Anatomically, the vascular wall (excluding capillaries and lymphatic capillaries) is organized into three concentric layers from the lumen outwards: The intima, media and adventitia (11). Functionally, the media acts as the central hub for vascular tension regulation, housing circumferentially arranged VSMCs intertwined with elastic/collagen fiber networks. This arrangement endows vessels with both active contractility and passive elastic recoil (12). Ultrastructurally, VSMCs exhibit an elongated spindle-shaped morphology, containing cytoplasmic contractile units, force-transducing dense bodies and calcium-regulating sarcoplasmic reticulum (13). However, in sepsis, this structural organization is disrupted: VSMC detachment from the ECM and degradation of elastic fibers impair vascular compliance, exacerbating hypotension. The changes in VSMCs from physiological conditions to septic conditions are shown in Fig. 1.

Studies employing single-cell transcriptomics and lineage tracing techniques have revealed the distinct origins of VSMCs: hindlimb/inguinal-axillary venous VSMCs predominantly stem from the lateral plate mesenchyme (14); SMCs in the proximal thoracic aorta are derived from the second heart field and cardiac neural crest (15); and coronary artery SMCs partly originate from epicardial cells that migrate into the heart during development (16). These differences in embryonic origins, combined with varied responses to local microenvironmental signals, confer upon VSMCs tissue-specific molecular profiles and functional characteristics.

Under physiological conditions, VSMCs maintain a robust contractile capacity, which is crucial for the dynamic regulation of blood flow and pressure (17). This contractile ability is regulated by the phosphorylation of myosin light chain (MLC) through two primary pathways: The calcium-dependent MLC kinase (MLCK)/MLC signaling pathway and the calcium-sensitized Rho/Rho-associated protein kinase (ROCK) signaling pathway.

Regarding the MLCK/MLC signaling pathway, an increase in the intracellular calcium ion concentration ([Ca²⁺]i) occurs via the opening of voltage-gated or receptor-gated calcium channels, or release from intracellular stores (18). Free calcium ions bind to calmodulin, activating MLCK; MLCK catalyzes the phosphorylation of the 19th serine residue on regulatory MLC, activating the Mg²⁺-ATPase activity of myosin heads. This induces a conformational change in myosin, enhancing its binding to actin (19). MLC phosphatase (MLCP)-mediated dephosphorylation of MLC reduces myosin-actin binding, inhibiting contraction. Regarding the Rho/ROCK signaling pathway (20), activation of RhoA leads to ROCK activation, which inhibits MLCP activity, thereby maintaining or increasing MLC phosphorylation levels by preventing dephosphorylation (21). ROCK can also directly phosphorylate MLC to promote myosin contraction (22). Additionally, the calcium-sensitized pathway is associated with actin cytoskeleton remodeling, such as via cofilin phosphorylation, which inhibits actin filament depolymerization, further enhancing contraction (23). In summary, these two signaling pathways work together to regulate VSMC contractility: The calcium-dependent pathway facilitates acute responses to fluctuations in [Ca²⁺]i, whereas the calcium-sensitized pathway prolongs contraction.

Upon encountering injury or stimulation by growth factors, VSMCs undergo a response characterized by enhanced proliferation, migration and synthesis of extracellular components, a phenomenon known as phenotypic switching (24). The main subtypes of VSMCs are as follows: i) Contractile VSMCs are characterized by a high concentration of myofilaments, a slender spindle-shaped morphology and robust contractility. ii) Synthetic VSMCs are characterized by an abundance of rough endoplasmic reticulum and Golgi apparatus, downregulation of contractile proteins, and upregulation of ECM components and inflammatory factors. Other identified phenotypes include osteogenic, macrophage-like, mesenchymal-like and fibroblast-like VSMCs (24). Under physiological conditions, VSMCs typically exhibit a quiescent state characterized by low proliferative and migratory activity. However, in response to pathological stimuli, such as vascular injury, diabetes or hypertension, VSMCs undergo phenotypic plasticity, transitioning from a contractile state to secretory/inflammatory phenotypes with increased proliferative, migratory and matrix-synthetic functions (25).

Effective communication between endothelial cells (ECs) and VSMCs is a complex physiological process essential for maintaining vascular structure and function, allowing cells to adapt to mechanical injury, shear stress and chemical stimuli through pathways such as Notch signaling, cytokine secretion and exosomal trafficking (12,24). The conserved Notch signaling pathway facilitates interactions between adjacent cells: ECs express Jagged1 ligands that bind to Notch3 receptors on VSMCs, inhibiting their transition from contractile to synthetic phenotypes (24). Additionally, ECs regulate VSMC metabolism, influencing phenotypic plasticity. In coculture models, hypoxic ECs increase lactate production, whereas the knockout of lactate dehydrogenase A (LDHA) reduces osteogenic marker expression and VSMC apoptosis (26). Cytokine secretion serves as another crucial regulatory mechanism. Factors such as prostanoids, arachidonic acid, acid metabolites and NO, which are released by ECs, have distinct effects on VSMC function (12). Furthermore, exosomes serve a notable role in vascular remodeling; in atherosclerosis models, endothelial autophagy facilitates the transfer of microRNA (miRNA/miR)-204-5p via exosomes to VSMCs, inhibiting endothelial apoptosis and VSMC calcification (27). This multidimensional crosstalk highlights the interconnection of ECs and VSMCs in preserving vascular health or contributing to pathological processes.

Sepsis induces marked metabolic reprogramming in VSMCs, disrupting their function and contributing to disease pathogenesis. Systemic circulatory failure and microcirculatory dysfunction collectively impair cellular oxygen uptake and utilization, triggering metabolic remodeling (5). Under septic conditions, the energy metabolism of VSMCs transitions from oxidative phosphorylation (OXPHOS) to aerobic glycolysis, a metabolic reprogramming observed across various cell types. This glycolytic switch, characterized by increased glucose uptake and upregulation of hexokinase 2, supports the migratory activity of VSMCs (28).

Upregulated glycolysis results in excess lactate production, leading to lactic acidosis. This metabolic disturbance inhibits mitochondrial respiration (OXPHOS) and glutamine catabolism, decreasing cellular ATP levels and altering the NAD⁺/NADH ratio (8). These sequential effects contribute to the phenotypic transition and functional decline of VSMCs, exacerbating sepsis-induced vascular dysfunction. Notably, glycolysis and lactate directly promote VSMC migration and proliferation. In sepsis-induced systemic cellular injury, elevated plasma LDH levels are indicative of tissue injury, a common feature observed in severe sepsis (29,30). At the mechanistic level, lysine 5 crotonylation enhances the tetramer formation of LDHA, increasing lactate production to drive the migration and proliferation of VSMCs (31). These combined metabolic disturbances impair VSMCs contractility and provoke phenotypic alterations, worsening the vascular pathophysiology induced by sepsis.

