Key Points Szeto–Schiller-31–mediated mitoprotection is phospholipid scramblase 3–dependent.Phospholipid scramblase 3 is required for recovery after AKI. Background The synthetic tetrapeptide Szeto–Schiller (SS)-31 shows promise in alleviating mitochondrial dysfunction associated with common diseases. However, the precise pharmacological basis of its mitoprotective effects remains unknown. Methods To uncover the biological targets of SS-31, we performed a genome-scale clustered regularly interspaced short palindromic repeats screen in human kidney-2, a cell culture model where SS-31 mitigates cisplatin-associated cell death and mitochondrial dysfunction. The identified hit candidate gene was functionally validated using knockout cell lines, small interfering RNA-mediated downregulation, and tubular epithelial–specific conditional knockout mice. Biochemical interaction studies were also performed to examine the interaction of SS-31 with the identified target protein. Results Our primary screen and validation studies in hexokinase 2 and primary murine tubular epithelial cells showed that phospholipid scramblase 3 (PLSCR3), an understudied inner mitochondrial membrane protein, was essential for the protective effects of SS-31. For in vivo validation, we generated tubular epithelial–specific knockout mice and found that Plscr3 gene ablation did not influence kidney function under normal conditions or affect the severity of cisplatin and rhabdomyolysis-associated AKI. However, Plscr3 gene deletion completely abrogated the protective effects of SS-31 during cisplatin and rhabdomyolysis-associated AKI. Biochemical studies showed that SS-31 directly binds to a previously uncharacterized N-terminal domain and stimulates PLSCR3 scramblase activity. Finally, PLSCR3 protein expression was found to be increased in the kidneys of patients with AKI. Conclusions PLSCR3 was identified as the essential biological target that facilitated the mitoprotective effects of SS-31 in vitro and in vivo.

IntroductionApolipoprotein-L1 (APOL1) is a primate-specific protein component of high-density lipoprotein (HDL). Two variants of APOL1 (G1 and G2), provide resistance to parasitic infections in African Americans but are also implicated in kidney-related diseases and transplant outcomes in recipients. This study aims to identify these risk variants using a novel probe-independent quantitative real-time PCR method in a high African American recipient cohort. Additionally, it aims to develop a new stratification approach based on a haplotype-centric model.MethodsGenomic DNA was extracted from recipient PBMCs using SDS lysis buffer and proteinase K. A quantitative PCR assay with modified forward primers and a common reverse primer enabled us to quantitatively identify single nucleotide polymorphisms (SNPs) and the 6-bp deletion. Additionally, we used Sanger sequencing to verify our QPCR findings.ResultsOur novel probe-independent qPCR effectively distinguished homozygous wild-type, heterozygous SNPs/deletions, and homozygous SNPs/deletions, with at least 4-fold differences. A high prevalence of APOL1 variants was observed (18% two-risk alleles, 34% one-risk allele) in our recipient cohort. Intriguingly, no significant impact of recipient APOL1 variants on transplant outcomes was observed up to 12-month of follow-ups. Ongoing research will encompass more time points and a larger patient cohort, allowing for a comprehensive evaluation of G1/G2 variant subgroups categorized by new haplotype scores, enriching our understanding.ConclusionOur cost-effective and rapid qPCR technique facilitates APOL1 genotyping within hours. Prospective and retrospective studies will enable comparisons with long-term allograft rejection, potentially predicting early/late-stage transplant outcomes based on haplotype evaluation in this diverse group of kidney transplant recipients.

The exception point system for liver allocation in the United States allows for additional waitlist priority for candidates where the Model for End-Stage Liver Disease or Pediatric End-stage Liver Disease does not effectively represent their urgency or need for a transplant. In May 2019, the review process for liver exception cases transitioned from 11 Regional Review Boards (RRBs) to 1 National Liver Review Board (NLRB), intended to increase consistency nationwide, improve efficiency, and balance transplant access for candidates with and without exception scores. This report provides a review of liver exception request and review practices, waitlist outcomes, and transplant activity in the first 2 years after implementation of the NLRB and acuity circle–based distribution in the United States. We compared initial and extension exception request forms submitted from May 13, 2017 to May 13, 2019 (prepolicy or RRB era) to the period from February 4, 2020 to February 3, 2022 (postpolicy or NLRB era). During this time, the NLRB reviewed 10,083 initial exception requests and 12,686 extension requests. Notable postpolicy highlights include (1) an increase in the proportion of initial and extension requests that were automatically approved instead of manually reviewed; (2) a decrease in the overall approval rates of initial exception requests (87.8% for adult HCC, 64.3% for adult other diagnoses, and 71.5% for pediatric); and (3) reduction in the time from exception request submission to adjudication to a median of 3.73 days. The proportions of waitlist registration and deceased donor liver transplants for patients with exception scores decreased, and waitlist outcomes between patients with and without exception scores are now comparable. Implementation of the NLRB improved efficiency, reduced case workloads, and standardized criteria for exception cases, with similar waitlist outcomes between patients with and without exception scores and improved equity in terms of access to liver transplants.

