Reducing ischemic kidney injury through application of a synchronization modulation electric field to maintain Na+/K+-ATPase functions

Nanotechnology-Based Drug Delivery Systems for Treating Acute Kidney Injury

Acute kidney injury (AKI) is a disease that is characterized by a rapid decline in renal function and has a relatively high incidence in hospitalized patients. Sepsis, renal hypoperfusion, and nephrotoxic drug exposure are the main causes of AKI. The major therapy measures currently include supportive treatment, symptomatic treatment, and kidney transplantation. These methods are supportive treatments, and their results are not satisfactory. Fortunately, many new treatments that markedly improve the AKI therapy efficiency are emerging. These include antioxidant therapy, ferroptosis therapy, anti-inflammatory therapy, autophagy therapy, and antiapoptotic therapy. In addition, the development of nanotechnology has further promoted therapeutic effects on AKI. In this review, we highlight recent advances in the development of nanocarriers for AKI drug delivery. Emphasis has been placed on the latest developments in nanocarrier modification and design. We also summarize the applications of different nanocarriers in AKI treatment. Finally, the advantages and challenges of nanocarrier applications in AKI are summarized, and several nanomedicines that have been approved for clinical trials to treat diverse kidney diseases are listed.

Red-light-excited TiO2/Bi2S3 heterojunction nanotubes and photoelectric hydrogels mediate epidermal-neural network reconstruction in deep burns

Inspired by the strong light absorption of carbon nanotubes, we propose a fabrication approach involving one-dimensional TiO2/Bi2S3 QDs nanotubes (TBNTs) with visible red-light excitable photoelectric properties. By integrating the construction of heterojunctions, quantum confinement effects, and morphological modifications, the photocurrent reached 9.22 µA/cm2 which is 66 times greater than that of TiO2 nanotubes (TNTs). Then, a red light-responsive photoelectroactive hydrogel dressing (TBCHA) was developed by embedding TBNTs into a collagen/hyaluronic acid-based biomimetic extracellular matrix hydrogel with good biocompatibility, aiming to promote wound healing and skin function restoration. This approach is primarily grounded in the recognized significance of electrical stimulation in modulating nerve function and immune responses. Severe burns are often accompanied by extensive damage to epithelial-neural networks, leading to a loss of excitatory function and difficulty in spontaneous healing, while conventional dressings inadequately address the critical need for nerve reinnervation. Furthermore, we highlight the remarkable ability of the TBCHA photoelectric hydrogel to promote the reinnervation of nerve endings, facilitate the repair of skin substructures, and modulate immune responses in a deep burn model. This hydrogel not only underpins wound closure and collagen synthesis but also advances vascular reformation, immune modulation, and neural restoration. This photoelectric-based therapy offers a robust solution for the comprehensive repair of deep burns and functional tissue regeneration. STATEMENT OF SIGNIFICANCE: We explore the fabrication of 1D TiO2/Bi2S3 nanotubes with visible red-light excitability and high photoelectric conversion properties. By integrating heterojunctions, quantum absorption effects, and morphological modifications, the photocurrent of TiO2/Bi2S3 nanotubes could reach 9.22 µA/cm², which is 66 times greater than that of TiO2 nanotubes under 625 nm illumination. The efficient red-light excitability solves the problem of poor biosafety and low tissue penetration caused by shortwave excitation. Furthermore, we highlight the remarkable ability of the TiO2/Bi2S3 nanotubes integrated photoelectric hydrogel in promoting the reinnervation of nerve endings and modulating immune responses. This work proposes an emerging therapeutic strategy of remote, passive electrical stimulation, offering a robust boost for repairing deep burn wounds.

Electrostimulation suppresses allograft rejection via promoting lymphatic regulatory T cell migration mediated by lymphotoxin - lymphotoxin receptor β signaling

Conventional immunosuppressants that suppress allograft rejection cause various side effects. Although regulatory T cells (Tregs) are essential for allograft survival, the limited efficacy of Treg therapy demands improvement. Thus, it is imperative to seek new approaches to enhancing Treg suppression. Low-intensity electrostimulation (ES) has been shown to exert antiinflammatory effects without causing major adverse reactions. However, it remains unknown whether and how ES regulates alloimmunity. Here, we found that regional ES delayed murine skin allograft rejection and promoted long-term allograft survival induced by an mTOR inhibitor, rapamycin. ES also extended islet allograft survival. Mechanistically, ES enhanced the expression of lymphotoxin α (LTα) on Tregs after transplantation. Blockade of lymphotoxin β receptor-mediated nonclassical NFκB signaling suppressed lymphatic Treg migration and largely reversed the effects of ES on allograft survival. Moreover, ES failed to extend allograft survival when recipients lacked LTα/lymph nodes or if transferred Tregs lacked LTα. Therefore, ES promoted the lymphatic migration of CD4+Foxp3+ Tregs by upregulating their surface expression of LTα. Finally, ES augmented expression of LTα on murine or human Tregs, but not conventional T cells, while promoting their calcium influx in vitro. This ES-mediated upregulation of LTα relied on calcium influx. Thus, our findings have unveiled novel mechanisms underlying ES-mediated immunoregulation.