Shear stress is the fluid dynamic force exerted by blood flow on the vascular wall, and is influenced by factors such as vessel diameter, flow pulsatility, blood viscosity and velocity (32). Physiological shear stress is crucial for vascular homeostasis, whereas abnormal shear stress serves as a notable mechanical trigger for vascular pathology. Abnormal shear stress in sepsis arises from two mutually reinforcing mechanisms: Hemodynamic disturbances and vascular structural damage.

First, sepsis-induced hyperdynamic circulation creates a paradoxical hemodynamic state: Inflammatory vasodilation and hypovolemia drive hypotension, whereas compensatory cardiac responses attempt to maintain tissue perfusion (33). This imbalance is exacerbated by microcirculatory dysfunction, characterized by vasoregulatory failure, capillary shunting and microthrombosis, which further disrupts blood flow patterns and amplifies tissue hypoperfusion (34). Collectively, these changes alter flow velocity, pulsatility and distribution, laying the foundation for abnormal shear stress.

Second, sepsis-mediated vascular structural damage compromises the ability of the vascular wall to buffer shear stress. Pathological alterations include glycocalyx degradation, reduced red blood cell deformability, redistribution of membrane phospholipids, and endothelial injury driven by platelet and neutrophil extracellular trap formation (35,36). When the endothelial barrier is disrupted, VSMCs are directly exposed to pulsatile shear stress, an insult that is normally attenuated by the endothelial layer, directly triggering functional dysregulation of VSMCs (37). This structural breakdown forms the anatomical basis for abnormal shear stress in sepsis.

Notably, invasive therapies for sepsis can further perturb hemodynamics by altering flow velocity and patterns, thereby modifying intravascular shear stress (38-40). These treatment-related changes may either mitigate or exacerbate the phenotypic plasticity of VSMCs, highlighting the need for tailored clinical management to minimize iatrogenic vascular damage.

Sepsis-induced vascular dysfunction arises from a marked disruption of the EC-VSMC interaction network. In a physiological state, the close crosstalk between ECs and VSMCs serves a crucial role in maintaining vascular tone, structure and functional equilibrium (41). The presence of physiological laminar shear stress acting on ECs helps preserve the contractile phenotype of VSMCs, characterized by high α-smooth muscle actin (α-SMA) expression (42). Key paracrine pathways, such as endothelial NO synthase (eNOS)/NO, have a role in regulating platelet-derived growth factor signaling to facilitate flow-dependent vasodilation and adaptive remodeling processes (43,44). The ECM, which offers structural support, influences cellular signaling through its compositional and mechanical attributes (12,45).

Sepsis disrupts this balance through several mechanisms: i) Mechanical force-sensing dysregulation: Hemodynamic disturbances (such as hypotension and microcirculatory failure) alter physiological shear stress, compromising its role in preserving VSMCs contractility (46). ii) Aberrations in signaling pathways: Sepsis-induced inflammation, oxidative stress and endotoxemia disrupt communication between ECs and VSMCs. In acute kidney injury induced by lipopolysaccharide (LPS), endothelial calpain activation leads to p38 phosphorylation and upregulation of inducible NO synthase (iNOS), resulting in excessive production of NO and reactive oxygen species (ROS) that leads to EC apoptosis (47). Multiple signaling factors involved in EC-VSMC crosstalk exhibit altered expression or activity in response to sepsis. iii) ECM remodeling dysfunction: Inflammatory mediators trigger excessive ECM deposition (48), imbalanced degradation (for example, altered metalloproteinase activity) and abnormal cross-linking, disrupting vascular mechanics and intercellular chemical/mechanical signaling. iv) Altered vesicle-mediated communication: Extracellular vesicles (EVs) serve a crucial role in EC-VSMC communication (49). Sepsis alters the release and contents (proteins, mRNAs and miRNAs) of EVs: EVs derived from ECs containing miR-539 promote VSMC proliferation (49), potentially contributing to vascular repair or pathological remodeling. Other sepsis-regulated miRNAs similarly modulate EC-VSMC interactions through EVs.

These collective disruptions force VSMCs to switch from a normal contractile phenotype to a pathological, proinflammatory, proliferative, migratory or synthetic state. This phenotypic transition serves as the fundamental cellular mechanism contributing to sepsis-associated vasoplegia, increased permeability, abnormal remodeling and organ hypoperfusion.

Alterations in [Ca²⁺]i are crucial events for initiating vascular contraction, and calcium levels and the sensitivity of contractile proteins collectively determine the strength of contraction. Bacterial LPS, a prominent pathogen-associated molecular pattern (PAMP), serves a central role in sepsis and septic shock. In a rat model of endotoxemia, the administration of LPS has been shown to result in systolic hypotension, tachycardia, peritoneal neutrophil migration and elevated alanine aminotransferase levels at 24 h. Concurrently, VSMCs displayed disturbances in calcium homeostasis, such as reduced calcium influx, depletion of sarcoplasmic reticulum calcium, inactivation of Orai1 channels, and ultimately, sepsis-associated vasoplegia (50).

The precise mechanisms through which LPS mediates intracellular calcium dysregulation have not been fully elucidated. In microglia, LPS-induced mitochondrial fragmentation hinders the capacity for and rate of calcium uptake, leading to disruption of calcium homeostasis (51). In cardiomyocytes, the interaction between pyruvate kinase M2 (PKM2) and sarcoplasmic/endoplasmic reticulum calcium ATPase 2a is crucial for maintaining calcium balance; PKM2 deficiency exacerbates the LPS-induced disruption of calcium homeostasis and cardiac contractile dysfunction (52).

Another crucial mechanism is the reduced sensitivity of contractile proteins to calcium: Intravenous LPS administration in adult rabbits has been reported to result in a depression of the force-calcium relationship in cardiac tissue despite an increase in [Ca2⁺]i, indicating endotoxemia-induced ineffective calcium cycling and desensitization of myofibrils (53). Additionally, sepsis-associated vasoplegia is associated with a decrease in the expression of contractile proteins: LPS inhibits TGF-β control elements on the α-SMA promoter, leading to reduced α-SMA transcription and protein levels in human aortic and coronary VSMCs, and in rat aortic VSMCs (54).

