Development of hypothermic continuous perfusion preservation machine equipped with nonpulsatile pump and its clinical application

Impact of static cold storage VS hypothermic machine preservation on ischemic kidney graft: inflammatory cytokines and adhesion molecules as markers of ischemia/reperfusion tissue damage. Our preliminary results

At the present time, deceased heart-beating donor kidney allografts are usually stored cold. Extended-criteria donor (ECD) grafts show higher sensitivity to ischemia-reperfusion damage than standard kidneys. The increasing use of marginal organs in clinical transplantation urgently requires a more effective preservation system. Pulsatile hypothermic machine perfusion has shown major advantages over static cold storage in terms of reduced organ injury during preservation and improved early graft function. This preliminary study aims to compare pulsatile hypothermic machine perfusion and static cold storage of kidney allografts, outlining differences in the levels of early inflammatory cytokines (TNF-α, IL-2 and IL-1β) and soluble intracellular adhesion molecule (sICAM-1) in perfusion and preservation liquid.

Machine perfusion or cold storage in organ transplantation: indication, mechanisms, and future perspectives

Most organs are currently preserved by cold storage (CS) prior to transplantation. However, as more so called marginal donor organs are utilized, machine perfusion has regained clinical interest. Recent studies have demonstrated advantages of pulsatile perfusion over CS preservation for kidney transplantation. However, it remains unclear whether there is a significant benefit of one preservation method over the other in general, or, whether the utilization of particular preservation approaches needs to be linked to organ characteristics. Proposed protective mechanisms of pulsatile perfusion remain largely obscure. It can be speculated that pulsatile perfusion may not only provide nutrition and facilitate the elimination of toxins but also trigger protective mechanisms leading to the amelioration of innate immune responses. Those aspects may be of particular relevance when utilizing grafts with suboptimal quality which may have an increased vulnerability to ischemia/reperfusion injury and compromised repair mechanisms. This review aims to enunciate the principles of organ perfusion and preservation as they relate to indication, aspects of organ protection and to highlight future developments.

Attenuation of DNA damage in canine hearts preserved by continuous hypothermic perfusion

BACKGROUND

Continuous hypothermic perfusion is a novel cardiac preservation technique. Reactive oxygen species play a role in ischemia reperfusion injury and limit organ preservation. Oxidative stress mediates a DNA mismatch lesion (7, 8-dihydro-8-oxoguanine [8-oxo-G]), which is repaired by the enzymes MutY homologue (MYH), 8-oxo-G glycosylase (OGG1), and MutS homologue 2 (MSH2). We hypothesized that continuous hypothermic perfusion would allow for maintenance of cardiac function while attenuating myocardial DNA damage with respect to the current clinical practice of static preservation at 4 degrees C.

METHODS

In our canine orthotopic transplant model, donor hearts were harvested after echocardiograms, and hemodynamic studies were obtained and served as controls. The hearts were transplanted after 24 hours of continuous hypothermic perfusion or 4 hours of static preservation, and were studied for 6 hours. Quantification of 8-oxo-G lesions, MYH, OGG1, and MSH2 concentrations were performed on biopsies using immunohistochemistry.

RESULTS

Postimplant echocardiograms, completed in 7 continuously perfused and 8 statically preserved hearts, demonstrated good function and normal wall motion. Positive staining for 8-oxoG was markedly increased in the static preservation group. Staining density for MYH, OGG1, and MSH2 were significantly decreased in statically preserved hearts and equivalent between continuously perfused and control hearts.

CONCLUSIONS

The DNA damage assayed by 8-oxoG was significantly increased in statically preserved versus continuously perfused hearts. The DNA repair enzymes MYH, OGG1, and MSH2 were also markedly decreased in the static preservation versus continuous hypothermic perfusion groups. Continuous hypothermic perfusion reduces oxidative damage and extends preservation without compromising function.

