Composition of ex vivo perfusion solutions and kinetics define differential cytokine/chemokine secretion in a porcine cardiac arrest model of lung preservation

Background

Ex vivo lung perfusion (EVLP) uses continuous normothermic perfusion to reduce ischemic damage and to improve post-transplant outcomes, specifically for marginal donor lungs after the donation after circulatory death. Despite major efforts, the optimal perfusion protocol and the composition of the perfusate in clinical lung transplantation have not been identified. Our study aims to compare the concentration levels of cytokine/chemokine in different perfusion solutions during EVLP, after 1 and 9 h of cold static preservation (CSP) in a porcine cardiac arrest model, and to correlate inflammatory parameters to oxygenation capacities.

Methods

Following cardiac arrest, the lungs were harvested and were categorized into two groups: immediate (I-EVLP) and delayed EVLP (D-EVLP), after 1 and 9 h of CSP, respectively. The D-EVLP lungs were perfused with either Steen or modified Custodiol-N solution containing only dextran (CD) or dextran and albumin (CDA). The cytokine/chemokine levels were analyzed at baseline (0 h) and after 1 and 4 h of EVLP using Luminex-based multiplex assays.

Results

Within 4 h of EVLP, the concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-1α, and IL-1β increased significantly (P < 0.05) in all experimental groups. The CD solution contained lower concentration levels of TNF-α, IL-6, CXCL8, IFN-γ, IL-2, IL-12, IL-10, IL-4, IL-1RA, and IL-18 (P < 0.05) compared with those of the Steen solution. The concentration levels of all experimental groups have correlated negatively with the oxygenation capacity values (P < 0.05). Protein concentration levels did not reach statistical significance for I-EVLP vs. D-EVLP and CD vs. CDA solutions.

Conclusion

In a porcine cardiac arrest model, a longer period of CSP prior to EVLP did not result in an enhanced protein secretion into perfusates. The CD solution reduced the cytokine/chemokine secretion most probably by iron chelators and/or by the protecting effects of dextran. Supplementing with albumin did not further reduce the cytokine/chemokine secretion into perfusates. These findings may help in optimizing the preservation procedure of the lungs, thereby increasing the donor pool of organs.

Antagonist of sphingosine 1-phosphate receptor 3 reduces cold injury of rat donor hearts for transplantation

Cold storage is widely used to preserve an organ for transplantation; however, a long duration of cold storage negatively impacts graft function. Unfortunately, the mechanisms underlying cold exposure remain unclear. Based on the sphingosine-1-phosphate (S1P) signal involved in cold tolerance in hibernating mammals, we hypothesized that S1P signal blockage reduces damage from cold storage. We used an in vitro cold storage and rewarming model to evaluate cold injury and investigated the relationship between cold injury and S1P signal. Compounds affecting S1P receptors (S1PR) were screened for their protective effect in this model and its inhibitory effect on S1PRs was measured using the NanoLuc Binary Technology (NanoBiT)-β-arrestin recruitment assays. The effects of a potent antagonist were examined via heterotopic abdominal rat heart transplantation. The heart grafts were transplanted after 24-hour preservation and evaluated on day 7 after transplantation. Cold injury increased depending on the cold storage time and was induced by S1P. The most potent antagonist strongly suppressed cold injury consistent with the effect of S1P deprivation in vitro. In vivo, this antagonist enabled 24-hour preservation, and drastically improved the beating score, cardiac size, and serological markers. Pathological analysis revealed that it suppressed the interstitial edema, inflammatory cell infiltration, myocyte lesion, TUNEL-positive cell death, and fibrosis. In conclusion, S1PR3 antagonist reduced cold injury, extended the cold preservation time, and improved graft viability. Cold preservation strategies via S1P signaling may have clinical applications in organ preservation for transplantation and contribute to an increase in the donor pool.

Current intraoperative storage and handling practices of autologous bypass conduit: A survey of the royal australasian college of surgeons

During bypass surgery for peripheral arterial occlusive disease and ischaemic heart disease, autologous graft conduit including great saphenous veins and radial arteries are frequently stored in solution. Endothelial damage adversely affects the performance and patency of autologous bypass grafts, and intraoperative graft storage solutions have been shown to influence this process. The distribution of storage solutions currently used amongst Cardiothoracic and Vascular Surgeons from Australia and New Zealand is not well defined in the literature. The aim of this study was to determine current practices regarding autologous graft storage and handling amongst this cohort of surgeons, and discuss their potential relevance in the context of early graft failure. From this survey, the most frequently used storage solutions were heparinized saline for great saphenous veins, and pH-buffered solutions for radial arteries. Duration of storage was 30–45 min for almost half of respondents, although responses to this question were limited. Further research is required to investigate whether ischaemic endothelial injury generates a prothrombotic state, whether different storage media can alter this state, and whether this is directly associated with clinical outcomes of interest such as early graft failure.