Treatment of advanced liver disease using surgical modalities is possible due to the liver’s innate ability to regenerate following resection. Several key cellular events in the regenerative process converge at the mitochondria, implicating their crucial roles in liver regeneration. Mitochondria enable the regenerating liver to meet massive metabolic demands by coordinating energy production to drive cellular proliferative processes and vital homeostatic functions. Mitochondria are also involved in terminating the regenerative process by mediating apoptosis. Studies have shown that attenuation of mitochondrial activity results in delayed liver regeneration, and liver failure following resection is associated with mitochondrial dysfunction. Emerging mitochondria therapy (i.e., mitotherapy) strategies involve isolating healthy donor mitochondria for transplantation into diseased organs to promote regeneration. This review highlights mitochondria’s inherent role in liver regeneration.

Obesity is associated with chronic multi-system bioenergetic stress that may be improved by increasing the number of healthy mitochondria available across organ systems. However, treatments capable of increasing mitochondrial content are generally limited to endurance exercise training paradigms, which are not always sustainable long-term, let alone feasible for many patients with obesity. Recent studies have shown that local transfer of exogenous mitochondria from healthy donor tissues can improve bioenergetic outcomes and alleviate the effects of tissue injury in recipients with organ specific disease. Thus, the aim of this project was to determine the feasibility of systemic mitochondrial transfer for improving energy balance regulation in the setting of diet-induced obesity. We found that transplantation of mitochondria from lean mice into mice with diet-induced obesity attenuated adiposity gains by increasing energy expenditure and promoting the mobilization and oxidation of lipids. Additionally, mice that received exogenous mitochondria demonstrated improved glucose uptake, greater insulin responsiveness, and complete reversal of hepatic steatosis. These changes were, in part, driven by adaptations occurring in white adipose tissue. Together, these findings are proof-of-principle that mitochondrial transplantation is an effective therapeutic strategy for limiting the deleterious metabolic effects of diet-induced obesity in mice.

Operational tolerance (OT) after kidney transplantation is defined as stable graft acceptance without the need for immunosuppression therapy. However, it is not clear which cellular and molecular pathways are driving tolerance in these patients. In this first-of-its-kind pilot study, we assessed the immune landscape associated with OT using single-cell analyses. Peripheral mononuclear cells from a kidney transplant recipient with OT (Tol), 2 healthy individuals (HC), and a kidney transplant recipient with normal kidney function on standard-of-care immunosuppression (SOC) were evaluated. The immune landscape of the Tol was drastically different from that of SOC and emerged closer to the profile of HC. TCL1A+ naive B cells and LSGAL1+ regulatory T cells (Tregs) were in higher proportions in Tol. We were unable to identify the Treg subcluster in SOC. The ligand-receptor analysis in HC and Tol identified interactions between B cells, and Tregs that enhance the proliferation and suppressive function of Tregs. SOC reported the highest proportion of activated B cells with more cells in the G2M phase. Our single-cell RNA sequencing study identified the mediators of tolerance; however, it emphasizes the requirement of similar investigations on a larger cohort to reaffirm the role of immune cells in tolerance.

