Noninvasive measurement of 13Carbon turnover for evaluation of porcine renal grafts during ex vivo machine perfusion

BACKGROUND

Kidney transplantation suffers from a shortage of donor organs. Despite this, a lot of grafts are discarded due to inadequate quality. As many kidneys are afflicted by transient filtration failure early after preservation, classical renal function tests are not applicable to differentiate between prospective recovery or continuing deficit of renal function.

METHODS

Using normothermic machine perfusion as a platform for pre-implantation evaluation of the graft, we present a novel evaluative approach based on the metabolic turnover of 13C-acetate during isolated perfusion. After injection of the tracer, 13CO2 as a metabolic end-product can be quantified by high-precision laser-based spectroscopy in the gas outflow of the oxygenator. Three groups of porcine kidneys with graduated ischemic injury were investigated.

RESULTS

This quantitative approach is able to discriminate acceptable quality kidneys, most likely to recover within days from poor kidney grafts that are unlikely to regain notable glomerular function with high discriminatory power (area under the ROC curve 0.91; P < 0.001 By contrast, conventional renal function tests are rather ineffective under these circumstances.

CONCLUSIONS

This assessment method offers the potential to quantitatively assess donor kidney quality using a measurable output, salvaging donors that would otherwise have been discarded.

Polyphenols and Novel Insights Into Post-kidney Transplant Complications and Cardiovascular Disease: A Narrative Review

Kidney transplantation is the preferred treatment for end-stage kidney disease. It is, however, not devoid of complications. Delayed graft function related to ischemia-reperfusion injury (IRI), calcineurin inhibitor (CNI) nephrotoxicity, diabetes, and a particularly high-rate cardiovascular disease (CVD) risk, represent important complications following kidney transplantation. Oxidative stress and chronic low-grade inflammation are mechanisms of disease incompletely abrogated in stable kidney transplant recipient (KTR), contributing to the occurrence of these complications. Polyphenols, bioactive compounds with recognized antioxidant and anti-inflammatory properties have been strongly associated with prevention of CVD in the general population and have been shown to decrease IRI and antagonize CNI nephrotoxicity in animal experimental models, therefore they may have a role in prevention of complications in KTR. This narrative review aims to summarize and discuss current evidence on different polyphenols for prevention of complications, particularly prevention of CVD in KTR, pointing toward the need of further studies with potential clinical impact.

Prolonged warm ischemia time leads to severe renal dysfunction of donation-after-cardiac death kidney grafts

Kidney transplantation with grafts procured after donation-after-cardiac death (DCD) has led to an increase in incidence of delayed graft function (DGF). It is thought that the warm ischemic (WI) insult encountered during DCD procurement is the cause of this finding, although few studies have been designed to definitely demonstrate this causation in a transplantation setting. Here, we use a large animal renal transplantation model to study the effects of prolonged WI during procurement on post-transplantation renal function. Kidneys from 30 kg-Yorkshire pigs were procured following increasing WI times of 0 min (Heart-Beating Donor), 30 min, 60 min, 90 min, and 120 min (n = 3-6 per group) to mimic DCD. Following 8 h of static cold storage and autotransplantation, animals were followed for 7-days. Significant renal dysfunction (SRD), resembling clinical DGF, was defined as the development of oliguria < 500 mL in 24 h from POD3-4 along with POD4 serum potassium > 6.0 mmol/L. Increasing WI times resulted in incremental elevation of post-operative serum creatinine that peaked later. DCD120min grafts had the highest and latest elevation of serum creatinine compared to all groups (POD5: 19.0 ± 1.1 mg/dL, p < 0.05). All surviving animals in this group had POD4 24 h urine output < 500 cc (mean 235 ± 172 mL) and elevated serum potassium (7.2 ± 1.1 mmol/L). Only animals in the DCD120min group fulfilled our criteria of SRD (p = 0.003), and their renal function improved by POD7 with 24 h urine output > 500 mL and POD7 serum potassium < 6.0 mmol/L distinguishing this state from primary non-function. In a transplantation survival model, this work demonstrates that prolonging WI time similar to that which occurs in DCD conditions contributes to the development of SRD that resembles clinical DGF.

