Frontier system-on-chip (SoC) technology for microwave diagnostics (invited).

The next generation of fusion reactors, exemplified by projects such as the Demonstration Power Plant following the International Thermonuclear Experimental Reactor, faces the monumental challenge of proving the viability of generating electricity through thermonuclear fusion. This pursuit introduces heightened complexities in diagnostic methodologies, particularly in microwave-based diagnostics. The increased neutron fluence necessitates significant reductions in vessel penetrations and the elimination of internal diagnostics, posing substantial challenges. SoC technology offers a promising solution by enabling the miniaturization, modularization, integration, and enhancing the reliability of microwave systems. After seven years of research, our team successfully pioneered the V- and W-band system-on-chip approach, leading to the development of active transmitters and passive receiver modules applied in practical settings, notably within the DIII-D tokamak project. Arrays of these modules have supported microwave imaging diagnostics. New physics measurement results from the Electron Cyclotron Emission Imaging system on DIII-D provide compelling evidence of improved diagnostics following the adoption of SoC technology. Furthermore, we achieved a breakthrough in developing an F-band SoC, advancing higher frequency capabilities for fusion devices. These achievements represent a significant leap forward in fusion diagnostic technology, marking substantial progress toward establishing reliable and efficient plasma diagnostics for future fusion reactors.

Spatially organized cellular communities form the developing human heart.

The heart, which is the first organ to develop, is highly dependent on its form to function1,2. However, how diverse cardiac cell types spatially coordinate to create the complex morphological structures that are crucial for heart function remains unclear. Here we integrated single-cell RNA-sequencing with high-resolution multiplexed error-robust fluorescence in situ hybridization to resolve the identity of the cardiac cell types that develop the human heart. This approach also provided a spatial mapping of individual cells that enables illumination of their organization into cellular communities that form distinct cardiac structures. We discovered that many of these cardiac cell types further specified into subpopulations exclusive to specific communities, which support their specialization according to the cellular ecosystem and anatomical region. In particular, ventricular cardiomyocyte subpopulations displayed an unexpected complex laminar organization across the ventricular wall and formed, with other cell subpopulations, several cellular communities. Interrogating cell-cell interactions within these communities using in vivo conditional genetic mouse models and in vitro human pluripotent stem cell systems revealed multicellular signalling pathways that orchestrate the spatial organization of cardiac cell subpopulations during ventricular wall morphogenesis. These detailed findings into the cellular social interactions and specialization of cardiac cell types constructing and remodelling the human heart offer new insights into structural heart diseases and the engineering of complex multicellular tissues for human heart repair.

Circulating T cell specific extracellular vesicle profiles in cardiac allograft acute cellular rejection.

There is a critical need for biomarkers of acute cellular rejection (ACR) in organ transplantation. We hypothesized that ACR leads to changes in donor-reactive T cell small extracellular vesicle (sEV) profiles in transplant recipient circulation that match the kinetics of alloreactive T cell activation. In rodent heart transplantation, circulating T cell sEV quantities (P < .0001) and their protein and mRNA cargoes showed time-specific expression of alloreactive and regulatory markers heralding early ACR in allogeneic transplant recipients but not in syngeneic transplant recipients. Next generation sequencing of their microRNA cargoes identified novel candidate biomarkers of ACR, which were validated by stem loop quantitative reverse transcription polymerase chain reaction (n = 10). Circulating T cell sEVs enriched from allogeneic transplant recipients mediated targeted cytotoxicity of donor cardiomyocytes by apoptosis assay (P < .0001). Translation of the concept and EV methodologies to clinical heart transplantation demonstrated similar upregulation of circulating T cell sEV profiles at time points of grade 2 ACR (n = 3 patients). Furthermore, T cell receptor sequencing of T cell sEV mRNA cargo demonstrated expression of T cell clones with intact complementarity determining region 3 signals. These data support the diagnostic potential of T cell sEVs as noninvasive biomarker of ACR and suggest their potential functional roles.

Survival and treatment in older patients with ewing sarcoma: an analysis of the national cancer database.

