Hypothermic machine perfusion with metformin-University of Wisconsin solution for ex vivo preservation of standard and marginal liver grafts in a rat model

AIM To compare the effect of University of Wisconsin(UW) solution with or without metformin, an AMP-activated protein kinase(AMPK) activator, for preserving standard and marginal liver grafts of young and aged rats ex vivo by hypothermic machine perfusion(HMP).METHODS Eighteen young(4 mo old) and 18 aged(17 mo old)healthy male SD rats were selected and randomly divided into three groups: control group, UW solution perfusion group(UWP), and UW solution with metformin perfusion group(MUWP). Aspartate aminotransferase(AST), alanine aminotransferase(ALT), lactate dehydrogenase(LDH), interleukin-18(IL-18), and tumor necrosis factor-alpha(TNF-α) in the perfused liquid were tested. The expression levels of AMPK and endothelial nitric oxide synthase(e NOS) in liver sinusoidal endothelial cells were also examined.Additionally, microscopic evaluation of the harvested perfused liver tissue samples was done. RESULTS AST, ALT, LDH, IL-18 and TNF-α levels in the young and aged liver-perfused liquid were, respectively,significantly lower in the MUWP group than in the UWP group(P < 0.05), but no significant differences were found between the young and aged MUWP groups.Metformin increased the expression of AMPK and e NOS protein levels, and promoted the extracellular release of nitric oxide through activation of the AMPK-e NOS mediated pathway. Histological examination revealed that in the MUWP group, the extent of liver cells and tissue damage was significantly reduced compared with the UWP group.CONCLUSION The addition of metformin to the UW preservative solution for ex vivo HMP can reduce rat liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats.

Using old liver grafts for liver transplantation: Where are the limits?

The scarcity of ideal liver grafts for orthotopic liver transplantation (OLT) has led transplant teams to investigate other sources of grafts in order to augment the donor liver pool. One way to get more liver grafts is to use marginal donors, a not well-defined group which includes mainly donors &#x0003e; 60 years, donors with hypernatremia or macrosteatosis &#x0003e; 30%, donors with hepatitis C virus or hepatitis B virus positive serologies, cold ischemia time &#x0003e; 12 h, non-heart-beating donors, and grafts from split-livers or living-related donations. Perhaps the most practical and frequent measure to increase the liver pool, and thus to reduce waiting list mortality, is to use older livers. In the past years the results of OLT with old livers have improved, mainly due to better selection and maintenance of donors, improvements in surgical techniques in donors and recipients, and intra- and post-OLT management. At the present time, sexagenarian livers are generally accepted, but there still exists some controversy regarding the use of septuagenarian and octogenarian liver grafts. The aim of this paper is to briefly review the aging process of the liver and reported experiences using old livers for OLT. Fundamentally, the series of septuagenarian and octogenarian livers will be addressed to see if there is a limit to using these aged grafts.

Reuse of liver grafts following the brain death of the initial recipient

AIM: To determine if there is a reasonable prospect of success of a re-use liver transplantation.METHODS: We systematically searched for reports of liver graft re-use using electronic searches of PubMed and Web of Knowledge. We performed hand searches of references lists of articles reporting re-use of grafts.RESULTS: A systematic review of the literature reveals 28 liver transplantations using previously transplanted grafts. First and second recipients ranged in age from 4 to 72 years and 29 to 62 years respectively. Liver disease in the first recipient was varied including 5(18%) patients with fulminant liver failure who died subsequently of cerebral edema. The second transplanta-tion was performed after a median interval of 5 d(one day-13 years). Viral hepatitis was present in 3(11%) of the initial recipients and in 8(29%) of final recipients. Hepatocellular carcinoma was present in 6(21%) of the final recipients. Early survival after the final transplantation was 93%, whereas long-term survival was 78% with a mean follow-up of 23.3(3-120) mo.CONCLUSION: Outcomes of transplantation using previously transplanted grafts in this select population are similar to those seen with conventional grafts.