Introduction Apolipoprotein-L1 (APOL1) is a primate-specific protein component of high- density lipoprotein (HDL). Two variants of APOL1 (G1 and G2), provide resistance to parasitic infections in African Americans but are also implicated in kidney-related diseases and transplant outcomes in recipients. This study aims to identify these risk variants using a novel probe- independent quantitative real-time PCR method in a high African American recipient cohort. Additionally, it aims to develop a new stratification approach based on haplotype-centric model. Methods Genomic DNA was extracted from recipient PBMCs using SDS lysis buffer and proteinase K. Quantitative PCR assay with modified forward primers and a common reverse primer enabled us to identify single nucleotide polymorphisms (SNPs) and the 6-bp deletion quantitatively. Additionally, we used sanger sequencing to verify our QPCR findings. Results Our novel probe-independent qPCR effectively distinguished homozygous wild-type, heterozygous SNPs/deletion, and homozygous SNPs/deletion, with at least 4-fold differences. High prevalence of APOL1 variants was observed (18% two-risk alleles, 34% one-risk allele) in our recipient cohort. Intriguingly, up to 12-month follow-up revealed no significant impact of recipient APOL1 variants on transplant outcomes. Ongoing research will encompass more time points and a larger patient cohort, allowing a comprehensive evaluation of G1/G2 variant subgroups categorized by new haplotype scores, enriching our understanding. Conclusions Our cost-effective and rapid qPCR technique facilitates APOL1 genotyping within hours. Prospective and retrospective studies will enable comparisons with long-term allograft rejection, potentially predicting early/late-stage transplant outcomes based on haplotype evaluation in this diverse group of kidney transplant recipients.

PURPOSEOur study hypothesis was that once daily dosing of extended-release tacrolimus (XRT) would be a safe and effective immunosuppression (IS) with the potential to decrease adverse events (AEs) associated with immediate release tacrolimus (IRT) after liver transplantation (LT).METHODSAll patients receiving LT at our center received rabbit anti-thymocyte globulin (RATG) induction therapy. Eligible patients were randomized in a 1:1 fashion to receive either XRT or IRT. Antimicrobial prophylaxis was the same between arms, and both groups received an antimetabolite for the first 6 months following LT. Patients were then followed at pre-determined study intervals for the following year after LT. We administered the RAND-36SF survey to assess patient's health-related quality of life at pre-determined intervals. All analysis was performed with an intention to treat basis.RESULTSWe screened 194 consecutive patients and enrolled 110. Our control and study arms were well matched. Transplant characteristics were similar between groups. At all timepoints, both arms had similar serum creatinine and estimated glomerular filtration rate (eGFR), calculated by MDRD6 equation, with post-transplant GFRs between 60 and 70 mL/min/1.73 m2 . Tacrolimus trough levels were similar between arms. The XRT arm had fewer AEs (166) and fewer serious AEs (70) compared to IRT (201 and 99, respectively). AEs most commonly were renal, infectious, or gastrointestinal in nature. While not statistically significant, XRT was held temporarily (25 vs. 35 cases) or discontinued (3 vs. 11 cases) less frequently than IRT and had fewer instances of rejection (7 vs. 12 cases).CONCLUSIONThis analysis showed that XRT is safe and effective as de novo maintenance IS in a steroid-free protocol with RATG.

Chronic allograft dysfunction (CAD), characterized histologically by interstitial fibrosis and tubular atrophy, is the major cause of kidney allograft loss. Here, using single nuclei RNA sequencing and transcriptome analysis, we identified the origin, functional heterogeneity, and regulation of fibrosis-forming cells in kidney allografts with CAD. A robust technique was used to isolate individual nuclei from kidney allograft biopsies and successfully profiled 23,980 nuclei from five kidney transplant recipients with CAD and 17,913 nuclei from three patients with normal allograft function. Our analysis revealed two distinct states of fibrosis in CAD; low and high extracellular matrix (ECM) with distinct kidney cell subclusters, immune cell types, and transcriptional profiles. Imaging mass cytometry analysis confirmed increased ECM deposition at the protein level. Proximal tubular cells transitioned to an injured mixed tubular (MT1) phenotype comprised of activated fibroblasts and myofibroblast markers, generated provisional ECM which recruited inflammatory cells, and served as the main driver of fibrosis. MT1 cells in the high ECM state achieved replicative repair evidenced by dedifferentiation and nephrogenic transcriptional signatures. MT1 in the low ECM state showed decreased apoptosis, decreased cycling tubular cells, and severe metabolic dysfunction, limiting the potential for repair. Activated B, T and plasma cells were increased in the high ECM state, while macrophage subtypes were increased in the low ECM state. Intercellular communication between kidney parenchymal cells and donor-derived macrophages, detected several years post-transplantation, played a key role in injury propagation. Thus, our study identified novel molecular targets for interventions aimed to ameliorate or prevent allograft fibrogenesis in kidney transplant recipients.

