Updates on Heart Transplantation

Effectiveness of exercise-based cardiac rehabilitation for patients with left ventricular assist device: A systematic review and meta-analysis

PURPOSE

Exercise-based cardiac rehabilitation (EBCR) improves functional capacity in heart failure (HF). However, data on the effect of EBCR in patients with advanced HF and left ventricular assist devices (LVADs) are limited. This meta-analysis aimed to evaluate the impact of EBCR on the functional ability of LVAD patients by comparing the corresponding outcome indicators between the EBCR and ST groups.

METHODS

PubMed, Embase, Clinical Trials, and Cochrane Library databases were searched for studies assessing and comparing the effects of EBCR and standard therapy (ST) in patients following LVAD implantation. Using pre-defined criteria, appropriate studies were identified and selected. Data from selected studies were extracted in a standardized fashion, and a meta-analysis was performed using a fixed-effects model. The protocol was registered on INPLASY (202340073).

RESULTS

In total, 12 trials involving 477 patients were identified. The mean age of the participants was 52.9 years, and 78.6% were male. The initiation of EBCR varied from LVAD implantation during the index hospitalization to 11 months post-LVAD implantation. The median rehabilitation period ranged from 2 weeks to 18 months. EBCR was associated with improved peak oxygen uptake (VO2) in all trials. Quantitative analysis was performed in six randomized studies involving 214 patients (EBCR: n = 130, ST: n = 84). EBCR was associated with a significantly high peak VO2 (weighted mean difference [WMD] = 1.64 mL/kg/min; 95% confidence interval [CI], 0.20-3.08; p = .03). Similarly, 6-min walk distance (6MWD) showed significantly greater improvement in the EBCR group than in the ST group (WMD = 34.54 m; 95% CI, 12.47-56.42; p = .002) in 266 patients (EBCR, n = 140; ST, n = 126). Heterogeneity was low among the included trials. None of the included studies reported serious adverse events related to EBCR, indicating the safety of EBCR after LVAD implantation.

CONCLUSION

This study demonstrated that EBCR following LVAD implantation is associated with greater improvement in functional capacity compared with ST as reflected by the improved peak VO2 and 6MWD values. Considering the small number of patients in this analysis, further research on the clinical impact of EBCR in LVAD patients is warranted.

Exploring personalized treatment for cardiac graft rejection based on a four-archetype analysis model and bioinformatics analysis

Heart transplantation is the gold standard for treating patients with advanced heart failure. Although improvements in immunosuppressive therapies have significantly reduced the frequency of cardiac graft rejection, the incidences of T cell-mediated rejection (TCMR) and antibody-mediated rejection remain almost unchanged. A four-archetype analysis (4AA) model, developed by Philip F. Halloran, illustrated this problem well. It provided a new dimension to improve the accuracy of diagnoses and an independent system for recalibrating the histology guidelines. However, this model was based on the invasive method of endocardial biopsy, which undoubtedly increased the postoperative risk of heart transplant patients. Currently, little is known regarding the associated genes and specific functions of the different phenotypes. We performed bioinformatics analysis (using machine-learning methods and the WGCNA algorithm) to screen for hub-specific genes related to different phenotypes, based Gene Expression Omnibus accession number GSE124897. More immune cell infiltration was observed with the ABMR, TCMR, and injury phenotypes than with the stable phenotype. Hub-specific genes for each of the four archetypes were verified successfully using an external test set (accession number GSE2596). Logistic-regression models based on TCMR-specific hub genes and common hub genes were constructed with accurate diagnostic utility (area under the curve > 0.95). RELA, NFKB1, and SOX14 were identified as transcription factors important for TCMR/injury phenotypes and common genes, respectively. Additionally, 11 Food and Drug Administration-approved drugs were chosen from the DrugBank Database for each four-archetype model. Tyrosine kinase inhibitors may be a promising new option for transplant rejection treatment. KRAS signaling in cardiac transplant rejection is worth further investigation. Our results showed that heart transplant rejection subtypes can be accurately diagnosed by detecting expression of the corresponding specific genes, thereby enabling precise treatment or medication.

Feasibility Value of Right Ventricular Longitudinal Shortening Fraction and the Prognostic Implications in Patients With Heart Transplantation

BACKGROUND

Right ventricular longitudinal shortening fraction (RVLSF) is a 2-dimensional speckle tracking echocardiography parameter based on tricuspid annular displacement analysis that could be used to assess right ventricular (RV) systolic function. The value of RVLSF in the assessment of RV systolic function in recipients of heart transplantation (HT) and whether RVLSF can replace strain parameters remains unknown.

METHODS AND RESULTS

A total of 153 adult patients who underwent HT were consecutively enrolled in this prospective longitudinal study. All subjects were examined by conventional transthoracic 2-dimensional echocardiography and 2-dimensional speckle tracking echocardiography to evaluate the RV end-diastolic basal diameter, RV end-diastolic area, fractional area change, peak systolic velocity of tricuspid annulus, tricuspid annular plane systolic excursion, RV free wall strain, and RVLSF. Cox proportional hazards regression was used to test if the parameters of interest had independent prognostic value for adverse outcome prediction in patients who underwent HT. A significant positive correlation was found between the measurements of RVLSF and RV free wall strain (r=0.927, P<0.001). Compared with the event-free group, the adverse outcome group displayed reduced RVLSF and RV free wall strain and higher age (P<0.001, <0.001, =0.016, respectively) in patients who underwent HT. RVLSF and RV free wall strain were independently associated with poor prognosis in multivariable analysis (both P<0.001).

CONCLUSIONS

RVLSF assessment provides an effective evaluation of RV longitudinal systolic function in the transplanted hearts and has prognostic value for adverse outcomes in patients undergoing HT.

Early post-transplant hyperglycemia and post-transplant diabetes mellitus following heart transplantation

INTRODUCTION

Heart transplantation is an important treatment for end-stage heart failure. Early post-transplant hyperglycemia (EPTH) and post-transplant diabetes mellitus (PTDM) are common following heart transplantation and are associated with increased morbidity and mortality.

AREAS COVERED

This review summarizes the clinical characteristics, diagnosis, and treatment of EPTH and PTDM in cardiac transplant patients, incorporating findings from non-cardiac solid organ transplant studies where relevant due to limited heart-specific research.

EXPERT OPINION

EPTH following heart transplantation is common yet understudied and is associated with the later development of PTDM. PTDM is associated with adverse outcomes including infection, renal dysfunction, microvascular disease, and an increased risk of re-transplantation and mortality. Risk factors for EPTH include the post-operative immunosuppression regimen, recipient and donor age, body mass index, infections, and chronic inflammation. Early insulin treatment is recommended for EPTH, whereas PTDM management is varied and includes lifestyle modification, anti-glycemic agents, and insulin. Given the emerging evidence on the transplant benefits associated with effective glucose control, and the cardioprotective potential of newer anti-glycemic agents, further focus on the management of EPTH and PTDM within heart transplant recipients is imperative.

