Immune phenotyping in a pediatric multicenter transplant study: Suitability of a preformulated dry-antibody panel system.

Flow-cytometric immune phenotyping is influenced by cryopreservation and inter-laboratory variability limiting comparability in multicenter studies. We assessed a system of optimized, pre-mixed dry-antibody panel tubes requiring small amounts of whole blood for validity, reliability and challenges in a Canadian multicenter study (POSITIVE) with long-distance sample shipping, using standardized protocols. Thirty-seven children awaiting solid-organ transplant were enrolled for parallel immune-phenotyping with both validated, optimized in-house panels and the dry-antibody system. Samples were collected before, 3 and 12 months post-transplant. Quality-assurance measures and congruence of phenotypes were compared using Bland-Altman comparisons, linear regression and group comparisons. Samples showed excellent lymphocyte viability (mean 94.8 %) and recovery when processed within 30 h. Comparing staining methods, significant correlations (Spearman correlation coefficient >0.6, p < 0.05), mean difference <5 % and variation 2SD <25 % were found for natural-killer, T and B cells, including many immunologically important cell subsets (CD8+, naïve, memory CD4+ T; switched-memory, transitional B). Some subgroups (plasmablasts, CD1d+CD5hi B cells) showed weak correlations, limiting interpretation reliability. The dry-antibody system provides a reliable method for standardized analysis of many immune phenotypes after long-distance shipping when processed within 30 h, rendering the system attractive for pediatric studies due to small blood amounts required and highly standardized processing and analysis.

ABO-incompatible heart transplantation-evolution of a revolution.

In the 1990s, neonates born with severe congenital heart disease faced more than 50% mortality awaiting an ABO-compatible (ABOc) transplant donor. This desperate situation, together with knowledge of gaps in the adaptive immune system in early childhood, led to the clinical exploration of intentional ABO-incompatible (ABOi) heart transplantation. In 2001, West et al. reported the first series of 10 infants in Canada. Since then, consideration of ABOi heart donors has become the standard of care for children awaiting transplantation in the first few years of life, resulting in reduced wait times and better organ utilization with noninferior post-transplant outcomes compared to ABOc recipients. This state-of-the-art review discusses the clinical development and evolution, underlying and resulting immunological aspects, current challenges, and future directions of ABOi heart transplantation.

Let's get physical: Aerobic capacity, muscle strength, and muscle endurance after pediatric heart transplantation.

BACKGROUND: Pediatric heart (HTx) and kidney transplant (KTx) recipients may have lower physical fitness than healthy children. This study sought to quantify fitness levels in transplant recipients, investigate associations to clinical factors and quality of life, and identify whether a quick, simple wall-sit test is feasible as a surrogate for overall fitness for longitudinal assessment. METHODS: Aerobic capacity (6-min walk test, 6MWT), normalized muscle strength, muscle endurance, physical activity questionnaire (PAQ), and quality of life (PedsQL™) were prospectively assessed in transplanted children and matched healthy controls. RESULTS: Twenty-two HTx were compared to 20 controls and 6 KTx. 6MWT %predicted was shorter in HTx (87.2 [69.9-118.6] %) than controls (99.9 [80.4-120] %), but similar to KTx (90.3 [78.6-115] %). Muscle strength was lower in HTx deltoids (6.15 [4.35-11.3] kg/m2) and KTx quadriceps (9.27 [8.65-19.1] kg/m2) versus controls. Similarly, muscle endurance was lower in HTx push-ups (28.6 [0-250] %predicted), KTx push-ups (8.35 [0-150] %predicted), HTx curl-ups (115 [0-450] %predicted), and KTx wall-sit time (18.5 [10.0-54.0] s) than controls. In contrast to HTx with only 9%, all KTx were receiving steroid therapy. The wall-sit test significantly correlated with other fitness parameters (normalized quadriceps strength R = .31, #push-ups R = .39, and #curl-ups R = .43) and PedsQL™ (R = .36). CONCLUSIONS: Compared to controls, pediatric HTx and KTx have similarly lower aerobic capacity, but different deficits in muscle strength, likely related to steroid therapy in KTx. The convenient wall-sit test correlates with fitness and reported quality of life, and thus could be a useful easy routine for longitudinal assessment.

Advancing mouse models for transplantation research.

Mouse models have been instrumental in understanding mechanisms of transplant rejection and tolerance, but cross-study reproducibility and translation of experimental findings into effective clinical therapies are issues of concern. The Mouse Models in Transplantation symposium gathered scientists and physician-scientists involved in basic and clinical research in transplantation to discuss the strengths and limitations of mouse transplant models and strategies to enhance their utility. Participants recognized that increased procedure standardization, including the use of prespecified, defined endpoints, and statistical power analyses, would benefit the field. They also discussed the generation of new models that incorporate environmental and genetic variables affecting clinical outcomes as potentially important. If implemented, these strategies are expected to improve the reproducibility of mouse studies and increase their translation to clinical trials and, ideally, new Food and Drug Administration-approved drugs.

