Kidney transplantation in children and adolescents: an analysis of United Network for Organ Sharing Database.

Specific pediatric allocation schemes can not only lead to minimization of waiting time, but also to better clinical outcomes for children with end-stage renal disease. The outcome of 4125 deceased donor kidney transplants (DDKT) aged 5-35 years were compared with those of 6456 living donor kidney transplants (LDKT) using univariate and multivariate Cox regression analyses. Unadjusted graft survival rates of DDKT were significantly lower than those of LDKT (hazards ratio [HR] = 1.53; P < .001). Chronic rejection was reported in 416 (10.1%) of 4125 in the DDKT group compared with 537 (8.3%) of 6456 in the LDKT group (P < .001). Among African American recipients, 67 (3.4%) grafts were lost due to noncompliance as a contributory cause of failure compared with 126 (1.5%) among other races (P < .001). A significantly lower incidence of noncompliance was observed in children (0.9%) compared with adolescents (2.2% in ages 10-14; P < .001) and high teens (2.0% in ages 15-20; P < .001). Multivariate analysis showed that adjusted graft survival rates of LDKT were superior to DDKT (HR = 1.22; P < .001) after adjusting for recipient race, recipient age, regraft status, and HLA mismatch. The differences of long-term graft survival rates between DDKT and LDKT have not been reduced (4% at 1 year, 10% at 3 years, and 12% at 5 years for unadjusted survival rates and 3% at 1 year, 6% at 3 years, and 9% at 5 years adjusted survival rates). In our analysis presented here the difference in graft survival between LDKT and DDKT has doubled compared with earlier analysis. Therefore, we recommend LDKT whenever possible as a first choice for pediatric transplant recipients.

Permanent, lowered HLA class I expression using lentivirus vectors with shRNA constructs: Averting cytotoxicity by alloreactive T lymphocytes.

Transplantation of many tissues requires histocompatibility matching of human leukocyte antigens (HLA) to prevent graft rejection, to reduce the level of immunosuppression needed to maintain graft survival, and to minimize the risk of graft-versus-host disease, particularly in the case of bone marrow transplantation. However, recent advances in fields of gene delivery and genetic regulation technologies have opened the possibility of engineering grafts that display reduced levels of HLA expression. Suppression of HLA expression could help to overcome the limitations imposed by extensive HLA polymorphisms that restrict the availability of suitable donors, necessitate the maintenance of large donor registries, and complicate the logistics of procuring and delivering matched tissues and organs to the recipient. Accordingly, we investigated whether knockdown of HLA by RNA interference (RNAi), a ubiquitous regulatory system that can efficiently and selectively inhibit the expression of specific gene products, would enable allogeneic cells to evade immune recognition. For efficient and stable delivery of short hairpin-type RNAi constructs (shRNA), we employed lentivirus-based gene transfer vectors, which provide a delivery system that can achieve integration into genomic DNA, thereby permanently modifying transduced graft cells. Our results show that lentivirus-mediated delivery of shRNA targeting pan-Class I and allele-specific HLA can achieve efficient and dose-dependent reduction in surface expression of HLA in human cells, associated with enhanced resistance to alloreactive T lymphocyte-mediated cytotoxicity, while avoiding MHC-non-restricted killing. We hypothesize that RNAi-induced silencing of HLA expression has the potential to create histocompatibility-enhanced, and, eventually, perhaps "universally" compatible cellular grafts.

Expanding the donor kidney pool: utility of renal allografts procured in a setting of uncontrolled cardiac death.

The chronic shortage of deceased kidney donors has led to increased utilization of donation after cardiac death (DCD) kidneys, the majority of which are procured in a controlled setting. The objective of this study is to evaluate transplantation outcomes from uncontrolled DCD (uDCD) donors and evaluate their utility as a source of donor kidneys. From January 1995 to December 2004, 75,865 kidney-alone transplants from donation after brain death (DBD) donors and 2136 transplants from DCD donors were reported to the United Network for Organ Sharing. Among the DCD transplants, 1814 were from controlled and 216 from uncontrolled DCD donors. The log-rank test was used to compare survival curves. The incidence of delayed graft function in controlled DCD (cDCD) was 42% and in uDCD kidneys was 51%, compared to only 24% in kidneys from DBD donors (p < 0.001). The overall graft and patient survival of DCD donors was similar to that of DBD donor kidneys (p = 0.66; p = 0.88). Despite longer donor warm and cold ischemic times, overall graft and patient survival of uDCD donors was comparable to that of cDCD donors (p = 0.65, p = 0.99). Concerted efforts should be focused on procurement of uDCD donors, which can provide another source of quality deceased donor kidneys.

Graft loss in three patients with donor-specific antibody (DSA).

1. All patients had donor-specific antibodies and lost their transplant. 2. Flow PRA did not correlate with the transplant dysfunction. 3. In GT the DSA monitored could be used to monitor the effectiveness of the plasmapheresis. 4. DSA was strongly associated with transplant dysfunction and graft loss.

