Gift of Hope Organ and Tissue Donor Network

Ex vivo machine perfusion has been growing in utility for preserving donor organs prior to transplantation. This modality has tremendous potential for bioengineering and conditioning organs prior to transplantation using small molecule or advanced therapeutics. To safely translate potential interventions, well characterized models of disease are crucial for testing the therapeutic and possible side effects that could manifest from the interventions. Acute cellular rejection remains a significant complication in organ transplantation that affects transplant recipients with significant morbidity and mortality. This disease could potentially be mitigated with therapeutic intervention during ex vivo machine perfusion. A porcine animal model of acute rejection could be characterized in order to translate human biological processes with high fidelity. The Yucatan pig breed has been increasingly used in both biomedical research and xenotransplantation applications given its similarity to the human heart. A challenge with utilizing this pig breed for designing a model of acute rejection is its highly conserved ancestral lineage, which could make it difficult to induce acute rejection in a timely and consistent manner. We present a detailed characterization of a porcine model of acute rejection based on swine leukocyte antigen mismatching paired with a limited period of clinically relevant immunosuppression. The result is a robust and consistent protocol that results in fulminant acute rejection of an intra-abdominally transplanted heart.

Abstract Background Characterization of transplant transmitted infections associated with drowned organ donors and the recipients is not well delineated, posing challenges for optimal management and prophylaxis strategies. Broader organ sharing may pose additional considerations due to pathogen variation. Methods We reviewed 22 potential donor disease transmission events (PDDTEs) from drowned donors reported to the Organ Procurement and Transplantation Network (OPTN) ad hoc Disease Transmission Advisory Committee (DTAC) from 2017-2022 to estimate the incidence of PDDTEs among all US drowned organ donors and identify the most common pathogens in this setting. We also characterized donor/recipient epidemiology, infection timing and risk factors, and recipient survival. Results From 2017-2022, drowning was the mechanism of death in 777/74,232 (1.0%) of all US organ donors, from whom 2500 organs were transplanted. Among the 22 PDDTEs, there were 70 organ recipients. The median donor age was 17.5 years (range 1-70 years) and lung recipients accounted for 5/70 organ recipients. All PDDTE reports were submitted due to recipient disease, and index cases occurred 2-19 days post-transplant. 7/22 (7/777 drowned donors, 0.9%) PDDTEs were associated with pathogens consistent with plausible waterborne transmission, of which 4 were due to invasive molds (Zygomycetes and Scedosporium) and 3 were due to bacteria (Pseudomonas and Legionella). Of the 21 organ recipients from these 7 donors, 8 had proven or probable infections. 6/8 recipients had severe infection with 3 deaths, all from invasive mold infections. There were no identifiable infection risk factors related to drowning water source, donor immersion time, or geographic region. However, donor/recipient regional discordance occurred in 5/21 recipients, demonstrating the trend in broader organ sharing. Conclusion Though rare, organ recipients are at risk for transplant transmitted infection from drowned donors, particularly invasive mold infections. All infections occurred within the first month after transplant with high associated mortality. Though optimal management and prophylaxis strategies in these scenarios remain uncertain, post-transplant vigilance for early infection is paramount. Disclosures Helen S. Te, MD, CVS Caremark: Advisor/Consultant Lara A. Danziger-Isakov, MD, MPH, Aicuris: clinical research contract, paid to institutio|Ansun BioPharma: clinical research contract, paid to institution|Astellas: Advisor/Consultant|Astellas: clinical research contract, paid to institutio|Merck: clinical research contract, paid to institutio|Pfizer: Grant/Research Support|Takeda: clinical research contract, paid to institutio Anil J. Trindade, MD, CareDx, Inc.: Advisor/Consultant|CareDx, Inc.: Grant/Research Support|TFF Pharmaceuticals: Advisor/Consultant|Veloxis Pharmaceuticals, Inc.: Grant/Research Support

Introduction: Guidelines for establishing death by neurological criteria in the pediatric population recommend an observation period of at least 12 hours between two separate brain death exams. Due to a myriad of factors, the observation period is often longer than 12 hours. Patients who progress to brain death make up the majority of deceased organ donors; however, it is unknown whether the length of the observation period is associated with consent to organ donation. We hypothesize that a longer time interval between the two exams will be positively associated with the decision to donate. Methods: This is a retrospective cohort study of patients < 18 years old declared dead by neurological criteria between 2017-2022 at Comer Children’s Hospital in Chicago, IL. The electronic health record was used to collect demographic and brain death exam data. Qualitative data was also abstracted from provider notes to better understand the timing of brain death exams and families’ decision to donate. STATA was then used to perform descriptive statistics and logistic regression (p< 0.05). Results: 55 patients met inclusion criteria. 35 of 55 (63.6%) patient families consented to organ donation, and 20 (36.4%) patient families declined. The average time between brain death exams for all patients was 25.3+/-17.1 hours. Of those who consented to donation, the average time between exams was 23.7+/-15 hours, while those who did not consent had an average time between exams of 28.0+/-19.8 hours. African American patients represented 67.3% (n=37) of study participants and 74.3% (n=26) of organ donors. There were no statistically significant findings associated with likelihood to consent to donation. Conclusions: In this single institution retrospective cohort study, more time between brain death exams was not associated with the decision to pursue organ donation. A shorter time interval between clinical exams may indicate a family’s acceptance of brain death and therefore willingness to consider donation. Longer time intervals may be related to grieving time and a reluctance to accept the diagnosis of brain death. Future work should focus on identifying the qualitative factors that may impact families’ decisions around donation as well as how to optimize donation discussions with a family-centered approach.