Simply Adding Oxygen during Hypothermic Machine Perfusion to Combat the Negative Effects of Ischemia-Reperfusion Injury: Fundamentals and Current Evidence for Kidneys

The use of high-risk renal grafts for transplantation requires optimization of pretransplant preservation and assessment strategies to improve clinical outcomes as well as to decrease organ discard rate. With oxygenation proposed as a resuscitative measure during hypothermic machine preservation, this review provides a critical overview of the fundamentals of active oxygenation during hypothermic machine perfusion, as well as the current preclinical and clinical evidence and suggests different strategies for clinical implementation.

Therapeutic Effects of Curcumin against Bladder Cancer: A Review of Possible Molecular Pathways

There are concerns about the increased incidence of cancer both in developing and developed countries. In spite of recent progress in cancer therapy, this disease is still one of the leading causes of death worldwide. Consequently, there have been rigorous attempts to improve cancer therapy by looking at nature as a rich source of naturally occurring anti-tumor drugs. Curcumin is a well-known plant-derived polyphenol found in turmeric. This compound has numerous pharmacological effects such as antioxidant, anti-inflammatory, antidiabetic and anti-tumor properties. Curcumin is capable of suppressing the growth of a variety of cancer cells including those of bladder cancer. Given the involvement of various signaling pathways such as PI3K, Akt, mTOR and VEGF in the progression and malignancy of bladder cancer, and considering the potential of curcumin in targeting signaling pathways, it seems that curcumin can be considered as a promising candidate in bladder cancer therapy. In the present review, we describe the molecular signaling pathways through which curcumin inhibits invasion and metastasis of bladder cancer cells.

High Throughput Proteomic Exploration of Hypothermic Preservation Reveals Active Processes within the Cell Associated with Cold Ischemia Kinetic

The demand for organs to be transplanted increases pressure on procurement centers, to the detriment of organ quality, increasing complications. New preservation protocols are urgently needed, requiring an in-depth understanding of ischemia-reperfusion mechanisms. We performed a proteomic analysis using LC-MS/MS-TOF data analyzed through R software and Cytoscape's ClueGO application, comparing the proteome of kidney endothelial cells, key cell type, subjected to 3, 6, 12, 19, and 24 h of cold ischemia and 6 h reperfusion. Critical pathways such as energy metabolism, cytoskeleton structure/transport system, and gene transcription/translation were modulated. Important time windows were revealed: a-during the first 3 h, central proteins were upregulated within these pathways; b-the majority of these upregulations were maintained until 12 h cold ischemia time (CIT); c-after that time, the overall decrease in protein expression was observed; d-at reperfusion, proteins expressed in response to cold ischemia were all downregulated. This shows that cold ischemia is not a simple slowing down of metabolism, as deep changes take place within the proteome on major pathways. Time-sensitive expression of key protein reveals possible quality biomarkers as well as potential targets for new strategies to maintain or optimize organ quality.

Preclinical Modeling of DCD Class III Donation: Paving the Way for the Increased Use of This Challenging Donor Type

Deceased after circulatory death (DCD) donors offer a viable solution to the current organ shortage, particularly the Maastricht Class III (arrest subsequent to cessation of life support in the hospital). Although current results from these donors are very satisfactory, the number of included donors is too low and future expansion of inclusion criteria will likely decrease organ quality, with negative consequences on the complication rate. This donor type thus represents a priority in terms of scientific exploration, so as to study it in controlled settings and prepare for future challenges. Hence, we mimicked the DCD Class III clinical conditions a Large White pig model. Herein, we detail the different strategies attempted to attain our objectives, including technical approaches such as animal positioning and ventilator settings, as well as pharmacological intervention to modulate blood pressure and heart rate. We highlight the best combination of factors to successfully reproduce DCD Class III conditions, with perfusion pressures and functional warm ischemia (hypoperfusion) closely resembling clinical situations. Finally, we detail the functional and histological impacts of these conditions. Such a model could be of critical value to explore novel management alternative for these donors, presenting a uniquely adapted platform for such therapeutics as normothermic regional circulation and/or pharmacological intervention.

