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Journal of Hepatology Oct 2019Hepatic ischemia-reperfusion injury (IRI) is a major complication of hemorrhagic shock, liver resection and transplantation. YAP, a key downstream effector of the Hippo...
BACKGROUND & AIMS
Hepatic ischemia-reperfusion injury (IRI) is a major complication of hemorrhagic shock, liver resection and transplantation. YAP, a key downstream effector of the Hippo pathway, is essential for determining cell fate and maintaining homeostasis in the liver. We aimed to elucidate its role in IRI.
METHODS
The role of YAP/Hippo signaling was systematically studied in biopsy specimens from 60 patients after orthotopic liver transplantation (OLT), and in a mouse model of liver warm IRI. Human biopsy specimens were collected after 2-10 h of cold storage and 3 h post-reperfusion, before being screened by western blot. In the mouse model, the role of YAP was probed by activating or inhibiting YAP prior to ischemia-reperfusion.
RESULTS
In human biopsies, high post-OLT YAP expression was correlated with well-preserved histology and improved hepatocellular function at postoperative day 1-7. In mice, the ischemia insult (90 min) triggered intrinsic hepatic YAP expression, which peaked at 1-6 h of reperfusion. Activation of YAP protected the liver against IR-stress, by promoting regenerative and anti-oxidative gene induction, while diminishing oxidative stress, necrosis/apoptosis and the innate inflammatory response. Inhibition of YAP aggravated hepatic IRI and suppressed repair/anti-oxidative genes. In mouse hepatocyte cultures, activating YAP prevented hypoxia-reoxygenation induced stress. Interestingly, YAP activation suppressed extracellular matrix synthesis and diminished hepatic stellate cell (HSC) activation, whereas YAP inhibition significantly delayed hepatic repair, potentiated HSC activation, and enhanced liver fibrosis at 7 days post-IRI. Notably, YAP activation failed to protect Nrf2-deficient livers against IR-mediated damage, leading to extensive fibrosis.
CONCLUSION
Our novel findings document the crucial role of YAP in IR-mediated hepatocellular damage and liver fibrogenesis, providing evidence of a potential therapeutic target for the management of sterile liver inflammation in transplant recipients.
LAY SUMMARY
In the clinical arm, graft YAP expression negatively correlated with liver function and tissue damage after human liver transplantation. YAP activation attenuated hepatocellular oxidative stress and diminished the innate immune response in mouse livers following ischemia-reperfusion injury. In the mouse model, YAP inhibited hepatic stellate cell activation, and abolished injury-mediated fibrogenesis up to 7 days after the ischemic insult.
Topics: Animals; Apoptosis; Cell Cycle Proteins; Cells, Cultured; Disease Models, Animal; Hippo Signaling Pathway; Humans; Inflammation; Liver; Liver Diseases; Liver Transplantation; Oxidative Stress; Protein Serine-Threonine Kinases; Reperfusion Injury; Shock, Hemorrhagic; Signal Transduction; Transcription Factors; Warm Ischemia
PubMed: 31201834
DOI: 10.1016/j.jhep.2019.05.029 -
Nature Aug 2022After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death. Yet with...
After cessation of blood flow or similar ischaemic exposures, deleterious molecular cascades commence in mammalian cells, eventually leading to their death. Yet with targeted interventions, these processes can be mitigated or reversed, even minutes or hours post mortem, as also reported in the isolated porcine brain using BrainEx technology. To date, translating single-organ interventions to intact, whole-body applications remains hampered by circulatory and multisystem physiological challenges. Here we describe OrganEx, an adaptation of the BrainEx extracorporeal pulsatile-perfusion system and cytoprotective perfusate for porcine whole-body settings. After 1 h of warm ischaemia, OrganEx application preserved tissue integrity, decreased cell death and restored selected molecular and cellular processes across multiple vital organs. Commensurately, single-nucleus transcriptomic analysis revealed organ- and cell-type-specific gene expression patterns that are reflective of specific molecular and cellular repair processes. Our analysis comprises a comprehensive resource of cell-type-specific changes during defined ischaemic intervals and perfusion interventions spanning multiple organs, and it reveals an underappreciated potential for cellular recovery after prolonged whole-body warm ischaemia in a large mammal.
