Project description:Ischemia-reperfusion injury (IRI) is a major cause of morbidity and mortality following conventional lung transplantation and warm ischemia may limit success of transplanting lungs from non-heart-beating donors. We sought to determine alterations in gene expression in rat lung tissue subjected to warm ischemia in vivo followed by reperfusion. Keywords: time course
Project description:Ischemia reperfusion (I/R) promotes the severity of cardiomyocyte injur. Our study provides a potential new therapeutic strategy to alleviate ischemia reperfusion injury.
Project description:Primary graft dysfunction (PGD), which is caused primarily by ischemia–reperfusion injury (IRI), is a major obstacle in lung transplantation. Here, we developed an orthotopic, single-lung transplant pig model to simulate prolonged cold IRI. After 24 hours of cold ischemia and 8 hours of warm reperfusion, the transplanted lung exhibited severe allograft injury. Subsequent single-cell RNA sequencing (scRNA-seq) revealed significant changes in alveolar macrophages after IRI, with prominently enriched ferroptosis pathways. Transmission electron microscopy (TEM) confirmed characteristic ferroptosis changes in lung macrophages, and decreased GPX4 expression in macrophages indicated increased susceptibility to ferroptosis. Overall, our pig orthotopic left lung transplant model effectively simulates IRI after transplantation, which offers a valuable platform for more detailed investigations of early reperfusion injury to pulmonary grafts. Moreover, we preliminarily demonstrated the importance of macrophage ferroptosis in IRI, suggesting that inhibiting macrophage ferroptosis may be a promising therapeutic strategy for lung IRI.
Project description:Ischemia reperfusion (IR) is an unavoidable step of organ transplantation. IR-induced injury constrains the number of donor lungs used for transplant. Here we performed longitudinal single-cell RNA sequencing (scRNA-seq) from human lungs of six individuals who underwent lung transplantation. Lung biopsies were collected after cold preservation and 2-hour reperfusion for each individual resulting in the profiling of 108,613 cells in total.
Project description:BACKGROUND: Hypovolemia is common in lung donors before or after brain death. However, its impact on primary graft function (PGD) remains obscure. METHODS: A clinically relevant two-hit model of PGD was established by integrating hypovolemic shock (HS) and cold ischemia-reperfusion in a mouse model of orthotopic lung transplantation (LTx) from C57BL/6 to Balb/c. At -48 hours, HS was induced to donor by withdrawal of blood from femoral artery and keeping the mean arterial pressure at 15±5 mmHg for 4 h. At -24 hours, donor lungs were retrieved from mice with or without HS and stored at 0ºC until transplantation. CD11b-DTR mice were used as donor and treated with Diphtheria Toxin (DT) to deplete graft-infiltrating macrophages. RESULTS: HS mainly caused macrophage-predominant infiltration around pulmonary artery injury systemic inflammatory response, but little impairment of lung function even if in combination with cold ischemia-reperfusion. Transcriptional profiling showed HS pretreatment increased pulmonary damage and alveolar remodeling but ameliorated inflammatory infiltration when compared to one-hit model of 12 hours cold ischemia-reperfusion injury. The allografts with donor DT-treatment one day ahead of HS showed injury and dysfunction at donation and worsened further at 24 hours reperfusion, whereas the allografts with recipient DT-treatment immediately after transplantation showed similar function and histology to the control treated with saline. CONCLUSION: Donor hypovolemia causes pulmonary artery injury and infiltration but has little impact on allograft function, even in combination with 24 h cold ischemia. Graft-infiltrating macrophages are critical in protecting graft from HS-induced injury and cold ischemia-reperfusion injury.
Project description:Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell’s condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ~0.007 mM could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.
Project description:Ischemia-reperfusion (IR) in lung transplantation activates genes in inate inflammation and cell death. Multiple programmed cell death (PCD) pathways have been proposed to be involved in IR injury in lung transplantation. However, the status of these pathways in human lung transplants remain unknown. Study on the genes related PCD and their relationship with inflammation and signaling pathways in human lung transplants during IR.
Project description:This study aims to determine changes in transcriptomic profiles in lymphatic vessels in response to ischemia-reperfusion injury, which mimics conditions in liver transplantation. This experiment will determine the potential role of lymphatic vessels during the ischemia-reperfusion injury in the liver.
Project description:Our understanding on mechanisms of ischemia-reperfusion induced lung injury during lung preservation and transplantation is based on clinical observations and animal studies. Herein, we used cell and systems biology approaches to explore these mechanisms at transcriptomics levels, especially by focusing on the differences between human lung endothelial and epithelial cells, which are crucial for maintaining essential lung structure and function. Human pulmonary microvascular endothelial cells and human lung epithelial cells were cultured to confluent, subjected to different cold ischemic time (CIT) to mimic static cold storage with preservation solution, and then subjected to warm reperfusion with serum containing culture medium to similar lung transplantation. Cell morphology, viability and transcriptomic profiles were studied. Ischemia-reperfusion induced a CIT time-dependent cell death, which was associated with dramatic changes in gene expression. Under normal control conditions, endothelial cells showed gene clusters enriched in vascular process and inflammation, while epithelial cells showed gene clusters enriched in protein biosynthesis and metabolism. CIT 6 h alone or after reperfusion had little effects on these phenotypic characteristics. After CIT 18 h, protein biosynthesis related gene clusters disappeared in epithelial cells; after reperfusion, metabolism-related gene cluster in epithelial cells and multiple gene clusters in the endothelial cells also disappeared. Human pulmonary endothelial and epithelial cells have distinct phenotypic transcriptomic signatures. Severe cellular injury reduces these gene expression signatures in a cell type dependent manner. Therapeutics that preserve these transcriptomic signatures may represent new treatment to prevent acute lung injury during lung transplantation.