Gluconate-Lactobionate-Dextran Perfusion Solutions Attenuate Ischemic Injury and Improve Function in a Murine Cardiac Transplant Model

Static cold storage is the cheapest and easiest method and current gold standard to store and preserve donor organs. This study aimed to compare the preservative capacity of gluconate-lactobionate-dextran (Unisol) solutions to histidine-tryptophan-ketoglutarate (HTK) solution. Murine syngeneic heterotopic heart transplantations (Balb/c-Balb/c) were carried out after 18 h of static cold storage. Cardiac grafts were either flushed and stored with Unisol-based solutions with high-(UHK) and low-potassium (ULK) ± glutathione, or HTK. Cardiac grafts were assessed for rebeating and functionality, histomorphologic alterations, and cytokine expression. Unisol-based solutions demonstrated a faster rebeating time (UHK 56 s, UHK + Glut 44 s, ULK 45 s, ULK + Glut 47 s) compared to HTK (119.5 s) along with a better contractility early after reperfusion and at the endpoint on POD 3. Ischemic injury led to a significantly increased leukocyte recruitment, with similar degrees of tissue damage and inflammatory infiltrate in all groups, yet the number of apoptotic cells tended to be lower in ULK compared to HTK. In UHK- and ULK-treated animals, a trend toward decreased expression of proinflammatory markers was seen when compared to HTK. Unisol-based solutions showed an improved preservative capacity compared with the gold standard HTK early after cardiac transplantation. Supplemented glutathione did not further improve tissue-protective properties.

CXCR4 blockade reduces the severity of murine heart allograft rejection by plasmacytoid dendritic cell-mediated immune regulation

Allograft-specific regulatory T cells (T_reg cells) are crucial for long-term graft acceptance after transplantation. Although adoptive T_reg cell transfer has been proposed, major challenges include graft-specificity and stability. Thus, there is an unmet need for the direct induction of graft-specific T_reg cells. We hypothesized a synergism of the immunotolerogenic effects of rapamycin (mTOR inhibition) and plerixafor (CXCR4 antagonist) for T_reg cell induction. Thus, we performed fully-mismatched heart transplantations and found combination treatment to result in prolonged allograft survival. Moreover, fibrosis and myocyte lesions were reduced. Although less CD3⁺ T cell infiltrated, higher T_reg cell numbers were observed. Noteworthy, this was accompanied by a plerixafor-dependent plasmacytoid dendritic cells-(pDCs)-mobilization. Furthermore, in vivo pDC-depletion abrogated the plerixafor-mediated T_reg cell number increase and reduced allograft survival. Our pharmacological approach allowed to increase T_reg cell numbers due to pDC-mediated immune regulation. Therefore pDCs can be an attractive immunotherapeutic target in addition to plerixafor treatment.

Anti-osteosarcoma effect of antiserum against cross antigen TPD52 between osteosarcoma and Trichinella spiralis

BACKGROUND

Trichinella spiralis (T. spiralis) is a parasite occurring worldwide that has been proven to have antitumour ability. However, studies on the antitumour effects of cross antigens between the tumour and T. spiralis or antibodies against cross antigens between tumours and T. spiralis are rare.

METHODS

To study the role of cross antigens between osteosarcoma and T. spiralis, we first screened the cDNA expression library of T. spiralis muscle larvae to obtain the cross antigen gene tumour protein D52 (TPD52), and prepared fusion protein TPD52 and its antiserum. The anti-osteosarcoma effect of the anti-TPD52 antiserum was studied using cell proliferation and cytotoxicity assays as well as in vivo animal models; preliminary data on the mechanism were obtained using western blot and immunohistochemistry analyses.

RESULTS

Our results indicated that TPD52 was mainly localized in the cytoplasm of MG-63 cells. Anti-TPD52 antiserum inhibited the proliferation of MG-63 cells and the growth of osteosarcoma in a dose-dependent manner. The tumour inhibition rate in the 100 μg treatment group was 61.95%. Enzyme-linked immunosorbent assay showed that injection of anti-TPD52 antiserum increased the serum levels of IFN-γ, TNF-α, and IL-12 in nude mice. Haematoxylin and eosin staining showed that anti-TPD52 antiserum did not cause significant pathological damage. Apoptosis of osteosarcoma cells was induced by anti-TPD52 antiserum in vivo and in vitro.

CONCLUSIONS

Anti-TPD52 antiserum exerts an anti-osteosarcoma effect by inducing apoptosis without causing histopathological damage.