Lesson learnt from 60 years of liver transplantation:Advancements,challenges,and future directions

Over the past six decades,liver transplantation(LT)has evolved from an experimental procedure into a standardized and life-saving intervention,reshaping the landscape of organ transplantation.Driven by pioneering breakthroughs,technological advancements,and a deepened understanding of immunology,LT has seen remarkable progress.Some of the most notable breakthroughs in the field include advances in immunosuppression,a revised model for end-stage liver disease,and artificial intelligence(AI)-integrated imaging modalities serving diagnostic and therapeutic roles in LT,paired with ever-evolving technological advances.Additionally,the refinement of transplantation procedures,resulting in the introduction of alternative transplantation methods,such as living donor LT,split LT,and the use of marginal grafts,has addressed the challenge of organ shortage.Moreover,precision medicine,guiding personalized immunosuppressive strategies,has significantly improved patient and graft survival rates while addressing emergent issues,such as short-term complications and early allograft dysfunction,leading to a more refined strategy and enhanced postoperative recovery.Looking ahead,ongoing research explores regenerative medicine,diagnostic tools,and AI to optimize organ allocation and posttransplantation car.In summary,the past six decades have marked a transformative journey in LT with a commitment to advancing science,medicine,and patient-centered care,offering hope and extending life to individuals worldwide.

Large-for-size syndrome prophylaxis in infant liver recipients with low body mass

Transplantation of the left lateral section(LLS)of the liver is now an established practice for treating advanced diffuse and unresectable focal liver diseases in children,with variants of the LLS primarily used in infants.However,the surgical challenge of matching the size of an adult donor's graft to the volume of a child's abdomen remains significant.This review explores historical developments,various approaches to measuring the required functional liver mass,and techniques to prevent complications associated with large-for-size grafts in infants.

Outcomes of right-lobe and left-lobe living-donor liver transplantations using small-for-size grafts

AIM To analyze the outcomes of living-donor liver transplantation(LDLT) using left-lobe(LL) or right-lobe(RL) small-for-size(SFS) grafts.METHODS Prospectively collected data of adult patients who underwent LDLT at our hospital in the period from January 2003 to December 2013 were reviewed. The patients were divided into the RL-LDLT group and the LL-LDLT group. The two groups were compared in terms of short-and long-term outcomes, including incidence of postoperative complication, graft function, graft survival, and patient survival. A SFS graft was defined as a graft with a ratio of graft weight(GW) to recipient standard liver volume(RSLV)(GW/RSLV) of < 50%. The Urata formula was used to estimate RSLV.RESULTS Totally 218 patients were included for analysis, with 199 patients in the RL-LDLT group and 19 patients in the LL-LDLT group. The two groups were similar in terms of age(median, 53 years in the RL-LDLT group and 52 years in the LL-LDLT group, P = 0.997) but had significantly different ratios of men to women(165:34 in the RL-LDLT group and 8:11 in the LL-LDLT group, P < 0.0001). The two groups were also significantly different in GW(P < 0.0001), GW/RSLV(P < 0.0001), and graft cold ischemic time(P = 0.007). When it comes to postoperative complication, the groups were comparable(P = 0.105). Five patients died in hospital,4(2%) in the RL-LDLT group and 1(5.3%) in the LLLDLT group(P = 0.918). There were 38 graft losses, 33(16.6%) in the RL-LDLT group and 5(26.3%) in the LL-LDLT group(P = 0.452). The 5-year graft survival rate was significantly better in the RL-LDLT group(95.2% vs 89.5%, P = 0.049). The two groups had similar 5-year patient survival rates(RL-LDLT: 86.8%, LL-LDLT: 89.5%, P = 0.476).CONCLUSION The use of SFS graft in LDLT requires careful tailormade surgical planning and meticulous operation. LLLDLT can be a good alternative to RL-LDLT with similar recipient outcomes but a lower donor risk. Further research into different patient conditions is needed in order to validate the use of LL graft.

Volumetric assessment of hepatic grafts using a light detection and ranging system for 3D scanning:Preliminary data

BACKGROUND Liver transplantation has evolved into a safe life-saving operation and remains the golden standard in the treatment of end stage liver disease.The main limiting factor in the application of liver transplantation is graft shortage.Many strategies have been developed in order to alleviate graft shortage,such as living donor partial liver transplantation and split liver transplantation for adult and pediatric patients.In these strategies,liver volume assessment is of paramount importance,as size mismatch can have severe consequences in the success of liver transplantation.AIM To evaluate the safety,feasibility,and accuracy of light detection and ranging(LIDAR)3D photography in the prediction of whole liver graft volume and mass.METHODS Seven liver grafts procured for orthotopic liver transplantation from brain deceased donors were prospectively measured with an LIDAR handheld camera and their mass was calculated and compared to their actual weight.RESULTS The mean error of all measurements was 17.03 g(range 3.56-59.33 g).Statistical analysis of the data yielded a Pearson correlation coefficient index of 0.9968,indicating a strong correlation between the values and a Student’s t-test P value of 0.26.Mean accuracy of the measurements was calculated at 97.88%.CONCLUSION Our preliminary data indicate that LIDAR scanning of liver grafts is a safe,cost-effective,and feasible method of ex vivo determination of whole liver volume and mass.More data are needed to determine the precision and accuracy of this method.