Enhancing Liver Transplant Outcomes through Liver Precooling to Mitigate Inflammatory Response and Protect Mitochondrial Function

Transplanted organs experience several episodes of ischemia and ischemia-reperfusion. The graft injury resulting from ischemia-reperfusion (IRI) remains a significant obstacle to the successful survival of transplanted grafts. Temperature significantly influences cellular metabolic rates because biochemical reactions are highly sensitive to temperature changes. Consequently, lowering the temperature could reduce the degradative reactions triggered by ischemia. In mitigating IRI in liver grafts, the potential protective effect of localized hypothermia on the liver prior to blood flow obstruction has yet to be explored. In this study, we applied local hypothermia to mouse donor livers for a specific duration before stopping blood flow to liver lobes, a procedure called "liver precooling". Mouse donor liver temperature in control groups was controlled at 37 °C. Subsequently, the liver donors were preserved in cold University of Wisconsin solution for various durations followed by orthotopic liver transplantation. Liver graft injury, function and inflammation were assessed at 1 and 2 days post-transplantation. Liver precooling exhibited a significant improvement in graft function, revealing more than a 47% decrease in plasma aspartate transaminase (AST) and alanine aminotransferase (ALT) levels, coupled with a remarkable reduction of approximately 50% in liver graft histological damage compared to the control group. The protective effects of liver precooling were associated with the preservation of mitochondrial function, a substantial reduction in hepatocyte cell death, and a significantly attenuated inflammatory response. Taken together, reducing the cellular metabolism and enzymatic activity to a minimum level before ischemia protects against IRI during transplantation.

Roles of Akirin1 in early prediction and treatment of graft kidney ischemia‒reperfusion injury

Ferroptosis is a predominant contributor to graft kidney ischemia‒reperfusion injury (IRI), resulting in delayed graft function (DGF). However, much less is known about the early predicting biomarkers and therapeutic targets of DGF, especially aiming at ferroptosis. Here, we propose a precise predicting model for DGF, relying on the Akirin1 level in extracellular vesicles (EVs) derived from recipient urine 48 h after kidney transplant. In addition, we decipher a new molecular mechanism whereby Akirin1 induces ferroptosis by strengthening TP53-mediated suppression of SLC7A11 during the graft kidney IRI process, that is, Akirin1 activates the EGR1/TP53 axis and inhibits MDM2-mediated TP53 ubiquitination, accordingly upregulating TP53 in two ways. Meanwhile, we present the first evidence that miR-136-5p enriched in EVs secreted by human umbilical cord mesenchymal stem cells (UM-EVs) confers robust protection against ferroptosis and graft kidney IRI by targeted inhibition of Akirin1 but knockout of miR-136-5p in UM sharply mitigates the protection of UM-EVs. The functional and mechanistic regulation of Akirin1 is further corroborated in an allograft kidney transplant model in wild-type and Akirin1-knockout mice. In summary, these findings suggest that Akirin1, which prominently induces ferroptosis, is a pivotal biomarker and target for early diagnosis and treatment of graft kidney IRI and DGF after kidney transplant.

Bioelectric stimulation controls tissue shape and size

Epithelial tissues sheath organs and electro-mechanically regulate ion and water transport to regulate development, homeostasis, and hydrostatic organ pressure. Here, we demonstrate how external electrical stimulation allows us to control these processes in living tissues. Specifically, we electrically stimulate hollow, 3D kidneyoids and gut organoids and find that physiological-strength electrical stimulation of ∼ 5 - 10 V/cm powerfully inflates hollow tissues; a process we call electro-inflation. Electro-inflation is mediated by increased ion flux through ion channels/transporters and triggers subsequent osmotic water flow into the lumen, generating hydrostatic pressure that competes against cytoskeletal tension. Our computational studies suggest that electro-inflation is strongly driven by field-induced ion crowding on the outer surface of the tissue. Electrically stimulated tissues also break symmetry in 3D resulting from electrotaxis and affecting tissue shape. The ability of electrical cues to regulate tissue size and shape emphasizes the role and importance of the electrical micro-environment for living tissues.