Evaluating a Telemedicine Video Game-Linked High-Intensity Interval Training Exercise Programme in Paediatric Heart Transplant Recipients.

Paediatric heart transplant recipients (HTRs) have reduced exercise capacity, physical activity (PA), health-related quality of life (HRQoL), and self-efficacy towards PA. Exercise interventions have demonstrated improvements in exercise capacity and functional status in adult HTRs, with a specific emerging interest in the role of high-intensity interval training (HIIT). Studies of exercise interventions in paediatric HTRs have been limited and nonrandomized to date. HIIT has not yet been evaluated in paediatric HTRs. We thus seek to evaluate the safety and feasibility of a randomized crossover trial of a 12-week, home-based, video game-linked HIIT intervention using a cycle ergometer with telemedicine and remote physiological monitoring capabilities (MedBIKE) in paediatric HTRs. The secondary objective is to evaluate the impact of the intervention on (1) exercise capacity, (2) PA, (3) HRQoL and self-efficacy towards PA, and (4) sustained changes in secondary outcomes at 6 and 12 months after intervention. After a baseline assessment of the secondary outcomes, participants will be randomized to receive the MedBIKE intervention (12 weeks, 36 sessions) or usual care. After the intervention and a repeated assessment, all participants will cross over. Follow-up assessments will be administered at 6 and 12 months after the MedBIKE intervention. We anticipate that the MedBIKE intervention will be feasible and safely yield sustained improvements in exercise capacity, PA, HRQoL, and self-efficacy towards PA in paediatric HTRs. This study will serve as the foundation for a larger, multicentre randomized crossover trial and will help inform exercise rehabilitation programmes for paediatric HTRs.

La tolérance à l'effort, le niveau d'activité physique (AP), le score de la qualité de vie liée à la santé (QVLS) ainsi que l'auto-efficacité à la pratique d'une AP se trouvent diminués chez les patients pédiatriques ayant reçu une transplantation cardiaque. Il a été montré que les exercices physiques permettent d'améliorer la tolérance à l'effort ainsi que le statut fonctionnel chez les patients adultes ayant reçu une transplantation cardiaque. D'ailleurs, le rôle de l'entraînement par intervalles de haute intensité (EIHI) suscite depuis peu un nouvel intérêt à cet égard. Les études réalisées à ce jour sur les programmes d'activité physique chez les patients pédiatriques ayant reçu une transplantation cardiaque sont toutefois peu nombreuses et ne reposent pas sur une répartition aléatoire. De plus, l'EIHI n'a pas encore été évalué chez ce groupe de patients. La présente étude a donc pour objectif d'évaluer la faisabilité et l'innocuité d'un essai clinique croisé à répartition aléatoire d'une durée de 12 semaines chez des patients pédiatriques ayant reçu une transplantation cardiaque. Le programme d'activité physique prendra la forme d'un EIHI à la maison au moyen d'un jeu vidéo et d'une bicyclette ergométrique permettant une assistance et une surveillance des données physiologiques à distance (MedBIKE). Les objectifs secondaires de l'étude consistent à évaluer les effets du programme sur : 1) la tolérance à l'effort; 2) le niveau d'AP; 3) la QVLS ainsi que l'auto-efficacité à la pratique d'une AP; et 4) le maintien des améliorations relatives aux critères d'évaluation se-condaires à 6 et 12 mois. Après une évaluation initiale des critères d'évaluation secondaires, les participants seront répartis aléatoirement dans le groupe suivant le programme à l'aide du vélo MedBIKE (36 séances réparties sur 12 semaines) ou dans le groupe recevant le traitement usuel. Tous les participants changeront ensuite de groupe, et une nouvelle évaluation des critères d'évaluation se-condaires sera effectuée. Les évaluations de suivi auront lieu 6 et 12 mois après la fin du programme. On s'attend à ce que ce dernier soit sûr, facile à suivre et accompagné d'améliorations soutenues de la tolérance à l'effort, du niveau d'AP, de la QVLS et de l'auto-efficacité à la pratique d'une AP chez les patients pédiatriques ayant reçu une transplantation cardiaque. Cette étude servira de modèle à un essai clinique croisé, multicentrique, à répartition aléatoire de plus grande envergure. Elle permettra aussi de générer des renseignements utiles pour les programmes de réadaptation destinés aux patients pédiatriques ayant reçu une transplantation cardiaque.

First-in-human therapy with Treg produced from thymic tissue (thyTreg) in a heart transplant infant.

Due to their suppressive capacity, regulatory T cells (Tregs) have attracted growing interest as an adoptive cellular therapy for the prevention of allograft rejection, but limited Treg recovery and lower quality of adult-derived Tregs could represent an obstacle to success. To address this challenge, we developed a new approach that provides large quantities of Tregs with high purity and excellent features, sourced from thymic tissue routinely removed during pediatric cardiac surgeries (thyTregs). We report on a 2-year follow-up of the first patient treated worldwide with thyTregs, included in a phase I/II clinical trial evaluating the administration of autologous thyTreg in infants undergoing heart transplantation. In addition to observing no adverse effects that could be attributed to thyTreg administration, we report that the Treg frequency in the periphery was preserved during the 2-year follow-up period. These initial results are consistent with the trial objective, which is to confirm safety of the autologous thyTreg administration and its capacity to restore the Treg pool.