How to protect liver graft with nitric oxide

Organ preservation and ischemia reperfusion injury associated with liver transplantation play an important role in the induction of graft injury. One of the earliest events associated with the reperfusion injury is endothelial cell dysfunction. It is generally accepted that endothelial nitric oxide synthase （e-NOS） is cell-pro- tective by mediating vasodilatation, whereas inducible nitric oxide synthase mediates liver graft injury after transplantation. We conducted a critical review of the literature evaluating the potential applications of regulating and promoting e-NOS activity in liver preservation and transplantation, showing the most current evidence to support the concept that enhanced bioavailability of NO derived from e-NOS is detrimental to ameliorate graft liver preservation, as well as preventing subse- quent graft reperfusion injury. This review deals mainly with the beneficial effects of promoting ＂endogenous＂ pathways for NO generation, via e-NOS inducer drugs in cold preservation solution, surgical strategies such as ischemic preconditioning, and alternative ＂exogenous＂ pathways that focus on the enrichment of cold storage liquid with NO donors. Finally, we also provide a basic bench-to-bed side summary of the liver physiology and cell signalling mechanisms that account for explaining the e-NOS protective effects in liver preservation and transplantation.

Nuclear factor-KB decoy oligodeoxynucleotides attenuates ischemia/reperfusion injury in rat liver graft

AIM： To evaluate the protective effect of NF-kB decoy oligodeoxynucleotides （ODNs） on ischemia/reperfusion （I/R） injury in rat liver graft. METHODS： Orthotopic syngeneic rat liver transplantation was performed with 3 h of cold preservation of liver graft in University of Wisconsin solution containing phosphorothioated double-stranded NF-kB decoy ODNs or scrambled ODNs. NF-kB decoy ODNs or scrambled ODNs were injected intravenously into donor and recipient rats 6 and 1 h before operation, respectively. Recipients were killed 0 to 16 h after liver graft reperfusion. NF-kB activity in the liver graft was analyzed by electrophoretic mobility shift assay （EMSA）. Hepatic mRNA expression of TNF-α, IFN-γ and intercellular adhesion molecule-1 （ICAM-1） were determined by semiquantitative RT-PCR. Serum levels of TNF-α and IFN-γ were measured by enzyme-linked immunosorbent assays （ELISA）. Serum level of alanine transaminase （ALT） was measured using a diagnostic kit. Liver graft myeloperoxidase （MPO） content was assessed. RESULTS： NF-kB activation in liver graft was induced in a time-dependent manner, and NF-kB remained activated for 16 h after graft reperfusion. NF-kB activation in liver graft was significant at 2 to 8 h and slightly decreased at 16 h after graft reperfusion. Administration of NF-kB decoy ODNs significantly suppressed NF-kB activation as well as mRNA expression of TNF-α, IFN-γ, and ICAM-1 in the liver graft. The hepatic NF-kB DNA binding activity [presented as integral optical density （IOD） value] in the NF-kB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat （2.16±0.78 vs 36.78 ±6.35 and 3.06±0.84 vs 47.62± 8.71 for IOD value after 4 and 8 h of reperfusion, respectively, P〈0.001）. The hepatic mRNA expression level of TNF-α, IFN-γ and ICAM-1 rpresented as percent of β-actin mRNA （%）] in the NF-kB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat （8.31 ±3.48 vs 46.37±10.65 and 7.46± 3.72 vs 74.82±12.25 for hepatic TNF-α mRNA, 5.58±2.16 vs 50.46±9.35 and 6.47±2.53 vs 69.72±13.41 for hepatic IFN-γ mRNA, 6.79 ±2.83 vs 46.23±8.74 and 5.28±2.46 vs 67.44±10.12 for hepatic ICAM-1 mRNA expression after 4 and 8 h of reperfusion, respectively, P〈0.001）. Administration of NF-kB decoy ODNs almost completely abolished the increase of serum level of TNF-α and IFN-γ induced by hepatic ischemia/reperfusion, the serum level （pg/mL） of TNF-α and in the NF-kB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat （42.7±13.6 vs 176.7±15.8 and 48.4±15.1 vs 216.8±17.6 for TNF-α level, 31.5±12.1 vs 102.1±14.5 and 40.2±13.5 vs 118.6±16.7 for IFN-γ level after 4 and 8 h of reperfusion, respectively, P〈0.001）. Liver graft neutrophil recruitment indicated by MPO content and hepatocellular injury indicated by serum ALT level were significantly reduced by NF-kB decoy ODNs, the hepatic MPO content （A655） and serum ALT level （IU/L） in the NF-kB decoy ODNs treatment group rat was significantly lower than that of the I/R group rat （0.17±0.07 vs 1.12±0.25 and 0.46±0.17 vs 1.46±0.32 for hepatic MPO content, 71.7±33.2 vs 286.1±49.6 and 84.3±39.7 vs 467.8±62.3 for ALT level after 4 and 8 h of reperfusion, respectively, P〈0.001）. CONCLUSION： The data suggest that NF-kB decoy ODNs protects against I/R injury in liver graft by suppressing NF-kB activation and subsequent expression of proinflammatory mediators.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool.Those include extended criteria donors, such as elderly people, steatotic livers,donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960 s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion(NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury.Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose.Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