BACKGROUND: Ewing sarcoma (EWS) is a malignancy which primarily arises in adolescence and has been studied extensively in this population. Much less is known about the rare patient cohort over the age of 40 at diagnosis. In this study, we describe the survival outcomes and clinical characteristics of this population. METHODS: This retrospective cohort study utilized the National Cancer Database (NCDB) to identify 4600 patients diagnosed between 2004 through 2019. Of these patients, 4058 were under the age of 40 and 542 were over 40. Propensity score 1:1 matching was performed according to sex and race. Univariate and multivariate logistic regression was performed to generate odds ratios (OR) and a Multivariate Cox regression model was used to generate a hazard ratio (HR) for patients over 40. Kaplan-Meier curves were used to estimate survival from diagnosis to death between age groups. Chi-square tests were used to compare demographic and socioeconomic patient characteristics. IBM statistics version 27.0 was used. p < 0.05 was used to indicate statistical significance. RESULTS: EWS patients older than 40 experienced worse survival outcomes compared to patients under the age of 40. 5-year survival was 44.6% for older patients vs. 61.8% for younger patients (p < 0.05). A multivariate Cox proportional hazards model showed that age was independently associated with inferior survival. (HR 1.96; p < 0.05). EWS patients over the age of 40 were more likely to have tumors originating from the vertebral column (16.1% vs 8.9%; p < 0.05) and cranium (5.3% vs. 2.9%; p < 0.05) and had a higher rate of axial tumors (31.6% vs. 18.5%; p < 0.05) compared to patients under 40. Additionally, patients older than 40 experienced a significantly longer delay between the date of diagnosis and initiation of systemic treatment (36.7 days vs. 24.8 days; p < 0.05) and were less likely to receive adjuvant chemotherapy (93.4% vs. 97.9%; p < 0.05). CONCLUSION: An age over 40 is associated with decreased survival for patients with EWS. Due to the rarity of EWS in this cohort, the optimal role of systemic treatment remains unknown and has yet to be clearly elucidated. Consequently, our findings suggest that older patients receive disparities in treatment which may be contributing to decreased survival rates.

Clustering-independent estimation of cell abundances in bulk tissues using single-cell RNA-seq data.

Single-cell RNA-sequencing has transformed the study of biological tissues by enabling transcriptomic characterizations of their constituent cell states. Computational methods for gene expression deconvolution use this information to infer the cell composition of related tissues profiled at the bulk level. However, current deconvolution methods are restricted to discrete cell types and have limited power to make inferences about continuous cellular processes like cell differentiation or immune cell activation. We present ConDecon, a clustering-independent method for inferring the likelihood for each cell in a single-cell dataset to be present in a bulk tissue. ConDecon represents an improvement in functionality and accuracy with respect to current deconvolution methods. Using ConDecon, we discover the implication of neurodegenerative microglial inflammatory pathways in the mesenchymal transformation of ependymoma, recapitulate spatial patterns of cell differentiation during zebrafish embryogenesis, and make temporal inferences from bulk ATAC-seq data. Overall, ConDecon significantly enhances our understanding of dynamic cellular processes within bulk tissue samples.

Cell Layers: uncovering clustering structure in unsupervised single-cell transcriptomic analysis.

Motivation: Unsupervised clustering of single-cell transcriptomics is a powerful method for identifying cell populations. Static visualization techniques for single-cell clustering only display results for a single resolution parameter. Analysts will often evaluate more than one resolution parameter but then only report one. Results: We developed Cell Layers, an interactive Sankey tool for the quantitative investigation of gene expression, co-expression, biological processes and cluster integrity across clustering resolutions. Cell Layers enhances the interpretability of single-cell clustering by linking molecular data and cluster evaluation metrics, providing novel insight into cell populations. Availability and implementation: https://github.com/apblair/CellLayers.

Midterm outcomes and durability of sinus segment preservation compared with root replacement for acute type A aortic dissection.

