Factors influencing long-term graft loss. The Collaborative Transplant Study

A Short History of Skin Grafting in Burns: From the Gold Standard of Autologous Skin Grafting to the Possibilities of Allogeneic Skin Grafting with Immunomodulatory Approaches

Due to groundbreaking and pioneering developments in the last century, significant improvements in the care of burn patients have been achieved. In addition to the still valid therapeutic standard of autologous split-thickness skin grafting, various commercially available skin substitutes are currently available. Significant progress in the field of tissue engineering has led to the development of promising therapeutic approaches. However, scientific advances in the field of allografting and transplant immunology are of great importance. The achievement of various milestones over the past decades has provided thought-provoking impulses in the field of skin allotransplantation. Thus, biologically viable skin allotransplantation is still not a part of the clinical routine. The purpose of this article is to review the achievements in burn surgery with regards to skin allotransplantation in recent years.

Role of donor age and acute rejection episodes on long-term graft survival in cadaveric kidney transplantations

Cadaveric donors can provide an effective solution to the problem of organ shortage, and many factors that may affect the functioning and survival of cadaveric kidneys have been studied. We aimed to clarify the impact of donor age and acute rejection episodes on long-term graft and patient survival in patients receiving cadaveric renal transplants. We retrospectively evaluated the long-term outcomes of 207 patients who had received cadaveric renal transplants between 1985 and 2004. Mean recipient age, HLA mismatch, mean donor age, delayed graft function (DGF), mean cold ischemia time, acute rejection episodes in the first 6 months after transplantation, and 1-, 3-, and 5-year graft survivals were evaluated. Two study groups were created according to donor age: group 1 (n = 126) was composed of patients receiving kidneys from donors younger than 50 years, and group 2 (n = 81) was composed of patients receiving kidneys from donors 50 years of age or older. Mean recipient age, HLA mismatch, and mean cold ischemia time between groups were not different. The DGF rate in group 1 was 40% (n = 50) and in group 2 was 46% (n = 37) (P > .05). The 1-, 3-, and 5-year survival rates of patients without acute rejection within the first 6 months after transplantation in group 1 (58/126; 46%) versus those in group 2 (46/81; 57%) were 95% versus 90%, 65% versus 60%, and 40% versus 35%, respectively (P > .05). The 1-, 3-, and 5-year graft survival rates of patients with acute rejection within the first 6 months in group 1 (n = 68) versus those in group 2 (n = 35) were 93% versus 89%, 71% versus 55%, and 44% versus 28%, respectively (P = .005). There was no significant difference in 1-, 3-, and 5-year survival rates between patients with DGF in both groups. Acute rejection episodes within the first 6 months after cadaveric transplantation, especially in patients receiving kidneys from donors older than 50 years, were shown to affect 5-year survival of the kidney graft. However, cadaver age alone had no negative effect on 5-year graft survival rates. Cadaveric donors older than 50 years may be a solution to the organ shortage in the treatment of end-stage renal disease.

Advantages of short-time ureteric stenting for prevention of urological complications in kidney transplantation: an 18-year experience

We retrospectively studied the incidence of urological complications in a consecutive series of 590 patients (group B) who received a kidney transplant (KT) with a ureteral stent from January 1994 to December 2002. The ureteral stent was sewn to the bladder catheter during the surgical procedure and left in situ for a mean time of 10 days (range 8 to 12 days). The results were compared to a consecutive series of 414 patients who received a KT from March 1986 to December 1993 without a ureteral stent (group A). The two groups were comparable in terms of donor and recipient gender, ischemia time, delayed graft function, and chronic rejection incidence, but differed in mean donor age (44.1 vs 36.0 years), mean recipient age (45.4 vs 39.1 years), living/cadaveric donor rate (19.8% vs 11.9%), arterial lesions and bench reconstruction rate (11.1 vs 3.5%), as well as acute rejection episodes (11.7% vs 29.2%). Complications were seen in nine patients in group B (1.5%) and 17 patients in group A (4.1%) (P < .0001). Urinary leaks presented in two patients in group B (0.3%) and 11 patients in Group A (2.6%; P < .0001), while stenosis was present in six patients in group B (1.5%) and 7 in group A (1.2%) (P = NS). Urological complications such as urinary tract infection and macroscopic hematuria were similar in both groups. Time to presentation of a leak was within 2 weeks from KT in 10 patients (92.3%), while stenosis presented early in four patients (one in group B and four in group A). Of the stenoses, 69.3% presented late (beyond 12 weeks) in five patients in group B and three in Group A. In conclusion, our data suggest that routine use of double pigtail ureteral stent significantly decreased the incidence of leaks and early stenoses, but it did not modify late stenosis incidence. In the last decade, risk factors for urological complications have been increasing over time, namely, older donors and older recipients, living donation, length of dialysis, and the use of grafts with arterial lesions. Therefore we believe that a ureteral stent should be routinely considered to afford the advantage to protect the urinary anastomosis in the early postoperative period when the incidence of complications is highest, without the need of cystoscopy for its removal.