Topics: Animals; Cell Death; Cell Survival; Cytoprotection; Gene Expression Profiling; Ischemia; Organ Specificity; Perfusion; Swine; Warm Ischemia
PubMed: 35922506
DOI: 10.1038/s41586-022-05016-1 -
Seminars in Nephrology Nov 2019Although kidney oxygen tensions are heterogenous, and mostly below renal vein level, the nephron is highly dependent on aerobic metabolism for active tubular transport.... (Review)
Review
Although kidney oxygen tensions are heterogenous, and mostly below renal vein level, the nephron is highly dependent on aerobic metabolism for active tubular transport. This renders the kidney particularly susceptible to hypoxia, which is considered a main characteristic and driver of acute and chronic kidney injury, albeit the evidence supporting this assumption is not entirely conclusive. Kidney transplants are exposed to several conditions that may interfere with the balance between oxygen supply and consumption, and enhance hypoxia and hypoxic injury. These include conditions leading to and resulting from brain death of kidney donors, ischemia and reperfusion during organ donation, storage and transplantation, postoperative vascular complications, vasoconstriction induced by immunosuppression, and impaired perfusion resulting from interstitial edema, inflammation, and fibrosis. Acute graft injury, the immediate consequence of hypoxia and reperfusion, results in delayed graft function and increased risk of chronic graft failure. Although current strategies to alleviate hypoxic/ischemic graft injury focus on limiting injury (eg, by reducing cold and warm ischemia times), experimental evidence suggests that preconditioning through local or remote ischemia, or activation of the hypoxia-inducible factor pathway, can decrease hypoxic injury. In combination with ex vivo machine perfusion such approaches hold significant promise for improving transplantation outcomes.
Topics: Animals; Humans; Ischemic Preconditioning; Kidney; Kidney Transplantation; Oxygen; Oxygen Consumption; Reperfusion Injury
PubMed: 31836038
DOI: 10.1016/j.semnephrol.2019.10.005 -
The Journal of Hand Surgery Oct 2021A persistent challenge that has limited access and delivery of digit replantation surgery is timing, as ischemia time has traditionally been considered an important... (Review)
Review
A persistent challenge that has limited access and delivery of digit replantation surgery is timing, as ischemia time has traditionally been considered an important determinant of success. However, reports that the viability of amputated digits decreases after 6 hours of warm ischemia and 12 hours of cold ischemia are largely anecdotal. This review evaluates the quality and generalizability of available evidence regarding ischemia times after digit amputation and reported outcomes of "delayed" replantation. We identify substantial limitations in the literature supporting ischemia time cutoffs and recent evidence supporting the feasibility of delayed digit replantation. The current treatment approach for amputation injuries often necessitates transfers or overnight emergency procedures that increase costs and limit availability of digit replantation nationwide. Evidence-based changes to digit replantation protocols could lead to broader availability of this service, as well as improved care quality.
Topics: Amputation, Surgical; Amputation, Traumatic; Finger Injuries; Fingers; Humans; Replantation
PubMed: 34376294
DOI: 10.1016/j.jhsa.2021.07.007 -
Current Opinion in Organ Transplantation Jun 2020Increasing number of patients with end-stage heart failure and those with improved survivorship from selective utilization of implantable mechanical circulatory support... (Review)
Review
PURPOSE OF REVIEW
Increasing number of patients with end-stage heart failure and those with improved survivorship from selective utilization of implantable mechanical circulatory support devices have added further burden and complexity to the transplant waitlist and on the rate-limiting availability of donor hearts from the standard pathway of donation after brain death. Unlike this conventional route, the increasing clinical use of donation after circulatory death (DCD) donor hearts necessitates a closer understanding of the logistics involved in the DCD process as well as of the risks associated with the unique pathophysiological consequences in this setting.
RECENT FINDINGS
Notwithstanding a higher incidence of delayed graft function, the clinical utilization of DCD hearts for cardiac transplantation over the past five years has demonstrated this to be a well-tolerated and strategic alternative with excellent medium-term clinical outcomes.
SUMMARY
The uptake of DCD heart transplantation remains selective and currently confined to Australia, the United Kingdom, Belgium, and more recently the USA. A more significant adoption will only come about through: a concerted effort to resolve the ethical and clinical controversies; a better understanding of postconditioning strategies; continued resolve to reduce the obligatory period of warm ischemia; and from better extracorporeal platforms that permit functional viability assessment of the DCD donor heart.
Topics: Brain Death; Female; Heart Transplantation; Humans; Male; Middle Aged; Tissue Donors; Tissue and Organ Procurement
PubMed: 32374575
DOI: 10.1097/MOT.0000000000000758 -
Canadian Journal of Kidney Health and... 2023Prolonged warm ischemia time (WIT) and cold ischemia time (CIT) are independently associated with post-transplant graft failure; their combined impact has not been...