The potential regulatory mechanisms of calcium homeostasis in VSMCs are illustrated in Fig. 2. Physiologically, Ca²⁺ enters VSMCs via voltage-dependent calcium channel, receptor-operated calcium channel, transient receptor potential channel and store-operated calcium channel, and intracellular calcium handling is regulated by plasmalemmal calcium ATPase, sodium-calcium exchanger and organelles (mitochondria and endoplasmic reticulum). GPCR activation triggers a signaling cascade via phospholipase Cβ/γ, which hydrolyze phosphatidylinositol 4,5-bisphosphate into inositol 1,4,5-trisphosphate (IP3); IP3 binds to endoplasmic reticulum receptors to release Ca²⁺ and elevate cytoplasmic Ca²⁺ levels. In sepsis and septic shock, LPS disrupts this finely balanced regulatory network by impairing calcium homeostasis through interference with calcium channels, intracellular calcium stores and calcium transporters. It also reduces myofibrillar calcium sensitivity and suppresses α-actinin expression (54). This decrease in α-actinin further undermines the structural integrity of the actin cytoskeleton, synergistically weakening myosin-actin interactions and VSMC contractility.

The injury to VSMCs induced by sepsis results from a complex interaction of factors, including direct invasion by pathogens and injury caused by virulence factors. Pathogens disrupt cellular structures through their metabolic activities or through the action of secreted virulence factors, such as pore-forming toxins, exfoliative toxins and superantigens, leading to inflammatory processes that ultimately result in tissue necrosis (6). For example, bacterial sepsis, the predominant form of sepsis (55), has been shown to induce injury to VSMCs and impair their contractile function in a rat model of CLP (56). Different pathogens have unique effects: Chlamydia pneumoniae infection triggers an increase in mitochondrial ROS (mtROS) via Toll-like receptor (TLR)2, activating the JunB-Fra-1/matrix metalloproteinase-2 pathway to facilitate VSMC migration (57). By contrast, human cytomegalovirus enhances the expression of a disintegrin and metalloproteinase domain 9, promoting VSMC proliferation, migration and transition from a contractile to a synthetic phenotype (58). Notably, COVID-19 infection also induces a shift in the phenotype of VSMCs, worsening vascular dysfunction (59). These mechanisms underscore the direct involvement of pathogens and their virulence factors in inducing injury to VSMCs.

Moreover, pathogens indirectly damage VSMCs through the release of virulence factors, such as endotoxins and exotoxins. These molecules, which are essential for pathogen-induced tissue injury or immune response evasion, include LPS, exotoxins (such as cytotoxins, neurotoxins and enterotoxins), secretory systems and catalases (6). For example, LPS, a crucial component of gram-negative bacteria, serves a pivotal role in the pathogenesis of sepsis. Research has demonstrated that LPS enhances the expression of regulator of G-protein signaling 1, activates the JNK-p38 signaling pathway, and induces a shift in VSMCs from a contractile to a synthetic phenotype, thereby promoting proliferation, and contributing to the development and rupture of infectious intracranial aneurysms (60). In vitro studies have revealed that lipoteichoic acid from Staphylococcus aureus or Streptococcal Streptolysin O stimulates the expression of iNOS in rat VSMCs, leading to excessive NO production and subsequent vascular dysfunction, mechanisms closely associated with vasoplegia in gram-positive septic shock (61,62). Additionally, staphylococcal α-toxin directly causes coronary vasoconstriction and impairs myocardial contractility, a process mediated by the production of thromboxane A2 (63). In conclusion, sepsis-induced VSMC injury involves a variety of mechanisms, including direct invasion by pathogens, the release of virulence factors and the activation of inflammatory cascades. These insults disrupt the contractility of VSMCs and promote phenotypic transition, thereby contributing to the development of vasoplegia. Table I presents a summary of the pathogenic effects and molecular mediators of common pathogens on VSMCs (57-67).

PAMPs released by invading microorganisms are recognized by the host immune system, initiating innate immunity and the subsequent cytokine storm, a characteristic feature of sepsis (6,68). Cytokine release syndrome involves the extensive secretion of ILs, interferons (IFNs), TNF and colony-stimulating factors, driving systemic inflammation (69,70). These cytokines serve crucial roles not only in regulating immunity and tissue repair, but also in influencing the physiology of VSMCs and the progression of diseases. Numerous studies have shown that inflammatory factors modulate the phenotype and function of VSMCs through distinct mechanisms. For example, the constitutive expression of the IL-1α precursor stimulates proliferation in human saphenous vein VSMCs (71), whereas IL-1β enhances the migration and invasion of human aortic SMCs through the p38 MAPK/angiopoietin-2 signaling pathway (72). TNF-α rapidly alters the expression of contractile and synthetic markers in vitro, promoting VSMC proliferation and migration at low concentrations (73). In sepsis, immune cells, including macrophages, neutrophils, T cells and natural killer cells, secrete substantial amounts of pro-inflammatory cytokines, with IFN-γ serving as a central mediator in regulating VSMC function (69). A previous study in a non-septic setting has demonstrated that IFN-γ secreted by decidual natural killer cells induces long non-coding RNA MEG3, thereby modulating VSMC migration and apoptosis, suggesting a conserved role for IFN-γ-regulated pathways in VSMC function (74). Furthermore, various other cytokines also participate in this regulatory network. Table II provides a summary of representative inflammatory factors, their regulatory effects on VSMCs and the underlying signaling pathways (71-101). These mechanisms collectively contribute to sepsis-induced vasoplegia.

The immunopathogenesis of sepsis is characterized by dysregulated immune responses, involving both hyperinflammation and immunosuppression (102). In sepsis, PAMPs and damage-associated molecular patterns (DAMPs) activate the host immune system, leading to cytokine storms and the aberrant activation of signaling pathways; events that compromise the function of VSMCs. These dysregulated signaling cascades are closely associated with VSMC inflammation, phenotypic switching and functional impairment. In addition to classical inflammatory pathways, emerging mechanisms, including NLRP3 inflammasome activation, mtROS release and the dysregulation of mechanosensitive ion channels, have recently been identified as critical regulators of VSMCs pathobiology in sepsis.

