Kidney ischaemia–reperfusion injury (IRI) is a common pathophysiological event underlying acute kidney injury (AKI) after shock, major surgery, renal transplantation, and some forms of cardiovascular disease. IRI occurs when renal blood flow is abruptly reduced (ischaemia), followed by restoration of perfusion (reperfusion). Paradoxically, reperfusion—essential for tissue survival—can worsen damage through oxidative stress, inflammatory cascades, endothelial dysfunction, and microvascular impairment. The result is tubular epithelial injury, loss of brush border function, apoptosis and necrosis in renal cells, and progressive impairment of glomerular filtration.
Mechanistically, ischaemia limits oxygen and adenosine triphosphate (ATP) production, disrupting ionic homeostasis. ATP depletion drives failure of Na+/K+-ATPase, cell swelling, and mitochondrial dysfunction. On reperfusion, sudden oxygen availability fuels reactive oxygen species (ROS) generation, including superoxide and hydroxyl radicals, overwhelming endogenous antioxidant systems. ROS trigger lipid peroxidation, DNA damage, and activation of stress-responsive signaling pathways such as NF-κB and MAP kinases. In parallel, reperfusion promotes endothelial activation and leukocyte recruitment. Adhesion molecules increase, neutrophils and monocytes infiltrate the interstitium, and cytokines such as TNF-α and IL-1β amplify inflammation. Complement activation and coagulation pathway dysregulation can further aggravate microvascular thrombosis and capillary rarefaction.
A key feature of IRI is that injury is not limited to direct cell death. It also includes dysregulated repair. After IRI, surviving tubular cells undergo maladaptive proliferation, impaired differentiation, and epithelial-to-mesenchymal transition (EMT)-like programs, contributing to fibrosis and chronic kidney disease risk. In animal models and in human pathology, IRI is associated with activation of inflammasomes, disturbances in autophagy, and altered tubular stem/progenitor cell dynamics. The degree of damage depends on ischaemia duration, perfusion conditions, baseline comorbidities, and genetic factors.
Current clinical management is largely supportive: optimizing hemodynamics, avoiding nephrotoxins, maintaining oxygen delivery, and using individualized fluid strategies. No universally effective pharmacotherapy exists that reliably prevents progression from AKI to long-term dysfunction. This therapeutic gap has intensified interest in regenerative and immunomodulatory cell-based approaches, particularly mesenchymal stromal cells (MSCs).
MSCs are multipotent stromal cells obtained from adult tissues (for example, bone marrow, adipose tissue, umbilical cord, or other sources). While MSCs can exhibit differentiation potential under certain conditions, their most clinically relevant effects in injury models are increasingly understood as paracrine. MSCs secrete a complex milieu of bioactive factors—growth factors, anti-inflammatory cytokines, and extracellular vesicles—that can modulate the injured microenvironment. In kidney IRI, MSC-derived signals may reduce ROS burden, attenuate leukocyte infiltration, and promote tubular cell survival pathways. They can influence macrophage polarization toward a more reparative phenotype and dampen pro-inflammatory cytokine networks.
Another therapeutic mechanism involves MSC effects on endothelial integrity and microcirculatory function. By improving nitric oxide bioavailability and reducing oxidative endothelial stress, MSCs may restore capillary perfusion and limit hypoxia-reperfusion cycles. MSCs also appear to influence tubular regeneration by enhancing proliferation and migration of epithelial cells and by shaping extracellular matrix remodeling to reduce fibrotic signaling.
Importantly, MSC efficacy may vary by tissue origin. Cells from different donor compartments can differ in proliferation kinetics, secretome composition, immunogenicity, and susceptibility to stress-induced senescence. In a kidney IRI mouse model, comparing MSCs derived from distinct tissue sources allows investigators to determine which source provides the most favorable balance of anti-inflammatory, antioxidative, and pro-regenerative effects. Typical preclinical endpoints include serum creatinine and blood urea nitrogen, histological injury scoring (tubular necrosis, cast formation), apoptosis markers, oxidative stress indicators, and inflammatory cell quantification.
Evaluating MSCs in IRI models also addresses translational constraints. For example, heterogeneity in MSC preparation, dosing, timing of administration (prophylactic vs rescue after injury), and route of delivery (intravenous vs local administration) can change outcomes. Preclinical studies often test early administration windows because inflammatory amplification is time-sensitive. However, even with improvements, complete functional normalization may not occur, particularly when injury is severe.
Beyond cells themselves, the downstream biology is crucial. Effective interventions in IRI typically converge on core nodes: reducing ROS, limiting inflammation, preserving endothelial function, and supporting orderly tubular repair. These targets align with mechanistic expectations: if ROS and inflammatory recruitment are suppressed, mitochondrial function and cell survival improve; if microvascular perfusion is restored, oxygen gradients normalize; if regeneration signals dominate, the transition from acute injury to maladaptive fibrosis is less likely.
Therefore, studies assessing human MSCs from different tissue origins in kidney ischaemia–reperfusion injury are valuable for identifying more effective cell sources and refining mechanistic hypotheses. By linking cellular origin to specific therapeutic pathways and functional outcomes, such research can guide future translational development of MSC-based therapies aimed at reducing AKI burden and preventing progression to chronic kidney disease.
Source: @adipose_papers
Adipose Papers: Assessing the efficacy of human mesenchymal stromal cells of different tissue origins in a mouse model of kidney ischaemia reperfusion injury. #breaking
— @adipose_papers May 1, 2026
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