OBJECTIVE: The durability of root repair for acute type A aortic dissection is not well studied in the context of aortic insufficiency and stability of the sinuses of Valsalva. We compared clinical and functional outcomes in patients undergoing root repair and replacement for acute type A aortic dissection. METHODS: Of 716 patients undergoing surgery for acute type A aortic dissection, 585 (81.7%) underwent root repair and 131 (18.3%) underwent root replacement. Survival, cumulative incidence of reoperation, aortic insufficiency, and sinuses of Valsalva dilation were compared between the 2 groups. RESULTS: Survival at 1, 5, and 10 years was 84.1% versus 77.3%, 70.8% versus 69.2%, 57.6% versus 58.0% in the root repair and replacement groups, respectively (P = .69). Cumulative incidence of reoperation at 1, 5, and 10 years was 0.0% versus 0.8%, 1.4% versus 3.8%, and 3.4% versus 8.6% in the root repair and root replacement groups, respectively (P = .011). Multivariable Cox regression identified sinuses of Valsalva diameter 45 mm or more as a risk factor for proximal aortic reoperation (hazard ratio, 9.06; 95% confidence interval, 1.26-65.24). In a repeated-measures, linear, mixed-effects model, root replacement was associated with smaller follow-up of sinuses of Valsalva dimensions (ß = -0.66, P < .001). In an ordinal longitudinal mixed model, root replacement was associated with lower severity of postoperative aortic insufficiency (ß = -3.10, P < .001). CONCLUSIONS: Survival is similar, but the incidence of aortic insufficiency and root dilation may be greater after root repair compared with root replacement for acute type A aortic dissection.

Midterm outcomes of emergency surgery for acute type A aortic dissection in octogenarians.

OBJECTIVE: The incidence of elderly patients with acute type A aortic dissection is increasing. A recent analysis of the International Registry of Acute Aortic Dissection failed to show a mortality benefit with surgery compared with medical management in octogenarians. Therefore, we compared our institutional outcomes of emergency surgery for acute type A aortic dissection in octogenarians versus septuagenarians to understand the outcomes of surgical intervention in elderly patients. METHODS: From 2002 to 2017, 70 octogenarians (aged ≥80 years) and 165 septuagenarians (70-79 years) underwent surgery for acute type A aortic dissection (N = 235, total). Quality of life was assessed by the RAND Short Form-36 quality of life survey. Midterm clinical and functional data were obtained retrospectively. RESULTS: At baseline, septuagenarians had a higher prevalence of diabetes (20.6% vs 5.7%, P = .01). The prevalence of cardiopulmonary resuscitation was 4.8% versus 10.0% (P = .24) in septuagenarians and octogenarians. The prevalence of cardiogenic shock was 18.2% versus 27.1% (P = .17). Thirty-day/in-hospital mortality was 21.2% versus 28.6% (P = .29). Multivariable logistic regression identified cardiogenic shock as an independent risk factor for in-hospital mortality (odds ratio, 10.07; 95% confidence interval, 2.30-44.03) in octogenarians. Survival at 5 years was 49.7% (42.1%-58.6%) versus 34.2% (23.9%-48.8%) in septuagenarians and octogenarians, respectively. Responses to the quality of life survey were no different between septuagenarians and octogenarians across all 8 quality of life categories. CONCLUSIONS: Clinical outcomes after surgery for acute type A aortic dissection are similar in octogenarians and septuagenarians. For discharged survivors, quality of life remains favorable and does not differ between the 2 groups.

Human-gained heart enhancers are associated with species-specific cardiac attributes.