Impact of 24 h continuous hypothermic perfusion on heart preservation by assessment of oxidative stress

INTRODUCTION

Despite investigating numerous solutions, additives, and techniques over the last two decades, extending donor heart preservation beyond 4-6 h has not been achieved. Hypothermic heart preservation (HP) induces oxidative stress (OS) with reactive oxygen species (ROS) production, causing DNA cleavage and impairing repair. Quantification of cardiomyocyte concentrations of DNA damage by-products (8-oxoG) and mismatch repair enzymes (MYH, OGG-1, MSH2) reflects the severity of OS. If increased repair enzyme production is insufficient to repair injury, cell death occurs and functional outcomes are impacted. We investigated continuous hypothermic perfusion (CHP), a new form of HP, and the mechanism of injury associated with hypothermic storage, by assessing functional outcome and OS after allotransplantation of canine hearts.

METHODS

Fourteen canine hearts were harvested using standard techniques after baseline echocardiograms and haemodynamic parameters were obtained. The hearts were implanted after 24 h CHP (n = 10) or 4 h static preservation (SP; n = 4). After weaning from cardiopulmonary bypass (CPB), recipients were kept alive for 6 h. Repeat echocardiograms and haemodynamic parameters were obtained. Quantification of MYH, OGG-1, and MSH2 concentrations were performed on biopsies using immunohistochemistry and Western blot analysis.

RESULTS

Twelve out of 14 hearts (8/10 CHP; 4/4 SP) were successfully weaned on moderate inotropic support. Post-implant echocardiogram, completed in 6/10 CHP and 2/4 SP hearts, demonstrated hyperdynamic function and normal wall motion. The expression and activity of DNA repair enzymes was identical between normal baseline and CHP hearts.

CONCLUSION

CHP reduces OS associated with prolonged hypothermic preservation and may allow longer preservation periods without compromising function. CHP offers several potential advantages: (1) resuscitation of non-beating heart donor organs, (2) time for HLA tissue typing, (3) facilitate interventions improving graft function, and (4) increased organ sharing.

Creatinine in the Dog: A Review

Creatinine is the analyte most frequently measured in human and veterinary clinical chemistry laboratories as an indirect measure of glomerular filtration rate (GFR). Although creatinine metabolism and the difficulties of creatinine measurement have been reviewed in human medicine, similar reviews are lacking in veterinary medicine. The aim of this review is to summarize information and data about creatinine metabolism, measurement, and diagnostic significance in the dog. Plasma creatinine originates from the degradation of creatine and creatine phosphate, which are present mainly in muscle and in food. Creatinine is cleared by glomerular filtration with negligible renal secretion and extrarenal metabolism, and its clearance is a good estimate of GFR. Plasma and urine creatinine measurements are based on the nonspecific Jaffé reaction or specific enzymatic reactions; lack of assay accuracy precludes proper interlaboratory comparison of results. Preanalytical factors such as age and breed can have an impact on plasma creatinine (P-creatinine) concentration, while many intraindividual factors of variation have little effect. Dehydration and drugs mainly affect P-creatinine concentration in dogs by decreasing GFR. P-creatinine is increased in renal failure, whatever its cause, and correlates with a decrease in GFR according to a curvilinear relationship, such that P-creatinine is insensitive for detecting moderate decreases of GFR or for monitoring progression of GFR in dogs with severely reduced kidney function. Low sensitivity can be obviated by determining endogenous or exogenous clearance rates of creatinine. A technique for determining plasma clearance following IV bolus injection of exogenous creatinine and subsequent serial measurement of P-creatinine does not require urine collection and with additional studies may become an established technique for creatinine clearance in dogs.

Liver and kidney preservation by perfusion

The clinical boundaries of transplantation have been set in an era of simple cold storage. Research in organ preservation has led to the development of flush solutions that buffer the harsh molecular conditions which develop during ischaemia, and provide stored organs that are fit to sustain life after transplantation. Although simple and efficient, this method might be reaching its limit with respect to the duration, preservation, and the quality of organs that can be preserved. In addition, flush preservation does not allow for adequate viability assessment. There is good evidence that preservation times will be extended by the provision of continuous cellular substrate. Stimulation of in-vivo conditions by ex-vivo perfusion could also mean that marginal organs will be salvaged for transplantation. Perfusion will also allow for assessing the viability of organs before transplantation in a continuous fashion. The cumulative effect of these benefits would include expansion of the donor pool, less risk of primary non-function, and extension of the safe preservation period. Use of non-heart-beating donors, international organ sharing, and precise calculation of the risk of primary organ failure could become standard.