Discovery Pipeline for AKI: Molecules, Mechanisms, Models, and Targets

Abstract

Background:

Acute kidney injury (AKI) represents a multifaceted clinical syndrome marked by precipitous loss of kidney function, high morbidity and mortality, and a strong propensity for progression to chronic kidney disease. Collectively, these challenges underscore the imperative to delineate conserved molecular and signaling networks that are uniformly engaged across diverse AKI etiologies.

Summary:

Herein, we survey five emerging research domains poised to transform AKI pathophysiology and therapeutic paradigms. First, lymphatic network remodeling has been implicated as a critical determinant of renal immunodynamics and interstitial fluid homeostasis, whereby modulation of VEGF-C/D signaling reshapes immune cell trafficking and fibrogenic responses. Second, we will cover emerging evidence that positions macrophage ferritin heavy chain as a key regulator of macrophage phenotype and subsequent kidney ferroptosis susceptibility via coordinated regulation of synuclein-α, and Spic. Third, we will emphasize incorporating development as a biological variable into experimental design based on evidence that identifies age-dependent divergences in injury susceptibility, and progression of disease. Fourth, we cover mechanosensitive ion channels that are activated by therapeutic ultrasound offering novel opportunities to harness the cholinergic anti-inflammatory pathway for nephroprotection. Finally, targeting tubular epithelial cell senescence and mitochondrial bioenergetics as a promising approach to limit progression of kidney disease will be discussed.

Key Messages:

Collectively, these emerging mechanisms deepen our understanding of AKI pathophysiology and unveil novel therapeutic targets with the potential to transform the treatment landscape.

Introduction

AKI is a common and serious clinical syndrome, particularly prevalent among hospitalized and critically ill patients [1]. Its etiology is multifactorial, encompassing a wide range of insults that disrupt kidney homeostatic landscape and trigger complex injury responses [2]. While the kidney possesses remarkable regenerative capacity, severe or sustained injury can overwhelm reparative mechanisms, leading to maladaptive repair, persistent inflammation, fibrosis, and ultimately, progression to CKD [3, 4]. In this review, we explore recent advances in the pathophysiological understanding of AKI, with a focus on the molecular and cellular pathways involved in disease severity and progression. We highlight the emerging recognition of development and aging as critical biological variables that influence susceptibility and response to injury, and we discuss the therapeutic potential of targeting mechanosensitive ion channels as a novel strategy for mitigating severity of AKI. An integrative overview of the principal themes and mechanistic pathways addressed in this review is depicted in Figure 1.

Figure 1.

Schematic illustrating emerging discovery pipeline for AKI

Roles of lymphatics and lymphangiogenesis in AKI

Lymphatic vessels are found in nearly all vascularized tissues and close the circulatory loop by providing a route for fluid, macromolecules, and immune cells that have extravasated from blood vessels to be returned. In doing so, lymphatics play an important role in maintaining tissue homeostasis; lymphatic dysfunction results in fluid accumulation and the inability of immune cells to reach the draining lymph node impacts the tissue immune response [5]. During inflammation, increased expression of the lymphatic growth factors vascular endothelial growth factor-C and -D (VEGF-C and VEGF-D, respectively) drives lymphangiogenesis or the expansion of the lymphatic network seemingly with the goal of increasing fluid clearance capacity or immunoregulation [5]. Indeed, recent immunological studies in cancer and infection have highlighted the interactions of lymphatic endothelial cells with various immune cell populations as critical to functional immune responses [6]. This makes targeting lymphatic vessels, lymphangiogenesis, or lymphatic-immune interactions an attractive potential target to craft a more beneficent response to inflammation, for example, in AKI.