Prolonged travel time to transplantation center is associated with poor outcomes following heart transplantation

BACKGROUND

This study aims to examine the impact of home-to-transplantation center travel time as a potential barrier to healthcare accessibility.

METHODS

Observational study examined adult heart transplant recipients who received a graft between 2012 and 2022 in the United States. Travel time was calculated using the Google Distance Matrix API between the recipient's residence and transplantation center. A multivariable parametric survival model was fitted to minimize confounding bias.

RESULTS

Among the 25,923 recipients that met the selection criteria, the median travel time was 51 ​min and 95 ​% of recipients lived within a 5-h radius of their center. White recipients experienced longer median travel times (62 ​min, p ​< ​0.001) compared to Black (36 ​min) or Hispanic (40 ​min) recipients. A travel time of 1-2 ​h (survival time ratio [STR] 0.867, p ​= ​0.035) or >2 ​h (STR 0.873, p ​= ​0.026) away from the transplantation center was independently associated with lower long-term survival rates.

CONCLUSION

Extended travel times to transplantation centers may negatively impact long-term survival outcomes for heart transplant recipients, suggesting the need to address this potential barrier to healthcare accessibility.

Digital pathology in cardiac transplant diagnostics: from biopsies to algorithms

In the field of heart transplantation, the ability to accurately and promptly diagnose cardiac allograft rejection is crucial. This comprehensive review explores the transformative role of digital pathology and computational pathology, especially through machine learning, in this critical domain. These methodologies harness large datasets to extract subtle patterns and valuable information that extend beyond human perceptual capabilities, potentially enhancing diagnostic outcomes. Current research indicates that these computer-based systems could offer accuracy and performance matching, or even exceeding, that of expert pathologists, thereby introducing more objectivity and reducing observer variability. Despite promising results, several challenges such as limited sample sizes, diverse data sources, and the absence of standardized protocols pose significant barriers to the widespread adoption of these techniques. The future of digital pathology in heart transplantation diagnostics depends on utilizing larger, more diverse patient cohorts, standardizing data collection, processing, and evaluation protocols, and fostering collaborative research efforts. The integration of various data types, including clinical, demographic, and imaging information, could further refine diagnostic precision. As researchers address these challenges and promote collaborative efforts, digital pathology has the potential to become an integral part of clinical practice, ultimately improving patient care in heart transplantation.

Exosomal Cargo: Pro-angiogeneic, anti-inflammatory, and regenerative effects in ischemic and non-ischemic heart diseases - A comprehensive review

Heart diseases are the primary cause of mortality and morbidity worldwide which inflict a heavy social and economic burden. Among heart diseases, most deaths are due to myocardial infarction (MI) or heart attack, which occurs when a decrement in blood flow to the heart causes injury to cardiac tissue. Despite several available diagnostic, therapeutic, and prognostic approaches, heart disease remains a significant concern. Exosomes are a kind of small extracellular vesicles released by different types of cells that play a part in intercellular communication by transferring bioactive molecules important in regenerative medicine. Many studies have reported the diagnostic, therapeutic, and prognostic role of exosomes in various heart diseases. Herein, we reviewed the roles of exosomes as new emerging agents in various types of heart diseases, including ischemic heart disease, cardiomyopathy, arrhythmia, and valvular disease, focusing on pathogenesis, therapeutic, diagnostic, and prognostic roles in different areas. We have also mentioned different routes of exosome delivery to target tissues, the effects of preconditioning and modification on exosome's capability, exosome production in compliance with good manufacturing practice (GMP), and their ongoing clinical applications in various medical contexts to shed light on possible clinical translation.

Survival Benefit of Solid-Organ Transplantation: 10-Year Update

IMPORTANCE

Transplantation has transformed into a burgeoning field that is rapidly evolving to optimize organ distribution and survival outcomes. The years since 2012 (the last comprehensive study) have seen changes in transplantation, such as advances in immunotherapy and novel indices, that necessitate an updated analysis of survival benefit.

DESIGN

Our goal was to determine the survival benefit for solid-organ transplants in the United Network for Organ Sharing (UNOS) database for a three decade period and provide updates on advancements since 2012. Our retrospective analysis examined data containing U.S. patient records from September 1, 1987, to September 1, 2021.

RESULTS

We found that 3,430,272 life-years were saved over our transplant period (4.33 life-years saved per patient); kidney-1,998,492 life-years; liver -767,414; heart-435,312; lung-116,625; pancreas-kidney-123,463; pancreas-30,575; intestine-7901. After matching, 3,296,851 life-years were saved. Life-years saved and median survival increased for all organs between 2012 and 2021. Compared to 2012, median survival increased in kidney (from 12.4 to 14.76 years), liver (from 11.6 to 14.59), heart (9.5 to 11.73), lung (5.2 to 5.63), pancreas-kidney (from 14.5 to 16.88), pancreas (from 13.3 to 16.10). When compared to 2012, the percent transplanted increased in kidney, liver, heart, lung, and intestine, while pancreas-kidney and pancreas show decreased percent transplanted.

CONCLUSION

Our study underscores the tremendous survival benefits of solid organ transplantation (over 3.4 million life-years saved) and shows improvements since 2012. Our study also highlights areas of transplantation, notably pancreas transplants, that may necessitate reinvigorated attention.

Explainable synthetic image generation to improve risk assessment of rare pediatric heart transplant rejection

Expert microscopic analysis of cells obtained from frequent heart biopsies is vital for early detection of pediatric heart transplant rejection to prevent heart failure. Detection of this rare condition is prone to low levels of expert agreement due to the difficulty of identifying subtle rejection signs within biopsy samples. The rarity of pediatric heart transplant rejection also means that very few gold-standard images are available for developing machine learning models. To solve this urgent clinical challenge, we developed a deep learning model to automatically quantify rejection risk within digital images of biopsied tissue using an explainable synthetic data augmentation approach. We developed this explainable AI framework to illustrate how our progressive and inspirational generative adversarial network models distinguish between normal tissue images and those containing cellular rejection signs. To quantify biopsy-level rejection risk, we first detect local rejection features using a binary image classifier trained with expert-annotated and synthetic examples. We converted these local predictions into a biopsy-wide rejection score via an interpretable histogram-based approach. Our model significantly improves upon prior works with the same dataset with an area under the receiver operating curve (AUROC) of 98.84% for the local rejection detection task and 95.56% for the biopsy-rejection prediction task. A biopsy-level sensitivity of 83.33% makes our approach suitable for early screening of biopsies to prioritize expert analysis. Our framework provides a solution to rare medical imaging challenges currently limited by small datasets.

Change in First-year Intravascular Ultrasound Results Predicts Adverse Events in Heart Transplant Recipients: Implications for Clinical Trial Endpoints

BACKGROUND

Heart transplantation (HTx) is an established therapeutic option for patients with advanced heart failure who are refractory to conventional guideline-directed treatments. This study aimed to reassess whether intravascular ultrasound variables could predict adverse events after HTx in the modern era.