Significant HLA matching effect in a large urban transplant center composed primarily of minorities.

In more than 1300 deceased donor transplants, including 75% Hispanics, African-Americans, and Asians, a significant effect of mismatching (MM) was observed for zero to three MM compared to more than three MM (P < .02). There was a significantly better patient survival (P < .002), shorter hospital stay (P < .001), and a trend toward lowered immunosuppression. Zero to three MM were present in 48% of the recipient population in part due to the pre-UNOS algorithm that assigns points for zero MM and other MM grades. However, recently only zero MM receive points, therefore fewer zero to three MM recipients would be expected. The largest minority population is Hispanic. We postulated that at least part of the effect was associated with socioeconomic status and English as a second language parameters of our Hispanic population. Zero to three MM was found to decrease risk and should be used prospectively in minority donor/recipient combinations.

Renal biopsy donor group: the influence of glomerulosclerosis on transplant outcomes.

The UNOS donor population was examined from 1999 to 2002, and approximately 25% of the over 23,000 donors were biopsied (Bx). There was a significant trend (P < .001) of older donors, cardiovascular accident, and hypertension in the Bx group versus the non-Bx group. The percent GS was directly correlated (P < .001) to graft survival, delayed graft function, and primary nonfunction. Cox regression showed significant relative risk (RR) for >10% GS, hypertension, donors over the age of 50, and African American recipients. RR in donors with >10% GS could be ameliorated (P < .001) by choosing donors with <5 HLA-A, -B, or -DR mismatches (MM), or recipients who were nonsensitized, and/or first transplant. Risk should be managed in donors by choosing appropriate recipients and high-risk immunosuppresion protocols.

Multiplexed analysis of polymorphisms in the HLA gene complex using bead array chips.

A novel custom bead array technology is introduced, and it is applied to multiplexed analysis of highly polymorphic human leukocyte antigen (HLA) genetic loci. Our technology combines the construction of probe libraries on color-encoded microparticles (beads) with semiconductor chip processing to produce custom-designed high-density bead array chips in large quantities. Using this novel assay format, two modes of parallel molecular typing of the HLA complex were implemented, namely direct hybridization, illustrated here for class II HLA-DR, and a novel format of on-chip polymerase-mediated primer elongation, illustrated here for class I HLA-A, HLA-B, and HLA-DR using patient and reference cell-line DNA samples. Hybridization-mediated multiplexed analysis of polymorphism method was validated with 142 samples, resulting in 100% concordance with sequence-specific oligonucleotide typing results and a concomitant average of 40% less allele ambiguity. In addition, elongation and hybridization reactions were combined to identify multiple polymorphisms on the same phase of DNA for allele identification.

The influence of donor age on kidney graft survival in the 1990s.

Based on analyses of the UNOS Registry data for cadaver kidney transplants performed between 1991-1999 we showed that: 1. 15-40 year old donor kidneys provided the best one-year graft survival rates. When donors were analyzed with recipients, younger (0-10) and older (70-90) donors and recipients (Table 2) had the lowest one-year graft success rates. 2. Chronic loss rate, the constant rate of graft loss between one and 5 years, showed younger donor kidneys had a significantly lower chronic loss rate compared with each older donor category. Apparently the younger donor kidneys have a resiliency and nephron reserve that provides better long-term function. However, they may have lower short-term (1-yr) graft survival rates, possibly due to their small size. 3. Black and White donor kidneys had similar one-year graft survival rates; however, in every age group, recipients of White donor kidneys had significantly better 5-year graft survival rates than Black donor kidneys. There was also a noticeably lower chronic loss rate among recipients of White than Black donor kidneys. 4. HLA-matched White donor kidneys had better one- and 5-year graft survival rates and lower chronic loss rates than HLA-mismatched kidneys. The matching effect was lost when the donor age increased beyond age 40. PRA had an effect both at one and 5 years after transplantation. The chronic loss rate was similar with high and low PRA. Therefore, PRA had a relatively short-term effect. 5. Cold ischemia time had a modest effect after 35 hours both at one and 5 years. However, the chronic loss rate was unaffected by CIT, suggesting prolonged ischemia time had a relatively short-term effect. 6. More focused attention on sensitization and lowered CIT can both have a significant effect on short-term graft survival rates. However, both matching and younger donor organs provide the best opportunity for better long-term graft success rates.

BCX-34: a novel T-cell selective immunosuppressant: purine nucleoside phosphorylase (PNP) inhibitor.

We evaluated the efficacy of a new purine nucleoside phosphorylase inhibitor, BCX-34, as an immunosuppressive agent. BCX-34 showed a complete inhibitory effect on the proliferation of T-cells in an in vitro system, whereas no influence was observed in B-cell lines. In addition, it was revealed that this inhibitory effect was not due to the suppression of interleukin-2 production. Therefore, BCX-34 might be a potentially useful drug that can be used in combination, not competition, with cyclosporine A and FK506.