Methotrexate and electrostimulation cooperate to alleviate the relapse of psoriasiform skin inflammation by suppressing memory T cells

Methotrexate (MTX) is an immunosuppressant used to treat autoimmune diseases, including psoriasis. However, like other immunosuppressants, MTX alone does not prevent their recurrence. Electrostimulation (ES) has been utilized to treat some inflammatory disorders without any major side-effect. But it remains unknown if ES alone, or together with MTX, ameliorates autoimmune disease relapse: a sticky medical problem. In particular, the mechanisms underlying ES action remain unclear. The objective of this study was to determine an impact of ES and/or MTX on psoriasis relapse and their potential cooperation. We found that regional ES, but not MTX, ameliorated psoriasiform skin inflammation recurrence. Interestingly, treatment with both MTX and ES further prevented psoriasis recurrence compared to ES alone. Moreover, ES downregulated potassium channel Kv1.3 on T-cells and reduced CD4+/CD8+ effector memory (TEM) and CD8+ skin-resident memory T (TRM) cells, while ES plus MTX further decreased CD8+ TEM/TRM cells compared to ES alone. However, ES failed to further attenuate psoriasis recurrence or suppress T cell memory in Kv1.3-deficient mice, whereas lack of Kv1.3 itself ameliorated psoriasis relapse by shrinking T cell memory pool. Importantly, ES moderately inhibited T-cell proliferation in vitro. ES also reduced human CD8+ TRM cells and attenuated human skin lesions in humanized mice grafted with lesional skin from patients with recurrent psoriasis, with an enhanced efficacy in mice treated with both ES and MTX. Thus, ES and MTX cooperated to prevent psoriasis relapse by reducing T-cell memory via targeting potassium channel Kv1.3. Our studies may be implicated for treating human psoriasis.

Nephroprotective Effects of Cardamonin on Renal Ischemia Reperfusion Injury/UUO-Induced Renal Fibrosis

Acute kidney injury and chronic renal fibrosis are intractable pathological processes to resolve, yet limited strategies are able to effectively address them. Cardamonin (CAD) is a flavonoid with talented antioxidant, anti-inflammatory capacity, and satisfactory biosafety. In our study, animal and cellular models of renal ischemia/reperfusion (I/R) and unilateral ureteral obstruction (UUO) were successfully constructed to confirm whether CAD confers protective effects and underlying mechanisms. Animal experiments demonstrated that CAD application (100 mg/kg) distinctly ameliorated tissue damage and improved renal function. Meanwhile, the continuous oral administration of CAD after UUO surgery efficiently inhibited renal fibrosis as confirmed by hematoxylin-eosin (H&E), Sirius red, and Masson staining as well as the downregulated mRNA and protein expression of collagen I, α-smooth muscle actin (α-SMA), collagen III, and fibronectin. Interestingly, in transforming growth factor β1 (TGF-β1)-stimulated and hypoxia/reoxygenation (H/R)-exposed human kidney-2 (HK-2) cells, protective effects of CAD were again authenticated. Meanwhile, we performed bioinformatics analysis and constructed the "ingredient-target-pathway-disease" network to conclude that the potential mechanisms of CAD protection may be through the regulation of oxidative stress, inflammation, apoptosis, and mitogen-activated protein kinase (MAPK) pathway. Furthermore, experimental data validated that CAD evidently decreased the reactive oxygen species (ROS) production and malondialdehyde (MDA) content while depressing the mRNA and protein expression of inflammatory markers (tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and Il-1β) and inhibiting apoptosis as evidenced by decreased levels of P53, BAX, cleaved caspase-3, and apoptotic rate in renal I/R and UUO models. In addition, the impact of CAD on restraining oxidative stress and inflammation was attributed to its ability to elevate antioxidant enzyme activities including catalase, superoxide dismutase 1 (SOD1), and superoxide dismutase 2 (SOD2) and to inhibit the inflammation-associated MARK/nuclear factor-κB (MAPK/NF-κB) signaling pathway. In conclusion, cardamonin restored the antioxidative capacity to block oxidative stress and suppressed the MAPK/NF-κB signaling pathway to alleviate inflammatory response, thus mitigating I/R-generated acute kidney injury/UUO-induced renal fibrosis in vivo and in vitro, which indicated the potential therapeutic advantage of cardamonin in attenuating acute and chronic kidney injuries.

