Protective effects of hypothermic ex vivo perfusion on ischemia/reperfusion injury and transplant outcomes

The future of islet transplantation beyond the BLA approval: challenges and opportunities

This opinion paper explores the path forward for islet transplantation as a cell therapy for type 1 diabetes, following the Biologics License Application (BLA) approval. The authors review key challenges and opportunities that lie ahead. After a brief overview of the history of human islet transplantation, the paper examines the FDA's regulatory stance on isolated islet cells and the requirements for obtaining a BLA. The authors discuss the significance of this approval and the critical steps necessary to broaden patient access, such as scaling up production, clinical integration, reimbursement frameworks, post-marketing surveillance, and patient education initiatives. The paper highlights that the approval of LANTIDRA as an allogeneic cell transplant for uncontrolled type 1 diabetes marks the beginning of new chapters in improving islet transplantation. The authors emphasize essential areas for development, including advancements in islet manufacturing, optimization of transplant sites, islet encapsulation, exploration of unlimited cell sources, and gene editing technologies. In conclusion, the future of islet transplantation beyond the BLA approval presents challenges and opportunities. While significant regulatory milestones have been reached, hurdles remain. Innovations in stem cell-derived islets, cell encapsulation, and gene editing show promise in enhancing graft survival, expanding the availability of transplantable cells, and reducing the reliance on immunosuppressive drugs. These advancements could pave the way for more accessible, durable, and personalized diabetes treatments.

Enhancing Liver Transplant Outcomes through Liver Precooling to Mitigate Inflammatory Response and Protect Mitochondrial Function

Transplanted organs experience several episodes of ischemia and ischemia-reperfusion. The graft injury resulting from ischemia-reperfusion (IRI) remains a significant obstacle to the successful survival of transplanted grafts. Temperature significantly influences cellular metabolic rates because biochemical reactions are highly sensitive to temperature changes. Consequently, lowering the temperature could reduce the degradative reactions triggered by ischemia. In mitigating IRI in liver grafts, the potential protective effect of localized hypothermia on the liver prior to blood flow obstruction has yet to be explored. In this study, we applied local hypothermia to mouse donor livers for a specific duration before stopping blood flow to liver lobes, a procedure called "liver precooling". Mouse donor liver temperature in control groups was controlled at 37 °C. Subsequently, the liver donors were preserved in cold University of Wisconsin solution for various durations followed by orthotopic liver transplantation. Liver graft injury, function and inflammation were assessed at 1 and 2 days post-transplantation. Liver precooling exhibited a significant improvement in graft function, revealing more than a 47% decrease in plasma aspartate transaminase (AST) and alanine aminotransferase (ALT) levels, coupled with a remarkable reduction of approximately 50% in liver graft histological damage compared to the control group. The protective effects of liver precooling were associated with the preservation of mitochondrial function, a substantial reduction in hepatocyte cell death, and a significantly attenuated inflammatory response. Taken together, reducing the cellular metabolism and enzymatic activity to a minimum level before ischemia protects against IRI during transplantation.

Normothermic Preservation of the Intestinal Allograft

Intestinal allotransplantation was first described in the 1960s and successfully performed in the 1980s. Since that time, less progress has been made in the preservation of the allograft before transplantation and static cold storage remains the current standard. Normothermic machine perfusion represents an opportunity to simultaneously preserve, assess, and recondition the organ for transplantation and improve the procurement radius for allografts. The substantial progress made in the field during the last 60 years, coupled with the success of the preclinical animal model of machine perfusion-preserved intestinal transplantation, suggest we are approaching the point of clinical application.

Can We Predict Kidney Graft Function and Graft Survival Using Hypothermic Machine Perfusion Parameters From Donors After Circulatory Death?

Background

Hypothermic machine perfusion (HMP) reduces renal injury in donation after circulatory death donors with a high Kidney Donor Profile Index (KDPI). This study aims to characterize the correlation between KDPI, HMP parameters, and donor vitals during the withdrawal period in predicting short- and long-term graft outcomes.

Methods

ANOVA with Tukey's honestly significant difference tests compared the relationship between average flow, average resistance, peak resistance, flow slope, and resistance slope on day 30, 1-y, and 3-y eGFR, and days of delayed graft function. Graft and recipient survival rates were assessed using Kaplan-Meier analysis.

Results

The data for 72 grafts were suitable for analysis. Kidneys with KDPI >50% had a significantly higher day 30, and 1-y posttransplant eGFR, if HMP average flow was >150 mL/min, or the average resistance was <0.15 mm Hg/mL/min, compared with kidneys with also KDPI >50% but had not achieved the same pump parameters. There were no significant differences in the Kaplan-Meier analysis, considering recipient or graft survival, regardless of the KPDI score with 3- or 5-y outcomes.

Conclusions

Use of average resistance and average flow from a HMP, in conjunction with KDPI, may be predictive of the short- and long-term function of donation after circulatory death kidney transplants.

Overcoming the longest cold ischemia time yet seen in Korea using hypothermic machine perfusion in deceased donor kidney transplantation: a case report

To address a donor kidney shortage, marginal grafts have been applied in deceased donor kidney transplantation (DDKT). These grafts exhibit comparatively unfavorable outcomes, particularly when cold ischemia time (CIT) is prolonged. Hypothermic machine perfusion (HMP) has been investigated to mitigate the effects of prolonged CIT during graft transport. The present case involved successful management of the longest CIT recorded in Korea by employing HMP in DDKT. The donor was a 54-year-old man (Korean Kidney Donor Profile Index, 82%) with diabetes. The recipient, a 51-year-old man on peritoneal dialysis, had end-stage renal disease secondary to diabetic nephropathy. Following procurement, the left kidney was preserved using HMP. Inclement weather delayed graft transportation; consequently, the total CIT was 28 hours and 6 minutes, with the kidney preserved by HMP for 22 hours and 35 minutes. Postoperative graft function gradually recovered, and urine output was satisfactory. Delayed graft function was not observed, and the patient was discharged on postoperative day 13 without significant complications. Five months after surgery, his serum creatinine level was 1.7 mg/dL. Successful DDKT with a marginal donor graft via HMP, despite the longest CIT yet observed in Korea, underscores the usefulness of HMP in enhancing graft quality and preserving function.

Cryopreservation of tissues and organs: present, bottlenecks, and future

Tissue and organ transplantation continues to be an effective measure for saving the lives of certain critically ill patients. The organ preservation methods that are commonly utilized in clinical practice are presently only capable of achieving short-term storage, which is insufficient for meeting the demand for organ transplantation. Ultra-low temperature storage techniques have garnered significant attention due to their capacity for achieving long-term, high-quality preservation of tissues and organs. However, the experience of cryopreserving cells cannot be readily extrapolated to the cryopreservation of complex tissues and organs, and the latter still confronts numerous challenges in its clinical application. This article summarizes the current research progress in the cryogenic preservation of tissues and organs, discusses the limitations of existing studies and the main obstacles facing the cryopreservation of complex tissues and organs, and finally introduces potential directions for future research efforts.