Lymphatic vessel’s roles in the kidney, like in most tissues, are both fluid and pressure regulation and immune cell trafficking and regulation. Past elegant physiology studies have examined the impacts of lymphatic ligation on interstitial fluid pressures and transport that have effects on various aspects of renal function including filtration and concentrating capacity. These studies are the subject of two excellent recommended review articles with the general view that lymphatics play a positive role in renal physiological homeostasis and function [7, 8]. This is highlighted in a 1967 study by Lilienfeld and colleagues in which they ligated the renal lymphatic vessels of one canine kidney and found increased edema and urine flow within days [9]. Interestingly, this also resulted in a marked increase in systolic blood pressure in the test animals [9]. Indeed, the interplay between lymphatic function and lymphangiogenesis in blood pressure regulation and tissue (and whole body) sodium handling has been studied in the skin and kidney by several groups with the general finding that more lymphatics results in lower blood pressure and increased sodium clearance [10]. It is logical to hypothesize then that lymphatics and lymphangiogenesis would therefore be beneficial in AKI, but the results to date are far from clear.

AKI leads to an upregulation of VEGF-C and VEGF-D and resultant lymphangiogenesis [11]. This process takes 7 days or more until significantly more lymphatic vessels are noted and occurs across many models of mouse and rat kidney injury [12, 11, 5]. Hasegawa and colleagues demonstrated that VEGF-C delivered via osmotic minipump from the time of a unilateral ureteral obstruction (UUO) increased kidney lymphangiogenesis and reduced tissue fibrosis and macrophage numbers [13]. Conversely, Pei and colleagues demonstrated that blocking VEGF-C/D signaling during UUO could improve AKI outcomes by reducing immune cell numbers and limiting fibrosis [12]. Kasinath and colleagues also identified that removal of the renal lymph node could improve the kidney outcomes in a model of crescentic glomerulonephritis [14]. We identified that induction of kidney-specific lymphangiogenesis through local overexpression of VEGF-D prior to injury resulted in improved kidney function and reduced fibrosis following ischemia reperfusion injury or podocyte ablation [15]. What was consistent across these highlighted studies was that manipulating lymphangiogenesis alters specific populations of immune cells.

Is lymphangiogenesis following an AKI good or bad for inflammation resolution? This is an important question in the potential progression of an AKI to CKD or even the increased risk of future CKD. Creed and colleagues recently performed single cell RNA sequencing on lymphatic endothelial cells isolated from mouse kidneys 3 days following a nephrotoxic cisplatin injury [16]. While approximately ¾ of the gene pathways identified as upregulated were involved in vasculogenesis (this being the time lymphatic expansion is underway), the remaining pathways were linked to regulatory T cell responses [16]. The impact, timing, and extent of endogenous lymphangiogenesis or lymphangiogenic targeting likely impacts kidney-to-lymph node communication and lymphatic-immune interactions in an injury (and perhaps age or sex)-specific response. It was recently identified in mice that an AKI results in longterm alterations to the kidney lymphatic architecture and function [17]. Lymphatic endothelial cells are a small fraction of kidney cells, but, excitingly, more human genetic data is becoming available on lymphatic responses to AKI [18]. While the molecular characteristics associated with AKI-related lymphangiogenesis are increasingly recognized, their functional significance remains to be fully elucidated. The field may soon be able to gain clarity on whether lymphangiogenesis can be targeted to inhibit the adaptive immune response or could it make the response protective? Or does the extent of lymphatic expansion remaining post AKI indicate future CKD risk or protection? These answers may make lymphatic modulation an important component of the AKI response.

Iron, immunity, and injury: A macrophage-centric FtH–Spic–Snca axis linking ferroptosis to AKI pathogenesis

Irrespective of the initiating insult, a consistent immunological hallmark of AKI is the involvement of macrophages (MΦ), which are critical in orchestrating both injury and repair processes [19, 20]. Dysregulated iron metabolism is a common feature in AKI and is frequently observed during the clinical progression of CKD [21, 22]. Importantly MΦ are central at the intersection of iron metabolism and response to injurious signals [23, 24].