Impact of early cytomegalovirus infection and disease on long-term recipient and kidney graft survival

BACKGROUND

The impact of cytomegalovirus (CMV) infection and disease on long-term outcome after kidney transplantation is still unsettled.

METHODS

Between 1994 and 1997, 397 consecutive first kidney graft recipients and 74 retransplants were included in the study and followed prospectively until December 31, 2001. CMV infection (CMV pp65 antigenemia) and CMV disease were recorded once weekly during the first 100 days after transplantation. No CMV prophylaxis or preemptive therapy was given. In a multiple Cox proportional hazard model allowing time-dependent covariates, the effects of asymptomatic CMV infection and CMV disease, recipient age and gender, retransplantation, living donor, panel-reactive cytotoxid antibodies, acute rejection, and graft loss were tested on overall mortality beyond 100 days post-transplantation. In a similar analysis, the effect of asymptomatic CMV infection and CMV disease plus other factors were tested on death censored graft loss beyond 100 days.

RESULTS

Median (range) follow up time was 66.6 (<1-86.9) months. The incidence of CMV infection and disease during the first 100 days was 62.8% and 23.4%, respectively. The number of total deaths was 96 (20%), 82 occurred after the first 100 days. Independent risk factors for overall mortality beyond 100 days were asymptomatic CMV infection, RR = 2.90 (95% CI 1.61-5.22) (P= 0.001), CMV disease, RR = 2.50 (95% CI 1.31-4.79) (P= 0.006), both compared to no infection or disease, recipient age, RR = 1.066 per year (95% CI 1.048-1.084) (P < 0.001), and graft loss in the whole study period RR = 7.88 (95% CI 4.75-13.08) (P < 0.001). Asymptomatic CMV infection and CMV disease were not independent risk factors for death censored graft loss, but they significantly reduced graft survival uncensored for death, (log rank P= 0.001, respectively).

CONCLUSION

Asymptomatic CMV infection and overt CMV disease during the first 100 days increase the risk of recipient mortality beyond 100 days. This raises the question whether CMV prophylaxis should be given routinely after kidney transplantation.

Optimizing the long-term outcome of renal transplants: opportunities created by sirolimus

This review focuses upon the sirolimus-based cyclosporine elimination studies and the light they shed on choice of the best long-term immunosuppressive strategy for managing the balance between prevention of loss of grafts from antigen specific immune responses or from chronic nephrotoxicity. The underlying strategy of both cyclosporine elimination studies was to treat patients with a uniform therapy for the first 3 months and then wean off the cyclosporine therapy in one cohort. The Phase II study was conducted in 246 recipients in 17 centers in the USA and Europe. Thus 97 patients were treated with full-dose cyclosporine, fixed-dose sirolimus and corticosteroids, and 100 patients received reduced-dose cyclosporine and trough concentration controlled sirolimus with corticosteroids until 3 months when the dose of cyclosporine was tapered progressively. The phase III study was undertaken in 525 patients in 57 centers in Australia, Canada and Europe with randomization for cyclosporine elimination undertaken at 3 months and implemented over the next 4-6 weeks. The primary outcome of renal function was better in the elimination arms of both studies and, in the phase III study, continued to improve for up to 2 years. Both studies demonstrated better renal function, equivalent patient and graft survival and no difference in acute rejection rates. These studies have shown that one of the successful strategies for improving the longer term graft survival rates includes the continuous use of sirolimus and steroids, without calcineurin inhibitors.

Recipient hypertension potentiates chronic functional and structural injury of rat renal allografts

BACKGROUND

Systemic hypertension affects many allograft recipients, is an important risk factor for chronic graft dysfunction, and is linked to reduced graft survival. The condition may up-regulate the expression of inflammatory host cells and their products. These, in turn, may significantly injure vascular endothelium and other components of allografted kidneys.