METHODS

One hundred primary HTx recipients with available serial intravascular ultrasound examination results of the left anterior descending artery 4-8 wk and 1 y after HTx were enrolled, with an average follow-up duration of 5.7 y. The primary endpoint was a composite of all-cause death, nonfatal major adverse cardiac events, and angiographic cardiac allograft vasculopathy.

RESULTS

Forty-three patients developed primary endpoints. The baseline maximal intimal thickness was independently associated with the primary endpoint (hazard ratio, 8.24; 95% confidential interval [CI], 3.21-21.21; P  < 0.001), and the optimal cutoff value was 0.64 mm. A change in the plaque atheroma volume in a proximal 20-mm segment from the left anterior descending artery bifurcation >1.05 mm 3 /mm (hazard ratio, 2.75; 95% CI, 1.28-5.89; P  = 0.009) and a change in the first-year maximal intimal thickness >0.27 mm (hazard ratio, 2.63; 95% CI, 1.05-6.56; P  = 0.04) were independent predictors of the primary endpoint 1 y after intravascular ultrasonography.

CONCLUSIONS

The aforementioned important clinical implications of intravascular ultrasound parameters are useful predictors of outcomes, which may be considered endpoints in modern clinical HTx trials.

Pacemaker Implantation following Heart Transplantation: Analysis of a Nation-Wide Database

BACKGROUND

The 2018 United-Network-for-Organ-Sharing (UNOS) allocation-system changes resulted in greater recognition of mechanical circulatory support (MCS), leading to more heart transplantations (HTx) in patients with MCS. We aimed to investigate the effect of the new UNOS allocation system on the need for a permanent pacemaker and associated complications following HTx.

METHODS

The UNOS Registry was questioned, to identify patients that received HTx in the US between 2000 and 2021. The primary objectives were to identify risk factors for the need for a pacemaker implantation following HTx.

RESULTS

49,529 HTx patients were identified, 1421 (2.9%) requiring a pacemaker post-HTx. Patients who required a pacemaker were older (53.9 ± 11.5 vs. 52.6 ± 12.8 years, p < 0.001), more frequently white (73% vs. 67%; p < 0.001) and less frequently black (18% vs. 20%; p < 0.001). In the pacemaker group, UNOS status 1A (46% vs. 41%; p < 0.001) and 1B (31% vs. 27%; p < 0.001) were more prevalent, and donor age was higher (34.4 ± 12.4 vs. 31.8 ± 11.5 years; p < 0.001). One-year survival was no different between the groups (HR: 1.08; 95% CI: 0.85, 1.37; p = 0.515). An era effect was observed (per year: OR: 0.97; 95% CI: 0.96, 0.98; p = 0.003), while ECMO pre-transplant was associated with lower risk of a pacemaker (OR: 0.41; 95% CI: 0.19, 0.86; p < 0.001).

CONCLUSIONS

While associated with various patient and transplant characteristics, pacemaker implantation does not seem to impact one-year survival after HTx. The need for pacemaker implantation was lower in the more recent era and in patients who required ECMO pre-transplant, a finding explained by recent advances in perioperative care.

Exploring the needs and barriers for death education in China: Getting answers from heart transplant recipients' inner experience of death

Background

Promoting reflection about death may support better living, and how to carry out death education is an important issue to be addressed across the world. The purpose of the current study was to explore the attitude of heart transplant recipients toward death and their inner real experience to provide information for the development of death education strategies.

Methods

A phenomenological qualitative study was conducted using a snowball method. A total of 11 patients who had undergone heart transplantation more than 1-year ago were recruited for the current study for semi-structured interviews.

Results

A total of five themes were identified: "Not avoid talking about death," "Feeling fear about the pain in the process of death", "Wanting a good death at the end of life," "The richness of feelings during near-death is surprising," and "Being close to death makes people more receptive to death."

Conclusion

Heart transplant recipients have a positive attitude toward death and wish for "good death" at the end of life. These patients' near-death experiences and positive attitudes toward death during the course of their illness provided evidence of the need for death education in China and supported the experiential approach to death education.

Effect of Wuzhi preparations on tacrolimus in CYP3A5 expressers during the early period after transplantation: A real-life experience from heart transplant recipients

BACKGROUND

Genetic polymorphisms and drug interactions are associated with tacrolimus exposure. This study aimed to evaluate the effect of Wuzhi (WZ) preparations on tacrolimus (TAC) concentration and dose requirements in heart transplant recipients with the CYP3A5*1 allele during the early period after transplantation.

METHODS

A total of 167 adult heart transplant recipients with the CYP3A5*1 allele were included and divided into the WZ group (n = 115) and the WZ-free group (n = 52). Blood trough concentrations of TAC were detected and the dose-adjusted concentration (C₀/D) and dose requirement for achieving the TAC therapeutic range were compared between the two groups. The change in C₀/D and dose of TAC were evaluated before and after co-administration with WZ preparations.

RESULTS

No significant differences in TAC C₀/D and dose requirement were observed between the WZ and WZ-free groups. However, the TAC C₀/D in the WZ group was significantly increased an average of 2.10-fold after co-administration of WZ. Moreover, the degree of elevation was related to the dose of the active ingredient (Schisantherin A). Furthermore, ALT, AST, and TB levels were significantly reduced after administration of WZ preparations.

CONCLUSION

Co-administration of the WZ/TAC preparation, in heart transplant recipients carrying the CYP3A5*1 allele, considerably increased TAC concentration (C₀/D) while decreased high levels of leading indicators in the liver function. More importantly, the effect of the WZ/TAC preparation on C₀/D was a dose-dependent event. However, our finding needs to be further confirmed in a larger sample size.

Optimizing Anastomoses Technique in Orthotopic Heart Transplantation: Comparison of Biatrial, Bicaval and Modified Bicaval Technique

Implantation techniques for orthotopic heart transplantation (HTx) have evolved over the centuries. Recently new approaches of modified bicaval techniques to minimize warm ischemia are gaining popularity in the literature. Between 2010 and 2022 n = 238 patients underwent HTx in our department. The recipients were retrospectively reviewed and divided regarding their anastomoses’ technique. Anastomoses were sutured either in biatrial (n = 37), bicaval (n = 191) or in a modified bicaval (n = 10) manner with suturing of the superior cava vein and A. pulmonalis anastomosis after removing the aortic cross-clamp during the reperfusion. Warm ischemia was 62 ± 11 min for biatrial, 66 ± 15 min for bicaval, but only 48 ± 10 min for modified bicaval technique (p < 0.001). The incidence of severe primary graft dysfunction (PGD) was comparable between biatrial (27.0%) and bicaval (28.8%) anastomoses. In contrast, in patients with modified bicaval technique PGD occurred only in a single patient (10.0%). The incidence of postoperative pacemaker implantation was 18.2% for biatrial compared to 3.0% for bicaval and 0.0% for modified bicaval technique (p = 0.01). The modified bicaval technique enables to decrease the crucial warm ischemia during HTx compared to both biatrial and regular bicaval techniques. Therefore, we strongly recommend bicaval anastomoses, ideally in a modified manner.