The heart, a vital organ which is first to develop, has adapted its size, structure and function in order to accommodate the circulatory demands for a broad range of animals. Although heart development is controlled by a relatively conserved network of transcriptional/chromatin regulators, how the human heart has evolved species-specific features to maintain adequate cardiac output and function remains to be defined. Here, we show through comparative epigenomic analysis the identification of enhancers and promoters that have gained activity in humans during cardiogenesis. These cis-regulatory elements (CREs) are associated with genes involved in heart development and function, and may account for species-specific differences between human and mouse hearts. Supporting these findings, genetic variants that are associated with human cardiac phenotypic/disease traits, particularly those differing between human and mouse, are enriched in human-gained CREs. During early stages of human cardiogenesis, these CREs are also gained within genomic loci of transcriptional regulators, potentially expanding their role in human heart development. In particular, we discovered that gained enhancers in the locus of the early human developmental regulator ZIC3 are selectively accessible within a subpopulation of mesoderm cells which exhibits cardiogenic potential, thus possibly extending the function of ZIC3 beyond its conserved left-right asymmetry role. Genetic deletion of these enhancers identified a human gained enhancer that was required for not only ZIC3 and early cardiac gene expression at the mesoderm stage but also cardiomyocyte differentiation. Overall, our results illuminate how human gained CREs may contribute to human-specific cardiac attributes, and provide insight into how transcriptional regulators may gain cardiac developmental roles through the evolutionary acquisition of enhancers.

Long-term outcomes of aortic root procedures for heterogenous ascending aneurysm disease in bicuspid aortic valve syndrome.

OBJECTIVE: Surgery for ascending aneurysms in bicuspid aortic valve syndrome primarily includes Bentall root replacement, aortic valve replacement with supracoronary ascending aorta replacement (AVRSCAAR), and valve-sparing root reimplantation (VSRR). Comparative analysis of long-term clinical and functional outcomes of these procedures is detailed. METHODS: From 1997 to 2017, 635 patients with bicuspid aortic valve undergoing root complex-focused procedures electively were stratified by valvulopathy (ie, aortic stenosis vs aortic insufficiency) and substratified into ascending or root aneurysm phenotype. Inverse probability weights were calculated to adjust for baseline differences. RESULTS: Kaplan-Meier curves for all-cause mortality demonstrated no difference between Bentall versus AVRSCAAR for aortic stenosis and aortic insufficiency presentations (log-rank P > .05). In patients with aortic stenosis, multivariable Cox regression showed significantly decreased risk of stroke for biologic AVRSCAAR (hazard ratio, 0.04; P = .013). Aortic reoperation rates were similar for biologic versus mechanical valves (P = .353). In patients with aortic insufficiency, similar long-term mortality (hazard ratio, 0.95; P = .93), but lower stroke risk in biologic AVRSCAAR group by Cox regression, and lower aortic reoperation rate was noted (coefficient < 0.01; P < .001). Comparing Bentall to VSRR, mortality (hazard ratio, 0.12; P = .022) was significantly improved in patients undergoing VSRR, but recurrence of moderate or greater aortic insufficiency was higher in VSRR by multistate model (beta coefficient 2.63; P < .001). CONCLUSIONS: A tailored approach to heterogeneous ascending aneurysm pathologies in bicuspid aortic valve syndrome utilizing Bentall, AVRSCAAR, and VSRR procedures renders excellent long-term clinical and functional outcomes, with biologic conduits showing equivalent to improved clinical outcomes.

Circulating Donor Lung-specific Exosome Profiles Enable Noninvasive Monitoring of Acute Rejection in a Rodent Orthotopic Lung Transplantation Model.

BACKGROUND: There is a critical need for development of biomarkers to noninvasively monitor for lung transplant rejection. We investigated the potential of circulating donor lung-specific exosome profiles for time-sensitive diagnosis of acute rejection in a rat orthotopic lung transplant model. METHODS: Left lungs from Wistar transgenic rats expressing human CD63-GFP, an exosome marker, were transplanted into fully MHC-mismatched Lewis recipients or syngeneic controls. Recipient blood was collected between 4 h and 10 d after transplantation, and plasma was processed for exosome isolation by size exclusion column chromatography and ultracentrifugation. Circulating donor exosomes were profiled using antihuman CD63 antibody quantum dot on the nanoparticle detector and via GFP trigger on the nanoparticle flow cytometer. RESULTS: In syngeneic controls, steady-state levels of circulating donor exosomes were detected at all posttransplant time points. Allogeneic grafts lost perfusion by day 8, consistent with acute rejection. Levels of circulating donor exosomes peaked on day 1, decreased significantly by day 2, and then reached baseline levels by day 3. Notably, decrease in peripheral donor exosome levels occurred before grafts had histological evidence of acute rejection. CONCLUSIONS: Circulating donor lung-specific exosome profiles enable an early detection of acute rejection before histologic manifestation of injury to the pulmonary allograft. As acute rejection episodes are a major risk factor for the development of chronic lung allograft dysfunction, this biomarker may provide a novel noninvasive diagnostic platform that can translate into earlier therapeutic intervention for lung transplant patients.