Iron is essential for aerobic life, but unrestrained, it can catalyze the formation of reactive oxygen species (ROS), leading to cellular and tissue damage. An intriguing, highly conserved molecule that has the capacity of sequestering large amounts of iron in a safe, soluble, and bioavailable form is ferritin [25]. It is made up of heavy (FtH) and light (FtL) chains where FtH possesses ferroxidase activity catalyzing the conversion of pro-oxidant ferrous iron (Fe²⁺) into the less reactive ferric form (Fe³⁺) [26]. During injurious conditions, compounded by release of intracellular heme moieties, FtH acts as a safeguard, sequestering labile iron and limiting lipid peroxidation [27, 28]. The central role of iron in driving cellular and tissue damage is underscored by the process of ferroptosis, an iron-dependent, non-apoptotic form of regulated cell death characterized by lipid peroxidation and oxidative membrane damage [29]. Aberrant renal iron deposition and ferroptosis have been identified as key contributors to the pathogenesis of AKI and its progression to CKD [30]. Ferroptosis can propagate in a synchronized, wave-like manner across cell populations, generating a characteristic spatiotemporal pattern of cell death [31]. This propagation may be exacerbated by increased expression of ferroportin (sole known iron exporter), which promotes ferrous iron efflux from ferroptotic cells, in conjunction with the release of iron-containing heme from dying cells, thereby fueling further oxidative injury [32]. Pharmacological inhibitors of ferroptosis, such as ferrostatin-1 and liproxstatin-1, have demonstrated potent efficacy in mitigating ferroptosis in various AKI models [30]. Based on these observations we recently examined the contribution of myeloid FtH in pathogenesis of AKI. Our results identify a novel regulatory axis involving myeloid ferritin heavy chain (FtH), synuclein-α (Snca), and the transcription factor Spic, which governs macrophage iron metabolism and ferroptosis during kidney injury. Specifically, FtH deficiency in MΦ induces a reprogramming of MΦ toward an iron-recycling profile via upregulation of Spic, an ETS-family transcription critical for the development of iron-recycling MΦ [33]. This reprogramming leads to iron accumulation, increased oxidative stress, and ferroptosis within kidney tissues, ultimately exacerbating AKI. In addition to its role in iron homeostasis, FtH has been found to modulate MΦ phenotypic response by regulating transcriptional programs that include Snca [33]. Snca encodes a small, intrinsically disordered protein traditionally known for its involvement in neurodegenerative diseases, particularly Parkinson’s disease [34]. Beyond its neurological functions, emerging evidence highlights a critical role for Snca in immune regulation and pro-inflammatory signaling [34]. Moreover, Snca expression and function are tightly linked to iron metabolism, as the protein can bind several metals, including iron, a process that promotes its pathological accumulation [35]. Monomeric Snca possesses ferrireductase activity, thereby intensifying oxidative stress and promoting ferroptosis [36, 33]. Snca accumulates in leukocyte-enriched kidney diseases across species, suggesting a broader role for Snca beyond the central nervous system, particularly in the pathogenesis of iron mediated inflammatory diseases [33]. Intriguingly, emerging evidence also implicates kidney disease as a potential contributor to aberrant Snca accumulation and propagation from the kidney to the central nervous system, which may predispose individuals to the development and progression of Parkinson’s disease [37]. These findings place Snca within a broader pathophysiological framework that bridges systemic iron dysregulation, inflammation, and neurodegeneration. Collectively, these findings suggest that FtH plays a central role in modulating MΦ phenotype and function through a previously unrecognized FtH–Spic–Snca regulatory axis. Specifically, MΦ-expressed FtH suppresses the expression of Snca, which in turn reduces ferrireductase activity, thereby limiting ROS generation and lipid peroxidation. Additionally, by decreasing the intracellular labile iron pool, MΦ-FtH downregulates the expression of the transcription factor Spic. This reduction in Spic expression is associated with decreased levels of ferroportin, potentially representing a critical mechanism by which MΦ-FtH limits the availability of free ferrous iron (Fe²⁺) within the injured microenvironment, thereby mitigating iron-driven oxidative damage and ferroptosis.