Hepatic ischemia–reperfusion injury (IRI) is one of the main factors for early allograft dysfunction (EAD), which may lead to graft rejection, graft loss, or shortened graft life in liver transplantation. Hepatic IRI appears to be inevitable during the majority of liver procurement and transportation of donor organs, resulting in a cascade of biological changes. The activation of signaling pathways during IRI results in the up- and downregulation of genes and microRNAs (miRNAs). miRNAs are ~21 nucleotides in length and well-characterized for their role in gene regulations; they have recently been used for therapeutic approaches in addition to their role as biomarkers for many diseases. miRNAs that are associated with hepatic IRI in in vitro and in vivo animal models are comprehensively summarized in this review. In those studies, the manipulation of miRNAs has been shown for the inhibition of aggravated immune response, reduction of apoptosis, stimulation of tissue repair, and enhancement of cell recovery to attenuate liver damage. Therefore, the utilization of liver-specific miRNA holds great potential as a therapeutic agent to improve early allograft dysfunction, hepatic injury, and patient outcome.

Triple negative breast cancer (TNBC) is one of the most aggressive cancers diagnosed amongst women with a high rate of treatment failure and a poor prognosis. Mitochondria have been found to be key players in oncogenesis and tumor progression by mechanisms such as altered metabolism, reactive oxygen species (ROS) production and evasion of apoptosis. Therefore, mitochondrial infusion is an area of interest for cancer treatment. Studies in vitro and in vivo demonstrate mitochondrial-mediated reduction in glycolysis, enhancement of oxidative phosphorylation (OXPHOS), reduction in proliferation, and an enhancement of apoptosis as effective anti-tumor therapies. This review focuses on mitochondrial dysregulation and infusion in malignancies, such as TNBC.

BACKGROUND:It has long been debated whether cava anastomosis should be performed with the piggyback technique or cava replacement, with or without veno-venous bypass (VVB), with or without temporary portocaval shunt (PCS) in the setting of liver transplantation. OBJECTIVES:To identify whether different cava anastomotic techniques and other maneuvers benefit the recipient regarding short-term outcomes and to provide international expert panel recommendations. DATA SOURCES:Ovid MEDLINE, Embase, Scopus, Google Scholar, and Cochrane Central. METHODS:A systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel (CRD42021240979). RESULTS:Of 3205 records screened, 307 publications underwent full-text assessment for eligibility and 47 were included in qualitative synthesis. Four studies were randomized control trials. Eighteen studies were comparative. The remaining 25 were single-center retrospective noncomparative studies. CONCLUSION:Based on existing data and expert opinion, the panel cannot recommend one cava reconstruction technique over another, rather the surgical approach should be based on surgeon preference and center dependent, with special consideration toward patient circumstances (Quality of evidence: Low | Grade of Recommendation: Strong). The panel recommends against routine use of vevo-venous bypass (Quality of evidence: Very Low | Grade of Recommendation: Strong) and against the routine use of temporary porto-caval shunt (Quality of evidence: Very Low | Grade of Recommendation: Strong).

Introduction: Chronic allograft dysfunction (CAD), characterized by interstitial fibrosis and tubular atrophy (IFTA), is the main cause of late graft loss in kidney transplantation. This study dissects the molecular and cellular heterogeneity of the human kidney stroma and immune cells driving CAD. Methods: Using single-nuclei RNA sequencing, 41,893 nuclei were evaluated from 8 rare kidney allograft biopsies (6 CAD and 3 normal patients). These needle biopsies were collected on average at ≥15-months posttransplanation and were stored in the cryopreservative, RNAlater. Following, integrative analysis was applied including pathway and enrichment analysis, pseudotime trajectories, and ligand receptor analyses. XY chromosome linked gene expression analysis was also used to determine the origin of both immune and nonimmune cells in sex-mismatch transplants. Results: Two states of fibrosis were discovered (low and high ECM) that differ based on significant alterations in kidney subclusters, immune cell proportions and phenotypes, and intercellular communication. Pseudotime trajectories revealed a mixed tubule cluster, a key intermediate of injured proximal tubular cells, that transitioned to an activated fibroblast cluster also enriched in myofibroblasts markers. Such differentiation of proximal tubular cells was the main driver of fibrosis. Unique to high ECM, MT1 performed replicative repair evidenced by dedifferentiation and nephrogenic transcriptional signatures. Conversely, low ECM did not show a strong replicative repair signature. Differences in immune cell populations highlighted the dynamic nature of immune responses, some of which, promoted severe metabolic dysfunction and limited repair in low ECM or perpetual tissue regeneration and sustained injury in high ECM. Low ECM was characterized by increased dendritic cells (cDCs, pDCs), mast cells, and monocytes (MO1, MO2) whereas high ECM was characterized by increased B cells, T cells (CD8+ T cells, NKs, and Tregs), and plasma cells. Moreover, 65 ligand-receptor pairs between kidney cells and donor-derived macrophages (previously unidentified after several years post-transplantation) played a novel role in injury propagation. Conclusion: This work improves our understanding of targetable cell types and regulatory mechanisms involved in tissue repair. Interventions aimed at graft fibrogenesis likely require a more targeted approach based on the unique molecular pathways characterizing each condition. National Institutes of Health grant R01DK109581. National Institutes of Health grant R01DK122682 (VRM).

