Does University of Wisconsin solution harm the transplanted heart?

Hyperbranched polyglycerol as a colloid in cold organ preservation solutions

Hydroxyethyl starch (HES) is a common colloid in organ preservation solutions, such as in University of Wisconsin (UW) solution, for preventing graft interstitial edema and cell swelling during cold preservation of donor organs. However, HES has undesirable characteristics, such as high viscosity, causing kidney injury and aggregation of erythrocytes. Hyperbranched polyglycerol (HPG) is a branched compact polymer that has low intrinsic viscosity. This study investigated HPG (MW-0.5 to 119 kDa) as a potential alternative to HES for cold organ preservation. HPG was synthesized by ring-opening multibranching polymerization of glycidol. Both rat myocardiocytes and human endothelial cells were used as an in vitro model, and heart transplantation in mice as an in vivo model. Tissue damage or cell death was determined by both biochemical and histological analysis. HPG polymers were more compact with relatively low polydispersity index than HES in UW solution. Cold preservation of mouse hearts ex vivo in HPG solutions reduced organ damage in comparison to those in HES-based UW solution. Both size and concentration of HPGs contributed to the protection of the donor organs; 1 kDa HPG at 3 wt% solution was superior to HES-based UW solution and other HPGs. Heart transplants preserved with HPG solution (1 kDa, 3%) as compared with those with UW solution had a better functional recovery, less tissue injury and neutrophil infiltration in syngeneic recipients, and survived longer in allogeneic recipients. In cultured myocardiocytes or endothelial cells, significantly more cells survived after cold preservation with the HPG solution than those with the UW solution, which was positively correlated with the maintenance of intracellular adenosine triphosphate and cell membrane fluidity. In conclusion, HPG solution significantly enhanced the protection of hearts or cells during cold storage, suggesting that HPG is a promising colloid for the cold storage of donor organs and cells in transplantation.

The optimal pressure for initial flush with UW solution in heart procurement

OBJECTIVE

University of Wisconsin (UW) solution is widely used in organ preservation. Some investigators have reported that high pressure during initial flush with UW solution may induce vasoconstriction and endothelial damage, because of its high potassium content and high viscosity. However, using lower pressure during the initial flush may lead to irregular distribution of the solution and incomplete flushing of blood components from coronary vascular beds. This experimental study evaluated the effects of a range of initial flush pressures during heart procurement, followed by orthotopic transplantation of the graft after 12 hours of preservation.

MATERIALS AND METHODS

Twelve pairs of adult mongrel dogs, weighing 9 to 14 kg, formed the recipient-donor combinations. After determining hemodynamic status by measuring cardiac output, left ventricular pressure (LVP), and maximum positive and negative change in LVP (+/-LVdP/dt), donor hearts were excised. Coronary vascular beds were flushed with 4 degrees C UW solution at a pressure of 60 mm Hg in the low-pressure group (n = 6) and at 120 mm Hg in the high-pressure group (n = 6). After 12 hours of cold preservation, orthotopic transplantation was performed using cardiopulmonary bypass (CPB). The hemodynamics of the transplanted graft were assessed by comparing recovery rates (%) from donor hearts 2 hours after weaning from CPB. Endothelin-1 (ET-1) levels were measured in the blood obtained from the coronary sinus 30 minutes after reperfusion. The transplanted grafts were then harvested for histologic study and measurement of adenosine triphosphate (ATP) content.

RESULTS

Cardiac output, LVP, LVdP/dt and myocardial tissue ATP content were significantly better (p < 0.05) in the high-pressure group than in the low-pressure group. We found no significant differences in ET-1 levels between the groups. Transmission electron microscopic findings revealed that degeneration of the mitochondria was less extensive in the high-pressure group than in the low-pressure group. We observed no obvious ultrastructural damage to the endothelial cells in either group.

CONCLUSION

When using UW solution in heart procurement, high pressure is better to completely wash out the blood components and distribute the solution.

Pretransplant rinse of hearts preserved with colloid-free UW solution and more effective heart preservation: studies in a rat abdominal heart transplant model

BACKGROUND

University of Wisconsin solution (UW) provides effective heart preservation under hypothermic conditions, but it can be deleterious at warmer temperatures. Re-warming during the implantation of the graft may be a problem. This study examined the damaging effect of peri-operative warm ischemia in a transplant setting and recovery from such damage. The amelioration of damage by rinsing the graft before re-warming and transplantation was also examined.