A 90 nm-CMOS broadband receiver with 10 dB conversion gain and 15 dB noise figure in 80-110 GHz suitable for multi-pixel imaging arrays.

This paper describes the latest development of a W-band 90 nm-CMOS receiver chip that is suitable for use in radio-astronomical multi-pixel imaging arrays and other broadband scientific instruments. This circuit includes an RF-low-noise amplifier (LNA), mixer, intermediate-frequency amplifier (IF-Amp), local-oscillator (LO) tripler, and driving amplifier. With a tripler integrated into the circuit, the incoming 80-110 GHz spectrum can be directly down-converted to 2-32 GHz by the applied 26 GHz LO signal. The system architecture will be presented, with the corresponding sub-circuits discussed in detail. In the on-wafer measurement at room temperature, this receiver has around 10 dB gain and 15 dB noise figure across the whole frequency range, with 400 mW power dissipation under 1.8 V DC bias. By adding a compound-semiconductor LNA in front of this CMOS receiver chip, compact low-noise receiver modules can be easily constructed and deployed.

Recurrent aortic insufficiency after emergency surgery for acute type A aortic dissection with aortic root preservation.

OBJECTIVE: Patients with acute type A aortic dissection demonstrate a wide range of aortic insufficiency. Outcomes after valve resuspension and root repair are not well studied in the long term. We evaluated the long-term effects of preoperative aortic insufficiency in patients undergoing emergency root-preserving surgery for acute type A aortic dissection. METHODS: From 2002 to 2017, 558 of 776 patients with acute type A aortic dissection underwent native aortic valve resuspension and root reconstruction. Patients were stratified into 4 groups by preoperative aortic insufficiency grade (n = 539): aortic insufficiency less than 2+ (n = 348), aortic insufficiency = 2+ (n = 72), aortic insufficiency = 3+ (n = 49), and aortic insufficiency = 4+ (n = 70). Multivariable ordinal longitudinal mixed effects and multi-state transition models were used to assess risk factors for recurrent aortic insufficiency. RESULTS: The prevalence of cardiogenic shock in patients presenting with preoperative aortic insufficiency less than 2+, 2+, 3+, and 4+ was 53 of 348 (15.2%), 12 of 72 (16.7%), 10 of 49 (20.4%), and 24 of 70 (34.3%), respectively (P = .002). Postoperatively, 94.0% of patients had aortic insufficiency 1+ or less at discharge. Operative mortality was 34 of 348 (9.8%), 10 of 72 (13.9%), 6 of 49 (12.2%), and 12 of 70 (17.1%) (P = .303). In an ordinal mixed effects model, preoperative aortic insufficiency was associated with more severe postoperative aortic insufficiency. The multi-state transition model demonstrated that severe aortic insufficiency was associated with progression from no to mild aortic insufficiency (hazard ratio, 2.14; 95% confidence interval, 1.35-3.38), and progression from mild to moderate aortic insufficiency (hazard ratio, 5.70; 95% confidence interval, 1.88-17.30). CONCLUSIONS: Preoperative aortic insufficiency is an important predictor of recurrent aortic insufficiency in patients undergoing valve resuspension with root reconstruction for emergency acute type A aortic dissection repair. Increased echocardiographic surveillance for recurrent aortic insufficiency may be warranted in this cohort.

Circulating Donor Heart Exosome Profiling Enables Noninvasive Detection of Antibody-mediated Rejection.