Several therapeutic strategies have been explored to mitigate ferroptosis and kidney injury by targeting ferritin expression, iron metabolism, and antioxidant defenses. Ferroptosis inhibitors, such as ferrostatin-1 and liproxstatin-1, effectively suppress lipid peroxidation and ROS formation, thereby preventing cell death in multiple models of AKI [30]. Iron chelators, including deferoxamine, desferox, and ciclopirox, confer protection in cisplatin-induced and obstructive nephropathy by reducing labile iron and limiting iron-driven oxidative stress [38, 39]. Enhancing ferritin expression or inhibiting ferritinophagy (via NCOA4 modulation) further restricts iron release and attenuates ferroptotic damage [30]. Small molecules that elevate glutathione levels and GPX4 activity such as N-acetylcysteine and ebselen restore redox balance and reduce AKI severity [40]. Moreover, emerging genomic studies have identified Dipeptidase 1 (Dpep1) and charged multivesicular body protein 1A (Chmp1a) as novel regulators of ferroptosis through their roles in intracellular iron trafficking [41]. Collectively, these findings highlight that enhancing ferritin expression, stabilizing the GSH–GPX4 antioxidant system, and restricting free iron availability hold promise in mitigating the severity of AKI, mitigating its progression to CKD, and promoting kidney repair and regeneration.

Development as a biological variable (DABV) in experimental models of AKI

In humans, nephrogenesis is complete at approximately 34 weeks’ gestation, and postnatally, kidney function continues to develop, reaching mature function, corrected for body surface area, at approximately 19 months of age. Starting in the fourth decade of life, GFR decreases gradually declines in otherwise healthy patients. The time at which AKI occurs with respect to nephrogenesis, post-natal functional development, and aging likely impacts renal and systemic outcomes. The majority of experimental models of AKI are performed in young adult animals – during the relative plateau of normative and stable kidney function – discounting the impact of development and aging on pathophysiology [42]. Importantly, AKI occurs commonly in patients at both the younger and older spectrum of the human lifespan [43, 44]. The 26th ADQI Report on Pediatric AKI highlighted the need to incorporate DABV into preclinical models in order to explore pathophysiological differences in AKI in premature neonates compared to term neonates and older children [45, 46]. In addition to considerations of ongoing renal maturation, pediatric patients undergo significant growth and development systemically throughout childhood. Experimental models that incorporate DABV may shed insight into the impact of AKI on long-term systemic outcomes such as growth and neurocognitive development [47–49].These concepts also hold for elderly and geriatric patients compared to younger adults. Emerging and established preclinical models are incorporating DABV, including pre-gestational AKI, to investigate the impact of renal maturation and aging at the time of AKI on long-term outcomes.

Aged Models:

Rodent models have demonstrated that advanced age is associated with increased susceptibility to AKI. Marquez-Exposito et al. used a folic acid model of AKI in mice to compare outcomes in aged 1-year-olds compared to younger 3-month-old mice [50]. The aged cohorts demonstrated a significant increase in both inflammatory infiltrates and tubular damage 48 hours after injury. In a rat model of lipopolysaccharide-induced AKI, pups exhibited lower amounts of oxidative stress and renal fibrosis compared to adult rats [51]. Aged models can also incorporate fluctuations in sex hormones over the lifespan. For example, Boddu et al. demonstrated young female mice were protected from cisplatin-induced AKI compared to males, and that this protection in females waned with increased age [52].

Neonatal Models:

Because rodents undergo ex utero nephrogenesis, neonatal preclinical models provide an opportunity to develop models of AKI in both premature and term neonates, depending on the degree of nephrogenesis at the time of injury. Liberio et al. recently described two models of AKI in 5-day-old rat pups, using either bilateral ischemia-reperfusion AKI or an aristolochic acid model of nephrotoxicity, and used these models to explore the link between neonatal AKI and bronchopulmonary dysplasia [53]. In a model of perinatal asphyxia in 7-day-old Wistar rat pups, Lakat et al. showed hypoxemia (4% O2 for 15 minutes) resulted in AKI, and that 6 months later, survivors were more susceptible to ischemia-reperfusion AKI than normoxemic controls [54].