METHODS

Rat donor hearts were preserved for 2 hr (0 degrees C) as follows: Series A was preserved with colloid-free UW (MUW), St. Thomas' solution (ST), or calcium-supplemented MUW (MUW+Ca) followed by either transplantation or warming (22 degrees C) for 10 min before transplantation. Series B was preserved with MUW, rinsed with fresh MUW, ST, MUW+Ca, or low-potassium MUW before warming and transplantation. All heart isografts were transplanted heterotopically with an indwelling left intraventricular balloon-tipped catheter. Graft function was measured 1 and 7 days after transplantation.

RESULTS

Grafts re-warmed rapidly during implantation. Function (left ventricular developed pressure, contractility, and relaxation) was significantly and persistently diminished in MUW-preserved grafts subjected to additional warming before transplantation. Preservation with ST was less effective than MUW despite being unaffected by warming. Preservation with MUW+Ca and rinsing with fresh MUW or ST before re-warming allowed recovery of function within 7 days despite significantly diminished function on day 1.

CONCLUSION

This study demonstrated that an increase in the peri-transplant warm ischemic period was detrimental when hearts were preserved with MUW. Preservation with calcium-supplemented MUW or rinsing the heart with fresh MUW or ST before transplantation ameliorated this damage.

A multicenter, randomized, controlled trial of Celsior for flush and hypothermic storage of cardiac allografts

BACKGROUND

A multicenter, randomized, controlled, open-label trial was conducted to evaluate the safety and efficacy of Celsior when used for flush and hypothermic storage of donor hearts before transplantation.

METHODS

Heart transplant recipients were randomized to one of two treatment groups in which donor hearts were flushed and stored in either Celsior or conventional preservation solution(s) (control). Study subjects were followed for 30 days after transplantation.

RESULTS

A total of 131 heart transplant recipients were enrolled (Celsior, n = 64; control, n = 67). The treatment groups were evenly distributed in donor and recipient base line characteristics. Graft loss rate was lower in the Celsior group on day 7 (3% versus 9%) and on day 30 (6% versus 13%), but the difference was not statistically significant based on 95% confidence interval analysis. No significant difference was measured between the Celsior and control groups in 7-day patient survival (97% versus 94%) and the proportion of patients with one or more adverse events (Celsior, 88%; control 87%) or serious adverse events (Celsior, 38%; control, 46%). Significantly fewer patients in the Celsior group developed at least one cardiac-related serious adverse event (13% versus 25%).

CONCLUSIONS

Celsior was demonstrated to be as safe and effective as conventional solutions for flush and cold storage of cardiac allografts before transplantation.

Cell volume and ionic transport systems after cold preservation of coronary endothelial cells

BACKGROUND

Hypothermia-induced changes in cell volume and ionic transport systems of coronary endothelial cells may play a role in the development of coronary artery disease in cardiac transplant recipients.

METHODS

Coronary endothelial cells were incubated in University of Wisconsin solution or culture control medium for up to 48 hours at 4 degrees C. Parallel control cultures were incubated at 37 degrees C. Na/K-ATPase and Na/K/Cl cotransport activities were determined as ouabain- and furosemide-sensitive 86Rb+ uptake, respectively. Cell volume changes and cell death were analyzed by a FACScan flow cytometer and the release of lactate dehydrogenase, respectively.

RESULTS

Coronary endothelial cells stored in University of Wisconsin solution up to 6 hours showed an increased Na/K-ATPase activity compared to control cells, whereas no changes were observed in Na/K/Cl cotransport activity or cell volume. Long-term preservation (24 and 48 hours) was associated with a partial loss of cell viability, as demonstrated by lactate dehydrogenase release, and dramatic alterations in ionic transport system activities.

CONCLUSIONS

University of Wisconsin solution seems to prevent coronary endothelial cells Na/K/Cl cotransport activity changes during cold preservation, which could alter cell volume regulation and cause cell injury.

Heart and lung preservation for transplantation

Since the beginning of transplantation the search for optimal means of organ preservation has been ongoing. One of the major causes of death early following heart or lung transplantation is graft failure. Factors that play a role in this problem include recipient and donor issues, but clearly procurement techniques and preservation solutions are important. This article summarizes the history, current clinical practice, and research devoted to heart and lung preservation for transplantation.