Comparison of HTK and hypertonic citrate to intraarterial cooling in human non-heart-beating kidney donors

Assessing Kidney Graft Viability and Its Cells Metabolism during Machine Perfusion

Kidney transplantation is the golden treatment for end-stage renal disease. Static cold storage is currently considered the standard method of preservation, but dynamic techniques, such as machine perfusion (MP), have been shown to improve graft function, especially in kidneys donated by extended criteria donors and donation after circulatory death. With poor organ quality being a major reason for kidneys not being transplanted, an accurate, objective and reliable quality assessment during preservation could add value and support to clinicians’ decisions. MPs are emerging technologies with the potential to assess kidney graft viability and quality, both in the hypothermic and normothermic scenarios. The aim of this review is to summarize current tools for graft viability assessment using MP prior to implantation in relation to the ischemic damage.

The influence of perfusion solution on renal graft viability assessment

BACKGROUND

Kidneys from donors after cardiac or circulatory death are exposed to extended periods of both warm ischemia and intra-arterial cooling before organ recovery. Marshall's hypertonic citrate (HOC) and Bretschneider's histidine-tryptophan-ketoglutarate (HTK) preservation solutions are cheap, low viscosity preservation solutions used clinically for organ flushing. The aim of the present study was to evaluate the effects of these two solutions both on parameters used in clinical practice to assess organ viability prior to transplantation and histological evidence of ischemic injury after reperfusion.

METHODS

Rodent kidneys were exposed to post-mortem warm ischemia, extended intra-arterial cooling (IAC) (up to 2 h) with preservation solution and reperfusion with either Krebs-Hensleit or whole blood in a transplant model. Control kidneys were either reperfused directly after retrieval or stored in 0.9% saline. Biochemical, immunological and histological parameters were assessed using glutathione-S-transferase (GST) enzymatic assays, polymerase chain reaction and mitochondrial electron microscopy respectively. Vascular function was assessed by supplementing the Krebs-Hensleit perfusion solution with phenylephrine to stimulate smooth muscle contraction followed by acetylcholine to trigger endothelial dependent relaxation.

RESULTS

When compared with kidneys reperfused directly post mortem, 2 h of IAC significantly reduced smooth muscle contractile function, endothelial function and upregulated vascular cellular adhesion molecule type 1 (VCAM-1) independent of the preservation solution. However, GST release, vascular resistance, weight gain and histological mitochondrial injury were dependent on the preservation solution used.

CONCLUSIONS

We conclude that initial machine perfusion viability tests, including ischemic vascular resistance and GST, are dependent on the perfusion solution used during in situ cooling. HTK-perfused kidneys will be heavier, have higher GST readings and yet reduced mitochondrial ischemic injury when compared with HOC-perfused kidneys. Clinicians should be aware of this when deciding which kidneys to transplant or discard.

Kidney donation after cardiac death

There is continuing disparity between demand for and supply of kidneys for transplantation. This review describes the current state of kidney donation after cardiac death (DCD) and provides recommendations for a way forward. The conversion rate for potential DCD donors varies from 40%-80%. Compared to controlled DCD, uncontrolled DCD is more labour intensive, has a lower conversion rate and a higher discard rate. The super-rapid laparotomy technique involving direct aortic cannulation is preferred over in situ perfusion in controlled DCD donation and is associated with lower kidney discard rates, shorter warm ischaemia times and higher graft survival rates. DCD kidneys showed a 5.73-fold increase in the incidence of delayed graft function (DGF) and a higher primary non function rate compared to donation after brain death kidneys, but the long term graft function is equivalent between the two. The cold ischaemia time is a controllable factor that significantly influences the outcome of allografts, for example, limiting it to < 12 h markedly reduces DGF. DCD kidneys from donors < 50 function like standard criteria kidneys and should be viewed as such. As the majority of DCD kidneys are from controlled donation, incorporation of uncontrolled donation will expand the donor pool. Efforts to maximise the supply of kidneys from DCD include: implementing organ recovery from emergency department setting; improving family consent rate; utilising technological developments to optimise organs either prior to recovery from donors or during storage; improving organ allocation to ensure best utility; and improving viability testing to reduce primary non function.

Oxygenated hypothermic pulsatile perfusion versus cold static storage for kidneys from non heart-beating donors tested by in-line ATP resynthesis to establish a strategy of preservation

AIM

The scarcity of kidneys for transplantation impels an expansion of the donor source to include the use of organs from Maastricht II and Maastricht I non heart-beating donors. The aim of this study was to establish the best method to preserve kidneys from non heart-beating donors (NHBD): cold static storage (CSS) or perfusion. ATP production during kidney preservation has been retained as a measure of their energetic levels and, consequently, their viability. The presence of warm ischemia with both types of preservation was studied.