Use of the new preservation solution Custodiol-MP for ex vivo reconditioning of kidney grafts

Organ shortage and the increasing use of extended criteria donor grafts for transplantation drives efforts for more efficient organ preservation strategies from simple cold storage toward dynamic organ reconditioning. The choice of a suitable preservation solution is of high relevance in different organ preservation or reconditioning situations. Custodiol-MP is a new machine perfusion solution giving the opportunity to add colloids according to organ requirements. The present study aimed to compare new Custodiol-MP with clinically established Belzer MPS solution. Porcine kidneys were ischemically predamaged and cold stored for 20 hours. Ex vivo machine reconditioning was performed either with Custodiol-MP (n = 6) or with Belzer MPS solution (n = 6) for 90 minutes with controlled oxygenated rewarming up to 20°C. Kidney function was evaluated using an established ex vivo reperfusion model. In this experimental setting, differences between both types of perfusion solutions could not be observed. Machine perfusion with Custodiol-MP resulted in higher creatinine clearance (7.4 ± 8.6 mL/min vs. 2.8 ± 2.5 mL/min) and less TNC perfusate levels (0.22 ± 0.25 ng/mL vs. 0.09 ± 0.08 ng/mL), although differences did not reach significance. For short-term kidney perfusion Custodiol-MP is safe and applicable. Particularly, the unique feature of flexible colloid supplementation makes the solution attractive in specific experimental and clinical settings.

A novel histidine-tryptophan-ketoglutarate formulation ameliorates intestinal injury in a cold storage and ex vivo warm oxygenated reperfusion model in rats

AIM

The present study aims to evaluate protective effects of a novel histidine-tryptophan-ketoglutarate solution (HTK-N) and to investigate positive impacts of an additional luminal preservation route in cold storage-induced injury on rat small bowels.

METHODS

Male Lewis rats were utilized as donors of small bowel grafts. Vascular or vascular plus luminal preservation were conducted with HTK or HTK-N and grafts were stored at 4°C for 8 h followed by ex vivo warm oxygenated reperfusion with Krebs-Henseleit buffer for 30 min. Afterwards, intestinal tissue and portal vein effluent samples were collected for evaluation of morphological alterations, mucosal permeability and graft vitality.

RESULTS

The novel HTK-N decreased ultrastructural alterations but otherwise presented limited effect on protecting small bowel from ischemia-reperfusion injury in vascular route. However, the additional luminal preservation led to positive impacts on the integrity of intestinal mucosa and vitality of goblet cells. In addition, vascular plus luminal preservation route with HTK significantly protected the intestinal tissue from edema.

CONCLUSION

HTK-N protected the intestinal mucosal structure and graft vitality as a luminal preservation solution. Additional luminal preservation route in cold storage was shown to be promising.

HTK-N: Modified Histidine-Tryptophan-Ketoglutarate Solution-A Promising New Tool in Solid Organ Preservation

To ameliorate ischemia-induced graft injury, optimal organ preservation remains a critical hallmark event in solid organ transplantation. Although numerous preservation solutions are in use, they still have functional limitations. Here, we present a concise review of a modified Histidine-Tryptophan-Ketoglutarate (HTK) solution, named HTK-N. Its composition differs from standard HTK solution, carrying larger antioxidative capacity and providing inherent toxicity as well as improved tolerance to cold aiming to attenuate cold storage injury in organ transplantation. The amino acids glycine, alanine and arginine were supplemented, N-acetyl-histidine partially replaced histidine, and aspartate and lactobionate substituted chloride. Several in vitro studies confirmed the superiority of HTK-N in comparison to HTK, being tested in vivo in animal models for liver, kidney, pancreas, small bowel, heart and lung transplantation to adjust ingredients for required conditions, as well as to determine its innocuousness, applicability and potential advantages. HTK-N solution has proven to be advantageous especially in the preservation of liver and heart grafts in vivo and in vitro. Thus, ongoing clinical trials and further studies in large animal models and consequently in humans are inevitable to show its ability minimizing ischemia-induced graft injury in the sequel of organ transplantation.

Cold Storage Injury to Rat Small-bowel Transplants-Beneficial Effect of a Modified HTK Solution

BACKGROUND

The small bowel is prone to ischemic injury during transport before transplantation, an injury that endangers the recipient patient. The small-bowel mucosal microcirculation in particular appears to be highly sensitive to injury. Current preservation solutions such as histidine-tryptophan-ketoglutarate (HTK) solution provide some protection to the graft. However, these were developed decades ago and do not address several critical processes, such as hypoxia-induced membrane pores and free radical-mediated hypothermic injury.

METHODS

To protect the graft from cold ischemic injury, we implemented a modified HTK solution here, including glycine, alanine, and iron chelators in a heterotopic, syngeneic small-bowel transplantation model of the rat. The effects of the modified solution and its major components were compared against the conventional HTK solution using intravital microscopy in the early reperfusion period.