Application of Mesenchymal Stem Cells During Machine Perfusion: An Emerging Novel Strategy for Organ Preservation

Although solid organ transplantation remains the definitive management for patients with end-stage organ failure, this ultimate treatment has been limited by the number of acceptable donor organs. Therefore, efforts have been made to expand the donor pool by utilizing marginal organs from donation after circulatory death or extended criteria donors. However, marginal organs are susceptible to ischemia-reperfusion injury (IRI) and entail higher requirements for organ preservation. Recently, machine perfusion has emerged as a novel preservation strategy for marginal grafts. This technique continually perfuses the organs to mimic the physiologic condition, allows the evaluation of pretransplant graft function, and more excitingly facilitates organ reconditioning during perfusion with pharmacological, gene, and stem cell therapy. As mesenchymal stem cells (MSCs) have anti-oxidative, immunomodulatory, and regenerative properties, mounting studies have demonstrated the therapeutic effects of MSCs on organ IRI and solid organ transplantation. Therefore, MSCs are promising candidates for organ reconditioning during machine perfusion. This review provides an overview of the application of MSCs combined with machine perfusion for lung, kidney, liver, and heart preservation and reconditioning. Promising preclinical results highlight the potential clinical translation of this innovative strategy to improve the quality of marginal grafts.

Double-lobectomy in a steatotic liver transplantation rat model

Establishing a steatotic liver transplantation animal model can be a challenging process, which requires complex microsurgical technologies. The present study established a novel rat model of stable steatotic liver transplantation for marginal liver graft research, which notably minimized the number of animals used for the experiment. Briefly, male Sprague-Dawley rats (n=90) were fed with a high-fat diet (HFD; 60%, kJ) or standard chow diet (SCD) for 8 weeks. The liver enzymes and lipid levels were assessed every week, and the degree of steatosis was determined via hematoxylin and eosin and Oil Red O staining. The results demonstrated that there were no significant differences in alanine aminotransaminase and aspartate aminotransferase levels between the SCD and HFD groups (P>0.05), whereas the level of plasma triglyceride (TG) increased by 1.76-fold in the HFD group at week 2, and progressively decreased to baseline levels by week 8. Significantly higher levels of TG were observed in the HFD group compared with the SCD group at week 2 (P<0.05). In addition, the levels of plasma glucose (P<0.05), portal insulin (P<0.05) and content of liver lipid (P<0.01) increased in the HFD group compared with the SCD group. After 6 weeks, the liver steatosis was successfully formed and stable. Consequently, a rat liver developed hepatic macrovesicular steatosis >60%, which was subsequently used for transplantation after double-lobectomy. Post-transplantation survival rates in the HFD and SCD groups were as follows: Week 1, 80 vs. 100% and 1 month, 20 vs. 100%. A total of 20 rats were not sacrificed by performing double-lobectomy for biopsy. Taken together, the results of the present study suggest that rat liver double-lobectomy may be safely applied in steatotic liver transplantation without the need to sacrifice a large number of animals.

Internal-Illumination Photoacoustic Tomography Enhanced by a Graded-Scattering Fiber Diffuser

The penetration depth of photoacoustic imaging in biological tissues has been fundamentally limited by the strong optical attenuation when light is delivered externally through the tissue surface. To address this issue, we previously reported internal-illumination photoacoustic imaging using a customized radial-emission optical fiber diffuser, which, however, has complex fabrication, high cost, and non-uniform light emission. To overcome these shortcomings, we have developed a new type of low-cost fiber diffusers based on a graded-scattering method in which the optical scattering of the fiber diffuser is gradually increased as the light travels. The graded scattering can compensate for the optical attenuation and provide relatively uniform light emission along the diffuser. We performed Monte Carlo numerical simulations to optimize several key design parameters, including the number of scattering segments, scattering anisotropy factor, divergence angle of the optical fiber, and reflective index of the surrounding medium. These optimized parameters collectively result in uniform light emission along the fiber diffuser and can be flexibly adjusted to accommodate different applications. We fabricated and characterized the prototype fiber diffuser made of agarose gel and intralipid. Equipped with the new fiber diffuser, we performed thorough proof-of-concept studies on ex vivo tissue phantoms and an in vivo swine model to demonstrate the deep-imaging capability (~10 cm achieved ex vivo) of photoacoustic tomography. We believe that the internal light delivery via the optimized fiber diffuser is an effective strategy to image deep targets (e.g., kidney) in large animals or humans.

Human Small Intestine Transplantation: Segmental Susceptibility to Ischemia Using Different Preservation Solutions and Conditions

BACKGROUND AND AIMS

Among all transplanted abdominal organs, the small intestine is one of the most ischemia sensitive. Appropriate graft selection, procurement, and preservation are crucial for optimum graft and patient survival. We evaluated ischemic damage in human small intestine grafts under different hypothermic preservation conditions (cold static and continuous perfusion) and solutions: histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW).

METHODS

Fourteen small intestinal grafts were procured from deceased donors. HTK and UW were used for the vascular perfusion at the cross clamp, and UW, HTK, or Ringer Lactate were used for the luminal flush at the back table. Therefore, part of the same harvested intestine was stored in cold static storage and in continuous perfusion preservation (with intestinal perfusion unit) simultaneously. Histological samples were collected from the jejunum and ileum at different time points and different preservation conditions. The samples were collected before the initiation of cold storage (T0), after 8 hours of cold static (ST8), or after 8 hours of continuous perfusion preservation (PT8) (n = 161 samples). Blinded histological evaluation was conducted and ischemic damage was determined using the Park/Chiu scale.

RESULTS

The ileum had less ischemic damage than the jejunum, regardless of using static or continuous perfusion preservation. There was no significantly ischemic damage difference between intestinal grafts flushed and perfused with UW or HTK.

CONCLUSION

The jejunum is more susceptible to ischemic injury than the ileum. UW and HTK are equivalent to preserve intestinal graft. This suggests that selective transplantation of ileum could reduce ischemia-related postoperative complications.

Hypothermic machine perfusion after static cold storage improves ovarian function in rat ovarian tissue transplantation

OBJECTIVE

This study was performed to investigate the effect of hypothermic machine perfusion (HMP) after cold storage (CS) on ovarian transplantation.

METHODS

Rats aged 8-10 weeks were used as the donors and recipients for allotransplantation. Eighteen donor rats were divided into three groups: the fresh control (n = 6), cold storage (CS; n = 6), and hypothermic machine perfusion (HMP; n = 6) groups. The preservation solution contained Dulbecco's modified Eagle's medium/Ham's F-12 (1:1, v/v), 10% fetal bovine serum, 10 μg/ml insulin, 10 μg/ml transferrin, and 50 mIU/ml follicle-stimulating hormone (FSH). The donor ovaries in the CS and HMP groups were excised and then respectively subjected to 4 h of CS and 2 h of CS combined with 2 h of HMP at 4 °C, and then transplanted beneath the recipient's left renal capsule. At 7 days after transplantation, the ovaries were removed and blood samples were obtained for histological analysis, immunohistochemistry for CD31 and Ki67, and serum anti-Mullerian hormone (AMH) level estimation.

RESULTS

The HMP group showed significant increases in serum AMH and CD31-positive areas when compared to these values in the CS group (P < 0.05). However, no differences were noted in the total number of follicles or the Ki67-positive areas among the three groups.

CONCLUSION

Hypothermic machine perfusion after static cold storage is more effective than static CS alone for the short-term preservation of whole ovaries during transport. Whole ovary transplantation with vascular pedicle is our future research direction. Graphical Abstract The black rectangle in the figure shows the place where ligation and disconnection are required, the black dotted line shows the place where vascular forceps are used to clamp, and the black circle shows the place where the cannula is inserted This diagram was made for reviewers to understand more intuitively how my hypothermia mechanical perfusion model was built. Organs obtained in this way can be used for subsequent perfusion and whole ovarian transplantation.