Complex liver retransplantation to treat graft loss due to long-term biliary tract complication after liver transplantation: A case report

BACKGROUND Loss of graft function after liver transplantation(LT) inevitably requires liver retransplant. Retransplantation of the liver(Re LT) remains controversial because of inferior outcomes compared with the primary orthotopic LT(OLT).Meanwhile, if accompanied by vascular complications such as arterial and portal vein(PV) stenosis or thrombosis, it will increase difficulties of surgery. We hereby introduce our center’s experience in Re LT through a complicated case of ReLT.CASE SUMMARY We report a patient who suffered from hepatitis B-associated cirrhosis and underwent LT in December 2012. Early postoperative recovery was uneventful.Four months after LT, the patient’s bilirubin increased significantly and he was diagnosed with an ischemic-type biliary lesion caused by hepatic artery occlusion. The patient underwent percutaneous transhepatic cholangial drainage and repeatedly replaced intrahepatic biliary drainage tube regularly for 5 years.The patient developed progressive deterioration of liver function and underwent liver re-transplant in January 2019. The operation was performed in a classic OLT manner without venous bypass. Both the hepatic artery and PV were occluded and could not be used for anastomosis. The donor PV was anastomosed with the recipient’s left renal vein. The donor hepatic artery was connected to the recipient’s abdominal aorta. The bile duct reconstruction was performed in an end-to-end manner. The postoperative process was very uneventful and the patient was discharged 1 mo after retransplantation.CONCLUSION With the development of surgical techniques, portal thrombosis and arterial occlusion are no longer contraindications for ReLT.

Outflow reconstruction with arterial patch in domino liver transplantation: a new technical option

Domino liver transplantation（LT）, using livers from familial amyloidotic polyneuropathy（FAP） patients, is a well described technique useful to expand donor pool. One of the main difficulties of this type of LT arises from the necessity to share the vascular pedicles between the graft and the donor. The most important challenge resides in restoring a proper hepatic venous outflow in the FAP-liver recipient.This is specially challenging when using the piggy-back technique, because the hepatic stumps may be too short. To overcome this issue, surgeons explored several techniques using different types of venous grafts. We describe a new technical option by using an arterial graft from the deceased donor. By using both iliac arteries a long graft is created and sutured as needed to the hepatic vein stump. We describe herein this new technique employed in a domino liver recipient who underwent retransplantation for ischemic cholangitis. The procedure was performed using the piggy-back technique; the venous stump of the FAP liver was reconstructed with the arterial graft. The patient had uneventful postoperative and mid-term hepatic function, and anastomosis was patent 24 months after LT.