RESULTS

The amino acid glycine, added to HTK solution, slightly improved mucosal perfusion. Both, the modified base solution (without iron chelators) and iron chelators increased functional capillary density of the mucosa during the early reperfusion period. The complete modified solution (with glycine, alanine, and iron chelators) significantly increased the perfusion index, functional capillary density of the mucosa, and red blood cell velocity in the grafts after reperfusion in comparison with the grafts preserved with HTK.

CONCLUSIONS

The modified preservation solution improved the microcirculation of the transplants and needs detailed evaluation in further models of small-bowel transplantation.

Mitochondrial transplantation prolongs cold ischemia time in murine heart transplantation

BACKGROUND

Cold ischemia time (CIT) causes ischemia‒reperfusion injury to the mitochondria and detrimentally effects myocardial function and tissue viability. Mitochondrial transplantation replaces damaged mitochondria and enhances myocardial function and tissue viability. Herein we investigated the efficacy of mitochondrial transplantation in enhancing graft function and viability after prolonged CIT.

METHODS

Heterotopic heart transplantation was performed in C57BL/6J mice. Upon heart harvesting from C57BL/6J donors, 0.5 ml of either mitochondria (1 × 10⁸ in respiration buffer; mitochondria group) or respiration buffer (vehicle group) was delivered antegrade to the coronary arteries via injection to the coronary ostium. The hearts were excised and preserved for 29 ± 0.3 hours in cold saline (4°C). The hearts were then heterotopically transplanted. A second injection of either mitochondria (1 × 10⁸) or respiration buffer (vehicle) was delivered antegrade to the coronary arteries 5 minutes after transplantation. Grafts were analyzed for 24 hours. Beating score, graft function, and tissue injury were measured.

RESULTS

Beating score, calculated ejection fraction, and shortening fraction were significantly enhanced (p < 0.05), whereas necrosis and neutrophil infiltration were significantly decreased (p < 0.05) in the mitochondria group as compared with the vehicle group at 24 hours of reperfusion. Transmission electron microscopy showed the presence of contraction bands in vehicle but not in mitochondria grafts.

CONCLUSIONS

Mitochondrial transplantation prolongs CIT to 29 hours in the murine heart transplantation model, significantly enhances graft function, and decreases graft tissue injury. Mitochondrial transplantation may provide a means to reduce graft failure and improve transplantation outcomes after prolonged CIT.

Ischemia/reperfusion injury in vascularized tissue allotransplantation: tissue damage and clinical relevance

PURPOSE OF REVIEW

Ischemia and reperfusion injury (IRI) in vascularized tissue allotransplantation (VCA) remain largely undefined. Because VCA is comprised of different tissues, the sensitivity towards IRI may not be uniform. We, herein, attempt to address mechanistic aspects of IRI in VCA and provide a summary on potential technologies and targets for amelioration or treatment of IRI in this novel field.

RECENT FINDINGS

IRI results in a loosened architecture of musculature, hypertrophic, centrally located cell nuclei as well as a high degree of neovascularization. Mitochondria in muscle tissue show a high degree of degeneration after prolonged ischemia whereas the ultrastructure remains normal after short cold ischemia time (CIT). Muscle cell necrosis accompanied by a diffuse inflammatory infiltrate and vasculopathy of small vessels is observed after 30 h of CIT. Nerves revealed a high degree of separation and vacuolization of myelin lamellae because of Wallerian degeneration. Approaches to minimize IRI include use of novel preservation solutions, administration of antioxidative and anti-inflammatory molecules/drugs as well as the implementation of machine perfusion in the setting of VCA.

SUMMARY

Hand and face transplantations are logistically challenging procedures. Optimal planning and a highly congruent and motivated team are key to keep ischemia times to a minimum. In addition to pharmacological approaches, machine perfusion seems promising to help circumvent logistic problems and expand the donor pool in VCA.

Critical Ischemia Times and the Effect of Novel Preservation Solutions HTK-N and TiProtec on Tissues of a Vascularized Tissue Isograft

BACKGROUND

We herein investigate critical ischemia times and the effect of novel preservation solutions such as new histidine-tryptophan-ketoglutarate (HTK-N) and TiProtec on the individual tissues of a rat limb isograft.

METHODS

Orthotopic hind-limb transplantations were performed in male Lewis rats after 2 hours, 6 hours, or 10 hours of cold ischemia (CI). Limbs were flushed and stored in HTK-N, TiProtec, HTK, or saline solution. Muscle, nerve, vessel, skin, and bone samples were procured on day 10 for histology, immunohistochemistry, confocal and electron microscopy, and quantitative real-time polymerase chain reaction analysis.