Influence of Hypoxic Preservation Temperature on Endothelial Cells and Kidney Integrity

Ischemia-reperfusion (IR) injury is unavoidable during organ transplantation and impacts graft quality. New paradigms are emerging including preservation at higher temperature than “hypothermia” or “cold”: although 4°C remains largely used for kidney preservation, recent studies challenged this choice. We and others hypothesized that a higher preservation temperature, closer to physiological regimen, could improve organ quality. For this purpose, we used an in vitro model of endothelial cells exposed to hypoxia-reoxygenation sequence (mimicking IR) and an ex vivo ischemic pig kidneys static storage model. In vitro, 19°C, 27°C, and 32°C provided protection against injuries versus 4°C, by reducing cell death, mitochondrial dysfunction, leukocyte adhesion, and inflammation. However, ex vivo, the benefits of 19°C or 32°C were limited, showing similar levels of tissue preservation damage. Ex vivo 4°C-preserved kidneys displayed a trend towards reduced damage, including apoptosis. Macrophage infiltration, tubulitis, and necrosis were increased in the 19°C and 32°C versus 4°C preserved kidneys. Thus, despite a trend for an advantage of subnormothermia as preservation temperature, our in vitro and ex vivo models bring different insights in terms of preservation temperature effect. This study suggests that temperature optimization for kidney preservation will require thorough investigation, combining the use of complementary relevant models and the design of elaborated preservation solution and new technologies.

Emerging therapeutic strategies for transplantation-induced acute kidney injury: protecting the organelles and the vascular bed

INTRODUCTION

Renal ischemia-reperfusion injury (IRI) is a significant clinical challenge faced by clinicians in a broad variety of clinical settings such as perioperative and intensive care. Renal IRI induced acute kidney injury (AKI) is a global public health concern associated with high morbidity, mortality, and health-care costs. Areas covered: This paper focuses on the pathophysiology of transplantation-related AKI and recent findings on cellular stress responses at the intersection of 1. The Unfolded protein response; 2. Mitochondrial dysfunction; 3. The benefits of mineralocorticoid receptor antagonists. Lastly, perspectives are offered to the readers. Expert opinion: Renal IRI is caused by a sudden and temporary impairment of blood flow to the organ. Defining the underlying cellular cascades involved in IRI will assist us in the identification of novel interventional targets to attenuate IRI with the potential to improve transplantation outcomes. Targeting mitochondrial function and cellular bioenergetics upstream of cellular damage may offer several advantages compared to targeting downstream inflammatory and fibrosis processes. An improved understanding of the cellular pathophysiological mechanisms leading to kidney injury will hopefully offer improved targeted therapies to prevent and treat the injury in the future.

Individual and Combined Impact of Oxygen and Oxygen Transporter Supplementation during Kidney Machine Preservation in a Porcine Preclinical Kidney Transplantation Model

Marginal kidney graft preservation in machine perfusion (MP) is well-established. However, this method requires improvement in order to mitigate oxidative stress during ischemia-reperfusion, by using oxygenation or an O2 carrier with anti-oxidant capacities (hemoglobin of the marine worm; M101). In our preclinical porcine (pig related) model, kidneys were submitted to 1h-warm ischemia, followed by 23 h hypothermic preservation in Waves® MP before auto-transplantation. Four groups were studied: W (MP without 100%-O2), W-O2 (MP with 100%-O2; also called hyperoxia), W-M101 (MP without 100%-O2 + M101 2 g/L), W-O2 + M101 (MP with 100%-O2 + M101 2 g/L) (n = 6/group). Results: Kidneys preserved in the W-M101 group showed lower resistance, compared to our W group. During the first week post-transplantation, W-O2 and W-M101 groups showed a lower blood creatinine and better glomerular filtration rate. KIM-1 and IL-18 blood levels were lower in the W-M101 group, while blood levels of AST and NGAL were lower in groups with 100% O2. Three months after transplantation, fractional excretion of sodium and the proteinuria/creatinuria ratio remained higher in the W group, creatininemia was lower in the W-M101 group, and kidney fibrosis was lower in M101 groups. We concluded that supplementation with M101 associated with or without 100% O2 improved the Waves® MP effect upon kidney recovery and late graft outcome.

Efficacy of the natural oxygen transporter HEMO2 life® in cold preservation in a preclinical porcine model of donation after cardiac death

The growing use of marginal organs for transplantation pushes current preservation methods toward their limits, and the need for improvement is pressing. We previously demonstrated the benefits of M101, a natural extracellular oxygen carrier compatible with hypothermia, for the preservation of healthy renal grafts in a porcine model of autotransplantation. Herein, we use a variant of this preclinical model to evaluate M101 potential benefits both in static cold storage (CS) and in machine perfusion (MP) preservation in the transplantation outcomes for marginal kidneys. In the CS arm, despite the absence of obvious benefits within the first 2 weeks of follow-up, M101 dose-dependently improved long-term function, normalizing creatininemia after 1 and 3 months. In the MP arm, M101 improved short- and long-term functional outcomes as well as tissue integrity. Importantly, we provide evidence for the additivity of MP and M101 functional effects, showing that the addition of the compound further improves organ preservation, by reducing short-term function loss, with no loss of function or tissue integrity recorded throughout the follow-up. Extending previous observations with healthy kidneys, the present results point at the M101 oxygen carrier as a viable strategy to improve current organ preservation methods in marginal organ transplantation.

