Liver transplantation across the ABO barrier: the role of plasmapheresis

Pediatric Liver Transplantation Across the ABO Blood Group Barrier: Is It an Obstacle in the Modern Era?

BACKGROUND

The initial experience with ABO incompatible (ABOi) orthotopic liver transplantations (OLTs) was dismal. In the current study, we investigated whether ABOi pediatric OLTs could achieve acceptable patient outcomes. The option for ABOi transplantation is vital because critically ill children have limited access to donor liver allografts.

STUDY DESIGN

Kaplan-Meier and multivariate Cox analysis was performed on data collected from 13,179 pediatric OLT recipients in the United Network for Organ Sharing database, including 540 ABOi recipients. We also analyzed 18 pediatric recipients of ABOi OLTs at Texas Children's Hospital. Recipients were divided into 2 groups: transplanted between 1987 to 2002 (remote era) and 2002 to 2013 (modern era).

RESULTS

Analysis revealed 4 main points. First, there was a significant (p < 0.01) improvement in ABOi OLT survival in the modern era. Second, threshold analysis revealed superior outcomes (p < 0.01) for OLT recipients younger than 2 years of age. Third, survival outcomes for ABOi and ABO-identical OLTs were the same for recipients younger than 2 years: ABOi was 91.8% (1 year) and 88.4% (5 year), and ABO identical was 91.5% (1 year) and 86.7% (5 year) (p = 0.94). Lastly, we found identical OLT results when analyzing our own institutional experience. To date, there has been a 92.9% survival rate in the modern era compared with 75% in the remote era. All recipients younger than 2 years (n = 9) are still alive, compared with 78% of those older than 2 years.

CONCLUSIONS

This analysis revealed a significant improvement in the survival of ABOi liver transplant recipients in the modern era. Importantly, ABOi liver transplantation can be performed in recipients younger than 2 years of age with equivalent outcomes compared with ABO-identical recipients.

Recipient outcomes after ABO-incompatible liver transplantation: a systematic review and meta-analysis

Background

ABO-incompatible live transplantation (ILT) is not occasionally performed due to a relative high risk of graft failure. Knowledge of both graft and patient survival rate after ILT is essential for donor selection and therapeutic strategy. We systematically reviewed studies containing outcomes after ILT compared to that after ABO-compatible liver transplantation (CLT).

Methodology/Principal Findings

We carried out a comprehensive search strategy on MEDLINE (1966–July 2010), EMBASE (1980–July 2010), Biosis Preview (1969–July 2010), Science Citation Index (1981–July 2010), Cochrane Database of Systematic Reviews (Cochrane Library, issue 7, 2010) and the National Institute of Health (July 2010). Two reviewers independently assessed the quality of each study and abstracted outcome data. Fourteen eligible studies were included which came from various medical centers all over the world. Meta-analysis results showed that no significantly statistical difference was found in pediatric graft survival rate, pediatric and adult patient survival rate between ILT and CLT group. In adult subgroup, the graft survival rate after ILT was significantly lower than that after CLT. The value of totally pooled OR was 0.64 (0.55, 0.74), 0.92 (0.62, 1.38) for graft survival rate and patient survival rate respectively. The whole complication incidence (including acute rejection and biliary complication) after ILT was higher than that after CLT, as the value of totally pooled OR was 3.02 (1.33, 6.85). Similarly, in acute rejection subgroup, the value of OR was 2.02 (1.01, 4.02). However, it was 4.08 (0.90, 18.51) in biliary complication subgroup.

Conclusions/Significance

In our view, pediatric ILT has not been a contraindication anymore due to a similar graft and patient survival rate between ILT and CLT group. Though adult graft survival rate is not so satisfactory, ILT is undoubtedly life-saving under exigent condition. Most studies included in our analysis are observational researches. Larger scale of researches and Randomized-Control Studies are still needed.