RESULTS

Histomorphology of the muscle showed a mainly perivascular inflammatory infiltrate, fibrotic degeneration, and neovascularization after 6 hours and 10 hours of CI. However, centrally aligned nuclei observed in muscle fibers suggest for muscle regeneration in these samples. In addition to Wallerian degeneration, nerve injury was significantly aggravated (P = 0.032) after prolonged CI. Proinflammatory and regulatory cytokines were most significantly upregulated after 2-hour CI. Our data suggest no superiority of novel perfusates HTK-N and TiProtec in terms of tissue preservation, compared with HTK and saline.

CONCLUSIONS

Limiting CI time for less than 6 hours is the most significant factor to reduce tissue damage in vascularized tissue transplantation. Signs of muscle regeneration give rise that ischemic muscle damage in limb transplantation might be reversible to a certain extent.

Characterization of injury in isolated rat proximal tubules during cold incubation and rewarming

Organ shortage leads to an increased utilization of marginal organs which are particularly sensitive to storage-associated damage. Cold incubation and rewarming-induced injury is iron-dependent in many cell types. In addition, a chloride-dependent component of injury has been described. This work examines the injury induced by cold incubation and rewarming in isolated rat renal proximal tubules. The tissue storage solution TiProtec^® and a chloride-poor modification, each with and without iron chelators, were used for cold incubation. Incubation was performed 4°C for up to 168 h, followed by rewarming in an extracellular buffer (3 h at 37°C). After 48, 120 and 168 h of cold incubation LDH release was lower in solutions containing iron chelators. After rewarming, injury increased especially after cold incubation in chelator-free solutions. Without addition of iron chelators LDH release showed a tendency to be higher in chloride-poor solutions. Following rewarming after 48 h of cold incubation lipid peroxidation was significantly decreased and metabolic activity was tendentially better in tubules incubated with iron chelators. Morphological alterations included mitochondrial swelling and fragmentation being partially reversible during rewarming. ATP content was better preserved in chloride-rich solutions. During rewarming, there was a further decline of ATP content in the so far best conditions and minor alterations under the other conditions, while oxygen consumption was not significantly different compared to non-stored control tubules. Results show an iron-dependent component of preservation injury during cold incubation and rewarming in rat proximal renal tubules and reveal a benefit of chloride for the maintenance of tubular energy state during cold incubation.

Prolonged Mouse Cardiac Graft Cold Storage via Attenuating Ischemia-Reperfusion Injury Using a New Antioxidant-Based Preservation Solution

BACKGROUND

One of the major events in ischemia-reperfusion (I/R)-induced heart injury in cardiac transplantation is the generation of reactive oxygen species. We hypothesized that a novel preservation solution called SBI-SEIIKU II (SS-II) contains 3 antioxidant reagents: L-cysteine, glycine, ascorbic acid/ascorbic acid-2-phosphate magnesium, which can block the generation of reactive oxygen species to result in a prolongation of the cold storage time via attenuating I/R injury.

METHODS

C57BL/6CrSlc(B6) mice underwent syngeneic mice heterotopic heart transplantation, and the animals were derived into 3 groups: recipients with nonpreserved grafts (control group), recipients with grafts preserved in histidine-tryptophan-ketoglutarate (HTK) for 24 and 48 hours (HTK group), and recipients with grafts preserved in SS-II for 24 and 48 hours (SS-II group).

RESULTS

After 48 hours of preservation, there were no grafts that survived in the HTK group; however, the SS-II group had a high survival rate. After 24 hours of preservation, SS-II decreased the oxidative damage, myocardial apoptosis, and the infiltration of macrophages and neutrophils in the cardiac grafts in the early phase and suppressed the development of myocardial fibrosis in long-term grafts compared with HTK.

CONCLUSIONS

The SS-II prolongs the acceptable cold storage time and protects the myocardium from I/R injury via inhibiting oxidative stress-associated damage. We believe that this novel preservation solution may be simple and safe for use in the clinical transplantation field.

Influence of a modified preservation solution in kidney transplantation: A comparative experimental study in a porcine model

BACKGROUND/OBJECTIVE

Currently, due to lack of optimal donors, more marginal organs are transplanted. Therefore, there is a high interest to ameliorate preischemic organ preservation, especially for critical donor organs. In this regard, a new histidine-tryptophane ketoglutarate (HTK-N) solution has been designed and its protective efficacy was compared with the standard preservation solutions-University of Wisconsin solution and standard HTK or Custodiol (Bretschneider's solution).

METHODS

Seventy-two landrace pigs were included into the study, as donors and recipients. The donor kidneys were perfused during explantation with cold University of Wisconsin solution (n = 12), standard HTK (n = 12), or HTK-N solutions (n = 12), kept in the respective preservation solution at 4°C for 30 hours, implanted in the recipient pigs, and reperfused. The pigs survived in daily control for 7 days. The serum creatinine and blood urea nitrogen were assessed in pre- and postreperfusion phase on the 3^rd day and 7^th day posttransplantation. Additionally, tissue samples were taken to analyze the histopathological degree of tubular injury and regeneration before and after reperfusion.