Applied Bioengineering in Tissue Reconstruction, Replacement, and Regeneration

IMPACT STATEMENT

The use of autologous tissue in the reconstruction of tissue defects has been the gold standard. However, current standards still face many limitations and complications. Improving patient outcomes and quality of life by addressing these barriers remain imperative. This article provides historical perspective, covers the major limitations of current standards of care, and reviews recent advances and future prospects in applied bioengineering in the context of tissue reconstruction, replacement, and regeneration.

Initial perfusate purification during subnormothermic machine perfusion for porcine liver donated after cardiac death

Improvement of machine perfusion (MP) technologies is required to enhance organ quality for donor after cardiac death (DCD) grafts. Installing a dialyzer or a filter into the perfusion circuit to maintain the perfusate condition has some advantages. However, the consequences of purification perfusate during subnormothermic machine perfusion (SNMP) remain unexplained. In this study, the effects of initial purification perfusate with simple method of replacing the first 0.5-L perfusate during SNMP were investigated to consider installation effect of the filter or the dialyzer. Porcine liver grafts, which have 60-min warm ischemia time, were procured to imitate the DCD graft condition. Purified SNMP (PSNMP) results were compared with simple cold storage and conventional SNMP. In PSNMP, initial perfusate of 0.5 L was removed to substitute for purification. After preservation process, the preserved grafts were reperfused with diluted autologous blood for 2 h under normothermic machine perfusion condition to evaluate the liver function using an isolated reperfusion model. The vascular pressures, enzyme release rates and the metabolic indexes during reperfusion were analyzed. The pressures in the hepatic artery after reperfusion 60 min were significantly lower in PSNMP group compared with cold storage (CS) and SNMP groups. In addition, lactate dehydrogenase and alkaline phosphatase were significantly lower after PSNMP than after the CS or SNMP. Also, the metabolic indexes of hyaluronic acid and lactate were significantly decreased by purifying the perfusate in MP preservation than in CS or SNMP. The effectiveness of initial purification perfusate during SNMP was investigated.

Intravenous infusion of ulinastatin attenuates acute kidney injury after cold ischemia/reperfusion

BACKGROUND

Administration of ulinastatin was proved to protect many organs from ischemia/reperfusion (I/R) induced injury, yet its protective effects on renal I/R injury under cold condition and mechanism still remain unclear.

AIMS

In the present study, the protective effects of ulinastatin on renal cold I/R injury as well as its mechanism were investigated.

METHODS AND RESULTS

Renal cold I/R model was constructed via cross-clamping of left renal artery and vein at 4 °C. The ulinastatin was administrated and multi-methods were performed to evaluate the protective effects. The results showed that ulinastatin could mitigate the renal cold I/R injury. In addition, the attenuated kidney cold I/R injury by ulinastatin was also accompanied with its regulating capability of the microenvironment, such as decreased acute inflammatory response, oxidative stress damage and apoptosis, as well as attenuation of vasculature levels decrease, as evidence by reduced TNF-α, IL-6 mRNA expression, MDA levels and apoptosis, higher levels of SOD activity and CD31/α-SMA expression.

CONCLUSION

The present study suggested that ulinastatin might be clinically useful in reducing preservation injury induced by cold I/R during renal transplantation surgery.

Machine perfusion versus cold storage in renal preservation of deceased donors with brain death: systematic review and meta-analysis

With the increasing use of machine perfusion in kidney transplantation, it has been observed that dynamic ischemia correlates with the improvement of organ preservation. In this context, we performed a systematic review that aimed to evaluate the efficacy of the portable machine perfusion (LifePort Kidney Transporter Machine®), used in Brazil, compared to cold storage, regarding the delayed graft function of deceased donors with brain death. Literature search was carried out in LILACS, MEDLINE via PubMed, Scopus, Clarivate Analytics, Cochrane Library, Embase, and SciELO, as well as in Google Scholar manually. The systematic review consisted only of randomized clinical trials. For meta-analysis, relative risk and odds ratio were evaluated. Eighty-six documents were identified and two papers from European and Brazilian groups were selected at the end, with eligibility criteria for meta-analysis. In these, 374 kidneys were assigned to machine perfusion and 374 kidneys were assigned to cold storage. Delayed graft function was observed in 84 and 110 patients, respectively. In meta-analysis, a risk ratio of 0.7568 (p=0.0151) and an odds ratio of 0.6665 (p=0.0225) were obtained, both with a 95% confidence interval. Machine perfusion reduced the incidence of delayed graft function of deceased donors with brain death.

Hypothermic machine perfusion reduces the incidences of early allograft dysfunction and biliary complications and improves 1-year graft survival after human liver transplantation: A meta-analysis

BACKGROUND

The worldwide organ shortage continues to be the main limitation of liver transplantation. To bridge the gap between the demand and supply of liver grafts, it becomes necessary to use extended criteria donor livers for transplantation. Hypothermic machine perfusion (HMP) is designed to improve the quality of preserved organs before implantation. In clinical liver transplantation, HMP is still in its infancy.

METHODS

A systematic search of the PubMed, EMBASE, Springer, and Cochrane Library databases was performed to identify studies comparing the outcomes in patients with HMP versus static cold storage (SCS) of liver grafts. The parameters analyzed included the incidences of primary nonfunction (PNF), early allograft dysfunction (EAD), vascular complications, biliary complications, length of hospital stay, and 1-year graft survival.

RESULTS

A total of 6 studies qualified for the review, involving 144 and 178 liver grafts with HMP or SCS preservation, respectively. The incidences of EAD and biliary complications were significantly reduced with an odds ratio (OR) of 0.36 (95% confidence interval [CI] 0.17-0.77, P = .008) and 0.47 (95% CI 0.28-0.76, P = .003), respectively, and 1-year graft survival was significantly increased with an OR of 2.19 (95% CI 1.14-4.20, P = .02) in HMP preservation compared to SCS. However, there was no difference in the incidence of PNF (OR 0.30, 95% CI 0.06-1.47, P = .14), vascular complications (OR 0.69, 95% CI 0.29-1.66, P = .41), and the length of hospital stay (mean difference -0.30, 95% CI -4.10 to 3.50, P = .88) between HMP and SCS preservation.

CONCLUSIONS

HMP was associated with a reduced incidence of EAD and biliary complications, as well as an increased 1-year graft survival, but it was not associated with the incidence of PNF, vascular complications, and the length of hospital stay.

Extracorporeal Perfusion in Vascularized Composite Allotransplantation: Current Concepts and Future Prospects

Severe injuries of the face and limbs remain a major challenge in today's reconstructive surgery. Vascularized composite allotransplantation (VCA) has emerged as a promising approach to restore these defects. Yet, there are major obstacles preventing VCA from broad clinical application. Two key restrictions are (1) the graft's limited possible ischemia time, keeping the potential donor radius extremely small, and (2) the graft's immunogenicity, making extensive lifelong monitoring and immunosuppressive treatment mandatory. Machine perfusion systems have demonstrated clinical success addressing these issues in solid organ transplantation by extending possible ischemia times and decreasing immunogenicity. Despite many recent promising preclinical trials, machine perfusion has not yet been utilized in clinical VCA. This review presents latest perfusion strategies in clinical solid organ transplantation and experimental VCA in light of the specific requirements by the vascularized composite allograft's unique tissue composition. It discusses optimal settings for temperature, oxygenation, and flow types, as well as perfusion solutions and the most promising additives. Moreover, it highlights the implications for the utility of VCA as therapeutic measure in plastic surgery, if machine perfusion can be successfully introduced in a clinical setting.