Background. Long-term liver outcome in hepatitis C virus (HCV)-negative kidney recipients who acquired HCV infection from viremic donors is of intense interest in the transplant community. We evaluated the incidence of fibrosis in liver biopsy specimens of recipients who were transplanted with HCV-infected grafts. Methods. Patients were evaluated in the hepatology clinic, and 29 patients agreed to undergo liver biopsy. The liver histology was scored by the meta-analysis of histological data in viral hepatitis scoring system and was assessed by hepatopathologists. The fibrosis score was compared between patients who initiated direct-acting antiviral (DAA) within 6 wk (n = 6) and after 6 wk (n = 29). Results. Eighty-nine aviremic patients were transplanted with HCV-infected grafts between March 2018 and October 2019. All patients developed HCV infection and were treated with DAA treatment after kidney transplantation (median, 70 d; interquartile range, 55–85 d). All patients (n = 89) achieved sustained virologic response with DAA. The median follow-up time from kidney transplant to liver biopsy was 28 mo (interquartile range, 26–30 mo). Twenty-five patients (86%) had F0, and 4 patients (14%) had F1 fibrosis. No patient had advanced fibrosis (F3–F4). Grade 1 inflammation was present in 6 (21%) patients, whereas 26 (90%) patients had iron accumulation in the hepatocytes and reticuloendothelial cells. There was no difference in the fibrosis score between patients who received treatment within 6 wk versus after 6 wk (P = 0.55). Conclusions. Kidney transplantation of HCV-infected graft to HCV-negative recipients is safe and has no long-term liver-related complications with successful eradication of HCV. In our cohort, delayed treatment did not affect sustained virologic response or liver histology.

Introduction: FSGS is a complex pattern of injury that can lead to kidney failure and, consequently, end-stage renal disease. It is well known that podocyte injury and loss is a key pathogenic step. Despite concerted research efforts directed at classifying FSGS using a histologic, genetic, or molecular approach, a detailed understanding of the molecular mechanisms of FSGS pathogenies remain elusive. This study aimed to identify the cellular origin, molecular pathways, and cell-cell interactions contributing to FSGS using a human transplant model. Methods: Single nuclei RNA-seq was performed on the following human biopsies: i) normal allografts showing non-specific histology (N=4) and ii) FSGS allografts showing glomerular damage (N= 6). Gel-Bead V3 were captured by using the droplet-based 10X Genomic Chromium Platform. Data was analyzed in CellRanger 3.1.0. Downstream analyses were performed including evaluation of cell clusters via uniform manifold approximation and projection, gene and pathway enrichment analyses, intra- and inter-cluster comparative transcriptome analyses. Results: Using human allografts, a total of 40,078 single nuclei partitioned into 17 unique cell clusters. Stringent quality control metrics were met. We identified both common kidney cell types (e.g. proximal tubular and collecting duct principal cells) and rare cells (e.g. podocytes and immune cells). Comparative analysis between FSGS and normal kidney allografts, revealed a significant decline in endothelial cells and podocytes, as expected. There were 2 novel podocyte subclusters under different transcriptional programs. The podocyte 1 cluster displayed an injured podocyte phenotype enriched in Wnt signaling and actin filament-based pathways. The podocyte 2 cluster displayed a dysfunctional phenotype enriched in ECM deposition, cell morphogenesis, and cell-cell adhesion pathways. Critically, subcluster analysis revealed 10 endothelial cell types, which included glomerular, peritubular capillary, and arteriolar cells, and 6 immune cell clusters, which included macrophages/ monocytes, T cells, natural killer cells, and B cells. Immune cells were significantly increased, specifically in T memory cells, and their transcriptional profile was significantly altered in FSGS patients compared to normal. Conclusions: FSGS is characterized by a complex cellular and transcriptomic landscape, leading to further kidney injury.