Clinicopathological correlations in heart transplantation recipients complicated by death or re-transplantation

Purpose

This study aimed to identify and correlate pathological findings with clinical outcomes in patients after orthotopic heart transplantation (OHT) who either died or underwent a re-transplantation.

Methodology and study design

Single-center retrospective analysis of primary OHT patients who died or were re-transplanted between October 2012 and July 2021. Clinical data were matched with corresponding pathological findings from endomyocardial biopsies on antibody-mediated rejection, cellular rejection, and cardiac allograft vasculopathy. Re-assessment of available tissue samples was performed to investigate acute myocardial injury (AMI) as a distinct phenomenon. These were correlated with clinical outcomes, which included severe primary graft dysfunction. Patients were grouped according to the presence of AMI and compared.

Results

We identified 47 patients with truncated outcomes after the first OHT. The median age was 59 years, 36 patients (76%) were male, 25 patients (53%) had a prior history of cardiac operation, and 21 patients (45%) were supported with a durable assist device before OHT. Of those, AMI was identified in 22 (47%) patients (AMI group), and 25 patients had no AMI (non-AMI group). Groups were comparable in baseline and perioperative data. Histopathological observations in AMI group included a non-significant higher incidence of antibody-mediated rejection Grade 1 or higher (pAMR ≥ 1) (32% vs. 12%, P = 0.154), and non-significant lower incidence of severe acute cellular rejection (ACR ≥ 2R) (32% vs. 40%, P = 0.762). Clinical observations in the AMI group found a significantly higher occurrence of severe primary graft dysfunction (68% vs. 20%, P = 0.001) and a highly significant shorter duration from transplantation to death or re-transplantation (42 days [IQR 26, 120] vs. 1,133 days [711–1,664], P < 0.0001). Those patients had a significantly higher occurrence of cardiac-related deaths (64% vs. 24%, P = 0.020). No difference was observed in other outcomes.

Conclusion

In heart transplant recipients with a truncated postoperative course leading to either death or re-transplantation, AMI in endomyocardial biopsies was a common pathological phenomenon, which correlated with the clinical occurrence of severe primary graft dysfunction. Those patients had significantly shorter survival times and higher cardiac-related deaths. The presence of AMI suggests a truncated course after OHT.

Use of Levosimendan in Patients with Advanced Heart Failure: An Update

Levosimendan is an inodilator drug that, given its unique pharmacological actions and safety profile, represents a viable therapeutic option in patients with heart failure with reduced ejection fraction in the advanced stage of the disease (advHFrEF). Pulsed levosimendan infusion in patients with advHFrEF improves symptoms and clinical and hemodynamic status, prevents recurrent hospitalizations, and enables optimization of guidelines-directed medical therapy. Furthermore, considering its proprieties on right ventricular function and pulmonary circulation, levosimendan could be helpful for the prevention and treatment of the right ventricular dysfunction post-implanting a left ventricular assist device. However, to date, evidence on this issue is scarce and has yielded mixed results. Finally, preliminary experiences indicate that treatment with levosimendan at scheduled intervals may serve as a “bridge to transplant” strategy in patients with advHFrEF. In this review, we summarized the clinical pharmacology of levosimendan, the available evidence in the treatment of patients with advHFrEF, as well as a hypothesis for its use in patients with advanced heart failure with preserved ejection fraction.

An educational design and development project for pediatric heart transplant recipients and their families

PURPOSE

The purpose of this project is to systematically derive and develop educational content for children who have undergone heart transplants and their families to improve the families' and caregivers' ability to manage child health in South Korea.

DESIGN AND METHODS

This project developed educational content through the first three steps: "Analysis," "Design," and "Development" of the five steps outlined in the ADDIE (Analysis, Design, Development, Implementation, and Evaluation) model. The educational contents were derived from an analysis of six literature reviews and six studies, seven websites, and interviews with six caregivers of children who have undergone a heart transplant. Based on these analyses, educational items were designed. When a draft of the education contents was developed, the content validity was validated by ten experts.

RESULTS

Educational items were designed in nine major categories and 40 sub-categories. All contents were validated with a content validity index of at least 0.8 or higher and included in the education content for pediatric heart transplant families, with recommendations for further modification based on expert advice.

PRACTICE IMPLICATIONS

This project is meaningful in that it has developed health management education contents suitable for the situation in South Korea through analyzing previous studies and educational contents of domestic and international medical centers as well as an in-depth interview with caregivers.

Assessing the Relationship Between Molecular Rejection and Parenchymal Injury in Heart Transplant Biopsies

BACKGROUND

The INTERHEART study (ClinicalTrials.gov #NCT02670408) used genome-wide microarrays to detect rejection in endomyocardial biopsies; however, many heart transplants with no rejection have late dysfunction and impaired survival. We used the microarray measurements to develop a molecular classification of parenchymal injury.

METHODS

In 1320 endomyocardial biopsies from 645 patients previously studied for rejection-associated transcripts, we measured the expression of 10 injury-induced transcript sets: 5 induced by recent injury; 2 reflecting macrophage infiltration; 2 normal heart transcript sets; and immunoglobulin transcripts, which correlate with time. We used archetypal clustering to assign injury groups.

RESULTS

Injury transcript sets correlated with impaired function. Archetypal clustering based on the expression of injury transcript sets assigned each biopsy to 1 of 5 injury groups: 87 Severe-injury, 221 Late-injury, and 3 with lesser degrees of injury, 376 No-injury, 526 Mild-injury, and 110 Moderate-injury. Severe-injury had extensive loss of normal transcripts (dedifferentiation) and increase in macrophage and injury-induced transcripts. Late-injury was characterized by high immunoglobulin transcript expression. In Severe- and Late-injury, function was depressed, and short-term graft failure was increased, even in hearts with no rejection. T cell-mediated rejection almost always had parenchymal injury, and 85% had Severe- or Late-injury. In contrast, early antibody-mediated rejection (ABMR) had little injury, but late ABMR often had the Late-injury state.

CONCLUSION

Characterizing heart transplants for their injury state provides new understanding of dysfunction and outcomes and demonstrates the differential impact of T cell-mediated rejection versus ABMR on the parenchyma. Slow deterioration from ABMR emerges as a major contributor to late dysfunction.