The Notch signaling pathway is a highly conserved intercellular communication system that includes receptors, ligands and effector molecules. In mammals, this pathway comprises four Notch receptors (Notch1-4) and five ligands (Jagged1, Jagged2, Delta1, Delta3 and Delta4) (103). Under normal physiological conditions, Notch signaling serves a role in regulating VSMC differentiation and phenotype maintenance (24). However, under septic conditions, such as in a mouse model of CLP, the activity of the Notch pathway, particularly that of Notch3, is markedly reduced. This reduction is associated with the downregulation of the expression of Notch3 and its ligands Jagged1 and Delta4, resulting in impaired VSMC contractility (104). Moreover, in a mouse model of LPS-induced sepsis, Notch3 expression has been reported to be notably decreased in lung tissue, highlighting the essential role of Notch signaling in modulating VSMC function during sepsis (105).

The AMPK/FOXO pathway serves a critical role in cellular energy balance and the response to oxidative stress. AMPK, a key energy sensor, is activated under metabolic stress conditions, whereas FOXO transcription factors act as important downstream effectors of stress signaling. Upon activation, AMPK phosphorylates FOXO proteins, augmenting their transcriptional activity and consequently upregulating the expression of antioxidant and cytoprotective genes, such as SOD1 and SOD2, which facilitate peroxide degradation and mitigate the accumulation of ROS (106). In sepsis, tissue damage results in the release of extracellular histones, which serve as DAMPs. These external histones induce an inflammatory response and senescence in VSMCs in a dose-dependent manner through activation of AMPK/FOXO4 signaling (107). This signaling cascade connects the sensing of metabolic stress to the regulation of VSMC dysfunction during septic conditions, highlighting its role in integrating energy metabolism with inflammatory signaling networks.

The NF-κB pathway serves as a central transcriptional regulatory hub that controls cell proliferation, apoptosis, inflammatory responses and immune homeostasis (108). In sepsis, stimuli from pathogens and proinflammatory cytokines activate NF-κB, promoting its translocation to the nucleus and subsequently inducing downstream inflammatory genes, including HIF-1α (6). Preclinical studies have shown that the pharmacological inhibition of NF-κB signaling effectively reduces VSMC proliferation and activation, leading to the mitigation of pathological vascular remodeling (80,81). These findings underscore the crucial role of NF-κB in linking septic inflammation to VSMC dysfunction, positioning it as a potential therapeutic target for vascular complications associated with sepsis.

p38 MAPK is a crucial member of the MAPK family, which regulates cellular responses to environmental stressors and inflammatory stimuli (109). Consisting of four isoforms (α, β, γ and δ), p38 MAPK acts as a central transducer of signals from cell surface receptors to nuclear effectors, and is activated by various stressors and proinflammatory cytokines (110,111). In the context of sepsis, inflammatory factors such as IL-1β and IL-16 stimulate p38 MAPK activation, facilitating VSMC migration and invasion, processes that are fundamental to pathological vascular remodeling and dysfunction (72,84). This pathway links inflammatory signaling to alterations in VSMCs behavior, emphasizing its role in mediating sepsis-induced vascular pathology.

The PI3K/Akt signaling pathway serves as a central regulator of cell survival, proliferation and metabolic homeostasis (112). In sepsis, this pathway modulates inflammatory responses and vascular cell behavior. Research has indicated that the IL-2/IL-2 receptor system promotes VSMC proliferation and migration via the PI3K/Akt/mTOR axis, exacerbating vascular injury (75). Table III summarizes the key signaling pathways involved in VSMC injury during sepsis (24,72,75,80,81, 84,104-112).

Sepsis-induced vasoplegia is closely associated with dysregulated VSMC function, with emerging evidence highlighting three nonclassical regulatory mechanisms: NLRP3 inflammasome activation, mtROS overproduction and mechanosensitive ion channel dysfunction, which complement classical inflammatory pathways.

The NLRP3 inflammasome, which comprises the sensor NLRP3, adaptor ASC and effector pro-caspase-1, is activated through a two-stage pathway in sepsis: NF-κB-driven upregulation of NLRP3/pro-IL-1β (initiation) and assembly triggered by PAMPs or DAMPs (activation) (113,114). Direct evidence for its role in septic VSMC dysfunction remains scarce, with most data derived from indirect observations. For example, histones released as DAMPs by severely damaged cells in sepsis promote ASC-NLRP3 interactions in VSMCs, mediating VSMC inflammation and senescence (107), processes implicated in impaired VSMC contractility. Although characterized in the context of chronic kidney disease-related vascular calcification, Prevotella copri-derived LPS (a PAMP) has been shown to induce VSMC osteogenic differentiation in vitro via activation of the TLR4-NF-κB-NLRP3 inflammasome axis (115); notably, NF-κB blockade can abolish both inflammasome activation and the resulting VSMC phenotypic shift in a rat model of chronic kidney disease. Extrapolating from this mechanistic framework, these findings suggest that PAMP-mediated VSMC phenotypic perturbation in sepsis may also occur via inflammasome signaling pathways. Notably, NLRP3 is transcriptionally regulated by Runx2, which coordinates vascular matrix stiffness and VSMC inflammatory phenotypes (116). Although direct evidence in sepsis is lacking, matrix stiffness-induced VSMC dysfunction is a recognized contributor to decreased vascular compliance, a feature that overlaps with sepsis-induced vasoplegia (25,116). Given the critical role of NLRP3 inflammasome signaling in IL-1β production in VSMCs (117), crosstalk with the classical NF-κB pathway may be a possibility; for example, IL-1β released by activated VSMCs may further activate NF-κB, resulting in the formation of a feed-forward loop that amplifies VSMC inflammation and functional impairment.

Oxidative stress serves a pivotal role in the pathogenesis of sepsis. When the body is subjected to severe external insults, such as burns, shock or serious infections, cellular structural alterations lead to mitochondrial injury and a sudden surge in ROS and reactive nitrogen species (RNS) levels. An imbalance between oxidant and antioxidant systems allows oxidative stress products, including ROS and RNS, to inflict mitochondrial damage and compromise vital cellular components, such as lipids, proteins and nucleic acids (118). Sepsis-induced inflammatory stress triggers the production of excessive amounts of mtROS (119), a critical upstream regulator of VSMC dysfunction and NLRP3 inflammasome activation (120). Mechanistically, mtROS upregulate NLRP3 at the translational level rather than directly activating the assembled inflammasome (121), although the specific molecular events involved in sepsis remain unclear. Beyond NLRP3 modulation, mtROS enhance MAPK activity and promote DNA synthesis, stimulating VSMC proliferation (122,123). This may perturb vascular wall integrity and exacerbate sepsis-induced decreases in vascular compliance, but direct evidence linking mtROS-driven proliferation to vasoplegia is lacking.