Pre-gestational AKI:

AKI is common in women and men of childbearing age, and emerging preclinical models of pre-gestational AKI have been developed to interrogate the impact of pre-gestational AKI on gestational and progeny outcomes. Gillis et al. administered 45 minutes of bilateral ischemia-reperfusion AKI to female Sprague Dawley rats and mated them to healthy males one week later [55]. Females from the AKI group demonstrated increased uterine artery resistive indices, increased fetal demise, and smaller pups, consistent with intrauterine growth restriction. Hebert et al. established a pre-gestational model of rhabdomyolysis AKI in C57BL/6 mice via water deprivation followed by glycerol injection to both the damns and sires [56]. The progeny of the injured mice demonstrated renal insufficiency at 6 months of age.

Importantly, experimental models that incorporate DABV may shed critical insights that merit investigation in humans. For example, after rodent studies of young adult mice and rat pups demonstrated growth disparities following ischemia-reperfusion AKI compared to sham, investigators evaluated clinical cohorts of pediatric AKI to determine whether this signal translated to humans and found a correlation between pediatric AKI and poor growth [57, 58, 53, 59]. Once the signal has been verified in humans, experimental models can then be used to investigate potential mechanisms and identify novel therapeutic targets, following a bench-to-bedside-back-to-bench approach [46].

Harnessing therapeutic ultrasound to attenuate AKI

The inflammatory reflex is a neural circuit that regulates the body’s immune response to pathogens and tissue injury. The afferent arc is activated by cytokines and it transmits signals to the brain through the afferent vagus nerve which leads to activation of the efferent or motor limb resulting in suppression of inflammation. This efferent arc of the inflammatory reflex is known as the cholinergic anti-inflammatory pathway (CAP). In this pathway, signals from the efferent vagus nerve are transmitted to the splenic nerve, releasing norepinephrine (NE) in the spleen. NE binds to β2 adrenergic receptors on CD4+ T cells which release of acetylcholine (ACh). Finally, ACh binds to α7nAChRs on macrophages which reduces the production of pro-inflammatory cytokines such as TNFα [60]. Multiple methods have been used to activate this pathway leading to reduced inflammation in various diseases such as colitis, sepsis, rheumatoid arthritis, acute lung injury, diabetes, and obesity [61–63]. We have demonstrated that electrical VNS [64, 65], optogenetic VNS stimulation, and pulsed ultrasound (US) [66, 61, 67] can activate the CAP to reduce inflammation and kidney injury in AKI. Electrical stimulation of the vagus nerve 24 hours prior to kidney ischemia reperfusion injury reduced AKI. Activation of the CAP was implicated in the mechanism of protection by demonstrating the abolishment of protection in splenectomized mice and in mice lacking α7nAChRs. Furthermore, adoptive transfer of VNS conditioned α7nAChR splenocytes to naïve mice conferred protection. Optogenetics was used to further refine our understanding of the specific neural circuits involved [68]. Anterograde efferent fiber stimulation and anterograde sensory afferent fiber stimulation both conferred protection from AKI while retrograde stimulation did not. Two types of vagus nerve stimulators are currently available for clinical use-implantable and transcutaneous-both of which are FDA-approved for various indications. In addition, spleen targed pulsed ultrasound, through CAP activation, similarly demonstrated a protective effect from the development of ischemic AKI. Specifically, bursts of ultrasound (20 pulses of US with a duration of 1 second was delivered every 6 seconds for 2 minutes) delivered 24 hours prior to IRI reduced inflammation and improved renal function after AKI [66]. Thus, pulsed ultrasound provides a noninvasive, nonpharmacological means of activating the cholinergic anti-inflammatory pathway (CAP), analogous to electrical vagus nerve stimulation, which is currently being evaluated in clinical trials [NCT05685108].