Machine preservation of donor kidneys in transplantation

With increasing demands for 'less than ideal' kidneys for transplantation, machine perfusion of kidneys has been utilized to improve the preservation of kidneys during storage. Hypothermic machine perfusion (HMP) of renal allografts has been shown to reduce delayed graft function rates in both expanded criteria and donation after cardiac death renal allografts. However, the beneficial impact upon long-term graft function is unclear. There has been emerging evidence that both subnormothermic (room temperature) and normothermic machine perfusion (NMP) of allografts have beneficial effects with regards to early graft function, survival and injury in pre-clinical and early clinical studies. Additionally, machine perfusion allows functional assessment of the organ prior to transplantation. Ultimately, the greatest benefit of machine perfusion may be the ability to treat the organ with agents to protect the graft against ischemia reperfusion injury, while awaiting transplantation.

Beneficial Effect of Moderately Increasing Hypothermic Machine Perfusion Pressure on Donor after Cardiac Death Renal Transplantation

Background:

Vascular resistance and flow rate during hypothermic machine perfusion (HMP) of kidneys is correlated with graft function. We aimed to determine the effects of increasing HMP pressure versus maintaining the initial pressure on kidney transplantation outcomes.

Methods:

We retrospectively reviewed the data of 76 primary transplantation patients who received HMP-preserved kidneys from 48 donors after cardiac death between September 1, 2013, and August 31, 2015. HMP pressure was increased from 30 to 40 mmHg (1 mmHg = 0.133 kPa) in kidneys with poor flow and/or vascular resistance (increased pressure [IP] group; 36 patients); otherwise, the initial pressure was maintained (constant pressure group; 40 patients). Finally, the clinical characteristics and transplantation outcomes in both groups were assessed.

Results:

Delayed graft function (DGF) incidence, 1-year allograft, patient survival, kidney function recovery time, and serum creatinine level on day 30 were similar in both groups, with improved flow and resistance in the IP group. Among patients with DGF, kidney function recovery time and DGF duration were ameliorated in the IP group. Multivariate logistic regression analysis revealed that donor hypertension (odds ratio [OR]: 1.43, 95% confidence interval [CI]: 1.02–2.06, P = 0.035), donor terminal serum creatinine (OR: 1.27, 95% CI: 1.06–1.62, P = 0.023), warm ischemic time (OR: 3.45, 95% CI: 1.97–6.37, P = 0.002), and terminal resistance (OR: 3.12, 95% CI: 1.76–6.09, P = 0.012) were independent predictors of DGF. Cox proportional hazards analysis showed that terminal resistance (hazard ratio: 2.06, 95% CI: 1.32–5.16, P = 0.032) significantly affected graft survival.

Conclusion:

Increased HMP pressure improves graft perfusion but does not affect DGF incidence or 1-year graft survival.

Evaluation Using an Isolated Reperfusion Model for Porcine Liver Donated After Cardiac Death Preserved with Oxygenated Hypothermic Machine Perfusion

BACKGROUND Machine perfusion techniques offer a solution to the serious organ shortage. However, to assess the effects of machine perfusion, many detailed studies are required. In this study, an ex vivo reperfusion model using diluted autologous blood was confirmed to evaluate the utility of machine preservation for livers donated after cardiac death (DCD). In particular, beneficial effects of the oxygenated hypothermic machine perfusion (HMP) for DCD porcine livers are evaluated. MATERIAL AND METHODS Porcine livers were procured under warm ischemia time (WIT) of 60 min. The livers were preserved by hypothermic machine perfusion (HMP) or static cold storage (CS) for 4 h. After the preservation, the livers were perfused for 2 h using the ex vivo reperfusion model with diluted blood oxygenated by a membrane oxygenator at 35-38°C. RESULTS At 2 h of ex vivo reperfusion with 60 min of warm ischemic time (WIT), the portal vein pressure for CS was higher than HMP (18.8±15.9 vs. 7.5±3.9 [mmHg] in 60 min). Furthermore, LDH in CS was higher than HMP (528.5±149.8 vs. 194.1±32.2 [IU/L/100 g liver] in 60 min. P<0.05). Lactate after CS (60) was significantly higher than HMP (60) (8.67±0.39 vs. 5.68±0.60 [mmol/L] at 60 min. p<0.01). CONCLUSIONS The ex vivo reperfusion model can be used to evaluate the utility of machine perfusion. Advantages of HMP for DCD livers are evaluated with this model.

Development of an automated liver perfusion system: The benefit of a hemofilter

Introduction:

Liver perfusion machines are close to becoming a reality in the transplantation field. However, depending on the techniques used and the goals pursued, their application is limited in the research field. Here, we present the entire development of a perfusion system with self-made engineering, completely autonomous controls, and a high degree of versatility that allows the design of different studies on liver functionality.

Methods:

A user-friendly interface permits real-time monitoring and remote control by the devices within the circuit. Centrifugal pumps allow the perfusate enter the organ with controlled pressures and flows at both hepatic artery and portal vein. The implementation of a hemofilter as a novel tool permits to control and maintain homeostasis. Peristaltic pumps adjust pH, extraction rate, and total volume by means of sensors.

Results:

Real-time monitoring facilitates liver functionality assessment. The controlled system shows rapid stabilization and quick responses to changes during 6 h of perfusion experiments. Furthermore, the integration of a hemofilter helps the system to eliminate toxic waste and maintain homeostasis.

Discussion:

The machine provides the basis of a perfusion system with autonomous controls and the implementation of a hemofilter that enables a more efficient control of hemostasis. Moreover, the developed hardware and software are subjected to further tuning for additional purposes such as pathophysiologic studies, suboptimal grafts recovery, or recellularization of decellularized scaffolds among others.

Hypothermic machine perfusion attenuates ischemia/reperfusion injury against rat livers donated after cardiac death by activating the Keap1/Nrf2‑ARE signaling pathway

Hypothermic machine perfusion (HMP) has been demonstrated to be a more effective method for preserving livers donated after circulatory death (DCD) than cold storage (CS); however, the underlying mechanisms remain unclear. The aim of the present study was to investigate the protective effects of HMP on rat DCD livers and the possible role of the nuclear factor erythroid 2‑related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway. A total of 18 adult male rats were randomly divided into three groups: Control, HMP and CS (n=6 per group). To simulate the conditions of DCD liver transplantation, rat livers in the CS and HMP groups were subjected to 30 min warm ischemia following cardiac arrest and were then preserved by CS or HMP for 3 h. Subsequently, after 1 h of isolated reperfusion, the extent of ischemia/reperfusion injury (IRI) and cellular functions were assessed. During reperfusion, intrahepatic resistance and bile production were measured, and the perfusion fluid was collected for liver enzyme analysis. The liver tissues were then harvested for the assessment of malondialdehyde (MDA) production, superoxide dismutase (SOD) activity, ATP levels, as well as for histological analysis, immunohistochemistry and a terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Finally, the expression levels of the components associated with the Nrf2‑ARE signaling pathway were analyzed via western blotting and reverse transcription‑quantitative polymerase chain reaction. The results of the present study revealed that, compared with in the CS group, the HMP group exhibited higher levels of ATP, bile production and SOD activity, and improved histological results; however, lower levels of liver enzymes, apoptosis and MDA were detected. Additionally, the findings of the present study also suggested that the Nrf2‑ARE signaling pathway may be activated by the steady laminar flow of HMP. In conclusion, HMP may attenuate ischemia‑reperfusion injury to rat DCD livers via activation of the Nrf2‑ARE signaling pathway.