Different ischemic preconditioning for rat liver graft: protection and mechanism

OBJECTIVE: To investigate the protective mechanism of different ischemic preconditioning (IPC) to ischemia/reperfusion (I/R) injury of rat liver graft. METHODS: 192 Wistar rats were randomly divided into 4 groups (48 rats in each group): control group (group C), experimental group 1 (group E_1), experimental group 2 (group E_2), and experimental group 3 (group E_3). IPC was not carried out in group C. In the experimental groups, IPC was carried out by blocking blood flow of the portal vein and hepatic artery and then reperfusion by removal of the clamp before donor liver was resected. Group E_1: 5-minute ischemia and 10-minute reperfusion; Group E_2: 5-minute ischemia and 5-minute reperfusion and one more the same procedure; Group E_3: 10-minute ischemia and 15-minute reperfusion. Four hours after IPC, liver transplantations were performed. Recipient blood and graft samples were obtained to determine the levels of ALT, AST, TNF-α and apoptosis index at 0.5, 2, 6, 24 hours after portal vein reperfusion. RESULTS: At 0.5, 2 hours after portal vein reperfusion, the levels of TNF-α in the experimental groups E_1, E_2, and E_3 were significantly lower than in the control group (P<0.05), and the levels in group E_2 were significantly lower than in groups E_1 and E_3 (P<0.05). At 24 hours, the levels of TNF-α in group E_2 were significantly lower than in groups C, E_1 anti E_3 (P<0.05). At 2 and 6 hours, apoptosis index in the experimental groups E_1, E_2, and E_3 was significantly less than in the control group (P<0.05). Apoptosis index in group E_2 was significantly less than groups E_1 and E_3(P<0.05). At 24 hours apoptosis index in the experimental groups E_1, E_2 , and E_3 was significantly less than in the control group (P<0.05). CONCLUSIONS: Ischemic preconditioning could attenuate liver graft injury by decreasing apoptosis of hepatocytes and production of TNF-α. The method of IPC with 5-minute ischemia, 5-minute reperfusion and one more the same procedure is a better way to protect liver graft from ischemia-reperfusion injury.

Emergency re-routing of anterior sector venous outflow for right lobe living donor liver transplantation including the middle hepatic vein

BACKGROUND:Controversy remains over whether the middle hepatic vein should be included in the liver graft in right liver living donor liver transplantation.Congestion in the anterior sector of a right liver graft can cause graft malfunction,which is especially devastating in the case of a graft with marginal size in relation to recipient body size on top of poor pre-transplant recipient status.The case we report here highlighted the importance of the middle hepatic vein in right liver living donor liver transplantation.METHODS:We illustrated the rectification of outflow obstruction of the middle hepatic vein in the anterior sector of right liver graft caused by technical error during transplantation.The rectification was performed with emergency re-routing using an artificial conduit.RESULT:Congestion in the anterior sector of the graft improved immediately and the patient’s postoperative liver function test results improved gradually.CONCLUSIONS:The middle hepatic vein is important for effective drainage of the anterior sector of a right liver graft.The re-routing technique described in the report can also be applied to cases in which the middle hepatic vein is injured during hepatectomy requiring immediate reconstruction.

Adult to adult living related liver transplantation: Where do we currently stand?

Adult to adult living donor liver transplantation (AALDLT) was first preformed in the United States in 1997. The procedure was rapidly integrated into clinical practice, but in 2002, possibly due to the first widely publicized donor death, the number of living liver donors plummeted. The number of donors has since reached a steady plateau far below its initial peak. In this review we evaluate the current climate of AALDLT. Specifically, we focus on several issues key to the success of AALDLT: determining the optimal indications for AALDLT, balancing graft size and donor safety, assuring adequate outflow, minimizing biliary complications, and maintaining ethical practices. We conclude by offering suggestions for the future of AALDLT in United States transplantation centers.