While the ability of ultrasound to modulate the CAP to protect against AKI has been clearly demonstrated, the origin of these effects is unclear. Both thermal and mechanical effects have been implicated in therapeutic ultrasound. The thermal effects are the result of the absorption of ultrasound energy causing the heating of tissue, and these may dominate at high intensities. Mechanotransduction is the process by which mechanical stimuli are converted into electrical or chemical signals. Mechanosensitive ion channels sense position, movement, touch, pressure and pain and enable cells to transduce mechanical stimuli into electrochemical signals [69]. Eleven different channels, such as transient receptor potential (TRP) channel family, acid sensing ion channels (ASICs), Piezo ion channels, TWIK-related arachidonic acid activated K+ (TRAAK) channels, TREK channels, and Nav1.8 channels, have been shown to be activated by ultrasound stimulation [70, 71].The mechanical force from ultrasound opens these channels, inducing downstream signaling processes, eventually lead to changes in cellular behavior and the subsequent biological effects.

Piezos are a family of mechanosensitive ion channels that includes Piezo1 and Piezo2. Piezo1 is expressed in organs such as the bladder [72], heart [73], kidneys [74], lungs [75], and skin [76] . Piezo2, on the other hand, is expressed primarily in sensory neurons [77]. According to one review, nearly half of studies reported Piezo1 as the key mechanosensitive ion channel activated by ultrasound [71]. When Piezo1 is stimulated, the channel changes from a closed to open state which allows calcium, potassium and sodium ions to flow [78]. Piezo1 can regulate multiple biological functions including proliferation, migration, and apoptosis [79]. Piezo1 may also play a role in inflammation, however, the evidence is conflicting with some studies reporting a pro-inflammatory role while others suggest an anti-inflammatory role [80, 81]. Piezo1’s role in inflammation may therefore be context dependent. Furthermore, it may depend on the mechanical stimulus responsible for its activation. In our studies, we examine whether the effect of pulsed ultrasound to activate the CAP to reduce inflammation and AKI is through direct effects on spleen cell Piezo1 or through Piezo2 on sensory neurons. Hoffman et al. found that in neurons lacking piezo2, ultrasound thresholds required for activation were elevated [82]. It is possible that activation of multiple mechanosensitive ion channels by ultrasound underlies the conversion of mechanical stimuli and subsequent effects. Thus, future studies involving multiple channels will be important in revealing their relative contributions to the observed biological effects.

Tubular cell senescence and mitochondrial dysfunction: targets to limit maladaptive repair following AKI?

AKI pathogenesis is heterogeneous and multifactorial [83]: however, injury and regeneration of tubular epithelial cells (TECs) are central to both AKI development and recovery [84]. Several pathogenic mechanisms are involved, including loss of TEC polarity which impairs ion, glucose, and water transport as well as acid-base homeostasis. This alteration results in increased delivery of sodium and chloride to the distal tubule and macula densa, thereby triggering the tubulo-glomerular feedback and consequently impairing glomerular filtration rate (GFR) [85]. Loss of TEC polarity also involves diminished expression of key mRNAs and proteins, such as megalin and cubilin in murine models, alongside aberrant redistribution of Na⁺/K⁺-ATPase to the apical membrane. These alterations contribute to cytoskeletal disorganization and compromise intercellular tight junction integrity as well as protein reabsorption [86–88]. Furthermore, TEC death via necrosis and/or apoptosis significantly contributes to AKI pathophysiology. During sepsis, various circulating pro-apoptotic mediators promote TEC apoptosis, which is detectable on renal biopsies and may be mitigated by extracorporeal therapies such as polymyxin B hemoadsorption [89, 90].