Organ preservation: from the past to the future

Organ transplantation is the most effective therapy for patients with end-stage disease. Preservation solutions and techniques are crucial for donor organ quality, which is directly related to morbidity and survival after transplantation. Currently, static cold storage (SCS) is the standard method for organ preservation. However, preservation time with SCS is limited as prolonged cold storage increases the risk of early graft dysfunction that contributes to chronic complications. Furthermore, the growing demand for the use of marginal donor organs requires methods for organ assessment and repair. Machine perfusion has resurfaced and dominates current research on organ preservation. It is credited to its dynamic nature and physiological-like environment. The development of more sophisticated machine perfusion techniques and better perfusates may lead to organ repair/reconditioning. This review describes the history of organ preservation, summarizes the progresses that has been made to date, and discusses future directions for organ preservation.

Outcome Improvement for Hypothermic Machine Perfusion Versus Cold Storage for Kidneys From Cardiac Death Donors

Organ shortage has led to an increased use of kidneys from cardiac death donors (DCDs), but controversies about the methods of organ preservation still exist. This study aims to compare the effect of machine perfusion (MP) and cold storage (CS) in protecting kidneys harvested from DCDs. 141 kidney pairs from DCDs between July 2010 and July 2015 were included in this randomized controlled study. One kidney from each donor was randomly assigned to MP and the contralateral kidney was assigned to CS. Delayed graft function (DGF) rate, resistance index of renal arteries, early renal function, and survival rates were used to estimate the effect of preservation. The results showed that MP decreased the rate of DGF from 33.3 to 22.0% (P = 0.033). Ultrasound of the kidneys within 48 h after transplantation showed that the resistance index of renal main artery (0.673 ± 0.063 vs. 0.793 ± 0.124, P < 0.001), sub segmental artery (0.66 ± 0.062 vs. 0.764 ± 0.077, P < 0.001) and interlobular artery (0.648 ± 0.056 vs. 0.745 ± 0.111, P = 0.023) were all significantly lower in the MP group than those in the CS group. Furthermore, compared to the CS group, in the first 7 days following transplantation, the median urine volume was significantly higher (4080 mL vs. 3000 mL, P = 0.047) in kidneys sustained using MP and the median serum creatinine was remarkably lower (180 µmol/L vs. 390 µmol/L, P = 0.024). More importantly, MP group had higher 1- and 3-year graft survival rates (98% vs. 93%, P = 0.026; 93% vs. 82%, P = 0.036, respectively). Hypothermic MP improved the outcomes of DCD kidney transplantation.

Normothermic Ex Vivo Kidney Perfusion Following Static Cold Storage-Brief, Intermediate, or Prolonged Perfusion for Optimal Renal Graft Reconditioning?

Normothermic ex vivo kidney perfusion (NEVKP) demonstrated superior results compared to hypothermic storage in donation after circulatory death (DCD) kidney transplantation. It is unknown whether an optimal perfusion time exists following hypothermic storage to allow for the recovery of renal grafts from cold ischemic injury. In a porcine model of DCD kidney autotransplantation, the impact of initial static cold storage (SCS) (8 h) followed by various periods of NEVKP recovery was investigated: group A, 8 hSCS only (control); group B, 8 hSCS + 1 hNEVKP (brief NEVKP); group C, 8 hSCS + 8 hNEVKP (intermediate NEVKP); and group D, 8 hSCS + 16 hNEVKP (prolonged NEVKP). All grafts were preserved and transplanted successfully. One animal in group D was sacrificed and excluded by postoperative day 3 due to hind limb paralysis, but demonstrated good renal function. Postoperative graft assessment during 8 days' follow-up demonstrated lowest levels of peak serum creatinine for intermediate (C) and prolonged (D) NEVKP (p = 0.027). Histological assessment on day 8 demonstrated a significant difference in tubular injury (p = 0.001), with highest values for group B. These results suggest that longer periods of NEVKP following SCS are feasible and safe for postponing surgical transplant procedure and superior to brief NEVKP, reducing the damage caused during cold ischemic storage of renal grafts.

Continuous Normothermic Ex Vivo Kidney Perfusion Is Superior to Brief Normothermic Perfusion Following Static Cold Storage in Donation After Circulatory Death Pig Kidney Transplantation

Hypothermic preservation is known to cause renal graft injury, especially in donation after circulatory death (DCD) kidney transplantation. We investigated the impact of cold storage (SCS) versus short periods of normothermic ex vivo kidney perfusion (NEVKP) after SCS versus prolonged, continuous NEVKP with near avoidance of SCS on kidney function after transplantation. Following 30 min of warm ischemia, kidneys were removed from 30-kg Yorkshire pigs and preserved for 16 h with (A) 16 h SCS, (B) 15 h SCS + 1 h NEVKP, (C) 8 h SCS + 8 h NEVKP, and (D) 16 h NEVKP. After contralateral kidney resection, grafts were autotransplanted and pigs followed up for 8 days. Perfusate injury markers such as aspartate aminotransferase and lactate dehydrogenase remained low; lactate decreased significantly until end of perfusion in groups C and D (p < 0.001 and p = 0.002). Grafts in group D demonstrated significantly lower serum creatinine peak when compared to all other groups (p < 0.001) and 24-h creatinine clearance at day 3 after surgery was significantly higher (63.4 ± 19.0 mL/min) versus all other groups (p < 0.001). Histological assessment on day 8 demonstrated fewer apoptotic cells in group D (p = 0.008). In conclusion, prolonged, continuous NEVKP provides superior short-term outcomes following DCD kidney transplantation versus SCS or short additional NEVKP following SCS.

Ex Vivo Porcine Organ Perfusion Models as a Suitable Platform for Translational Transplant Research

In transplantation surgery, extending the criteria for organ donation to include organs that may have otherwise been previously discarded has provided the impetus to improve organ preservation. The traditional method of cold static storage (CS) has been tried and tested and is suitable for organs meeting standard criteria donation. Ex vivo machine perfusion is, however, associated with evidence suggesting that it may be better than CS alone and may allow for organ donation criteria to be extended. Much of our knowledge of organ preservation is derived from animal studies. We review ex vivo porcine organ perfusion models and discuss the relevance to the field of transplantation surgery. Following a systematic literature search, only articles that reported on experimental studies with focus on any aspect(s) of ex vivo and porcine perfusion of organs yet limited to the context of organ transplantation surgery were included. The database search and inclusion/exclusion criteria identified 22 journal articles. All 22 articles discussed ex vivo porcine organ perfusion within the context of transplant preservation surgery: 8 liver, 3 kidney, 3 lung, 2 pancreas/islet, 4 discussed a combined liver-kidney multiorgan model, 1 small bowel, and 1 cardiac perfusion model systems. The ex vivo porcine perfusion model is a suitable, reliable, and safe translational research model. It has advantages to investigate organ preservation techniques in a reproducible fashion in order to improve our understanding and has implications to extend the criteria for organ donation.

Machine Perfusion of Donor Livers for Transplantation: A Proposal for Standardized Nomenclature and Reporting Guidelines

With increasing demand for donor organs for transplantation, machine perfusion (MP) promises to be a beneficial alternative preservation method for donor livers, particularly those considered to be of suboptimal quality, also known as extended criteria donor livers. Over the last decade, numerous studies researching MP of donor livers have been published and incredible advances have been made in both experimental and clinical research in this area. With numerous research groups working on MP, various techniques are being explored, often applying different nomenclature. The objective of this review is to catalog the differences observed in the nomenclature used in the current literature to denote various MP techniques and the manner in which methodology is reported. From this analysis, we propose a standardization of nomenclature on liver MP to maximize consistency and to enable reliable comparison and meta-analyses of studies. In addition, we propose a standardized set of guidelines for reporting the methodology of future studies on liver MP that will facilitate comparison as well as clinical implementation of liver MP procedures.