Pig heart and lung xenotransplantation: Present status

The recent pig heart transplant in a patient at the University of Maryland Medical Center has stimulated renewed interest in the xenotransplantation of organs from genetically engineered pigs. The barriers to the use of pigs as sources of organs have largely been overcome by 2 approaches - (1) the deletion of expression of the three known pig carbohydrate xenoantigens against which humans have preformed antibodies, and (2) the transgenic introduction of human 'protective' proteins, such as complement-regulatory proteins. These gene modifications, coupled with immunosuppressive therapy based on blockade of the CD40/CD154 costimulation pathway, have resulted in survival of baboons with life-supporting pig heart grafts for almost 9 months. The initial clinical success at the University of Maryland reinforces encouraging preclinical results. It suggests that pig hearts are likely to provide an effective bridge to an allotransplant, but their utility for destination therapy remains uncertain. Because of additional complex immunobiological problems, the same approach has been less successful in preclinical lung xenograft transplantation, where survival is still measured in days or weeks. The first formal clinical trials of pig heart transplantation may include patients who do not have access to an allotransplant, those with contraindications for mechanical circulatory support, those in need of retransplantation or with a high level of panel-reactive antibodies. Infants with complex congenital heart disease, should also be considered.

Benefits of a Supervised Ambulatory Outpatient Program in a Cardiovascular Rehabilitation Unit Prior to a Heart Transplant: A Case Study

Preoperative peak oxygen uptake (V.O2peak) and ventilatory efficiency (V.E/V.CO2slope) are related to the vital prognosis after cardiac transplantation (HTx). The objective of our study was to evaluate the effects of exercise-based cardiac rehabilitation (ECR) program on the preoperative exercise capacity of a HTx candidate. A male patient, aged 50–55 years, with chronic heart failure was placed on the HTx list and performed 12 weeks of intensive ECR (5 sessions-a-week). Our results showed that the cardiac index continuously increased between the onset and the end of ECR (1.40 vs. 2.53 L.min–1.m2). The first 20 sessions of ECR induced a V.O2peak increase (15.0 vs. 19.3 ml.min–1.kg–1, corresponding to 42.0 and 53.0% of its maximal predicted values, respectively). The peak V.O2 plateaued between the 20th and the 40th ECR session (19.3 vs. 19.4 ml.min–1.kg–1) then progressively increased until the 60th ECR session to reach 25.7 ml.min–1.kg–1, i.e., 71.0% of the maximal predicted values. The slope of V.E/V.CO2 showed a biphasic response during the ECR program, with an increase between the onset and the 20th ECR session (58.02 vs. 70.48) and a decrease between the 20th and the 40th ECR session (70.48 vs. 40.94) to reach its minimal value at the 60th ECR session (31.97). After the first 40 sessions of the ECR program, the Seattle Heart Failure Model score predicted median survival time was estimated at 7.2 years. In conclusion, the improvement in exercise capacity and cardiorespiratory function following the ECR helped delay the heart transplant surgery in our patient awaiting heart transplantation.

Coronary Artery Revascularization in Heart Transplant Patients: A Systematic Review and Meta-analysis

BACKGROUND

Cardiac allograft vasculopathy (CAV) is the primary cause of late mortality after heart transplantation (HTx). We look to provide a comprehensive review of contemporary revascularization strategies in CAV.

METHODS

PubMed and Web of Science were systematically searched by 3 authors. 1,870 articles were initially screened and 24 were included in this review.

RESULTS

PCI is the main revascularization technique utilized in CAV. The pooled estimates for restenosis significantly favored DES over BMS (OR 4.26; 95% CI, 2.54-7.13; p< 0.00001; I2=4%). There was insufficient data to quantitatively compare mortality following DES versus BMS. There was no difference in short-term mortality between CABG and PCI. In-hospital mortality was 0.0% for CABG and ranged from 0.0-8.34% for PCI. 1-year mortality was 8.0% for CABG and 5.0-25.0% for PCI. CABG had a potential advantage at 5 years. 5-year mortality was 17.0% for CABG and ranged from 14-40.4% following PCI. Select measures of postoperative morbidity trended towards superior outcomes for CABG.

CONCLUSIONS

In CAV, PCI is the primary revascularization strategy utilized, with DES exhibiting superiority to BMS regarding postoperative morbidity. Further investigation into outcomes following CABG in CAV is required to conclusively elucidate the superior management strategy in CAV.

An Intervention Trial for Strengthening Medical Adherence after Heart Transplantation

INTRODUCTION

In heart transplant recipients, nonadherence is associated with higher risk of morbidity and mortality.

RESEARCH QUESTION

Can a psychoeducational intervention enhance adherence to medical recommendations?

DESIGN

We randomized 200 patients awaiting heart transplantation on the high urgency wait list to a manualized psychoeducational intervention or standard care. Follow-up continued to three years after transplantation. Primary endpoint was adherence to immunosuppressive medication, assessed at 3, 6, 12, 24, and 36 months posttransplant. Secondary endpoints were barriers to adherence during follow-up and clinical outcomes, including cardiac rejection within the first postoperative year and postoperative 3-year mortality.

RESULTS

Fifty patients died before or within the first 3 months of transplantation. The primary endpoint was analyzed in 66 patients in the intervention group and 66 in the control group. Both study groups showed almost maximal adherence to immunosuppressive medication throughout follow-up, with no significant time x treatment interaction (P>0.99). Likewise, there was no significant time x treatment interaction (P=0.41) on barriers to adherence. The percentage of patients with International Society for Heart and Lung Transplantation standard grade 1 and 2 rejection was in the intervention and control groups 82.5% and 78.7%, respectively, and 8.8% and 13.1%, respectively, without significant differences between study groups (P=0.75). Considering all randomized and transplanted patients in the intervention group (N=85) and control group (N=87), postoperative 3-year mortality was 29.4% and 27.6%, respectively (P=0.82).

CONCLUSIONS

Adherence to immunosuppressive medication was high, even without a complex, manualized psychoeducational intervention. The intervention had no significant positive impact on cardiac rejection and mortality.

Bioartificial pulsatile cuffs fabricated from human induced pluripotent stem cell-derived cardiomyocytes using a pre-vascularization technique

There is great interest in the development of techniques to bioengineer pulsatile myocardial tissue as a next-generation regenerative therapy for severe heart failure. However, creation of thick myocardial grafts for regenerative medicine requires the incorporation of blood vessels. In this study, we describe a new method of constructing a vascular network in vivo that allows the construction of thick human myocardial tissue from multi-layered cell sheets. A gelatin sheet pre-loaded with growth factors was transplanted onto the superficial femoral artery and vein of the rat. These structures were encapsulated together within an ethylene vinyl alcohol membrane and incubated in vivo for 3 weeks (with distal superficial femoral artery ligation after 2 weeks to promote blood flow to the vascular bed). Subsequently, six cardiomyocyte sheets were transplanted onto the vascular bed in two stages (three sheets, two times). Incubation of this construct for a further week generated vascularized human myocardial tissue with an independent circulation supplied by an artery and vein suitable for anastomosis to host vessels. Notably, laminating six cell sheets on the vascular bed in two stages rather than one allowed the creation of thicker myocardial tissue while suppressing tissue remodeling and fibrosis. Finally, the pulsatile myocardial tissue was shown to generate auxiliary pressure when wrapped around the common iliac artery of a rat. Further development of this technique might facilitate the generation of circulatory assist devices for patients with heart failure.