The repair of TECs following an AKI episode is pivotal for achieving the complete restoration of renal function. When TECs undergo maladaptive rather than adaptive repair, progressive renal fibrosis ensues, leading to the development of CKD and potentially progressing to end-stage kidney disease (ESKD). Maladaptive repair is characterized by dysregulated expression of growth factors, persistent activation of the pro-inflammatory M1 macrophage phenotype accompanied by chronic inflammatory infiltrates, microvascular rarefaction, myofibroblast proliferation, epithelial-to-mesenchymal transition (EMT), tubular atrophy, cellular senescence, and cell cycle arrest at the G2/M checkpoint. These interconnected mechanisms contribute collectively to tubular atrophy, interstitial fibrosis, glomerulosclerosis, and ultimately accelerate renal tissue aging [91].

One of the most peculiar aspects of maladaptive TEC repair is senescence: senescent cells actively secrete pro-inflammatory cytokines, thereby sustaining and amplifying tissue injury [92]. The precise phenotype of senescent cells remains to be fully characterized. Notably, elevated plasma and urinary concentrations of p21 have been proposed as putative biomarkers for both AKI and renal aging [93]. A further senescence-associated biomarker is the decreased expression of soluble Klotho [94]. Activation of the complement cascade is also implicated in these biological events, resulting in enhanced oxidative stress and augmented neutrophil infiltration, which collectively contribute to the pathophysiological process termed inflammaging [95]. This pathogenic mechanism appears to be at least in part limited by extracorporeal therapies using polymethylmethacrylate (PMMA) membranes [96]. In vivo studies in murine models of sepsis-associated AKI have demonstrated that such therapies effectively reduce renal and systemic levels of the terminal complement complex C5b-9 and mitigate Klotho down-regulation. The recent DEFENDER randomized controlled trial [97] demonstrated that, in patients admitted to intensive care unit presenting with at least one acute organ dysfunction, initiation of dapagliflozin was associated with a reduced need for initiation KRT: of note, SGLT2-inhibitors have been shown to limit cellular senescence [98].

Mitochondrial dysfunction represents another key mechanism contributing to TEC injury during AKI, with particular emphasis on the disruption of NAD⁺ (nicotinamide adenine dinucleotide) homeostasis. NAD⁺ is an essential cofactor for ATP biosynthesis and is critical for maintaining the high metabolic demand of TECs. During AKI, a significant depletion of NAD⁺ levels has been documented, attributed to both impaired NAD⁺ biosynthesis secondary to mitochondrial dysfunction and increased NAD⁺ consumption associated with renal injury [99, 100]. Restoration or increase of NAD⁺ mitochondrial synthesis has emerged as a potential therapeutic approach to prevent and/or ameliorate AKI, and to attenuate the maladaptive repair processes that follow renal insult [101].

Last, Mesenchymal Stem Cell (MSC) therapy and their products such as Extracellular Vesicles (EVs), may enhance renal functional recovery after AKI in murine models through by inhibiting senescence and sustaining mitochondrial function [102, 103]. Taken together, the results from experimental animal models and initial studies in humans highlighted the potential role of senescence and mitochondrial dysfunction as both biomarkers and therapeutic targets in AKI-to-CKD-progression. Hospitalized patients who experienced the most severe and persistent forms of AKI associated with sepsis or ischemia-reperfusion injury including Delayed Graft Function (DGF) in kidney transplantation may benefit from the evaluation of these biological alterations. As recently suggested by international consensus statements [104], this kind of interventions may represent an enrichment strategy for post-AKI follow-up, saving costs and selecting the right patients who need nephrological care to limit CKD progression.

Conclusion

Despite advances in management, AKI outcomes remain poor. Emerging insights into lymphatics, iron metabolism, mechanosensory pathways, macrophage reprogramming, ferroptosis, mitochondrial dysfunction, and tubular senescence offer new therapeutic targets. An integrated approach addressing these pathways while considering developmental stage and biological variability holds promise for advancing precision therapies and improving long-term outcomes in AKI.