Small extracellular vesicles delivering lncRNA WAC-AS1 aggravate renal allograft ischemia‒reperfusion injury by inducing ferroptosis propagation

Ferroptosis is a predominant contributor to renal ischemia reperfusion injury (IRI) after kidney transplant, evoking delayed graft function and poorer long-term outcomes. The wide propagation of ferroptosis among cell populations in a wave-like manner, developing the "wave of ferroptosis" causes a larger area of tubular necrosis and accordingly aggravates renal allograft IRI. In this study, we decipher a whole new metabolic mechanism underlying ferroptosis and propose a novel spreading pathway of the "wave of ferroptosis" in the renal tissue microenvironment, in which renal IRI cell-secreted small extracellular vesicles (IRI-sEVs) delivering lncRNA WAC-AS1 reprogram glucose metabolism in adjacent renal tubular epithelial cell populations by inducing GFPT1 expression and increasing hexosamine biosynthesis pathway (HBP) flux, and consequently enhances O-GlcNAcylation. Additionally, BACH2 O-GlcNAcylation at threonine 389 in renal tubular epithelial cells prominently inhibits its degradation by ubiquitination and promotes importin α5-mediated nuclear translocation. We present the first evidence that intranuclear BACH2 suppresses SLC7A11 and GPX4 transcription by binding to their proximal promoters and decreases cellular anti-peroxidation capability, accordingly facilitating ferroptosis. Inhibition of sEV biogenesis and secretion by GW4869 and knockout of lncRNA WAC-AS1 in IRI-sEVs both unequivocally diminished the "wave of ferroptosis" propagation and protected against renal allograft IRI. The functional and mechanistic regulation of IRI-sEVs was further corroborated in an allograft kidney transplant model and an in situ renal IRI model. In summary, these findings suggest that inhibiting sEV-mediated lncRNA WAC-AS1 secretion and targeting HBP metabolism-induced BACH2 O-GlcNAcylation in renal tubular epithelial cells may serve as new strategies for protecting against graft IRI after kidney transplant.

Macula Densa Nitric Oxide Synthase 1 Controls Renin Release and Renin-Dependent Blood Pressure Changes

BACKGROUND

The function of macula densa nitric oxide synthase 1 (NOS1) in the regulation of renin release is controversial. This study was conducted to further elucidate the role of macula densa NOS1 in renin release and blood pressure regulation in response to salt challenges and hemorrhagic shock.

METHODS

To investigate the specific role of NOS1 in the macula densa within the kidney in response to varying sodium concentrations in the diet, tissue macula densa-specific NOS1 knockout (MD-NOS1KO) and wild type (WT) mice were subjected to sequential low (0.1% NaCl) and high (1.4% NaCl) sodium diets. Separate groups of mice, consisting of both MD-NOS1KO subgroup and WT subgroup, were induced hemorrhagic shock by retro-orbital bleeding of 12 mL blood/kg body weight. Mean arterial pressure (MAP) was measured by a radio-telemetry system. Plasma renin concentration (PRC) was measured with the radioimmunoassay for both sodium diet and hemorrhagic shock experiments.

RESULTS

PRCs were 371 ± 95 and 411 ± 68 ng/mL/hr in WT and MD-NOS1KO mice fed a normal sodium diet, respectively. Low salt intake stimulated an increase in the renin release by about 260% in WT mice (PRC = 1364 ± 217 ng/mL/hr, p < 0.0001) compared to the PRC under normal salt diet. However, the stimulation was significantly blunted in MD-NOS1KO mice (PRC = 678 ± 104 ng/mL/hr, p < 0.001). High salt intake suppressed the PRC to about 61% of the PRC level under a normal salt diet (p < 0.0001). Deletion of macula densa NOS1 further inhibited renin release to 33% of the levels of a normal salt diet. Hemorrhagic shock induced about a 3-fold increase in PRC in WT mice, but only about a 54% increase in the MD-NOS1KO mice (p < 0.0001). The MAP values were substantially greater in WT mice than in MD-NOS1KO mice within the first 6 hours following hemorrhagic shock (p < 0.001). Thus, WT mice showed a much quicker recovery in MAP than MD-NOS1KO mice.

CONCLUSIONS

Our study demonstrated that macula densa NOS1 plays an important role in mediating renin release. This mechanism is essential in maintaining blood pressure under hypovolemic situations such as hemorrhagic shock.