Sex, T Cells, and the Microbiome in Natural ABO Antibody Production in Mice.

BACKGROUND: "Natural" ABO antibodies (Abs) are produced without known exposure to A/B carbohydrate antigens, posing significant risks for hyperacute rejection during ABO-incompatible transplantation. We investigated anti-A "natural" ABO antibodies versus intentionally induced Abs with regard to the need for T-cell help, the impact of sex, and stimulation by the microbiome. METHODS: Anti-A was measured by hemagglutination assay of sera from untreated C57BL/6 wild-type (WT) or T cell-deficient mice of both sexes. Human ABO-A reagent blood cell membranes were injected intraperitoneally to induce anti-A Abs. The gut microbiome was eliminated by maintenance of mice in germ-free housing. RESULTS: Compared with WT mice, CD4 + T-cell knockout (KO), major histocompability complex-II KO, and αß/γδ T-cell receptor KO mice produced much higher levels of anti-A nAbs; females produced dramatically more anti-A nAbs than males, rising substantially with puberty. Sensitization with human ABO-A reagent blood cell membranes did not induce additional anti-A in KO mice, unlike WT. Sex-matched CD4 + T-cell transfer significantly suppressed anti-A nAbs in KO mice and rendered mice responsive to A-sensitization. Even under germ-free conditions, WT mice of several strains produced anti-A nAbs, with significantly higher anti-A nAbs levels in females than males. CONCLUSIONS: Anti-A nAbs were produced without T-cell help, without microbiome stimulation, in a sex- and age-dependent manner, suggestive of a role for sex hormones in regulating anti-A nAbs. Although CD4 + T cells were not required for anti-A nAbs, our findings indicate that T cells regulate anti-A nAb production. In contrast to anti-A nAbs, induced anti-A production was T-cell dependent without a sex bias.

Perceived Needs Among Healthcare Providers Caring for Seriously Ill Adults Regarding Electronic Health Record Triggers for Palliative Care Referral.

Many healthcare facilities in the United States currently utilize electronic health record triggers to promote and facilitate palliative care referral. The purpose of this study was to explore perceived needs regarding electronic health record trigger criteria for palliative care referral among healthcare providers caring for seriously ill adult hospitalized patients in a teaching hospital in New York State. A qualitative descriptive approach was utilized with use of individual semistructured interviews. Braun and Clarke's Reflexive Thematic Analysis method was used to analyze data. Data analysis generated one overarching theme, I'm in Favor of an Electronic Health Record Automatic Trigger for Palliative Care , and three key themes, Build a Checklist Screening Tool Into Epic With Predefined Conditions and a Palliative Consult in the Admission Order Set , If Providers Call a Palliative Care Consult Sooner, We Give Patients a Better Quality of Life , and Providers Need to Be Aware of the Different Facets of What Palliative Care Actually Does. Findings revealed that all participants supported incorporating electronic health record palliative care triggers. Future research is needed exploring provider palliative care education approaches to promote understanding of palliative care services and to address personal and/or professional bias.

Prospective examination of HLA sensitization after VAD implantation in children and adults.

BACKGROUND: Ventricular assist devices (VADs) have improved survival to heart transplantation (HTx). However, VADs have been associated with development of antibodies against human leukocyte antigen (HLA-Ab) which may limit the donor pool and decrease survival post-HTx. Since HLA-Ab development after VAD insertion is poorly understood, the purpose of this prospective single-center study was to quantify the incidence of and evaluate risk factors for HLA-Ab development across the age spectrum following VAD implantation. METHODS: Adult and pediatric patients undergoing VAD placement as bridge to transplant or transplant candidacy between 5/2016 and 7/2020 were enrolled. HLA-Ab were assessed pre-VAD and at 1-, 3-, and 12-months post-implant. Factors associated with HLA-Ab development post-VAD implant were explored using univariate and multivariate logistic regression. RESULTS: 15/41 (37%) adults and 7/17 (41%) children developed new HLA-Ab post-VAD. The majority of patients (19/22) developed HLA-Ab within two months of implant. New class I HLA-Ab were more common (87% adult, 86% pediatric). Prior pregnancy was strongly associated with HLA-Ab development in adults post-VAD (HR 16.7, 95% CI 1.8-158, p = 0.01). Of the patients who developed new HLA-Ab post-VAD, in 45% (10/22) the HLA-Ab resolved while in 55% (12/22) the HLA-Ab persisted. CONCLUSION: More than one-third of adult and pediatric VAD patients developed new HLA-Ab early after VAD implant with the majority having class I antibodies. Prior pregnancy was strongly associated with post-VAD HLA-Ab development. Further studies are needed to predict regression or persistence of HLA-Ab developed post-VAD, to understand modulation of individuals' immune responses to sensitizing events, and to determine whether transiently detected HLA-Ab post-VAD recur and have long-term clinical impact post-heart transplantation.