IMPORTANCE:Ischemic cold storage (ICS) of livers for transplant is associated with serious posttransplant complications and underuse of liver allografts. OBJECTIVE:To determine whether portable normothermic machine perfusion preservation of livers obtained from deceased donors using the Organ Care System (OCS) Liver ameliorates early allograft dysfunction (EAD) and ischemic biliary complications (IBCs). DESIGN, SETTING, AND PARTICIPANTS:This multicenter randomized clinical trial (International Randomized Trial to Evaluate the Effectiveness of the Portable Organ Care System Liver for Preserving and Assessing Donor Livers for Transplantation) was conducted between November 2016 and October 2019 at 20 US liver transplant programs. The trial compared outcomes for 300 recipients of livers preserved using either OCS (n = 153) or ICS (n = 147). Participants were actively listed for liver transplant on the United Network of Organ Sharing national waiting list. INTERVENTIONS:Transplants were performed for recipients randomly assigned to receive donor livers preserved by either conventional ICS or the OCS Liver initiated at the donor hospital. MAIN OUTCOMES AND MEASURES:The primary effectiveness end point was incidence of EAD. Secondary end points included OCS Liver ex vivo assessment capability of donor allografts, extent of reperfusion syndrome, incidence of IBC at 6 and 12 months, and overall recipient survival after transplant. The primary safety end point was the number of liver graft-related severe adverse events within 30 days after transplant. RESULTS:Of 293 patients in the per-protocol population, the primary analysis population for effectiveness, 151 were in the OCS Liver group (mean [SD] age, 57.1 [10.3] years; 102 [67%] men), and 142 were in the ICS group (mean SD age, 58.6 [10.0] years; 100 [68%] men). The primary effectiveness end point was met by a significant decrease in EAD (27 of 150 [18%] vs 44 of 141 [31%]; P = .01). The OCS Liver preserved livers had significant reduction in histopathologic evidence of ischemia-reperfusion injury after reperfusion (eg, less moderate to severe lobular inflammation: 9 of 150 [6%] for OCS Liver vs 18 of 141 [13%] for ICS; P = .004). The OCS Liver resulted in significantly higher use of livers from donors after cardiac death (28 of 55 [51%] for the OCS Liver vs 13 of 51 [26%] for ICS; P = .007). The OCS Liver was also associated with significant reduction in incidence of IBC 6 months (1.3% vs 8.5%; P = .02) and 12 months (2.6% vs 9.9%; P = .02) after transplant. CONCLUSIONS AND RELEVANCE:This multicenter randomized clinical trial provides the first indication, to our knowledge, that normothermic machine perfusion preservation of deceased donor livers reduces both posttransplant EAD and IBC. Use of the OCS Liver also resulted in increased use of livers from donors after cardiac death. Together these findings indicate that OCS Liver preservation is associated with superior posttransplant outcomes and increased donor liver use. TRIAL REGISTRATION:ClinicalTrials.gov Identifier: NCT02522871.

With the development of novel prognostic tools derived from omics technologies, transplant medicine is entering the era of precision medicine. Currently, there are no established predictive biomarkers for posttransplant kidney function. A total of 270 deceased donor pretransplant kidney biopsies were collected and posttransplant function was prospectively monitored. This study first assessed the utility of pretransplant gene expression profiles in predicting 24-month outcomes in a training set (n = 174). Nearly 600 differentially expressed genes were associated with 24-month graft function. Grafts that progressed to low function at 24 months exhibited upregulated immune responses and downregulated metabolic processes at pretransplantation. Using penalized logistic regression modeling, a 55 gene model area under the receiver operating curve (AUROC) for 24-month graft function was 0.994. Gene expression for a subset of candidate genes was then measured in an independent set of pretransplant biopsies (n = 96) using quantitative polymerase chain reaction. The AUROC when using 13 genes with three donor characteristics (age, race, body mass index) was 0.821. Subsequently, a risk score was calculated using this combination for each patient in the validation cohort, demonstrating the translational feasibility of using gene markers as prognostic tools. These findings support the potential of pretransplant transcriptomic biomarkers as novel instruments for improving posttransplant outcome predictions and associated management.