Mechanosensitive ion channels, which transduce mechanical stimuli into electrochemical signals, are potential regulators of septic VSMC dysfunction. Hemodynamic instability and inflammatory mediators induced by sepsis have been implicated in disrupting the function of key mechanosensitive channels in VSMCs, such as Piezo1, transient receptor potential vanilloid (TRPV) channels and two-pore domain potassium channels (124-126). Existing data primarily come from non-VSMC tissues or systemic models: Piezo1 has been shown to be upregulated in the intestinal tissues of CLP-induced septic mice (125), and its established role in VSMC Ca²⁺ influx suggests potential perturbation of Ca²⁺ homeostasis (127). In addition, TRPV1 has been reported to be upregulated in a rat model of endotoxemia (126), which may promote Ca²⁺-dependent NO production and vasodilation in VSMCs. CLP-induced mice exhibit downregulation of TASK-1, TASK-2 and TREK-1 (124), with TREK 1 downregulation potentially altering VSMC membrane potential and inhibiting voltage-gated Ca²⁺ channel activation.

Sepsis-induced vasoplegia is characterized by VSMC hypocontractility, impaired vasomotor tone and resistance to catecholamines, prompting clinical investigations into conventional agents targeting VSMC function. The current review presents a comprehensive analysis of four principal drug classes, vasopressin analogues, phosphodiesterase (PDE) inhibitors, antioxidants and calcium sensitizers, integrating preclinical mechanisms, clinical trial data and key translational challenges, with an emphasis on a critical and balanced appraisal of their therapeutic potential and limitations. Table IV summarizes the preclinical and clinical evidence, underlying mechanisms and translational challenges of conventional VSMC-targeted therapies for sepsis-induced vasoplegia (133-156).

As the most extensively studied agents for sepsis-induced vasoplegia, vasopressin analogues [including arginine vasopressin (AVP), terlipressin and selepressin] constitute a cornerstone in the clinical management of VSMC dysfunction. However, their therapeutic application is constrained by a delicate equilibrium between hemodynamic efficacy, off-target toxicity and patient heterogeneity; these are critical barriers that have limited translational success beyond symptomatic relief. Unlike catecholamines, which rely on intact adrenergic signaling (often compromised in sepsis due to receptor desensitization), vasopressin analogues directly restore vascular contractility via V1a receptors expressed on VSMCs (133). Activation of V1a receptors triggers downstream signaling of phospholipases A, C and D, promoting inositol triphosphate-mediated intracellular Ca²⁺ mobilization from the sarcoplasmic reticulum and increasing MLC phosphorylation (134). Moreover, in LPS-challenged rats, terlipressin suppresses aortic iNOS expression and activity by inhibiting NF-κB nuclear translocation, thereby disrupting the pathogenic calcium-NO feedback loop and ameliorating aortic vasoplegia in response to vasoconstrictors (135). This dual mechanism provides vasopressin analogues with a distinct advantage in targeting the fundamental pathophysiology of sepsis-induced vasoplegia rather than merely alleviating hemodynamic instability.

Clinically, evidence for vasopressin analogues remains mixed, reflecting the complexity of balancing efficacy and safety. A multicenter, randomized, double-blind trial (n=778) comparing low-dose AVP with norepinephrine in catecholamine-dependent septic shock showed no significant reduction in 28-day mortality (35.4% vs. 39.3%, P=0.26) (136), indicating that restoring vascular tone alone is insufficient to reverse sepsis-related multiorgan dysfunction. Nonetheless, post hoc analysis of the VASST trial revealed a promising renal protective effect of AVP: In high-risk patients (a ≥1.5-fold increase in serum creatinine from baseline or >25% glomerular filtration rate (GFR) reduction within 7 days, sustained for >24 h), AVP was associated with a significantly lower incidence of AKI progression to 'Failure' [serum creatinine >3-fold baseline; ≥4.0 mg/dl (353.6 μmol/l) with an acute ≥0.5 mg/dl rise; or >75% GFR reduction] or 'Loss' (permanent renal failure requiring dialysis for >4 weeks) than norepinephrine (20.8% vs. 39.6%, P=0.03) (137). This benefit may stem from reduced renal vasodilation and preserved glomerular filtration pressure (137). The phase II TERLIVAP trial (n=45) demonstrated that, compared with continuous infusion of 0.03 U/h vasopressin or 15 μg/min norepinephrine, administration of 1.3 μg/kg/h terlipressin, a longer-acting prodrug of vasopressin, significantly reduced catecholamine requirements needed to achieve hemodynamic stability within 48 h (0.8±1.3 vs. 1.2±1.4 vs. 0.2±0.4 μg/kg/min; each P≤0.05) (138). Moreover, terlipressin treatment was associated with a lower incidence of rebound hypotension compared with the two comparator groups (P<0.05) (138). Selepressin, a selective V1a agonist designed to mitigate off-target toxicity, failed to meet the primary endpoint of ventilator- and vasopressor-free day reduction in the SEPSIS-ACT trial (n=868) (139).

PDE inhibitors modulate VSMC function by inhibiting the hydrolysis of cyclic nucleotides (cyclin adenosine monophosphate/cGMP), representing a mechanistically distinct approach to targeting sepsis-induced vasoplegia (140). However, their translational potential is constrained by context-dependent efficacy, off-target effects and a paucity of sepsis-specific clinical data, reflecting the gap between preclinical mechanistic insights and clinical reality. Mammalian PDEs are classified into 11 families, with PDE3, PDE4 and PDE5 being the most relevant to septic VSMC dysfunction because of their tissue distribution and cyclic nucleotide selectivity (157). Commonly used PDE inhibitors in clinical practice are classified based on their target PDE isoforms, as follows: PDE3 inhibitors, which target PDE3 (predominantly expressed in the heart and circulatory system), with milrinone as a prototypical agent; PDE4 inhibitors, which target PDE4 (primarily localized in the respiratory system, particularly the bronchial tissues), such as roflumilast; and PDE5 inhibitors, which target PDE5 (mainly expressed in the lungs and penile tissues), with sildenafil as a representative drug.