RESULTS

The three preservation groups were comparable in age, body weight, and hemodynamic parameters. According to statistical proof, they differed in none of the control parameters.

CONCLUSION

Although the new preservation HTK solution is in several points a well-thought-out modification of the standard HTK solution, its preservation efficacy, at least for kidney preservation in a pig model for 30 hours, seems to be comparable to the current used solutions. A real advantage, however, could be confirmed in clinical settings, where marginal organs may influence the clinical outcome.

Influence of oxygen concentration during hypothermic machine perfusion on porcine kidneys from donation after circulatory death

BACKGROUND

Hypothermic machine perfusion (HMP) for preservation led to compelling success for outcomes of renal transplantation. Application of different concentrations of oxygen during renal HMP has not been systematically analyzed. This study investigates the aspects of renal function and morphology in dependence of oxygen concentrations during HMP in a porcine donation after circulatory death model.

METHODS

After 30 min of warm ischemia, porcine kidneys were randomly assigned to preservation for 21 hr by HMP without oxygenation (HMPnoox), oxygenated HMP with air (HMPair), or 100% oxygen (HMPox100%). Afterward, kidneys were reperfused for 2 hr in an ex vivo model for assessment of function and integrity.

RESULTS

Application of HMPox100% led to significantly increased blood flow during reperfusion compared to HMPnoox. Preservation by HMPox100% led to a doubling of creatinine clearance after 90 and 120 min of reperfusion (13.4 and 12.0 mL/min) compared to preservation by HMPnoox (7.3 and 7.7 mL/min; P=0.01). Oxygenated HMP with air led to results between the two other groups. Fractional excretion of sodium demonstrated a strong tendency of higher values after HMPnoox compared to HMPox100% (P=0.096) and HMPair (P=0.09). Analysis of structural integrity during reperfusion demonstrated significantly higher values of lactate dehydrogenase resembling cell damage (P=0.02), higher values of gamma-glutamyl-transferase (gGT) resembling tubulus injury (P=0.048), and more pronounced tubular dilatation (P=0.02) after HMPnoox compared to HMPox100%.

CONCLUSION

The present study demonstrates that application of HMPox100% for kidneys from donations after circulatory death results in better renal function during early reperfusion compared to HMPnoox.

Custodiol-N, the novel cardioplegic solution reduces ischemia/reperfusion injury after cardiopulmonary bypass

BACKGROUNDS

On the basis of Custodiol preservation and cardioplegic solution a novel cardioplegic solution was developed to improve the postischemic cardiac and endothelial function. In this study, we investigated whether its reduced cytotoxicity and its ability to reduce reactive oxygen species generation during hypoxic condition have beneficial effects in a clinically relevant canine model of CPB.

METHODS

12 dogs underwent cardiopulmonary bypass with 60 minutes of hypothermic cardiac arrest. Dogs were divided into 2 groups: Custodiol (n = 6) and Custodiol-N (n = 6) (addition of L-arginin, N-α-acetyl-L-histidine and iron-chelators: deferoxamine and LK-614). Left ventricular hemodynamic variables were measured by a combined pressure-volume conductance catheter at baseline and after 60 minutes of reperfusion. Coronary blood flow, myocardial ATP content, plasma nitrate/nitrite and plasma myeloperoxidase levels were also determined.

RESULTS

The use of Custodiol-N cardioplegic solution improved coronary blood flow (58 ± 7 ml/min vs. 26 ± 3 ml/min) and effectively prevented cardiac dysfunction after cardiac arrest. In addition, the myocardial ATP content (12,8 ± 1,0 μmol/g dry weight vs. 9,5 ± 1,5 μmol/g dry weight) and plasma nitrite (1,1 ± 0,3 ng/ml vs. 0,5 ± 0,2 ng/ml) were significantly higher after application of the new cardioplegic solution. Furthermore, plasma myeloperoxidase level (3,4 ± 0,4 ng/ml vs. 4,3 ± 2,2 ng/ml) significantly decreased in Custodiol-N group.

CONCLUSIONS

The new HTK cardioplegic solution (Custodiol-N) improved myocardial and endothelial function after cardiopulmonary bypass with hypothermic cardiac arrest. The observed protective effects imply that the Custodiol-N could be the next generation cardioplegic solution in the protection against ischemia-reperfusion injury in cardiac surgery.