METHODS

Porcine kidneys presenting no warm ischemia or 30 minutes of warm ischemia were submitted to immediate oxygenated hypothermic pulsatile perfusion or immediate cold static storage. The study was divided into four groups. ATP resynthesis was measured after 8 h. of perfusion. ATP was assessed by in-line (31)P nuclear magnetic resonance spectroscopy (NMRS) during the preservations.

RESULTS

Only oxygenated perfusion could restore ATP in organs with warm ischemia. Initial cold static storage seems deleterious on organs having suffered from warm ischemia.

DISCUSSION

Only oxygenated perfusion could restore ATP in organs with warm ischemia. Initial cold static storage seems deleterious to organs having suffered from warm ischemia. Oxygenated perfusion must be introduced immediately after kidney removal from non heart-beating donors. In organs without warm ischemia, any kind of preservation is equivalent.

A comparison of hypothermic machine perfusion versus static cold storage in an experimental model of renal ischemia reperfusion injury

INTRODUCTION

There is increasing support for the use of hypothermic machine perfusion (HMP) in an attempt to reduce preservation injury. However, experimental evidence is needed to further examine the effects of HMP on renal ischemia reperfusion injury.

METHODS

Porcine kidneys were subjected to 10 min of warm ischemia followed by 18 hr of static cold storage with hyperosomolar citrate (HOC), histidine-tryptophan-ketoglutarate (HTK), or University of Wisconsin (UW) solutions or 18 hr HMP with Kidney Perfusion Solution using the Lifeport perfusion system. Renal function, oxidative damage, and morphology were assessed during 3 hr of reperfusion with autologous blood using an isolated organ perfusion system.

RESULTS

During reperfusion, intrarenal resistance was significantly lower in the HMP group compared with HOC and UW (area under the curve; HMP 3.8+/-1.7, HOC 9.1+/-4.3, UW 7.7+/-2.2, HTK 5.6+/-1.9 mm Hg/min; P=0.006), and creatinine clearance was significantly higher compared with the UW group (area under the curve creatinine clearance; HMP 9.8+/-7.3, HOC 2.2+/-1.7, UW 1.8+/-1.0, HTK 2.1+/-1.8 mL/min/100 g; P=0.004). Tubular function was significantly improved in the HMP group (P<0.05); however, levels of lipid peroxidation were significantly higher (P=0.005).

CONCLUSION

HMP demonstrated a reduced level of preservation injury compared with the static techniques resulting in improved renal and tubular function and less tubular cell inflammation during reperfusion.

Organ preservation with histidine-tryptophan ketogluatarate solution in clinical pancreas transplantation: an update of the indiana university experience

In May 2003, University of Wisconsin (UW) solution was replaced with Histidine-Tryptophan Ketoglutarate (HTK) solution as the preservation fluid for abdominal organ procurements in our center. Herein we have reported our updated results with HTK in pancreas transplantation. Between May 2003 and October 2006, 152 pancreas transplantations were performed in which 146 used HTK. The procedures were as follows: simultaneous kidney pancreas transplantation (n = 85; 55%), pancreas after kidney transplantation (n = 41; 30%), and solitary pancreas transplantation (n = 20; 15%). Donor and recipient data were collected with primary outcomes as primary nonfunction (PNF), and 30-day and 1-year graft and patient survival. Patient demographics are as follows: age (36 +/- 12 years), gender (males, 89: females, 57), race (white, 135; African American, 11). Mean flush volume was 3.8 +/- 1 L. The mean cold ischemia time was 8 +/- 3 hours. Mean warm ischemia time was 48 +/- 23 minutes. There were no cases of PNF in this cohort. Thirty-day and 1-year patient survival rates were 99% and 95%, respectively. The 30-day and 1-year graft survivals rates were 95% and 93%, respectively. There were 10 grafts lost with 7 vascular complications (6 venous and 1 arterial thrombosis). There were 2 cases of chronic rejection and 1 graft lost to noncompliance. These statistics compare favorably with International Pancreas Transplant Registry reported 1-year survival for pancreas allografts. All other patients were insulin independent by discharge. Serum fasting blood glucose and serial amylase remained comparable at all intervals posttransplantation to those of a historical UW cohort. Within this range of cold ischemia times, HTK appears to provide effective pancreas preservation.