BackgroundNormothermic machine perfusion (NMP) allows viability assessment and potential resuscitation of donor livers prior to transplantation. The immunological effect of NMP on liver allografts is undetermined, with potential implications on allograft function, rejection outcomes and overall survival. In this study we define the changes in immune profile of human livers during NMP.MethodsSix human livers were placed on a NMP device. Tissue and perfusate samples were obtained during cold storage prior to perfusion and at 1, 3, and 6 hours of perfusion. Flow cytometry, immunohistochemistry, and bead-based immunoassays were used to measure leukocyte composition and cytokines in the perfusate and within the liver tissue. Mean values between baseline and time points were compared by Student’s t-test.ResultsWithin circulating perfusate, significantly increased frequencies of CD4 T cells, B cells and eosinophils were detectable by 1 hour of NMP and continued to increase at 6 hours of perfusion. On the other hand, NK cell frequency significantly decreased by 1 hour of NMP and remained decreased for the duration of perfusion. Within the liver tissue there was significantly increased B cell frequency but decreased neutrophils detectable at 6 hours of NMP. A transient decrease in intermediate monocyte frequency was detectable in liver tissue during the middle of the perfusion run. Overall, no significant differences were detectable in tissue resident T regulatory cells during NMP. Significantly increased levels of pro-inflammatory and anti-inflammatory cytokines were seen following initiation of NMP that continued to rise throughout duration of perfusion.ConclusionsTime-dependent dynamic changes are seen in individual leukocyte cell-types within both perfusate and tissue compartments of donor livers during NMP. This suggests a potential role of NMP in altering the immunogenicity of donor livers prior to transplant. These data also provide insights for future work to recondition the intrinsic immune profile of donor livers during NMP prior to transplantation.

Cardiac transplantation is the gold standard treatment for end-stage heart failure. However, it remains limited by the number of available donor hearts and complications such as primary graft dysfunction and graft rejection. The recent clinical use of an ex vivo perfusion device in cardiac transplantation introduces a unique opportunity for treating cardiac allografts with therapeutic interventions to improve function and avoid deleterious recipient responses. Establishing a translational, large-animal model for therapeutic delivery to the entire allograft is essential for testing novel therapeutic approaches in cardiac transplantation. The porcine, heterotopic heart transplantation model in the intraabdominal position serves as an excellent model for assessing the effects of novel interventions and the immunopathology of graft rejection. This model additionally offers long-term survival for the pig, given that the graft is not required to maintain the recipient's circulation. The aim of this protocol is to provide a reproducible and robust approach for achieving ex vivo delivery of a therapeutic to the entire cardiac allograft prior to transplantation and provide technical details to perform a survival heterotopic transplant of the ex vivo perfused heart.

Background: Currently, 18% of deceased organ donors from our donor service area are positive for HBV, HCV and/or HIV. Moreover, 9% of procured tissue is eventually discarded due to viral sero-positive results. Therefore, expedient identification of donor viral sero-positive status would result in a more efficient and cost-effective use of procurement resources and promote procurement staff safety. This validation study of rapid HBV, HCV and HIV antibody pre-screen tests was performed as an initial step to clinical implementation. Materials & Methods: Archived serum samples were retrospectively tested with the Rapid HBV Panel Test (GENTAUR Molecular Products) (n=97), the OraQuick HCV Rapid Antibody Test (OraSure Technologies, Inc.) (n=93) and the OraQuick ADVANCE HIV-1/2 Rapid Antibody Tests (OraSure Technologies, Inc.) (n=135). Sensitivity and specificity were determined by comparison with results previously obtained with FDA-approved screening antibody tests. The rapid antibody pre-screen test results were reviewed and recorded by two separate technologists. Results: The positive and negative predictive values of the Rapid HBV Panel Test were 100% (95% CI = 85-100%) and 65% (95% CI = 53-76%), respectively (p<0.0001) (Table 1). The positive and negative predictive values of the OraQuick HCV Test were 100% (95% CI = 90-100%) and 89% (95% CI = 78-96%), respectively (p<0.0001) (Table 2). The positive and negative predictive values of the OraQuick ADVANCE HIV-1/2 Test were 100% (95% CI = 90-100%) and 97% (95% CI = 91-99%), respectively (p<0.0001) (Table 3). Of note, 42%, 54% and 50% of the sero-negative samples used in the HBV, HCV and HIV cohorts, respectively, were sero-positive for other viral makers. These data indicate that sero-positivity for other viruses does not induce false-positive results with these rapid pre-screen tests. Conclusion: Despite the lower sensitivity of the Rapid HBV Panel Test, the combined features of accuracy, ease of use and rapid test results (20-40 minutes) makes these pre-screen tests ideal for clinical application for early deceased donor evaluation.Table: No Caption available.