Complement-here, there and everywhere, but what about the transplanted organ?

The part of the innate immune system that communicates and effectively primes the adaptive immune system was termed "complement" by Ehrlich to reflect its complementarity to antibodies having previously been described as "alexine" (i.e protective component of serum) by Buchner and Bordet. It has been established that complement is not solely produced systemically but may have origin in different tissues where it can influence organ specific functions that may affect the outcome of transplanted organs. This review looks at the role of complement in particular to kidney transplantation. We look at current literature to determine whether blockade of the peripheral or central compartments of complement production may prevent ischaemic reperfusion injury or rejection in the transplanted organ. We also review new therapeutics that have been developed to inhibit components of the complement cascade with varying degrees of success leading to an increase in our understanding of the multiple triggers of this complex system. In addition, we consider whether biomarkers in this field are effective markers of disease or treatment.

Ex-vivo liver perfusion for organ preservation: Recent advances in the field

Liver transplantation is the optimal treatment for end-stage liver disease but is limited by the severe shortage of donor organs. This shortage has prompted increased utilization of marginal grafts from DCD and extended criteria donors, which poorly tolerate cold storage in comparison to standard criteria grafts. Ex-vivo liver perfusion (EVLP) technology has emerged as a potential alternative to cold storage for organ preservation, but there is no consensus regarding the optimal temperature or conditions for EVLP. Herein, we review recent advances in both pre-clinical and clinical studies, organized by perfusion temperature (hypothermic, subnormothermic, normothermic).

Extracorporeal Hypothermic Perfusion Device for Intestinal Graft Preservation to Decrease Ischemic Injury During Transportation

INTRODUCTION

The small intestine is one of the most ischemia-sensitive organs used in transplantation. To better preserve the intestinal graft viability and decrease ischemia-reperfusion injury, a device for extracorporeal perfusion was developed. We present the results for the first series of perfused human intestine with an intestinal perfusion unit (IPU).

METHODS

Five human intestines were procured for the protocol. (1) An experimental segment was perfused by the IPU delivering cold preservation solution to the vascular and luminal side continually at 4 ºC for 8 h. (2) Control (jejunum and ileum) segments were preserved in static cold preservation. Tissue samples were obtained for histopathologic grading according to the Park/Chiu scoring system (0 = normal, 8 = transmural infarction).

RESULTS

Jejunal experimental segments scored 2.2 with the Park/Chiu system compared to the control segments, which averaged 3.2. Overall scoring for ileum experimental and control segments was equal with 1.6.

CONCLUSION

This data presents proof of concept that extracorporeal intestinal perfusion is feasible. The evidence shows that the IPU can preserve the viability of human intestine, and histopathologic evaluation of perfused intestine is favorable. Our early results can eventually lead to expanding the possibilities of intestinal preservation.

Hypothermic Machine Perfusion Reduced Inflammatory Reaction by Downregulating the Expression of Matrix Metalloproteinase 9 in a Reperfusion Model of Donation After Cardiac Death

The exact mechanism by which hypothermic machine perfusion (HMP) improves the graft quality in kidney transplantation of donation after cardiac death (DCD) remains unclear. The aim of this study was to investigate the correlation between the expression of matrix metalloproteinase 9 (MMP-9) and inflammatory reaction in kidney ischemia-reperfusion (I/R) injury injury followed by cold storage (CS) or HMP model of DCD. New Zealand white rabbit kidneys were subjected to 35 min of warm ischemia and 1 h reperfusion, then preserved by either 1 h reperfusion (sham-operated group), 4 h CS or 4 h HMP in vivo. Kidneys were reperfused 24 h followed by further analysis. No treatment was given to rabbits in the normal control group. The expression of MMP-9, nuclear factor-κB (NF-κB), and MMP-2 mRNA were detected by real-time PCR (RT-PCR). MMP-9 was located by immunohistochemistry and immunofluorescence methods. Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), myeloperoxidase (MPO), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured by kits for each groups. Compared with the CS group, the expression of MMP-9 and NF-κB mRNA were downregulated in HMP group (P < 0.05). In contrast, expression of MMP-2 mRNA had no statistical significance between CS group and HMP group (P > 0.05). In normal control and sham-operated groups, a low level of MMP-9 expression was detected in glomeruli. However, positive signals of MMP-9 were mostly located in the tubulointerstitium and the vascular wall of CS and HMP groups. Expression of TNF-α, IL-6, MDA, and activity of MPO decreased while activity of SOD in the HMP group increased in contrast to the CS group (P < 0.05). In conclusion, inflammatory cytokines mediated MMP-9 expression through NF-κB band to MMP-9 promoter region, resulting in renal injury. Therefore, HMP reduced inflammatory reaction by downregulating the expression of MMP-9, which may be the mechanism of kidney protection in I/R injury.

Preventive Role of Endothelin Antagonist on Kidney Ischemia: Reperfusion Injury in Male and Female Rats

Background:

Renal ischemia/reperfusion injury (RIRI) is the most common cause of acute kidney injury. We tested the protective role of endothelin-1 receptor blocker; bosentan (BOS) in animal model of RIRI in two different genders.

Methods:

Male and female Wistar rats were assigned as sham operated (sham), control group (ischemia), and case group (ischemia + BOS) treated with BOS (50 mg/kg) 2 h before bilateral kidney ischemia induced by clamping renal vessels for 45 min followed by 24 h of renal reperfusion.

Results:

The RIRI significantly increased the serum levels of blood urea nitrogen and creatinine in both genders (P < 0.05). These values were significantly decreased by BOS in both genders. In male rats, the serum levels of malondialdehyde in the ischemia + BOS group were decreased significantly when compared with ischemia group (P < 0.05).

Conclusions:

BOS can be used in both genders to attenuate kidney ischemia injury possibly due to its effect in the renal vascular system.

Evaluation of hepatic vascular endothelial injury during liver storage by molecular detection and targeted contrast-enhanced ultrasound imaging

We hypothesized that lack of the high-energy phosphates during liver storage may potentially cause persistent injury to the vascular endothelium. Biopsies were obtained from livers obtained from beating heart human donors, stored either in the standard storage solution, that is, University of Wisconsin solution (UWS) or Celsior, and examined for various markers related to progressive endothelial injury. The expression of P2Y1 receptor, the major signal transduction machinery for adenosine triphosphate/adenosine diphosphate, decreased in hepatic vascular endothelial cells over time. Despite unaltered endothelial nitric oxide synthase (eNOS) levels, serine1177-phosphorylated eNOS, the active form of eNOS, progressively decreased with time. The production of nitric oxide enzyme decreased with time when liver tissues were examined in vitro. This also coincided with decreased interaction of eNOS with actin nucleating proteins like myristoylated alanine-rich C kinase substrate and Rac1, which plays a role in modulating the cytoskeleton and helps position eNOS in a favorable cytosolic position for active enzymatic activity. Conversely, the interaction of eNOS with caveolin1 was significantly increased 6 H after ex vivo storage. Finally, we demonstrated by targeted contrast-enhanced ultrasound that membrane-bound vascular cell adhesion molecule-1 in the hepatic vascular endothelial cell increased after 6 H of ex vivo storage. Overall, the results of this study provide evidence of a progressive hepatic vascular endothelial injury during the ex vivo storage. This may be a causative factor for ischemic cholangiopathy and delayed graft function post liver transplantation. © 2015 IUBMB Life, 68(1):51-57, 2015.