ABO-incompatible deceased donor liver transplantation in the United States: a national registry analysis

In the United States, ABO-incompatible liver transplantation (ILT) is limited to emergent situations when ABO-compatible liver transplantation (CLT) is unavailable. We analyzed the United Network for Organ Sharing database of ILT performed from 1990-2006 to assess ILT outcomes for infant (0-1 years; N = 156), pediatric (2-17 years; N = 170), and adult (> 17 years; N = 667) patients. Since 2000, the number of ILT has decreased annually, and there has been decreased use of blood type B donors and increased use of blood type A donors. Furthermore, ILT graft survival has improved for all age groups in recent years, beyond the improved graft survival attributable to era effect based on comparison to respective age group CLT. On matched control analysis, graft survival was significantly worse for adult ILT as compared to adult CLT. However, infant and pediatric ILTs did not have worse graft survival versus age-matched CLT. Adjusted analyses identified age-specific characteristics impacting ILT graft loss. For infants, transplant after 2000 and donor age < 9 years were associated with reduced risk of ILT graft loss. For pediatric patients, female recipient sex and donor age > 50 years were associated with increased risk of ILT graft loss. For adults, life support, repeat transplant, split grafts, and hepatocellular carcinoma were associated with increased risk of ILT graft loss. The current study identifies important trends in ILT in the United States in the modern immunosuppression era, as well as specific recipient, donor, and graft characteristics impacting ILT graft survival that could be utilized to guide ILT organ allocation in exigent circumstances. Liver Transpl 15:883-893, 2009. (c) 2009 AASLD.

Impact on outcomes after listing and transplantation, of a strategy to accept ABO blood group-incompatible donor hearts for neonates and infants

BACKGROUND

Recent data suggest that ABO blood group-incompatible donor hearts are immunologically well tolerated in infants undergoing transplantation.

METHODS

Competing-risks methodology was used to assess outcomes after listing and the impact of a strategy to accept heart grafts from any blood group donor for infants less than 18 months of age.

RESULTS

From 1992 to 2002, there were 91 listing episodes in 84 patients (including 20 fetuses; 50% were male and 63% had congenital heart disease). Beginning in 1995, a strategy to accept ABO-incompatible organs was adopted. Competing-risks analysis showed that after 20 months 60% underwent transplantation, 18% died, and less than 1% were still listed; the remaining 21% were de-listed because of a change of surgical strategy (9%), improved clinical condition (8%), and deterioration to ineligibility (4%). Risk factors for transplantation included only a strategy to accept ABO-incompatible organs (P <.001). Risk factors for death included failure to accept ABO-incompatible organs (P =.002) and Canadian listing status 3 (P =.085) or 4 (P <.001). Multivariable parametric models were used to create competing risk predictions for outcomes specific to status and ABO-incompatible strategy. Higher status resulted in greater mortality regardless of strategy, although for any status, more patients underwent transplantation and fewer died using a strategy to accept ABO-incompatible organs. Parametric modeling of time-related freedom from death or retransplantation demonstrated no significant difference at 4 years posttransplantation (P =.78) for ABO-incompatible (74%) versus ABO-compatible transplants (72%).

CONCLUSIONS

A strategy to accept ABO-incompatible donor hearts for infant transplantation significantly improves the likelihood of transplantation and reduces waiting list mortality while not adversely altering outcomes after transplantation.

A case of acute humoral rejection in liver transplantation: successful treatment with plasmapheresis and mycophenolate mofetil

We present a case of a 23-year-old female who underwent orthotopic liver transplantation (OLTx) for biliary atresia, 22 years after a failed Kasai operation. Unusually, her postoperative course was complicated by severe acute humoral rejection. In this case report, we discuss her management as well as the role of plasmapheresis in treating allograft dysfunction secondary to acute humoral rejection in liver transplant patients.