Effect of ulinastatin donor-pretreatment on liver graft during cold preservation in rats

Background Donor-pretreatment with ulinastatin may influence the liver graft during cold preservation. The aim of this research was to determine whether pretreatment of donor liver with Ulinastatin can attenuate cold preservation injury,and to explore the mechanism by which Ulinastatin affects the donor liver graft.Methods One hundred and forty-four Wistar rats were divided into the Ulinastatin treatment group （T group） pretreated with Ulinastatin 50 000 U/kg and control group （C group） treated with 0.9% normal saline via peritoneal injection prior to the anesthetization. After the abdominal cavity was opened and perfused with cold Ringer＇s lactate solution, the liver was harvested. The harvested liver was preserved in cold Ringer＇s lactate solution for 0, 2, 6, 24 hours, at which time the liver tissue was sampled for determination of dry weight and wet weight, Na＋-K＋-ATPase and Ca2＋-ATPase activity, lactic acid dehydrogenase （LDH） activity, lactic acid and malondialdehyde levels. Light microscopy and electron microscopy were used to observe liver morphology. The liver cold-preservation solution was taken for measurement of aspartate aminotransferase （AST） and alanine transaminase （ALT） levels. Correlation between ATPase activity and lactic acid level was analyzed by SPSS 13.0 for Windows.Results The morphology in the T group had improved cell boundaries vs. The C group at each time point. Dry weight to wet weight in the T group was lower than in the C group at 6 hours （P 〈0.05）, but the difference was not significant at 24 hours. ALT levels in the T group were lower than that in the C group at 6 hours （P 〈0.05） and 24 hours （P 〈0.01）. AST levels in the T group were lower than those in the C group at 2 hours （P〈0.05）, 6 hours （P 〈0.01） and 24 hours （P 〈0.01）.Na＋-K＋-ATPase activity in the T group was higher than in the C group and the mean difference between two groups was significant at 0 hour （P 〈0.05） and 2 hours （P 〈0.05）. Ca2＋-ATPase activity in the T group was higher than in the C group with the mean difference between two groups significant at 2 hours （P 〈0.05）. The T group had increased lactic acid levels at 0 hour （P 〈0.01） and 2 hours （P 〈0.05） compared with the C group, but there was no influence on the LDH activity at the same time. There were no obvious differences in the levels of malondialdehyde between the two groups at any time point. A linear correlation between Na＋-K＋-ATPase activity and lactic acid levels （r=0.295, P 〈0.05） was found.Conclusions Donor-pretreatment with ulinastatin may protect the cells in a liver graft from ischemia injury during cold preservation; the mechanism may be due to its promotion for cell glycolysis and its preservation of ATPase activity.

Current status of adult-to-adult living donor liver transplantation： surgical techniques and innovations

In response to critical organ shortage, transplant surgeons have utilized living donors in an attempt to decrease the mortality rate associated with waiting on the liver transplant list. Although the surgical techniques were first utilized clinically 15 years ago, the application of living donor liver transplantation （LDLT） has been somewhat limited by the steep learning curve associated with developing a program. Clinical success with LDLT in children was realized early, but the application of the techniques to adult patients has only occurred more recently. This procedure is now widely applied to adult recipients, with many technical improvements.

Intestinal microbiota dysbiosis and liver metabolomic changes during brain death

Background Whether a causative link exists between brain death(BD)and intestinal microbiota dysbiosis is unclear,and the distortion in liver metabolism associated with BD requires further exploration.Methods A rat model of BD was constructed and sustained for 9 h(BD group,n=6).The sham group(n=6)underwent the same procedures,but the catheter was inserted into the epidural space without ballooning.Intestinal contents and portal vein plasma were collected for microbiota sequencing and microbial metabolite detection.Liver tissue was resected to investigate metabolic alterations,and the results were compared with those of a sham group.Resultsα-diversity indexes showed that BD did not alter bacterial diversity.Microbiota dysbiosis occurred after 9 h of BD.At the family level,Peptostreptococcaceae and Bacteroidaceae were both decreased in the BD group.At the genus level,Romboutsia,Bacteroides,Erysipelotrichaceae_UCG_004,Faecalibacterium,and Barnesiella were enriched in the sham group,whereas Ruminococcaceae_UCG_007,Lachnospiraceae_ND3007_group,and Papillibacter were enriched in the BD group.Short-chain fatty acids,bile acids,and 132 other microbial metabolites remained unchanged in both the intestinal contents and portal vein plasma of the BD group.BD caused alterations in 65 metabolites in the liver,of which,carbohydrates,amino acids,and organic acids accounted for 64.6%.Additionally,80.0%of the differential metabolites were decreased in the BD group livers.Galactose metabolism was the most significant metabolic pathway in the BD group.Conclusions BD resulted in microbiota dysbiosis in rats;however,this dysbiosis did not alter microbial metabolites.Deterioration in liver metabolic function during extended periods of BD may reflect a continuous worsening in energy deficiency.