Hypothermic Machine Perfusion Decreases Renal Cell Apoptosis During Ischemia/Reperfusion Injury via the Ezrin/AKT Pathway

This study aimed to explore the potential mechanisms of hypothermic machine perfusion (HMP)-a more efficient way to preserve kidneys from donors after cardiac death than static cold storage (CS), then to provide the basis for further improving donor quality. Twelve healthy male New Zealand rabbits (12 weeks old, weighing 3.0 ± 0.3 kg) were randomly divided into two groups: the HMP group and CS group (n = 6). Rabbits' left kidney was subjected to 35 min of warm ischemic time by clamping the left renal pedicle and 1 h of reperfusion. The kidneys were then hypothermically (4-8°C) preserved in vivo for 4 h with HCA-II solution using HMP or CS methods. Then rabbits underwent a right nephrectomy and the kidney tissues were collected after 24 h of reperfusion. TUNEL staining was performed on paraffin sections to detect apoptosis, and the expressions of cleaved caspase-3, ezrin, AKT, and p-AKT in frozen kidney tissues were detected by Western blotting. The ezrin expression was further confirmed by immunohistochemistry analysis. The apoptosis rate and expression of cleaved caspase-3 in the HMP group were significantly lower than the CS group (P < 0.001 and P = 0.002), meanwhile the expression of cleaved caspase-3 in the HMP and CS groups was significantly increased compared with the normal group (P = 0.035 and P < 0.001), and the expression of ezrin and p-AKT in the HMP group was significantly higher than the CS group (P = 0.005, 0.014). HMP decreased the renal cell apoptosis rate during ischemia/reperfusion injury via the ezrin/AKT pathway.

Metabolomic analysis of perfusate during hypothermic machine perfusion of human cadaveric kidneys

BACKGROUND

The metabolic processes occurring within the preserved kidney during hypothermic machine perfusion (HMP) are not well characterized. The aim of this study was to use nuclear magnetic resonance (NMR) spectroscopy to examine the metabolomic profile of HMP perfusate from human cadaveric kidneys awaiting transplantation and to identify possible discriminators between the profiles of kidneys with delayed graft function (DGF) and immediate graft function (IGF).

METHODS

Perfusates from HMP kidneys were sampled at 45 min and 4 hr of preservation with the LifePort Kidney Transporter 1.0 (Organ Recovery Systems, Chicago, IL) using KPS-1. Prepared samples underwent 1-D Proton-NMR spectroscopy, and resultant spectra were analyzed. Clinical parameters were collected prospectively.

RESULTS

Perfusate of 26 transplanted cadaveric kidneys was analyzed; 19(73%) with IGF and 7(27%) with DGF. Glucose concentrations were significantly lower in DGF kidneys compared to those with IGF at both 45 min (7.772 vs. 9.459 mM, P = 0.006) and 4 hr (8.202 vs. 10.235 mM, P = 0.003). Concentrations of inosine and leucine were significantly different between DGF and IGF kidneys at 45 min (0.002 vs. 0.013 mM, P = 0.009 and 0.011 vs. 0.006 mM, P = 0.036), and gluconate levels were also significantly different between DGF and IGF kidneys at 4 hr (49.099 vs. 59.513 mM, P = 0.009).

CONCLUSION

Significant metabolic activity may be occurring in kidneys during HMP. The NMR spectroscopy of the perfusate can identify differences in the metabolomic profiles of DGF and IGF kidneys that might have a predictive role in viability assessment. Modification of harmful metabolic processes may improve outcomes for HMP kidneys.

A new method to measure intestinal secretion using fluorescein isothiocyanate-inulin in small bowel of rats

BACKGROUND

Small intestine ischemia can be seen in various conditions such as intestinal transplantation. To further understand the pathologic disruption in ischemia-reperfusion injury, we have developed a method to measure fluid changes in the intestinal lumen of rats.

METHODS

Two 10-cm rat intestine segments were procured, connected to the terminal apertures of a perfusion device, and continuously infused with 3 mL of HEPES solution (control solution) containing 50 μM of fluorescein isothiocyanate (FITC)-inulin. The perfusion device consists of concentric chambers that contain the perfused bowel segments, which are maintained at 37°C via H₂O bath. The individual chamber has four apertures as follows: two fill and/or drain the surrounding HEPES solution on the blood side of the tissue. The others provide flow of HEPES solution containing FITC-inulin through the lumens. The experimental intestine was infused with the same solution with 100 μM of Forskolin. A pump continuously circulated solutions at 6 mL/min. Samples were collected at 15-min intervals until 150 min and were measured by the nanoflourospectrometer.

RESULTS

A mean of 6-μM decrease in the FITC-inulin concentration in the Forskolin-treated experimental intestine was observed in comparison with that in the control intestine. The FITC-inulin count dilution in the experimental intestine is a result of an increase of fluid secretion produced by the effect of Forskolin, with P values <0.0001.

CONCLUSIONS

We demonstrate that it is possible to measure luminal fluid changes over time using our new modified perfusion system along with FITC-inulin to allow real-time determinations of fluid and/or electrolyte movement along the small intestine.

Does machine perfusion decrease ischemia reperfusion injury?

In 1990's, use of machine perfusion for organ preservation has been abandoned because of improvement of preservation solutions, efficient without perfusion, easy to use and cheaper. Since the last 15 years, a renewed interest for machine perfusion emerged based on studies performed on preclinical model and seems to make consensus in case of expanded criteria donors or deceased after cardiac death donations. We present relevant studies highlighted the efficiency of preservation with hypothermic machine perfusion compared to static cold storage. Machines for organ preservation being in constant evolution, we also summarized recent developments included direct oxygenation of the perfusat. Machine perfusion technology also enables organ reconditioning during the last hours of preservation through a short period of perfusion on hypothermia, subnormothermia or normothermia. We present significant or low advantages for machine perfusion against ischemia reperfusion injuries regarding at least one primary parameter: risk of DFG, organ function or graft survival.

Metabolic shift in liver: Correlation between perfusion temperature and hypoxia inducible factor-1α

AIM: To study at what temperature the oxygen carried by the perfusate meets liver requirements in a model of organ perfusion.

METHODS: In this study, we correlated hypoxia inducible factor (HIF)-1α expression to the perfusion temperature and the hepatic oxygen uptake in a model of isolated perfused rat liver. Livers from Wistar rats were perfused for 6 h with an oxygenated medium at 10, 20, 30 and 37 °C. Oxygen uptake was measured by an oxygen probe; lactate dehydrogenase activity, lactate release and glycogen were measured spectrophotometrically; bile flow was gravitationally determined; pH of the perfusate was also evaluated; HIF-1α mRNA and protein expression were analyzed by real time-polymerase chain reaction and ELISA, respectively.