Chimerism through the activation of invariant natural killer T cells prolongs graft survival after transplantation of induced pluripotent stem cell–derived allogeneic cardiomyocytes

The loss of functional cells through immunological rejection after transplantation reduces the efficacy of regenerative therapies for cardiac failure that use allogeneic induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). Recently, mixed-chimera mice with donor-specific immunotolerance have been established using the RGI-2001 (liposomal formulation of α-galactosyl ceramide) ligand, which activates invariant natural killer T (iNKT) cells. The present study aimed to investigate whether mixed chimerism, established using RGI-2001, prolongs graft survival in allogeneic iPSC-CM transplantation. Mixed-chimera mice were established via combinatorial treatment with RGI-2001 and anti-CD154 antibodies in an irradiated murine bone marrow transplant model. Luciferase-expressing allogeneic iPSC-CMs were transplanted into mixed-chimera and untreated mice, followed by in vivo imaging. RGI-2001 enhanced iNKT cell activation in mice, and mixed chimerism was successfully established. In vivo imaging revealed that while the allografts were completely obliterated within 2 weeks when transplanted to untreated mice, their survivals were not affected in the mixed-chimera mice. Furthermore, numerous CD3+ cells infiltrated allografts in untreated mice, but fewer CD3+ cells were present in mixed-chimera mice. We conclude that mixed-chimera mice established using RGI-2001 showed prolonged graft survival after allogeneic iPSC-CM transplantation. This donor-specific immunotolerance might increase the efficacy of regenerative therapies for heart failure with allogeneic iPSC-CMs.

Decellularized human amniotic membrane reinforced by MoS2-Polycaprolactone nanofibers, a novel conductive scaffold for cardiac tissue engineering

In order to regenerate myocardial tissues with functional characteristics, we need to copy some properties of the myocardium, such as its extracellular matrix and electrical conductivity. In this study, we synthesized nanosheets of Molybdenum disulfide (MoS2), and integrated them into polycaprolactone (PCL) and electrospun on the surface of decellularized human amniotic membrane (DHAM) with the purpose of improving the scaffolds mechanical properties and electrical conductivity. For in vitro studies, we seeded the mouse embryonic cardiac cells, mouse Embryonic Cardiac Cells (mECCs), on the scaffolds and then studied the MoS2 nanocomposites by scanning electron microscopy and Raman spectroscopy. In addition, we characterized the DHAM/PCL and DHAM/PCL-MoS2 by SEM, transmission electron microscopy, water contact angle measurement, electrical conductivity, and tensile test. Besides, we confirmed the scaffolds are biocompatible by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, MTT assay. Furthermore, by means of SEM images, it was shown that mECCs attached to the DHAM/PCL-MoS2 scaffold have more cell aggregations and elongated morphology. Furthermore, through the Real-Time PCR and immunostaining studies, we found out cardiac genes were maturated and upregulated, and they also included GATA-4, c-TnT, NKX 2.5, and alpha-myosin heavy chain in cells cultured on DHAM/PCL-MoS2 scaffold in comparison to DHAM/PCL and DHAM. Therefore, in terms of cardiac tissue engineering, DHAM nanofibrous scaffolds reinforced by PCL-MoS2 can be suggested as a proper candidate.

High-Intensity Interval Training Among Heart Failure Patients and Heart Transplant Recipients: A Systematic Review

High-intensity interval training (HIIT), an exercise training modality of cardiac rehabilitation, has shown growing evidence of improving cardiovascular patients' prognosis and health outcomes. This study aimed to identify and summarize the effects of HIIT in heart failure (HF) patients, heart transplantation (HTx) recipients, and HF patients before and after HTx. This systematic review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. For the past five years, a systematic search was done using PubMed, PubMed Central, Cochrane, Google Scholar, and ScienceDirect databases on September 15, 2021. Studies were selected based on the following predefined eligibility criteria: English-language randomized controlled trials (RCTs), observational studies, systematic reviews, and meta-analyses, which included HF patients and HTx patients, and assessment of effects HIIT. The relevant data were extracted to a predefined template. Consequently, quality assessment was done using each study's most commonly used assessment tools. The initial search generated 551 studies. Nine studies were included in the final selection - four RCTs, one cohort, one quasi-experimental study, two systematic reviews with meta-analyses, and one narrative review. HIIT was found to be generally superior or similar with other exercise training on VO2 peak, heart rate, LVEF, cardiac biomarkers, vascular function, blood pressure, body composition, and adverse events in HF patients and the aforementioned with QoL among HTx recipients. Data on cardiac remodeling and QoL of HF patients were inconclusive.

Production of functional cardiomyocytes and cardiac tissue from human induced pluripotent stem cells for regenerative therapy

The emergence of human induced pluripotent stem cells (hiPSCs) has revealed the potential for curing end-stage heart failure. Indeed, transplantation of hiPSC-derived cardiomyocytes (hiPSC-CMs) may have applications as a replacement for heart transplantation and conventional regenerative therapies. However, there are several challenges that still must be overcome for clinical applications, including large-scale production of hiPSCs and hiPSC-CMs, elimination of residual hiPSCs, purification of hiPSC-CMs, maturation of hiPSC-CMs, efficient engraftment of transplanted hiPSC-CMs, development of an injection device, and avoidance of post-transplant arrhythmia and immunological rejection. Thus, we developed several technologies based on understanding of the metabolic profiles of hiPSCs and hiPSC derivatives. In this review, we outline how to overcome these hurdles to realize the transplantation of hiPSC-CMs in patients with heart failure and introduce cutting-edge findings and perspectives for future regenerative therapy.

CHIR99021 Promotes hiPSC-Derived Cardiomyocyte Proliferation in Engineered 3D Microtissues

Cardiac tissue engineering is a promising strategy to generate human cardiac tissues for modeling cardiac diseases, screening for therapeutic drugs, and repairing the injured heart. Yet, several issues remain to be resolved including the generation of tissues with high cardiomyocyte density. Here, it is shown that the integration of the glycogen synthase kinase-3β inhibitor CHIR99021 in collagen I hydrogels promotes proliferation of human-induced pluripotent stem cell-derived (hiPSC) cardiomyocytes post-fabrication improving contractility of and calcium flow in engineered 3D cardiac microtissues. CHIR99021 has no effect on the gelation kinetics or the mechanical properties of collagen I hydrogels. Analysis of cell density and proliferation based on Ki-67 staining indicates that integration of CHIR99021 together with external CHIR99021 stimulation increases hiPSC-cardiomyocyte number by ≈2-fold within 7 d post-fabrication. Analysis of the contractility of engineered cardiac tissues after another 3 d in the absence of external CHIR99021 shows that CHIR99021-induced hiPSC-cardiomyocyte proliferation results in synchronized calcium flow, rhythmic beating, increased speed of contraction and contraction amplitude, and reduced peak-to-peak time. The CHIR99021-stimulated engineered cardiac microtissues exhibit spontaneous rhythmic contractions for at least 35 d. Collectively, the data demonstrate the potential of induced cardiomyocyte proliferation to enhance engineered cardiac microtissues by increasing cardiomyocyte density.