BACKGROUND
Prolonged warm ischemia time (WIT) and cold ischemia time (CIT) are independently associated with post-transplant graft failure; their combined impact has not been previously studied. We explored the effect of combined WIT/CIT on all-cause graft failure following kidney transplantation.
METHODS
The Scientific Registry of Transplant Recipients was used to identify kidney transplant recipients from January 2000 to March 2015 (after which WIT was no longer separately reported), and patients were followed until September 2017. A combined WIT/CIT variable (excluding extreme values) was separately derived for live and deceased donor recipients using cubic splines; for live donor recipients, the reference group was WIT 10 to <23 minutes and CIT >0 to <0.42 hours, and for deceased donor recipients the WIT was 10 to <25 minutes and CIT 1 to <7.75 hours. The adjusted association between combined WIT/CIT and all-cause graft failure (including death) was analyzed using Cox regression. Secondary outcomes included delayed graft function (DGF).
RESULTS
A total of 137 125 recipients were included. For live donor recipients, patients with prolonged WIT/CIT (60 to ≤120 minutes/3.04 to ≤24 hours) had the highest adjusted hazard ratio (HR) for graft failure (HR = 1.61, 95% confidence interval [CI] = 1.14-2.29 relative to the reference group). For deceased donor recipients, a WIT/CIT of 63 to ≤120 minutes/28 to ≤48 hours was associated with an adjusted HR of 1.35 (95% CI = 1.16-1.58). Prolonged WIT/CIT was also associated with DGF for both groups although the impact was more driven by CIT.
CONCLUSIONS
Combined WIT/CIT is associated with graft loss following transplantation. Acknowledging that these are separate variables with different determinants, we emphasize the importance of capturing WIT and CIT independently. Furthermore, efforts to reduce WIT and CIT should be prioritized.
PubMed: 37333478
DOI: 10.1177/20543581231178960 -
Sulforaphane Is Protective against Warm Ischemia/Reperfusion Injury and Partial Hepatectomy in Rats.International Journal of Molecular... Jan 2024Sulforaphane (SFN) has various beneficial effects on organ metabolism. However, whether SFN affects inflammatory mediators induced by warm hepatic ischemia/reperfusion...
Sulforaphane (SFN) has various beneficial effects on organ metabolism. However, whether SFN affects inflammatory mediators induced by warm hepatic ischemia/reperfusion injury (HIRI) is unclear. To investigate the hepatoprotective effects of SFN using an in vivo model of HIRI and partial hepatectomy (HIRI + PH), rats were subjected to 15 min of hepatic ischemia with blood inflow occlusion, followed by 70% hepatectomy and release of the inflow occlusion. SFN (5 mg/kg) or saline was randomly injected intraperitoneally 1 and 24 h before ischemia. Alternatively, ischemia was prolonged for 30 min to evaluate the effect on mortality. The influence of SFN on the associated signaling pathways was analyzed using the interleukin 1β (IL-1β)-treated primary cultured rat hepatocytes. In the HIRI + PH-treated rats, SFN reduced serum liver enzyme activities and the frequency of pathological liver injury, such as apoptosis and neutrophil infiltration. SFN suppressed tumor necrosis factor-alpha (TNF-α) mRNA expression and inhibited nuclear factor-kappa B (NF-κB) activation by HIRI + PH. Mortality was significantly reduced by SFN. In IL-1β-treated hepatocytes, SFN suppressed the expression of inflammatory cytokines and NF-κB activation. Taken together, SFN may have hepatoprotective effects in HIRI + PH in part by inhibiting the induction of inflammatory mediators, such as TNF-α, via the suppression of NF-κB in hepatocytes.
Topics: Animals; Rats; Hepatectomy; NF-kappa B; Tumor Necrosis Factor-alpha; Warm Ischemia; Reperfusion Injury; Inflammation Mediators; Interleukin-1beta; Ischemia; Sulfoxides; Isothiocyanates
PubMed: 38203749
DOI: 10.3390/ijms25010579 -
Transplantation Reviews (Orlando, Fla.) Oct 2019Ischemia has been a persistent and largely unavoidable element in solid organ transplantation, contributing to graft deterioration and adverse post-transplant outcomes.... (Review)
Review
Ischemia has been a persistent and largely unavoidable element in solid organ transplantation, contributing to graft deterioration and adverse post-transplant outcomes. In liver transplantation, where available organs arise with greater frequency from marginal donors (i.e., ones that are older, obese, and/or declared dead following cardiac arrest through the donation after circulatory death process), there is increasing interest using dynamic perfusion strategies to limit, assess, and even reverse the adverse effects of ischemia in these grafts. Normothermic perfusion, in particular, is used to restore the flow of oxygen and other metabolic substrates at physiological temperatures. It may be used in liver transplantation both in situ following cardiac arrest in donation after circulatory death donors or during part or all of the ex situ preservation phase. This review article addresses issues relevant to use of normothermic perfusion strategies in liver transplantation, including technical and logistical aspects associated with establishing and maintaining normothermic perfusion in its different forms and clinical outcomes that have been reported to date.