RESULTS: Livers perfused at 10 and 20 °C showed no difference in lactate dehydrogenase release after 6 h of perfusion (0.96 ± 0.23 vs 0.93 ± 0.09 mU/min per g) and had lower hepatic damage as compared to 30 and 37 °C (5.63 ± 0.76 vs 527.69 ± 45.27 mU/min per g, respectively, Ps < 0.01). After 6 h, tissue ATP was significantly higher in livers perfused at 10 and 20 °C than in livers perfused at 30 and 37 °C (0.89 ± 0.06 and 1.16 ± 0.05 vs 0.57 ± 0.09 and 0.33 ± 0.08 nmol/mg, respectively, Ps < 0.01). No sign of hypoxia was observed at 10 and 20 °C, as highlighted by low lactate release respect to livers perfused at 30 and 37 °C (121.4 ± 12.6 and 146.3 ± 7.3 vs 281.8 ± 45.3 and 1094.5 ± 71.7 nmol/mL, respectively, Ps < 0.02), and low relative HIF-1α mRNA (0.40 ± 0.08 and 0.20 ± 0.03 vs 0.60 ± 0.20 and 1.47 ± 0.30, respectively, Ps < 0.05) and protein (3.72 ± 0.16 and 3.65 ± 0.06 vs 4.43 ± 0.41 and 6.44 ± 0.82, respectively, Ps < 0.05) expression.

CONCLUSION: Livers perfused at 10 and 20 °C show no sign of liver injury or anaerobiosis, in contrast to livers perfused at 30 and 37 °C.

Hypothermic machine preservation facilitates successful transplantation of "orphan" extended criteria donor livers

Hypothermic machine preservation (HMP) remains investigational in clinical liver transplantation. It is widely used to preserve kidneys for transplantation with improved results over static cold storage (SCS). At our center, we have used HMP in 31 adults receiving extended criteria donor (ECD) livers declined by the originating United Network for Organ Sharing region ("orphan livers"). These cases were compared to ECD SCS cases in a matched cohort study design. Livers were matched for donor age, recipient age, cold ischemic time, donor risk index and Model for End-Stage Liver Disease (MELD) score. HMP was performed for 3-7 h at 4-8 °C using our previously published protocol. Early allograft dysfunction rates were 19% in the HMP group versus 30% in the control group (p = 0.384). One-year patient survival was 84% in the HMP group versus 80% in the SCS group (p = NS). Post hoc analysis revealed significantly less biliary complications in the HMP group versus the SCS group (4 vs. 13, p = 0.016). Mean hospital stay was significantly shorter in the HMP group (13.64 ± 10.9 vs. 20.14 ± 11.12 days in the SCS group, p = 0.001). HMP provided safe and reliable preservation in orphan livers transplanted at our center.

Liver transplantation with grafts obtained after cardiac death-current advances in mastering the challenge

The scarcity of donor livers has increased the interest in donation after cardiac death (DCD) as an additional pool to expand the availability of organs. However, the initial results of liver transplantation with DCD grafts have been suboptimal due to an increased rate of complications, as well as decreased graft survival. These challenges have led to many developments in DCD donation outcome, as well as basic and translational research. In this article we review the unique characteristics of DCD donors, nuances of DCD organ procurement, the effect of prolonged warm and cold ischemia times, and discuss major studies that compared DCD to donation after brain death liver transplantation, in terms of outcomes and complications. We also review the different methods of donor treatment that has been applied to ameliorate DCD organ outcome, and we discuss the role of machine perfusion techniques in organ reconditioning. We discuss the two major perfusion models, namely, hypothermic machine perfusion and normothermic machine perfusion; we compare both methods, and delineate their major differences.

Effects of transplantation with marrow-derived mesenchymal stem cells modified with survivin on renal ischemia-reperfusion injury in mice

PURPOSE

To determine whether renal injury induced by ischemia-reperfusion (I/R) could be further improved by mesenchymal stem cells (MSCs) modified with survivin.

MATERIALS AND METHODS

Lentiviral vectors were used to introduce the survivin gene into MSCs and the MSCs modified with survivin were transplanted into established mice models of renal I/R injury. Seven days later, serum creatinine (Scr) and blood urea nitrogen (BUN) were measured and the survival of MSCs was determined. Hematoxylin and eosin staining was used to assess renal pathological change. The expressions of hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) in kidney tissue were detected by western blot.

RESULTS

Mice transplanted with survivin-modified MSCs demonstrated good renal function recovery with Scr and BUN decline close to normal levels and improvement of renal I/R injury repair. Additionally, the survival of transplanted MSCs modified with survivin was enhanced and the expression of HGF and bFGF in kidney tissue was increased.

CONCLUSION

Our results demonstrated that MSCs engineered to over-express survivin could enhance their therapeutic effect on renal I/R injury in mice, probably via the improved survival ability of MSCs and increased production of protective cytokines in ischemic tissue.

Role of hypothermic machine perfusion in liver transplantation

Machine liver perfusion has significantly evolved during the last ten years to optimize extended criteria liver grafts and to address the worldwide organ shortage. This review gives an overview on available ex vivo and in vivo data on hypothermic machine liver perfusion. We discuss also possible protective pathways and show most recent clinical applications of hypothermic machine liver perfusion in human.

The benefits of hypothermic machine perfusion are enhanced with Vasosol and α-tocopherol in rodent donation after cardiac death livers

The use of hypothermic machine perfusion (HMP) has recently been used to show an improvement in both standard and extended criteria donor liver grafts but creating a more dynamic preservation environment that can be supplemented with a variety of additives to aid in cold temperature metabolism and vasodilatation. Increasing the benefits of HMP, we explore the use of α-tocopherol in reducing inflammatory markers and apoptotic pathways to reduce the incidence of preservation injury. We explored the use of a donation after cardiac death (DCD) rodent model to test the additive benefits of α-tocopherol in HMP. The addition of α-tocopherol reduced the level of alanine aminotransferase (ALT) over the course of reperfusion as well, reduced the levels of inflammatory cytokines within a 90 minute reperfusion biopsy. Further benefit was seen with α-tocopherol through the reduction of the level of caspase 3/7 in the circulation, shown to be a result of the reduction of the levels of Cytochrome C mRNA. Liver perfusion with Vasosol® and HMP could benefit further from the addition of α-tocopherol to existing formulations of Vasosol®.

Efficacy and safety of phenylephrine in the management of low systolic blood pressure after renal transplantation

BACKGROUND

Phenylephrine can be used to treat postoperative hypotension after renal transplantation. However, its effect on the renal allograft is unknown. We evaluated the safety and efficacy of this approach.

STUDY DESIGN

A retrospective cohort study of 307 renal transplant recipients between November 2005 and October 2011 was conducted, including 75 who required phenylephrine, 46 of whom were deceased donors renal transplant (DDRT) recipients and 29 who were living donor transplant (LDRT) recipients. These were compared with 75 controls matched by sex, age, type of transplant, and etiology of renal failure. The primary outcome was rate of delayed graft function (DGF). The following statistical tools were used: paired t-test for continuous data, McNemar's test for categorical data, and a nonlinear mixed decay model for change in serum creatinine (Cr).

RESULTS

Of 46 DDRT recipients who required phenylephrine, 17 developed DGF compared with 10 matched controls (relative risk [RR] 2.9, CI 1.4 to 6.0, p = 0.0040). Only one LDRT recipient required hemodialysis (DGF). No differences were noted in the number of hemodialysis treatments required (mean 2.7 in treatment group vs 3.4 in control). No significant differences were observed between phenylephrine and control groups in renal function on postoperative days 30, 90, and 365 Cr or graft survival. The immediate postoperative normalization of Cr was slower in the DDRT phenylephrine group compared with DDRT controls (p < 0.0001), but no difference in Cr was noted before discharge (p = 0.49).

CONCLUSIONS

Although there is a brief association between phenylephrine administration and a slower rate of transplanted kidney recovery, there is no clinically or statistically significant impaired outcome in the phenylephrine group at time of discharge. Administration of phenylephrine to support low blood pressure after renal transplant appears safe.