Subnormothermic machine perfusion for preservation of porcine kidneys in a donation after circulatory death model

Machine perfusion for preservation led to compelling success for the outcome of renal transplantation. Further refinements of methods to decrease preservation injury remain an issue of high interest. This study investigates functional and morphological aspects of kidneys preserved by subnormothermic (20 °C) machine perfusion (SNTM) compared with oxygenated hypothermic machine perfusion (HMPox) and cold storage (CS) in a donation after circulatory death (DCD) model. After 30 min of warm ischaemia, porcine kidneys were randomly assigned to preservation for 7 h by CS, HMPox or SNTM. Afterwards, kidneys were reperfused for 2 h with autologous blood in vitro for assessment of function and integrity. Application of SNTM for preservation led to significantly higher blood flow and urine output compared with both other groups. SNTM led to a twofold increased creatinine clearance compared with HMPox and 10-fold increased creatinine clearance compared with CS. Structural integrity was best preserved by SNTM. In conclusion, this is the first study on SNTM for kidneys from DCD donors. SNTM seems to be a promising preservation method with the potential to improve functional parameters of kidneys during reperfusion.

HTK-N, a modified HTK solution, decreases preservation injury in a model of microsteatotic rat liver transplantation

BACKGROUND

Ischemia/reperfusion injury is an obstacle especially in steatotic livers, including those with steatosis induced by acute toxic stress. Recently, a modified histidine-tryptophan-ketoglutarate (HTK) solution, HTK-N, has been developed. This solution contains N-acetylhistidine, amino acids, and iron chelators. This study was designed to test the effects of HTK-N on preservation injury to rat livers after acute toxic injury.

METHODS

Microvesicular steatosis was induced by a single dose of ethanol (8 g/kg BW). Livers were harvested and stored at 4 °C for 8 h with HTK or HTK-N before transplantation. Tissue and blood samples were taken at 1, 8, and 24 h after reperfusion to compare serum liver enzymes (aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase), standard histology, and immunohistochemistry for myeloperoxidase (MPO), caspase-3, and inducible nitric oxide synthase. Survival was compared after 1 week. For statistics, Analysis of Variance and t test were used.

RESULTS

HTK-N improved survival from 12.5% in HTK to 87.5% (p < 0.05). Furthermore, liver enzymes were decreased to 2-75% of HTK values (p < 0.05). Necrosis and leukocyte infiltration and MPO, caspase-3, and iNOS expression after transplantation were decreased (p < 0.05).

CONCLUSIONS

This study demonstrates that HTK-N protects liver grafts with microvesicular steatosis caused by acute toxic injury from cold ischemic injury better than standard HTK most likely via inhibition of hypoxic injury and oxidative stress and amelioration of the inflammatory reaction occurring upon reperfusion.

Reduction of chronic graft injury with a new HTK-based preservation solution in a murine heart transplantation model

OBJECTIVE

Aim of this study was to evaluate a new histidine-tryptophan-ketoglutarate (HTK)-based preservation solution on chronic isograft injury in comparison to traditional HTK solution.

METHODS

Hearts of C57BL/6J (H-2b) mice were stored for 15 h in 0-4 °C cold preservation solution and then transplanted heterotopically into C57BL/6J (H-2b) mice. Three groups were evaluated: HTK, the base solution of a new preservation solution and hearts without cold ischemia (control). Time to restoration of heartbeat was measured (re-beating time). Strength of the heartbeat was palpated daily and scored on a 4-level scale (palpation score). Animals were sacrificed after 60 days of observation (24 h for TGF-β expression). The transplanted hearts were evaluated histologically for myocardial damage, vasculopathy and interstitial fibrosis. TGF-β expression was assessed immunohistologically. All investigators were blinded to the groups. ANOVA and LSD post hoc test were used for statistical analysis.

RESULTS

The re-beating time was significantly shorter in hearts stored in the new solution (10.3±2.6 min vs. HTK 14.2±4.1 min; p<0.05). The palpation score was significantly higher in hearts stored in the new solution (2.3±0.4 vs. HTK 1.6±0.5; p<0.01). Hearts stored in the new solution showed a lower myocardial injury score (1.8±0.2 vs. HTK 2.2±0.7), less interstitial fibrosis (4.8±1.9% vs. HTK 8.5±3.8%, p<0.05), less vasculopathy (14.7±6.9% vs. 22.0±23.2%; p=0.06) and lower TGF-β1-expression (6.6±1.4% vs. HTK 12.0±4.6%).

CONCLUSION

The new HTK-based solution reduces the chronic isograft injury. This protective effect is likely achieved through several modifications and supplements into the new solution like N-acetyl-L-histidine, glycine, alanine, arginine and sucrose.

Hydrogen as additive of HTK solution fortifies myocardial preservation in grafts with prolonged cold ischemia

BACKGROUND

Recent evidences indicated that hydrogen (H2) can attenuate organ transplantation induced cold ischemia/reperfusion (I/R) injury if administrated perioperatively. In this study we evaluated whether administrating H2 during the prolonged cold ischemia stage by adding it to Histidine-Tryptophan-Ketoglutarate (HTK) solution fortifies preservation for cardiac grafts.