Paradoxical outcome of heart transplantation associated with institutional case volume

BACKGROUND

Previous studies in heart transplantation have shown an association between institutional case volume and outcomes. We aim to determine the case volume associated with optimal 1-year survival after transplantation.

METHODS AND RESULTS

The United Network for Organ Sharing (UNOS) national database was analyzed for adult patients who underwent orthotopic heart transplantation between January 2013 and December 2017. A total of 11,196 cases at 128 transplant centers were included. Risk-adjusted restricted cubic splines revealed a non-linear association between institutional case volume and 1-year post-transplant survival. In the risk-adjusted, random-effect Cox model with segmented linear splines, higher heart transplant volume up to 24 cases per year was associated with better 1-year survival (HR = .978 every additional case, 95% CI .963-.993), and optimal survival was maintained between 24 and 38 cases per year. However, further increase in volume above 38 transplants per year was associated with mildly decreased 1-year survival (HR = 1.007 every additional case, 95% CI 1.002-1.013).

CONCLUSIONS

The relationship between institutional case volume and heart transplant 1-year survival is non-linear, with optimal survival observed at institutional case volume of 24-38 cases per year.

LncRNA HCP5 in hBMSC-derived exosomes alleviates myocardial ischemia reperfusion injury by sponging miR-497 to activate IGF1/PI3K/AKT pathway

Ischemia/reperfusion (I/R) injury is an inevitable process during heart transplant and suppressing I/R injury could greatly improve the survival rate of recipients. Mesenchymal stem cells (MSCs) have positive effects on I/R. We aimed to investigate the mechanisms underlying the protective roles of MSCs in I/R. Both cell model and rat model of myocardial I/R were used. MTT assay and flow cytometry were used to measure cell viability and apoptosis, respectively. QRT-PCR and western blotting were employed to measure levels of lncRNA HCP5 (HLA complex P5), miR-497, apoptosis-related proteins, and insulin-like growth factor (IGF1)/PI3K/AKT pathway. Dual luciferase assay was used to validate interactions of HCP5 and miR-497, miR-497 and IGF1. Echocardiography was performed to evaluate cardiac function of rats. Serum levels of CK-MB and LDH were measured. H&E and Masson staining were used to examine morphology of myocardial tissues. hBMSC-derived exosomes (hBMSC-Exos) increased the viability of cardiomyocytes following hypoxia/reperfusion (H/R) and decreased apoptosis. H/R diminished HCP5 expression in cardiomyocytes while hBMSC-Exos recovered the level. Overexpression of HCP5 in hBMSC-Exos further enhanced the protective effects in H/R while HCP5 knockdown suppressed. HCP5 directly bound miR-497 and miR-497 targeted IGF1. miR-497 mimics or si-IGF1 blocked the effects of HCP5 overexpression. Further, hBMSC-Exos alleviated I/R injury in vivo and knockdown of HCP5 in hBMSC-Exos decreased the beneficial effects. AntagomiR-497 blocked the effects of HCP5 knockdown. HCP5 from hBMSC-Exos protects cardiomyocytes against I/R injury via sponging miR-497 to disinhibit IGF1/PI3K/AKT pathway. These results shed light on mechanisms underlying the protective role of hBMSC-Exos in I/R.

The State of the Heart Biopsy: A Clinical Review

Endomyocardial biopsy (EMB) is an invaluable and underused diagnostic tool for myocardial disease. The primary indications are surveillance of cardiac allograft rejection and the diagnosis of inflammatory and infiltrative cardiomyopathies. EMB is typically performed by sampling the right ventricular septum via the right internal jugular vein using fluoroscopic guidance. The diagnostic yield of EMB is improved by sampling both ventricles and with the use of guidance from imaging or electroanatomic mapping. The risk of major cardiac complications is operator dependent and < 1% in experienced centres. EMB is the gold standard and most common form of cardiac allograft rejection surveillance, whereas advanced cardiac imaging and donor-specific antibody quantification provide complementary information. Gene expression profiling is an alternative surveillance strategy to EMB for low-risk patients. EMB is recommended for myocarditis and can guide therapy for giant-cell myocarditis, necrotizing eosinophilic myocarditis, sarcoidosis, and immune checkpoint inhibitor myocarditis. There is growing interest in using EMB to guide therapy for viral myocarditis, although the uptake of this approach is limited to specialized centres. EMB has been replaced as a first-line test for infiltrative cardiomyopathy by nonbiopsy diagnostic techniques, but is still useful to clarify the diagnosis or disease subtype. The miniaturization of bioptomes and advances in laboratory techniques such as microarrays promises to improve the safety and yield of EMB. We review the contemporary use of EMB for cardiac allograft rejection, inflammatory cardiomyopathy, and infiltrative cardiomyopathy.

Markers of Immune Function in Heart Transplantation: Implications for Immunosuppression and Screening for Rejection

PURPOSE OF REVIEW

Recent developments in high-throughput DNA and RNA sequencing technologies have facilitated the development of noninvasive assays to monitor heart transplant rejection. In this review, we summarize existing assays employed for the surveillance of allograft rejection, as well as promising future directions for such tests in the molecular biology field.

RECENT FINDINGS

The AlloMap genome expression profiling assay remains the only noninvasive test for rejection surveillance and is incorporated into the International Society of Heart and Lung Transplantation guidelines. Other efforts have focused on messenger RNA (mRNA), microRNA (miRNA), and donor-derived cell-free DNA (dd-cfDNA) as potential viable biomarkers. Mitochondrial pathways in allograft necroptosis and inflammation signaling may represent a novel direction for future research endeavors. Although endomyocardial biopsy remains the gold standard, several converging areas of molecular biology could soon yield successful alternative methods of heart transplant rejection monitoring, with the distinct advantage of avoiding procedural complications.

Donor-recipient Matching in Heart Transplantation

Heart transplantation remains the treatment of choice for end-stage Heart Failure (HF). Due to the shortage of organs for transplantation and the occurrence of perioperative complications, a key problem is donor matching, which should result in increased survival and improved quality of life for patients. The success of this procedure depends on various parameters such as gender, weight, ABO blood group and Human Leukocyte Antigen (HLA) system of both the recipient and the donor. Furthermore, non-HLA antigens may also be valuable in donor-recipient matching. The aim of this article is to summarize the recent knowledge on the impact of various factors on accurate donor-recipient matching to heart transplantation.

Infective endocarditis in patients with heart transplantation

BACKGROUND

The incidence of nosocomial and health care-related infective endocarditis (IE) is increasing. Heart transplantation (HT) implies immunosuppression and frequent health care contact. Our aim was to describe the current profile and prognosis of IE in HT recipients.