Preclinical evidence for the role of PDE inhibitors in sepsis is conflicting, highlighting their model-dependent efficacy. In CLP-induced septic rats, the PDE4 inhibitor roflumilast reduced VSMC-derived inflammatory cytokine release (TNF-α and IL-6) and apoptosis, while stabilizing the microvascular barrier and improving renal perfusion (141,142). However, roflumilast worsened hemodynamic parameters [mean arterial pressure (MAP) and cardiac output] and failed to improve survival, likely because of its nonselective vasodilatory effects in the context of systemic inflammation (142). In the colon ascendens stent peritonitis model (a more clinically relevant polymicrobial sepsis model), PDE4 inhibition has been shown to stabilize the microvascular barrier and improve microcirculatory flow, supporting its potential in targeting sepsis-induced microvascular dysfunction (158). Similarly, the PDE5 inhibitor tadalafil improved basal renal blood flow in CLP-induced rats by increasing VSMC calcium sensitivity, but did not increase survival, suggesting that the benefits of isolated organ perfusion do not translate to systemic hemodynamic stability (143). Preclinical data on PDE3 inhibitors (for example, milrinone) present inherent contradictions, reflecting their context-dependent pleiotropic effects: Although milrinone restored mesenteric intestinal villus perfusion in rat models of endotoxemia, it concurrently aggravated systemic hypotension. Notably, despite this systemic hemodynamic deterioration, milrinone ameliorated intestinal mucosal hypoperfusion, underscoring a dissociation between systemic vascular tone and regional microcirculatory function (144,145).

Clinical evidence for the use of PDE inhibitors in sepsis-induced vasoplegia remains limited and inconclusive. A multicenter cohort study of 229 patients with septic shock revealed that compared with standard care, PDE3 inhibitors (milrinone and enoximone) did not improve lactate clearance, organ failure, length of Intensive Care Unit (ICU) or hospital stay, or mortality (159). Notably, the effects of PDE3 inhibitors on cardiogenic shock have also been evaluated, with a systematic review showing no differences in outcomes (early death, cardiac arrest, renal replacement therapy initiation) when PDE3 inhibitors were combined with other inotropes, findings that may be extrapolated to sepsis-related cardiomyopathy but not specifically to VSMC-mediated vasoplegia (160). To date, no large-scale randomized controlled trials (RCTs) have evaluated PDE4 or PDE5 inhibitors for sepsis-induced vasoplegia.

Antioxidants exist in various forms, each characterized by distinct mechanisms of action and clinical indications. They can broadly be categorized into those already in clinical use and others still under experimental investigation. As a water-soluble antioxidant, ascorbic acid (vitamin C) participates in numerous enzymatic and nonenzymatic reactions, and serves as a cofactor in multiple biological processes (161). The therapeutic potential of vitamin C in sepsis and critical illness has been studied for several decades; however, its clinical utility remains unclear. In vitro studies have demonstrated that vitamin C, when administered orally or added directly to cell cultures, promotes EC growth while inhibiting SMC proliferation (162,163). Preclinically, in LPS-induced septic rats, vitamin C has been shown to mitigate endotoxin-induced cardiomyopathy by inhibiting oxidative stress-related cytokine expression, thereby protecting myocardial tissue from damage (146). Clinical evidence remains contradictory: A meta-analysis of 12 RCTs revealed that intravenous vitamin C supplementation markedly reduced the duration of vasopressor therapy and improved Sequential Organ Failure Assessment scores in patients with septic shock, findings indirectly attributed to restored VSMC contractility, reducing catecholamine dependence (150). However, another randomized placebo-controlled trial reported that compared with placebo recipients, adults with sepsis receiving vasopressor therapy who were treated with intravenous vitamin C exhibited a greater risk of death at 28 days (risk ratio 1.17; 95% CI 0.98-1.40) (151). This contradiction is partly explained by sepsis-specific pharmacokinetic alterations: Critically ill patients have an increased volume of distribution and reduced renal clearance of vitamin C, leading to subtherapeutic concentrations in VSMCs despite high plasma levels.

Natural vitamin E (α-tocopherol), a lipid-soluble antioxidant, is selectively depleted in septic VSMCs because of increased oxidative consumption, with deficiency independently associated with severe septic shock (adjusted OR 6.75; 95% CI 2.45-18.60; P<0.001) (164). In an LPS-induced sepsis mouse model, vitamin E notably protected against sepsis-induced oxidative and inflammatory damage by preserving thiol-disulfide homeostasis and attenuating cytokine production (147). However, clinical evidence remains limited to retrospective analyses: a cohort study of 523 patients with sepsis in the ICU revealed that vitamin E supplementation was associated with reduced 28-day mortality (HR 0.75; 95% CI 0.59-0.95; P=0.019) (152). Given the current scarcity of robust clinical evidence, which is limited primarily to the results of retrospective cohort studies indicating possible benefits in vitamin E-deficient subpopulations, and persistent translational challenges, the therapeutic efficacy of vitamin E in patients with sepsis-induced vasoplegia requires substantiation through rigorously designed, prospective, multicenter RCT.

Mitoquinone mesylate (MitoQ) is a mitochondrion-targeted antioxidant characterized by a triphenyl phosphonium cation conjugated to ubiquinone, this structural design enables selective accumulation in mitochondria via membrane potential-dependent uptake, allowing it to specifically scavenge mtROS and protect cells from oxidative stress-induced mitochondrial dysfunction (148). MitoQ, a key regulator of VSMC homeostasis, has been validated in multiple preclinical models to mitigate vascular pathologies related to sepsis-induced VSMC dysfunction. In human aortic VSMCs, MitoQ has been reported to attenuate PM2.5-induced vascular fibrosis by modulating mitochondrial dynamics; specifically, it can suppress the transition of VSMCs from a contractile to a synthetic phenotype, and alleviate mitochondrial fragmentation and mitophagy (149). This phenotype-stabilizing effect is highly relevant to sepsis, in which VSMC phenotypic dedifferentiation is a key driver of vasoplegia. In an adenine-induced rat model of aortic calcification, MitoQ inhibited VSMC oxidative stress and apoptosis via activation of the Keap1/Nrf2 signaling pathway, downregulating the activity of oxidative factors and upregulating the activity of antioxidant enzymes, thereby attenuating vascular calcification and preserving VSMC contractile potential (165). Notably, in endotoxin-induced cardiac dysfunction models, Supinski et al (166) demonstrated that MitoQ may protect against cardiac mitochondrial damage by inhibiting mtROS overproduction, and suppressing the activation of caspase-9 and caspase-3. These preclinical findings underscore the multifaceted role of MitoQ in regulating VSMCs phenotype, mitochondrial function, and survival, supporting its potential as a targeted therapy for sepsis-induced vasoplegia.