METHODS

One hundred and twenty-eight Sprague-Dawley (SD) rats were equally randomized to four groups: three H2-rich HTK-treated groups with H2 of different concentrations and traditional HTK-treated group as the control group. Isolated hearts were mounted on the Langendorff apparatus for aerobic perfusion. Following baseline hemodynamic measurements, grafts were arrested and stored in HTK with or without H2 for 6h at 4°C. After this prolonged cold storage, grafts were reperfused and concerned parameters were examined.

RESULTS

Compared with the control group, preservation in H2-rich HTK significantly enhanced the percentage recovery of hemodynamic parameters, which was parallel to the diminished re-beating time and improved microscopic morphology of myocardium. Oxidative stress associated parameters including 8-hydroxy-2'-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) were decreased while myocardial superoxide dismutase (SOD) activity was preserved. Concentrations of inflammatory mediators including tumor necrosis factor-alpha (TNF-α) and Interleukin-6 (IL-6), percentage of TUNEL-positive cells, expression of pro-apoptotic molecule Bax, and caspase-3 activity were reduced while Bcl-2 mRNA and protein levels were up-regulated in H2-rich HTK groups. The protective effects of H2 were concentration dependent.

CONCLUSIONS

Hydrogen as additive of HTK solution fortifies HTK's preservation efficacy for cardiac grafts subjected to prolonged cold ischemia by inhibiting cold ischemia-induced up-regulation of oxidative stress, inflammation mediators, and apoptosis.

Improvement of the cold storage of isolated human hepatocytes

Increasing amounts of human hepatocytes are needed for clinical applications and different fields of research, such as cell transplantation, bioartificial liver support, and pharmacological testing. This demand calls for adequate storage options for isolated human liver cells. As cryopreservation results in severe cryoinjury, short-term storage is currently performed at 2-8°C in preservation solutions developed for the storage of solid organs. However, besides slowing down cell metabolism, cold also induces cell injury, which is, in many cell types, iron dependent and not counteracted by current storage solutions. In this study, we aimed to characterize storage injury to human hepatocytes and develop a customized solution for cold storage of these cells. Human hepatocytes were isolated from material obtained from partial liver resections, seeded in monolayer cultures, and, after a preculture period, stored in the cold in classical and new solutions followed by rewarming in cell culture medium. Human hepatocytes displayed cold-induced injury, resulting in >80% cell death (LDH release) after 1 week of cold storage in University of Wisconsin solution or cell culture medium and 3 h of rewarming. Cold-induced injury could be significantly reduced by the addition of the iron chelators deferoxamine and LK 614. Experiments with modified solutions based on the new organ preservation solution Custodiol-N showed that ion-rich variants were better than ion-poor variants, chloride-rich solutions better than chloride-poor solutions, potassium as main cation superior to sodium, and pH 7.0 superior to pH 7.4. LDH release after 2 weeks of cold storage in the thus optimized solution was below 20%, greatly improving cold storage of human hepatocytes. The results were confirmed by the assessment of hepatocellular mitochondrial membrane potential and functional parameters (resazurin reduction, glucagon-stimulated glucose liberation) and thus suggest the use of a customized hepatocyte storage solution for the cold storage of these cells.

Evaluation of functional and structural alterations in muscle tissue after short-term cold storage in a new tissue preservation solution

Storage of muscle preparations in vitro is required for the diagnosis of neuromuscular disorders and for electrophysiological tests. The current standard protocols for muscle storage or transport, i.e. placement on 0.9% NaCl-moistened gauze, lead to impaired function and structural alterations. For other tissues, however, improved preservation methods and solutions have recently been described. In this study, functional and structural alterations in the murine diaphragm were compared after storage on 0.9% NaCl-moistened gauze and after storage in different modifications of the new vascular preservation solution TiProtec®. Muscle force generation after nerve stimulation, histological parameters and ATP levels were investigated after 2.5 h of cold storage at 4°C in the different media and 0.5 h of rewarming at 25°C in Tyrode buffer. Murine diaphragms were injured during cold storage and rewarming, with the degree of the alteration being dependent on the type of solution used. There were no histological alterations and no caspase 3 activation in all groups. In contrast, diaphragms stored in the modified TiProtec solution showed markedly better performance concerning force generation after nerve stimulation (7.1 ± 1.1 cN · s) as well as higher ATP content (2.4 ± 0.7 μmol/g) and were superior to storage on 0.9% NaCl-moistened gauze (1.4 ± 0.4 cN · s; 0.3 ± 0.1 μmol/g). In conclusion, the modified TiProtec preservation solution showed promising results for short-term cold storage of murine diaphragms. For further evaluation, the transferability of these positive findings to storage conditions for muscles of other species, especially human muscle tissue, needs to be investigated.