BACKGROUND: Endomyocardial biopsy remains the gold standard for distinguishing types of immunologic injury-acute versus antibody-mediated rejection (AMR). Exosomes are tissue-specific extracellular microvesicles released by many cell types, including transplanted heart. Circulating transplant heart exosomes express donor-specific human leukocyte antigen (HLA) I molecules. As AMR is mediated by antibodies to donor HLAs, we proposed that complement deposition that occurs with AMR at tissue level would also occur on circulating donor heart exosomes. METHODS: Plasma exosomes in 4 patients were isolated by column chromatography and ultracentrifugation. Donor heart exosomes were purified using anti-donor HLA I antibody beads and complement C4d protein expression was assessed in this subset as marker for AMR. RESULTS: Three patients had no rejection episodes. Circulating donor heart exosomes showed troponin protein and mRNA expression at all follow-up time points. One patient developed AMR on day 14 endomyocardial biopsy that was treated with rituximab, IVIG/plasmapheresis. Time-specific detection of C4d protein was seen in donor heart exosome subset in this patient, which resolved with treatment. C4d was not seen in other 3 patients' donor exosomes. CONCLUSIONS: Anti-donor HLA I specificity enables characterization of circulating donor heart exosomes in the clinical setting. Further characterization may open the window to noninvasively diagnose rejection type, such as AMR.

Syncytiotrophoblast extracellular microvesicle profiles in maternal circulation for noninvasive diagnosis of preeclampsia.

Preeclampsia is the most common placental pathology in pregnant females, with increased morbidity and mortality incurred on the mother and the fetus. There is a need for improved biomarkers for diagnosis and monitoring of this condition. Placental syncytiotrophoblasts at the maternal-fetal interface release nanoparticles, including extracellular microvesicles, into the maternal blood during pregnancy. Syncytiotrophoblast extracellular microvesicles (STEVs) are being studied for their diagnostic potential and for their potential physiologic role in preeclampsia. We hypothesized that STEV profiles in maternal circulation would be altered under conditions of preeclampsia compared to normal pregnancy. Extracellular vesicles (EVs) released by BeWo cells in vitro showed high expression of syncytin-1, but no plac1 expression, demonstrating that trophoblast cell EVs express syncytin-1 on their surface. Placental alkaline phosphatase also showed high expression on BeWo EVs, but due to concern for cross reactivity to highly prevalent isoforms of intestinal and bone alkaline phosphatase, we utilized syncytin-1 as a marker for STEVs. In vivo, syncytin-1 protein expression was confirmed in maternal plasma EVs from Control and Preeclampsia subjects by Western blot, and overall, lower expression was noted in samples from patients with preeclampsia (n = 8). By nanoparticle analysis, EV profiles from Control and Preeclampsia groups showed similar total plasma EV quantities (p = 0.313) and size distribution (p = 0.415), but STEV quantitative signal, marked by syncytin-1 specific EVs, was significantly decreased in the Preeclampsia group (p = 2.8 × 10-11). Receiver operating characteristic curve demonstrated that STEV signal threshold cut-off of <0.316 was 95.2% sensitive and 95.6% specific for diagnosis of preeclampsia in this cohort (area under curve = 0.975 ± 0.020). In conclusion, we report that the syncytin-1 expressing EV profiles in maternal plasma might serve as a placental tissue specific biomarker for preeclampsia.

Fate of the Preserved Sinuses of Valsalva After Emergency Repair for Acute Type A Aortic Dissection.