Limonin, a natural ERK2 agonist, protects against ischemic acute kidney injury

Acute kidney injury (AKI) is a refractory clinical syndrome with limited effective treatments. Amid AKI, activation of the extracellular signal-regulated kinase (ERK) cascade plays a critical role in promoting kidney repair and regeneration. However, a mature ERK agonist in treating kidney disease remains lacking. This study identified limonin, a member of the class of compounds known as furanolactones, as a natural ERK2 activator. Employing a multidisciplinary approach, we systemically dissected how limonin mitigates AKI. Compared to vehicles, pretreatment of limonin significantly preserved kidney functions after ischemic AKI. We revealed that ERK2 is a significant protein linked to the limonin's active binding sites through structural analysis. The molecular docking study showed a high binding affinity between limonin and ERK2, which was confirmed by the cellular thermal shift assay and microscale thermophoresis. Mechanistically, we further validated that limonin promoted tubular cell proliferation and reduced cell apoptosis after AKI by activating ERK signaling pathway in vivo. In vitro and ex vivo, blockade of ERK abolished limonin's capacity of preventing tubular cell death under hypoxia stress. Our results indicated that limonin is a novel ERK2 activator with strong translational potential in preventing or mitigating AKI.

Restoration of metal homeostasis: a potential strategy against neurodegenerative diseases

Metal homeostasis is critical to normal neurophysiological activity. Metal ions are involved in the development, metabolism, redox and neurotransmitter transmission of the central nervous system (CNS). Thus, disturbance of homeostasis (such as metal deficiency or excess) can result in serious consequences, including neurooxidative stress, excitotoxicity, neuroinflammation, and nerve cell death. The uptake, transport and metabolism of metal ions are highly regulated by ion channels. There is growing evidence that metal ion disorders and/or the dysfunction of ion channels contribute to the progression of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Therefore, metal homeostasis-related signaling pathways are emerging as promising therapeutic targets for diverse neurological diseases. This review summarizes recent advances in the studies regarding the physiological and pathophysiological functions of metal ions and their channels, as well as their role in neurodegenerative diseases. In addition, currently available metal ion modulators and in vivo quantitative metal ion imaging methods are also discussed. Current work provides certain recommendations based on literatures and in-depth reflections to improve neurodegenerative diseases. Future studies should turn to crosstalk and interactions between different metal ions and their channels. Concomitant pharmacological interventions for two or more metal signaling pathways may offer clinical advantages in treating the neurodegenerative diseases.

Rapidly Blocking the Calcium Overload/ROS Production Feedback Loop to Alleviate Acute Kidney Injury via Microenvironment-Responsive BAPTA-AM/BAC Co-Delivery Nanosystem

Calcium overload and ROS overproduction, two major triggers of acute kidney injury (AKI), are self-amplifying and mutually reinforcing, forming a complicated cascading feedback loop that induces kidney cell "suicide" and ultimately renal failure. There are currently no clinically effective drugs for the treatment of AKI, excluding adjuvant therapy. In this study, a porous silicon-based nanocarrier rich in disulfide bond skeleton (<50 nm) is developed that enables efficient co-loading of the hydrophilic drug borane amino complex and the hydrophobic drug BAPTA-AM, with its outer layer sealed by the renal tubule-targeting peptide PEG-LTH. Once targeted to the kidney injured site, the nanocarrier structure collapses in the high glutathione environment of the early stage of AKI, releasing the drugs. Under the action of the slightly acidic inflammatory environment and intracellular esterase, the released drugs produce hydrogen and BAPTA, which can rapidly eliminate the excess ROS and overloaded Ca²⁺ , blocking endoplasmic reticulum/mitochondrial apoptosis pathway (ATF4-CHOP-Bax axis, Casp-12-Casp-3 axis, Cyt-C-Casp-3 axis) and inflammatory pathway (TNF-α-NF-κB axis) from the source, thus rescuing the renal cells in the "critical survival" state and further restoring the kidney function. Overall, this nanoparticle shows substantial clinical promise as a potential therapeutic strategy for I/R injury-related diseases.