Calcium sensitizers are a novel class of potential therapeutic agents for sepsis-induced vasoplegia that increase VSMC contractility without increasing intracellular calcium levels, thereby avoiding the risk of calcium overload and arrhythmia linked to catecholamines and vasopressin analogues (153-156). Levosimendan, a prototypical agent initially designed as an inotrope, has shown promise for treating septic vasoplegia because of its combined effects on cardiac cells and VSMCs, although its clinical use is limited by context-dependent vasodilation (156).

At the molecular level, levosimendan exerts VSMC-specific effects via two core mechanisms: i) Calcium sensitization: It binds to the N-terminal domain of troponin C (TnC) in VSMCs with high affinity, increasing the sensitivity of TnC to [Ca²⁺]i and promoting actin-myosin cross-bridge formation, even at physiological [Ca²⁺]i levels, thereby restoring contractile function compromised by NO-mediated calcium desensitization in sepsis (164). ii) Mitochondrial protection: It activates ATP-sensitive potassium (K-ATP) channels in VSMC mitochondria, reducing mtROS production and inhibiting caspase-9/-3-dependent apoptosis, thus preserving VSMC viability and the contractile phenotype in the context of septic oxidative stress (165). Unlike catecholamines, which rely on intact adrenergic signaling (often desensitized in sepsis), the direct modulation of contractile proteins by levosimendan is effective in catecholamine-resistant states.

Clinically, the efficacy of levosimendan in sepsis-related cardiovascular dysfunction has been supported by accumulating evidence, although data specific to sepsis-induced vasoplegia remain nuanced, reflecting a dual effect with context-dependent benefits. A systematic review and meta-analysis of 12 RCTs comparing levosimendan with dobutamine in patients with sepsis-induced cardiomyopathy revealed that levosimendan markedly improved hemodynamic parameters, tissue perfusion and biomarkers of myocardial injury, while reducing in-hospital mortality and ICU length of stay (155). With respect to the treatment of septic shock-related vasoplegia, a prospective, double-blind RCT demonstrated that compared with a placebo, levosimendan (0.2 μg/kg/min) improved sublingual microcirculatory blood flow, reflected by a 32% increase in the microcirculatory flow indices of small and medium vessels, which suggested that enhanced regional tissue perfusion was mediated by VSMC function restoration (156). Despite these benefits, the vasodilatory properties of levosimendan pose a notable constraint to its use in sepsis-induced vasoplegia. The activation of Kir channels and inhibition of protein kinase C by the drug in systemic VSMCs can induce dose-dependent vasodilation, leading to transient hypotension, an adverse effect that may exacerbate hemodynamic instability in patients with severe vasoplegia requiring high-dose vasopressors (153). This paradox highlights the context-dependent nature of the effects of levosimendan; while its effects on calcium sensitization and mitochondrial protection are beneficial for VSMC dysfunction, its vasodilatory actions may be detrimental in the context of notable hypotension.

Calcium homeostasis is a pivotal regulator of VSMC contractile function, and its disruption represents a central mechanism underlying vascular hyporeactivity in sepsis-induced vasoplegia. Pharmacological agents targeting calcium-handling mechanisms have diverse modes of action, including receptor modulation and ion channel blockade, and interact within a complex regulatory network. Table V summarizes the emerging therapeutic agents targeting VSMCs in sepsis-induced vasoplegia, focusing on modulating calcium homeostasis and reducing NO production (154,167-174).

One critical node in calcium homeostasis regulation is the calcium-sensing receptor (CaSR), a key mediator of extracellular calcium sensing that is pathologically overactivated in sepsis. In a rat model of traumatic hemorrhagic shock, Calhex-231 inhibited mitochondrial fragmentation and preserved mitochondrial morphology (154). Mitochondria serve a dual role in calcium buffering and energy production, and their structural integrity is vital for maintaining calcium sequestration and release in VSMCs. Calhex-231 has the potential to improve vascular reactivity in sepsis-induced vasoplegia, but its systemic administration may trigger adverse off-target reactions, primarily because of nonselective binding to CaSR in diverse tissues and interference with tissue-specific calcium signaling. As demonstrated in a study on pregnant human myometrium, Calhex-231 partially inhibits oxytocin-induced uterine contractions (175).

A contrasting approach to restoring calcium-dependent VSMC function involves the targeting of ion channels, with K-ATP channels emerging as key therapeutic nodes. Glibenclamide, a nonselective K-ATP channel blocker, has been shown to restore vascular tone in animal models of septic shock by preventing potassium ion efflux-induced VSMC hyperpolarization (176). In an ex vivo model of hypoxic human endotoxemia, its anti-inflammatory effect was attributed to reduced depolarization of hypoxic monocytes, which in turn decreased calcium influx (167). However, its nonselectivity poses critical off-target risks: K-ATP channels are highly expressed in pancreatic β cells and immune cells, and systemic glibenclamide administration may cause hypoglycemia and suppress monocyte phagocytic activity (139), both of which worsen outcomes in patients with sepsis. Additionally, a randomized, double-blind, placebo-controlled crossover pilot study (177) revealed a critical translational gap: The lack of efficacy of glibenclamide in reducing the dosage of norepinephrine compared with that of a placebo in patients with septic shock may be attributed to individual patient variations, such as the severity of the condition and the etiology, leading to diverse responses to and efficacy of the drug.

Whereas glibenclamide targets calcium influx via voltage-gated calcium channel, another agent, chloro-N6-(3-iodobenzyl) adenosine-5'-N-methyluronamide (IB-MECA), targets intracellular calcium release, highlighting the diversity of calcium handling defects in sepsis (168). IB-MECA blocks the overactivation of ryanodine receptor (RyR)-mediated Ca²⁺ release, a pathological feature of hypoxic VSMCs and hemorrhagic shock-associated vascular hyporeactivity (168). Compared with control cells, hypoxic VSMCs exhibit a marked increase in [Ca²⁺]i in response to RyR activation by caffeine, which is associated with the loss of vascular responsiveness to norepinephrine. The stimulation of A3 adenosine receptor (A₃AR, a G protein-coupled receptor subtype regulating calcium signaling) activity by IB-MECA directly counteracts this excessive RyR activity, thereby normalizing intracellular calcium dynamics. However, A₃AR is also expressed by immune cells (178), and the nonselective activation by IB-MECA may modulate cytokine production while impairing T-cell proliferation, a trade-off that could exacerbate immunosuppression in late-stage sepsis.