METHODS

Multicenter retrospective registry-based study in Spain and France that included cases between 2008 and 2019.

RESULTS

During the study period, 8305 HT were performed in Spain and France. We identified 18 IE cases (rate 0.2%). Median age was 57 years; 12 were men (67%). Valve involvement did not have a predominant location and three patients (16.7%) had atrial or ventricular vegetations without valve involvement. The median age-adjusted Charlson index was 4 (interquartile range 3-5). Eleven IE cases (61%) were nosocomial/health care-related. Median time (range) between HT and development of IE was 43 months (interquartile range 6-104). The major pathogens were Staphylococcus sp. (n = 8, 44%), Enterococcus sp. (n = 4, 22%), and Aspergillus sp. (n = 3, 17%). Although eight patients (44%) had a surgical indication, it was only performed in three cases (17%). Three patients (17%) died during the first IE hospital admission.

CONCLUSIONS

IE in HT recipients has specific characteristics. Valve involvement does not have a predominant location and non-valvular involvement is common. Three fifths have a nosocomial/health care-related origin. The major pathogens were staphylococci (44%), enterococci (22%), and Aspergillus (17%). In-hospital mortality was 17%.

Long-term effects of high-intensity training vs moderate intensity training in heart transplant recipients: A 3-year follow-up study of the randomized-controlled HITTS study

The randomized controlled High-Intensity Interval Training in De Novo Heart Transplant Recipients in Scandinavia (HITTS) study compared 9 months of high-intensity interval training (HIT) with moderate intensity continuous training in de novo heart transplant recipients. In our 3-year follow-up study, we aimed to determine whether the effect of early initiation of HIT on peak oxygen consumption (VO_2peak ) persisted for 2 years postintervention. The study's primary end point was the change in VO_2peak (mL/kg/min). The secondary end points were muscle strength, body composition, heart rate response, health-related quality of life, daily physical activity, biomarkers, and heart function. Of 78 patients who completed the 1-year HITTS trial, 65 entered our study and 62 completed the study tests. VO_2peak increased from baseline to 1 year and leveled off thereafter. During the intervention period, the increase in VO_2peak was larger in the HIT arm; however, 2 years later, there was no significant between-group difference in VO_2peak . However, the mean change in the anaerobic threshold and extensor muscle endurance remained significantly higher in the HIT group. Early initiation of HIT after heart transplantation appears to have some sustainable long-term effects. Clinical trial registration number: NCT01796379.

Investigation of hub genes and immune status in heart transplant rejection using endomyocardial biopsies

T cell‒mediated rejection (TCMR) and antibody‐mediated rejection (ABMR) are severe post‐transplantation complications for heart transplantation (HTx), whose molecular and immunological pathogenesis remains unclear. In the present study, the mRNA microarray data set GSE124897 containing 645 stable, 52 TCMR and 144 ABMR endomyocardial biopsies was obtained to screen for differentially expressed genes (DEGs) between rejected and stable HTx samples and to investigate immune cell infiltration. Functional enrichment analyses indicated roles of the DEGs primarily in immune‐related mechanisms. Protein‐protein interaction networks were then constructed, and ICAM1, CD44, HLA‐A and HLA‐B were identified as hub genes using the maximal clique centrality method. Immune cell infiltration analysis revealed differences in adaptive and innate immune cell populations between TCMR, ABMR and stable HTx samples. Additionally, hub gene expression levels significantly correlated with the degree and composition of immune cell infiltration in HTx rejection samples. Furthermore, drug‐gene interactions were constructed, and 12 FDA‐approved drugs were predicted to target hub genes. Finally, an external GSE2596 data set was used to validate the expression of the hub genes, and ROC curves indicated all four hub genes had promising diagnostic value for HTx rejection. This study provides a comprehensive perspective of molecular and immunological regulatory mechanisms underlying HTx rejection.

A simple and fast liquid chromatography tandem mass spectrometry method to determine cyclosporine A concentrations in endomyocardial biopsies

Measuring cyclosporine A (CsA), an immunosuppressive drug used to prevent heart transplant rejection, concentrations in myocardial biopsies might be more informative than its measurement in whole blood. Therefore, a fast, accurate and reproductive method to determine CsA concentration in this complex matrix is needed. We report the validation of a liquid chromatography tandem mass spectrometry method to measure CsA concentration in heart parenchyma, applicable to everyday practice. The method was found to be precise, accurate, reproducible, specific of CsA, and without any matrix effect or carry-over. The lower limit of quantification was 50 pg of CsA in myocardium. The method was linear up to 2000 pg of CsA in myocardium. Samples were found stable for one year at - 80 °C. At last, 40 drugs which could be prescribed to heart transplant recipients were tested with the method and showed no interference with CsA signal. The method was suitable to quantify CsA in endomyocardial biopsies from heart transplanted patients. This method allows designing clinical studies aiming at exploring the relationship between CsA intra-graft concentrations and outcome.

Novel heat shock protein 90 inhibitor improves cardiac recovery in a rodent model of donation after circulatory death

OBJECTIVE

Organ donation after circulatory death (DCD) is a potential solution for the shortage of suitable organs for transplant. Heart transplantation using DCD donors is not frequently performed due to the potential myocardial damage following warm ischemia. Heat shock protein (HSP) 90 has recently been investigated as a novel target to reduce ischemia/reperfusion injury. The objective of this study is to evaluate an innovative HSP90 inhibitor (HSP90i) as a cardioprotective agent in a model of DCD heart.

METHODS

A DCD protocol was initiated in anesthetized Lewis rats by discontinuation of ventilation and confirmation of circulatory death by invasive monitoring. Following 15 minutes of warm ischemia, cardioplegia was perfused for 5 minutes at physiological pressure. DCD hearts were mounted on a Langendorff ex vivo heart perfusion system for reconditioning and functional assessment (60 minutes). HSP90i (0.01 μmol/L) or vehicle was perfused in the cardioplegia and during the first 10 minutes of ex vivo heart perfusion reperfusion. Following assessment, pro-survival pathway signaling was evaluated by western blot or polymerase chain reaction.

RESULTS

Treatment with HSP90i preserved left ventricular contractility (maximum + dP/dt, 2385 ± 249 vs 1745 ± 150 mm Hg/s), relaxation (minimum -dP/dt, -1437 ± 97 vs 1125 ± 85 mm Hg/s), and developed pressure (60.7 ± 5.6 vs 43.9 ± 4.0 mm Hg), when compared with control DCD hearts (All P = .001). Treatment abrogates ischemic injury as demonstrated by a significant reduction of infarct size (2,3,5-triphenyl-tetrazolium chloride staining) of 7 ± 3% versus 19 ± 4% (P = .03), troponin T release, and mRNA expression of Bax/Bcl-2 (P < .05).

CONCLUSIONS

The cardioprotective effects of HSP90i when used following circulatory death might improve transplant organ availability by expanding the use of DCD hearts.