Impact of Hypothermia and Oxygen Deprivation on the Cytoskeleton in Organ Preservation Models

Ischemia reperfusion (IR) lesions are an unavoidable consequence of organ transplantation. Researching new therapeutics against these lesions requires the definition of early mechanisms. The cytoskeleton is composed of 3 types of filaments: microfilaments, intermediate filaments, and microtubules. We aimed to characterize the influence of preservation on their phenotype. In an in vitro model using primary human endothelial cells reproducing the conditions of organ preservation, two aspects were explored: (a) the impact of IR and cold ischemia time on each filament type, evaluating the roles of temperature, solution, and oxygen; and (b) the potential of cytoskeleton-mediated therapy to alleviate cell death. Results showed that intermediary filaments were unaffected, while microfilaments showed radical changes with disappearance of the structure replaced by a disorganized array of nodules; moreover, microtubules almost completely disappeared with time. Furthermore, temperature, and not oxygen deprivation or the solution, was the determining factor of the cytoskeleton's loss of integrity during preservation. Finally, pharmaceutical intervention could indeed preserve fiber structure but did not alter survival. Our work shows that improvement of preservation must include a more adapted temperature before considering oxygen, as it could profoundly improve cytoskeleton organization and thus cell fate. This highlights the importance of this structure for the development of new therapeutics and the definition of graft quality biomarkers.

Curcumin as Treatment for Bladder Cancer: A Preclinical Study of Cyclodextrin-Curcumin Complex and BCG as Intravesical Treatment in an Orthotopic Bladder Cancer Rat Model

Objective

To evaluate the antitumor effect of cyclodextrin-curcumin complex (CDC) on human and rat urothelial carcinoma cells in vitro and to evaluate the effect of intravesical instillations of CDC, BCG, and the combination in vivo in the AY-F344 orthotopic bladder cancer rat model. Curcumin has anticarcinogenic activity on urothelial carcinoma and is therefore under investigation for the treatment of non-muscle invasive bladder cancer. Curcumin and BCG share immunomodulating pathways against urothelial carcinoma.

Methods

Curcumin was complexed with cyclodextrin to improve solubility. Four human urothelial carcinoma cell lines and the AY-27 rat cell line were exposed to various concentrations of CDC in vitro. For the in vivo experiment, the AY-27 orthotopic bladder cancer F344 rat model was used. Rats were treated with consecutive intravesical instillations of CDC, BCG, the combination of CDC+BCG, or NaCl as control.

Results

CDC showed a dose-dependent antiproliferative effect on all human urothelial carcinoma cell lines tested and the rat AY-27 urothelial carcinoma cell line. Moreover, intravesical treatment with CDC and CDC+BCG results in a lower percentage of tumors (60% and 68%, respectively) compared to BCG (75%) or control (85%). This difference with placebo was not statistically significant (p=0.078 and 0.199, respectively). However, tumors present in the placebo and BCG-treated rats were generally of higher stage.

Conclusions

Cyclodextrin-curcumin complex showed an antiproliferative effect on human and rat urothelial carcinoma cell lines in vitro. In the aggressive orthotopic bladder cancer rat model, we observed a promising effect of CDC treatment and CDC in combination with BCG.

Targeting renal fibrosis: Mechanisms and drug delivery systems

Renal fibrosis is the common outcome of many chronic kidney diseases (CKD) independent of the underlying etiology. Despite a host of promising experimental data, currently available strategies only ameliorate or delay the progression of CKD but do not reverse fibrosis. One of the major impediments of translating novel antifibrotic strategies from bench to bedside is due to the intricacies of the drug delivery process. In this review, we briefly describe mechanisms of renal fibrosis and methods of drug transfer into the kidney. Various tools used in gene therapy to administer nucleic acids in vivo are discussed. Furthermore, we review the modes of action of protein- or peptide-based drugs with target-specific antibodies and cytokines incorporated in hydrogels. Additionally, we assess an intriguing new method to deliver drugs specifically to tubular epithelial cells via conjugation with ligands binding to the megalin receptor. Finally, plant-derived compounds with antifibrotic properties are also summarized.