METHODS

Lewis rats received orthotopic F344 renal allografts, a standard model of chronic rejection. Renovascular hypertension was produced by placing a silver clip (0.25 mm) on the renal artery of the retained contralateral native kidney 4 weeks after transplantation. Sham-clipped rats served as normotensive controls. Four recipient groups (Gp) were studied: Gp 1, rats with an allograft plus a clipped native kidney; Gp 2, those with an allograft and a sham-clipped native kidney; Gp 3, isografted animals with a clipped native kidney; and Gp 4, those bearing an isograft and a sham-clipped native kidney. Systolic blood pressure and proteinuria were measured every 2 weeks for 24 weeks. Grafts were assessed serially for morphologic and immunohistologic changes.

RESULTS

Systemic blood pressure rose to hypertensive levels in Gps 1 and 3 within a week of clipping but never increased in Gps 2 and 4. Proteinuria developed in hypertensive animals but remained at baseline in normotensive controls. Intimal thickening of allograft arteries progressed to luminal obliteration with extensive perivascular and interstitial fibrosis by 24 weeks. In contrast, vascular changes in isografts of hypertensive hosts were restricted to medial hypertrophy. Tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, platelet derived growth factor (PDGF), endothelin, Il-6, major histocompatibility complex (MHC) class II, and B7 were up-regulated in allografts in hypertensive hosts. Vascular deposition of immunoglobulin (IgG) was increased. These changes were markedly less pronounced in Gp 3 isografts and minimal in the kidneys of the normotensive animals of Gps 2 and 4.

CONCLUSIONS

An experimental model is presented that examines the influence of recipient hypertension in the pathogenesis of chronic dysfunction and injury developing in rat renal allografts over time.

Cardiovascular abnormalities and hypertension in the elderly dialysis patient

Elderly individuals comprise an ever-increasing proportion of patients on renal replacement therapy (RRT). As in younger patients, cardiovascular events are the major cause of death in the elderly on RRT, although the relative proportion succumbing to cardiovascular events is similar to that in young patients. An important observation is that the elderly are particularly likely to experience higher mortality if dialysis technique is suboptimal; they also experience particular benefit from successful renal transplantation. The latter observation has led to an "old for old" program in Europe.

Coadministration of either cyclosporine or steroids with humanized monoclonal antibodies against CD80 and CD86 successfully prolong allograft survival after life supporting renal transplantation in cynomolgus monkeys

BACKGROUND

Recent studies have shown some efficacy using monotherapy with monoclonal antibodies (mAb) against CD80 and CD86 receptors after life-supporting renal transplantation in non-human primates. Our study was designed to evaluate the efficacy of combinations of the same mAbs with either microemulsion cyclosporine (CsA) or steroids.

METHODS

Unilateral renal transplantation was performed in 16 blood group-matched and MLR-mismatched cynomolgus monkeys that were assigned to four different treatment groups. All monkeys in groups I, II, and IV were treated with the combination of a CD80 (h1F1) and CD86 (h3D1) mAb given at 20 mg/kg each preoperatively, then 5 mg/kg at weekly intervals starting postoperative (po) day 0 until poday 56 (9 doses). In group I the animals (n=4) were treated with mAbs only. In group II (n=4) mAbs were combined with a CsA regimen adjusted daily to maintain target 24 hr trough levels of 150-300 ng/ml CsA for poday 0 to poday 56. In group III (n=4) the animals received CsA monotherapy according to the same regimen as group II. In group IV methylprednisone was administered at 2 mg/kg IV on poday 0-2, then at 0.5 mg/kg/day prednisone per gavage that was and tapered to 0.2 mg/kg/day on which they were maintained until poday 56. All animals were off all immunosuppressive treatment after poday 56 and were then followed until poday 119.

RESULTS

The mean survival of groups I-IV was 74 (range 9-119 days), 113 (96-119 days), 39 (22-71 days), and 79 days (6 to 119), respectively. All animals in group I showed clinical evidence of acute severe rejection (fever, creatinine increase, anuria) within the first week posttransplant, including those that retained renal function until poday 119. Only one animal in group II had a moderate clinical rejection during the treatment period and three of four animals survived the intended follow-up period. All animals in group III had multiple biopsy proven or severe clinical rejection episodes within the first 21 days and only one animal survived beyond poday 40. Moderate or severe acute rejection was diagnosed in three of four animals of group IV within the first 28 days post transplant and only one animal survived until poday 119.

CONCLUSION

Our data show that combining a calcineurin inhibitor or prednisone with mAbs designed to block costimulatory signals does not antagonize the immunosuppressive efficacy of these mAbs. In addition, combining CsA with mAbs directed against the CD80 and CD86 receptors significantly prolongs graft survival when compared to CsA monotherapy. Therefore clinical trials of humanized mAbs to CD80 and CD86 used in combination with conventional immunosuppression can be considered.