ABO-INCOMPATIBLE HEART TRANSPLANTATION IN INFANTS: THE FREEMAN HOSPITAL EXPERIENCE

BACKGROUND

Incompatibility of the major blood groups A, B, and O has been an absolute contraindication for heart transplantation. However, because of immunologic immaturity, infants may have relative protection from hyperacute rejection and thus could undergo transplantation with ABO-mismatched organs.

METHODS

Since January 2000, the authors have adopted a policy of considering infants for ABO-incompatible heart transplantation. Serum isohemagglutinin titers were measured before, during, and after transplantation. Two infants (3 and 2 months old) and a 21-month-old child underwent ABO-incompatible heart transplantation. During cardiopulmonary bypass, plasma exchange was performed. No other antibody-removal procedures were performed. A routine immunosuppressive regimen was used, and rejection was monitored by endomyocardial biopsies. An additional two patients (31 and 18 months old) were worked up but were unsuitable for ABO-incompatible transplantation because of high isohemagglutinin titers. They were successfully bridged to transplantation and received heart transplants from ABO-compatible donors.

RESULTS

All three infants with ABO-incompatible heart transplants are fit and well, 40 months, 30 months, and 12 months postoperatively. All three had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred. No morbidity attributable to the ABO incompatibility has been observed.

CONCLUSIONS

ABO-mismatched heart transplantation may be undertaken safely and without any short-term adverse consequences in infants and young children in whom isohemagglutinin production is not yet established.

Absorption of anti-blood group A antibodies on P-selectin glycoprotein ligand-1/immunoglobulin chimeras carrying blood group A determinants: core saccharide chain specificity of the Se and H gene encoded alpha1,2 fucosyltransferases in different host cells

To specifically eliminate recipient anti-blood group ABO antibodies prior to ABO-incompatible organ or bone marrow transplantation, an efficient absorber of ABO antibodies has been developed in which blood group determinants may be carried at high density and by different core saccharide chains on a mucin-type protein backbone. The absorber was made by transfecting different host cells with cDNAs encoding a P-selectin glycoprotein ligand-1/mouse immunoglobulin G(2b) chimera (PSGL-1/mIgG(2b)), the H- or Se-gene encoded alpha1,2-fucosyltransferases (FUT1 or FUT2) and the blood group A gene encoded alpha1,3 N-acetylgalactosaminyltransferase (alpha1,3 GalNAcT). Western blot analysis of affinity-purified recombinant PSGL-1/mIgG(2b) revealed that different precursor chains were produced in 293T, COS-7m6, and Chinese hamster ovary (CHO)-K1 host cells coexpressing FUT1 or FUT2. FUT1 directed expression of H type 2 structures mainly, whereas FUT2 preferentially made H type 3 structures. None of the host cells expressing either FUT1 or FUT2 supported expression of H type 1 structures. Furthermore, the highest A epitope density was on PSGL-1/mIgG2(2b) made in CHO-K1 cells coexpressing FUT2 and the alpha1,3 GalNAcT. This PSGL-1/mIgG(2b) was used for absorption of anti-blood group A antibodies in human blood group O serum. At least 80 times less A trisaccharides on PSGL-1/mIgG(2b) in comparison to A trisaccharides covalently linked to macroporous glass beads were needed for the same level of antibody absorption. In conclusion, PSGL-1/mIgG(2b), if substituted with A epitopes, was shown to be an efficient absorber of anti-blood group A antibodies and a suitable model protein for studies on protein glycosylation.

ABO-incompatible heart transplantation in infants

BACKGROUND

Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens.

METHODS

We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors.

RESULTS

The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donor's blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donor's blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent.

CONCLUSIONS

ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Critical care apheresis: hepatic failure

Hepatic failure is a common feature of critical care. Most hepatic dysfunction in the ICU responds to medical management and metabolic support. The role of extracorporeal organ support in hepatic failure is not as well defined as it is in renal failure and pulmonary failure. Nevertheless, artificial organ support has been successful in the treatment of advanced liver failure. Hybrid bioartificial liver substitutes show great promise, especially as a bridge to liver transplant.