BACKGROUND: Patients with acute type A aortic dissection (ATAAD) present with heterogeneous involvement of the aortic root complex. Despite this variation, the aortic root can usually be preserved the majority of the time by Teflon (WL Gore, Newark, DE) inlay patch reconstruction of the dissected sinuses of Valsalva (SOV). In this study, we report the long term anatomic, functional, and clinical outcomes associated with the preserved SOV after surgery for ATAAD. METHODS: From 2002-2017, of 776 emergency ATAAD operations at a single institution, 558 (71.9%) underwent valve resuspension with SOV preservation. Echocardiography reports were reviewed to obtain postoperative SOV dimensions. Cumulative incidence of SOV dilation ≥ 4 5mm was calculated using the Fine-Gray method with death as a competing risk. Repeated-measures linear mixed effects model was used to determine risk factors for SOV growth over time. RESULTS: During the follow-up period, 62 of 558 (11.1%) patients developed SOV diameter ≥ 45 mm. Cumulative incidence of SOV dilation ≥ 45 mm at 1, 5, and 10 years was 5.5%, 12.4%, and 18.9% respectively. In a multivariable Cox regression model, preoperative SOV diameter ≥ 45 mm was associated with a hazard ratio of 14.11 (95% confidence interval 7.03-31.62) for postoperative SOV dilation ≥ 45 mm. In a repeated-measures linear mixed effects model, preoperative and discharge SOV diameter were significant predictors of SOV dilation. Postoperative time course was also identified as significant indicating growth over time. CONCLUSIONS: The preserved sinuses of Valsalva after surgery for ATAAD may be prone to progressive dilatation over time. Closer echocardiographic surveillance may be warranted in these patients.

Circulating exosomes derived from transplanted progenitor cells aid the functional recovery of ischemic myocardium.

The stem cell field is hindered by its inability to noninvasively monitor transplanted cells within the target organ in a repeatable, time-sensitive, and condition-specific manner. We hypothesized that quantifying and characterizing transplanted cell-derived exosomes in the recipient plasma would enable reliable, noninvasive surveillance of the conditional activity of the transplanted cells. To test this hypothesis, we used a human-into-rat xenogeneic myocardial infarction model comparing two well-studied progenitor cell types: cardiosphere-derived cells (CDCs) and c-kit+ cardiac progenitor cells (CPCs), both derived from the right atrial appendage of adults undergoing cardiopulmonary bypass. CPCs outperformed the CDCs in cell-based and in vivo regenerative assays. To noninvasively monitor the activity of transplanted CDCs or CPCs in vivo, we purified progenitor cell-specific exosomes from recipient total plasma exosomes. Seven days after transplantation, the concentration of plasma CPC-specific exosomes increased about twofold compared to CDC-specific exosomes. Computational pathway analysis failed to link CPC or CDC cellular messenger RNA (mRNA) with observed myocardial recovery, although recovery was linked to the microRNA (miRNA) cargo of CPC exosomes purified from recipient plasma. We further identified mechanistic pathways governing specific outcomes related to myocardial recovery associated with transplanted CPCs. Collectively, these findings demonstrate the potential of circulating progenitor cell-specific exosomes as a liquid biopsy that provides a noninvasive window into the conditional state of the transplanted cells. These data implicate the surveillance potential of cell-specific exosomes for allogeneic cell therapies.

Noninvasive diagnosis of recurrent autoimmune type 1 diabetes after islet cell transplantation.

Islet cell transplantation is curative therapy for patients with complicated autoimmune type 1 diabetes (T1D). We report the diagnostic potential of circulating transplant islet-specific exosomes to noninvasively distinguish pancreatic ß cell injury secondary to recurrent autoimmunity vs immunologic rejection. A T1D patient with hypoglycemic unawareness underwent islet transplantation and maintained normoglycemia until posttransplant day 1098 before requiring exogenous insulin. Plasma analysis showed decreased donor islet exosome quantities on day 1001, before hyperglycemia onset. This drop in islet exosome quantity signified islet injury, but did not distinguish injury type. However, analysis of purified transplant islet exosome cargoes showed decrease in insulin-containing exosomes, but not glucagon-containing exosomes, indicating selective destruction of transplanted ß cells secondary to recurrent T1D autoimmunity. Furthermore, donor islet exosome cargo analysis showed time-specific increase in islet autoantigen, glutamic acid decarboxylase 65 (GAD65), implicated in T1D autoimmunity. Time-matched analysis of plasma transplant islet exosomes in 3 control subjects undergoing islet cell transplantation failed to show changes in islet exosome quantities or intraexosomal cargo expression of insulin, glucagon, and GAD65. This is the first report of noninvasive diagnosis of recurrent autoimmunity after islet cell transplantation, suggesting that transplant tissue exosome platform may serve as a biomarker in islet transplant diagnostics.