Complementing agents that target calcium flux or release are therapies that increase calcium sensitivity, a mechanism that is particularly critical in advanced sepsis where calcium-handling machinery is severely disrupted. AVP and angiotensin II (Ang-II), which have been evaluated in rat models of hemorrhagic shock, increase calcium sensitivity in VSMCs (169,179). Unlike agents targeting calcium flux, they increase the affinity of myofilaments for calcium, a mechanism particularly relevant in sepsis, where calcium sensitivity is often impaired. These findings position them as potentially more effective in advanced sepsis, where calcium-handling machinery is severely disrupted. However, their clinical use is limited by nonselective vasoconstriction in noncritical vascular beds (such as renal and splanchnic circulation) and potential off-target immunomodulatory effects. For example, in early experimental hypotensive hyperdynamic sepsis, the intravenous infusion of Ang-II has been shown to decrease renal blood flow (180).

Excessive NO production by iNOS in VSMCs and other vascular cells is a major driver of vasodilation and vascular hyporeactivity in sepsis. This pathological process is mediated by NO-cGMP-protein kinase G signaling, which reduces VSMC calcium sensitivity and enhances intracellular calcium leakage. To counteract this, four key pharmacological agents have been developed, each of which target iNOS through distinct mechanisms and exhibit varying degrees of clinical translation potential. The present review has provided a summary for each of these agents, with a focus on how their mechanisms align with the pathophysiology of sepsis and where gaps persist in translating preclinical success to patient care.

Among iNOS-targeted therapies, selectivity for VSMC iNOS over eNOS is a critical criterion to avoid compromising endothelial barrier function, a common pitfall of nonspecific NOS inhibitors. Notably, 4-amino analogue of tetrahydrobiopterin (4-ABH4) addresses this need as a potent and selective inhibitor of SMC iNOS (170). Its mechanism relies on competing with BH4, a cofactor essential for iNOS catalytic activity, for binding to VSMC iNOS while sparing eNOS (due to the markedly greater affinity of eNOS for BH4). In an in vitro model of endotoxemia, this selectivity translated to tangible benefits: 4-ABH4 specifically inhibited VSMC iNOS activity, preventing excessive NO production without disrupting eNOS-mediated endothelial protection (170). As a result, it effectively blocked endotoxin-induced vascular hyporeactivity, making it a promising candidate for sepsis subtypes in which EC-VSMC crosstalk is preserved.

While 4-ABH4 directly targets iNOS catalytic activity, another agent, cyclosporin-A (CsA), takes an upstream approach by suppressing iNOS activation, highlighting the diversity of strategies for inhibiting iNOS. CsA reduces iNOS activation, decreases plasma nitrite/nitrate levels, increases blood pressure and markedly improves survival in rats with splanchnic artery occlusion shock (171). Despite these preclinical benefits, its clinical translation is hindered by two interconnected challenges: Nephrotoxicity, a condition that poses a marked risk in patients with sepsis and pre-existing renal impairment, and off-target immunosuppression. CsA induces distal renal tubular acidosis by inhibiting H pumps in the distal nephron (181). Furthermore, the primary mechanism through which CsA inhibits calcineurin-NFAT signaling is not restricted to VSMCs; it also suppresses T-cell proliferation and cytokine production, exacerbating the immunosuppressive phase of sepsis and increasing susceptibility to opportunistic infections (182).

Beyond direct or upstream iNOS inhibition, targeting the inflammatory signaling cascades that induce iNOS represents another viable strategy, one that aligns with the polymicrobial nature of clinical sepsis. Tubeimoside I (TBM), a triterpenoid saponin, reduces iNOS expression by inhibiting the TLR4-MyD88-NF-κB-iNOS signaling pathway (172). In a CLP-induced sepsis model, an intraperitoneal injection of 4 mg/kg TBM 1 h before surgery improved survival, ameliorated the MAP, and enhanced vascular responsiveness to norepinephrine and KCl in wild-type septic mice (172). Notably, iNOS gene knockout completely abrogated the protective effects of TBM, confirming that its therapeutic efficacy is mediated by reducing excessive NO production. Nevertheless, the translational applicability of TBM is hindered by nonspecific NF-κB inhibition. Off-target NF-κB inhibition in immune cells could attenuate the synthesis of proinflammatory cytokines during the hyperinflammatory stage, yet it might also impede macrophage phagocytosis.

Complementing single-mechanism iNOS inhibitors are agents that combine iNOS inhibition with adjunctive effects to address coexisting sepsis pathologies, such as oxidative stress, which amplifies VSMC dysfunction by modifying calcium-handling proteins (for example, RyRs). Andrographolide, evaluated in endotoxemia rats, restores vascular reactivity by downregulating iNOS in perivascular adipose tissue (173). U-74389G, which has been tested in septic models, combines iNOS inhibition with vascular protection (174); it reduces NO-mediated hyporeactivity via iNOS inhibition, reverses vascular failure and protects against endotoxin shock, addressing the broader pathological cascade of sepsis. However, andrographolide has poor bioavailability, and neither agent has validated biomarkers for iNOS activity or oxidative stress to enable precise patient stratification, hindering their clinical translation. Moreover, the nonselective tissue distribution of U-74389G increases the risk of off-target effects in organs with high metabolic activity, where it may disrupt normal NO signaling and exacerbate organ dysfunction.

The preceding assessment of calcium-modulating and iNOS-targeted strategies emphasizes the identification of promising VSMC-directed pathways for mitigating sepsis-induced vasoplegia in preclinical studies. However, the attainment of translational efficacy is consistently hindered by sepsis-specific obstacles in drug delivery and off-target effects. The following is a consolidation of the core challenges and actionable future directions to address them (25,34,70,150,178): i) Disrupted tissue distribution and bioavailability: Sepsis-induced increases in vascular permeability and organ dysfunction disrupt drug distribution, leading to reduced accumulation at VSMC sites and increased systemic exposure. ii) Lack of VSMC-specific targeting: Currently, agents demonstrate limited selectivity for VSMCs, resulting in off-target effects on immune cells and vital organs. iii) Formulation and dosing limitations: Challenges such as poor aqueous solubility, short half-lives and the need for parenteral administration present logistical barriers in critically ill patients with sepsis. Additionally, the lack of validated biomarkers hinders precise patient stratification, resulting in variable clinical responses. iv) Immunosuppressive paradox: A number of VSMC-targeted pathways serve vital roles in immune cell function. Nonspecific blockade of these pathways risks exacerbating sepsis-induced immunosuppression and increasing susceptibility to secondary infections, a notable unmet challenge in translating preclinical efficacy into clinical benefit.