Topics: Female; Graft Rejection; Graft Survival; Humans; Liver Transplantation; Male; Organ Preservation; Perfusion; Sensitivity and Specificity; Tissue and Organ Procurement; Warm Ischemia
PubMed: 31239189
DOI: 10.1016/j.trre.2019.06.001 -
Indian Journal of Urology : IJU :... 2020Since its introduction, robotic partial nephrectomy (RPN) has become increasingly popular, in part as a result of several advances in technique. The purpose of this... (Review)
Review
INTRODUCTION
Since its introduction, robotic partial nephrectomy (RPN) has become increasingly popular, in part as a result of several advances in technique. The purpose of this paper is to review these techniques as well as the perioperative, functional, and oncologic outcomes after RPN and compare these outcomes to those after laparoscopic partial nephrectomy (LPN) and open partial nephrectomy (OPN).
METHODS
A literature review was performed to identify papers and meta-analyses that compared outcomes after RPN to OPN or LPN. All meta-analyses were included in this review.
RESULTS
Technical advances that have contributed to improved outcomes after RPN include the first-assistant sparing technique, the sliding clip technique, early unclamping, and selective arterial clamping. All five meta-analyses that compared LPN to RPN found that RPN was associated with a shorter warm ischemia time (WIT), but that there were no differences in estimated blood loss (EBL) or operative times. Those meta-analyses that compared intraoperative and postoperative complications, conversion to open or radical nephrectomy, length of stay (LOS), and postoperative estimated glomerular filtration rate (eGFR) either found no difference or favored RPN. Four meta-analyses compared RPN to OPN. All four found that EBL, LOS, and postoperative complications favor RPN. There were no significant differences in intraoperative complications, conversion to radical nephrectomy, or positive surgical margin rates. One meta-analysis found that eGFR was better after RPN. Operative time and WIT generally favored OPN.
CONCLUSIONS
Several techniques have been described to improve outcomes after RPN. We believe that the literature shows that RPN is as good if not better than both LPN and OPN and has become the preferred surgical approach.
PubMed: 31983821
DOI: 10.4103/iju.IJU_174_19 -
Journal of Visualized Experiments : JoVE Jun 2023Porcine models of liver ex situ normothermic machine perfusion (NMP) are increasingly being used in transplant research. Contrary to rodents, porcine livers are...
Porcine models of liver ex situ normothermic machine perfusion (NMP) are increasingly being used in transplant research. Contrary to rodents, porcine livers are anatomically and physiologically close to humans, with similar organ size and bile composition. NMP preserves the liver graft at near-to-physiological conditions by recirculating a warm, oxygenated, and nutrient-enriched red blood cell-based perfusate through the liver vasculature. NMP can be used to study ischemia-reperfusion injury, preserve a liver ex situ before transplantation, assess the liver's function prior to implantation, and provide a platform for organ repair and regeneration. Alternatively, NMP with a whole blood-based perfusate can be used to mimic transplantation. Nevertheless, this model is labor-intensive, technically challenging, and carries a high financial cost. In this porcine NMP model, we use warm ischemic damaged livers (corresponding to donation after circulatory death). First, general anesthesia with mechanical ventilation is initiated, followed by the induction of warm ischemia by clamping the thoracic aorta for 60 min. Cannulas inserted in the abdominal aorta and portal vein allow flush-out of the liver with cold preservation solution. The flushed-out blood is washed with a cell saver to obtain concentrated red blood cells. Following hepatectomy, cannulas are inserted in the portal vein, hepatic artery, and infra-hepatic vena cava and connected to a closed perfusion circuit primed with a plasma expander and red blood cells. A hollow fiber oxygenator is included in the circuit and coupled to a heat exchanger to maintain a pO2 of 70-100 mmHg at 38 °C. NMP is achieved by a continuous flow directly through the artery and via a venous reservoir through the portal vein. Flows, pressures, and blood gas values are continuously monitored. To evaluate the liver injury, perfusate and tissue are sampled at predefined time points; bile is collected via a cannula in the common bile duct.
Topics: Humans; Swine; Animals; Organ Preservation; Liver; Liver Transplantation; Perfusion; Warm Ischemia
PubMed: 37358290
DOI: 10.3791/65336