Hepatocellular uptake of cyclodextrin-complexed curcumin during liver preservation: A feasibility study

The increasing demand for donor organs and the decreasing organ quality is prompting research toward new methods to reduce ischemia reperfusion injury (IRI). Several strategies have been proposed to protect preserved organs from this injury. Before curcumin/dextrin complex (CDC), a potent antioxidant and anti-inflammatory agent, can be used clinically we need to better understand the intracellular uptake under hypothermic conditions on a rat model of liver donation after circulatory death (DCD) and brain death (DBD). To be able to use the fluorescence of CDC for quantification the stability of CDC in different preservation solutions at 4°C or 37°C was investigated. Livers from Wistar rats were procured after being flushed-out through the portal vein using CDC-enriched preservation solutions and stored at 4°C for variable periods. The CDC signal was stable in different preservation solutions over a period of 4 h and allowed the rapid and lasting uptake of curcumin into cells. After 4 h of preservation, CDC was no longer visible microscopically, and HPLC analysis showed very low to non-detectable tissue levels of CDC, proving metabolization during preservation. However, the distribution of CDC was not affected by warm ischemia damage (p = 0.278) nor by flushing the livers before or after 4 h of cold storage and without a warm preflush. Finally, curcumin reduced oxidative stress, lowered histological injury and did not change gene expression after WI/cold storage. Therefore, the use of CDC flush solution for the initial organ flush can offer a promising approach to the enhancement of liver preservation and the maintenance of its quality.

Inhibition of complement improves graft outcome in a pig model of kidney autotransplantation

BACKGROUND

Ischemia reperfusion injury (IRI) induced immune response is a critical issue in transplantation. Complement and contact system activation are among its key mechanisms.

STUDY DESIGN

We investigated the benefits of pre-reperfusion treatment with recombinant human C1INH (rhC1INH), inhibitor of both complement and contact activation, in a pig model of kidney autotransplantation, subjecting the organ to 60 min warm ischemia prior to 24 h static preservation to maximize damage.

RESULTS

Serum creatinine measurement showed that treated animals recovered glomerular function quicker than the Vehicle group. However, no difference was observed in tubular function recovery, and elevated level of urinary NGal (Neutrophil gelatinase-associated lipocalin) and plasma AST (Aspartate Aminotransferase) were detected, indicating that treatment did not influence IRI-mediated tubular cell necrosis. Regarding chronic graft outcome, rhC1INH significantly prevented fibrosis development and improved function. Immunohistochemistry and western blot showed decreased invasion by macrophages and T lymphocytes, and reduction of epithelial to mesenchymal transition. We determined the effect of treatment on complement activation with immunofluorescence analyses at 30 min post reperfusion, showing an inhibition of C4d deposition and MBL staining in treated animals.

CONCLUSIONS

In this model, the inhibition of complement activation by rhC1INH at reperfusion, while not completely counteracting IRI, limited immune system activation, significantly improving graft outcome on the short and long term.

In silico pharmacology: Drug membrane partitioning and crossing

Over the past decade, molecular dynamics (MD) simulations have become particularly powerful to rationalize drug insertion and partitioning in lipid bilayers. MD simulations efficiently support experimental evidences, with a comprehensive understanding of molecular interactions driving insertion and crossing. Prediction of drug partitioning is discussed with respect to drug families (anesthetics; β-blockers; non-steroidal anti-inflammatory drugs; antioxidants; antiviral drugs; antimicrobial peptides). To accurately evaluate passive permeation coefficients turned out to be a complex theoretical challenge; however the recent methodological developments based on biased MD simulations are particularly promising. Particular attention is paid to membrane composition (e.g., presence of cholesterol), which influences drug partitioning and permeation. Recent studies concerning in silico models of membrane proteins involved in drug transport (influx and efflux) are also reported here. These studies have allowed gaining insight in drug efflux by, e.g., ABC transporters at an atomic resolution, explicitly accounting for the mandatory forces induced by the surrounded lipid bilayer. Large-scale conformational changes were thoroughly analyzed.