1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic Acid Acetoxymethyl Ester Loaded Reactive Oxygen Species Responsive Hyaluronic Acid-Bilirubin Nanoparticles for Acute Kidney Injury Therapy via Alleviating Calcium Overload Mediated Endoplasmic Reticulum Stress

Calcium overload is one of the early determinants of the core cellular events that contribute to the pathogenesis of acute kidney injury (AKI), which include oxidative stress, ATP depletion, calcium overload, and inflammatory response with self-amplifying and interactive feedback loops that ultimately lead to cellular injury and renal failure. Excluding adjuvant therapy, there are currently no approved pharmacotherapies for the treatment of AKI. Using an adipic dihydride linker, we modified the hyaluronic acid polymer chain with a potent antioxidant, bilirubin, to produce an amphiphilic conjugate. Subsequently, we developed a kidney-targeted and reactive oxygen species (ROS)-responsive drug delivery system based on the flash nanocomplexation method to deliver a well-known intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM, BA), with the goal of rescuing renal cell damage via rapidly scavenging of intracellularly overloaded Ca²⁺. In the ischemia-reperfusion (I/R) induced AKI rat model, a single dose of as-prepared formulation (BA 100 μg·kg^-1) 6 h post-reperfusion significantly reduced renal function indicators by more than 60% within 12 h, significantly alleviated tissular pathological changes, ameliorated tissular oxidative damage, significantly inhibited apoptosis of renal tubular cells and the expression of renal tubular marker kidney injury molecule 1, etc., thus greatly reducing the risk of kidney failure. Mechanistically, the treatment with BA-loaded NPs significantly inhibited the activation of the ER stress cascade response (IRE1-TRAF2-JNK, ATF4-CHOP, and ATF6 axis) and regulated the downstream apoptosis-related pathway while also reducing the inflammatory response. The BA-loaded NPs hold great promise as a potential therapy for I/R injury-related diseases.

MiR-20a-5p alleviates kidney ischemia/reperfusion injury by targeting ACSL4-dependent ferroptosis

Ischemia/reperfusion injury (IRI) is prone to occur after kidney transplantation, leading to delayed graft function (DGF). MicroRNAs play a crucial role in the pathogenesis of ischemia/reperfusion-induced acute kidney injury, and miR-20a-5p was found to be the most significantly upregulated gene in a DGF patient cohort. However, the roles of microRNAs in transplanted kidneys remain largely unknown. In this study, we found that miR-20a-5p was upregulated in the kidneys of acute kidney injury mice and in patients with DGF. We identified early growth response-1 as a critical upstream target and verified the binding of early growth response-1 to a predicted sequence in the promoter region of the miR-20a-5p gene. Functionally, the miR-20a-5p mimic attenuated IRI and postischemic renal fibrosis, whereas the miR-20a-5p inhibitor delivery aggravated IRI and fibrosis. Importantly, delivery of the miR-20a-5p mimic or inhibitor in the donor kidneys attenuated or aggravated renal loss and structural damage in cold storage transplantation injury. Furthermore, our study identified miR-20a-5p as a negative regulator of acyl-CoA synthetase long-chain family member 4 (ACSL4) by targeting the 3' untranslated region of ACSL4 mRNA, thereby inhibiting ACSL4-dependent ferroptosis. Our results suggest a potential therapeutic application of miR-20a-5p in kidney transplantation through the inhibition of ACSL4-dependent ferroptosis.

Melatonin in preservation solutions prevents ischemic injury in rat kidneys

Transplantation is lifesaving and the most effective treatment for end-stage organ failure. The transplantation success depends on the functional preservation of organs prior to transplantation. Currently, the University of Wisconsin (UW) and histidine-tryptophan-ketoglutarate (HTK) are the most commonly used preservation solutions. Despite intensive efforts, the functional preservation of solid organs prior to transplantation is limited to hours. In this study, we modified the UW solution containing components from both the UW and HTK solutions and analyzed their tissue-protective effect against ischemic injury. The composition of the UW solution was changed by reducing hydroxyethyl starch concentration and adding Histidine/Histidine-HCl which is the main component of HTK solution. Additionally, the preservation solutions were supplemented with melatonin and glucosamine. The protective effects of the preservation solutions were assessed by biochemical and microscopical analysis at 2, 10, 24, and 72 h after preserving the rat kidneys with static cold storage. Lactate dehydrogenase (LDH) activity in preservation solutions was measured at 2, 10, 24, and 72. It was not detectable at 2 h of preservation in all groups and 10 h of preservation in modified UW+melatonin (mUW-m) and modified UW+glucosamine (mUW-g) groups. At the 72nd hour, the lowest LDH activity (0.91 IU/g (0.63–1.17)) was measured in the mUW-m group. In comparison to the UW group, histopathological damage score was low in modified UW (mUW), mUW-m, and mUW-g groups at 10, 24, and 72 hours. The mUW-m solution at low temperature was an effective and suitable solution to protect renal tissue for up to 72 h.