Clinical implications of changing thyroglobulin and antithyroglobulin antibodies analytical methods in the follow-up of patients with differentiated thyroid carcinoma.

BACKGROUND AND AIMS: Patients' response to treatment in differentiated thyroid cancer (DTC) is classified according to serum thyroglobulin concentrations (Tg), usually using the American Thyroid Association guidelines and considering potential interfering anti-thyroglobulin antibodies (Ab-Tg). We aim to evaluate the clinical implications of changing Tg and Ab-Tg quantification method. MATERIAL AND METHODS: Tg and Ab-Tg were quantified in 82 serum samples (60 from DTC patients) by Elecsys and Access immunoassays. RESULTS: Elecsys immunoassay rendered higher values of Tg than Access: mean bias 5.03 ng/mL (95%CI:-14.14-24.21). In DTC patients, there was an almost perfect agreement for response classification (kappa index = 0.833). Discrepancies appeared in patients with undetermined response, with a more tendency to subclassification with Access. Ab-Tg showed a poor correlation (r = 0.5394). When Elecsys cut-off was reduced to 43 IU/mL, agreement for positive/negative classification improved from a kappa index of 0.607 to 0.650. Prospective study with personalized follow-up showed that only 6.3% of Tg results required an analytical confirmation, being confirmed 93% of them. CONCLUSIONS: Despite the biases observed, clinical impact of an analytical change is minimal in patients' management. However, cautious and personalized follow-up period after the change is still mandatory, especially in patients with Tg levels between 0.2 and 1 ng/mL.

FlowCT for the analysis of large immunophenotypic data sets and biomarker discovery in cancer immunology.

Large-scale immune monitoring is becoming routinely used in clinical trials to identify determinants of treatment responsiveness, particularly to immunotherapies. Flow cytometry remains one of the most versatile and high throughput approaches for single-cell analysis; however, manual interpretation of multidimensional data poses a challenge when attempting to capture full cellular diversity and provide reproducible results. We present FlowCT, a semi-automated workspace empowered to analyze large data sets. It includes pre-processing, normalization, multiple dimensionality reduction techniques, automated clustering, and predictive modeling tools. As a proof of concept, we used FlowCT to compare the T-cell compartment in bone marrow (BM) with peripheral blood (PB) from patients with smoldering multiple myeloma (SMM), identify minimally invasive immune biomarkers of progression from smoldering to active MM, define prognostic T-cell subsets in the BM of patients with active MM after treatment intensification, and assess the longitudinal effect of maintenance therapy in BM T cells. A total of 354 samples were analyzed and immune signatures predictive of malignant transformation were identified in 150 patients with SMM (hazard ratio [HR], 1.7; P < .001). We also determined progression-free survival (HR, 4.09; P < .0001) and overall survival (HR, 3.12; P = .047) in 100 patients with active MM. New data also emerged about stem cell memory T cells, the concordance between immune profiles in BM and PB, and the immunomodulatory effect of maintenance therapy. FlowCT is a new open-source computational approach that can be readily implemented by research laboratories to perform quality control, analyze high-dimensional data, unveil cellular diversity, and objectively identify biomarkers in large immune monitoring studies. These trials were registered at www.clinicaltrials.gov as #NCT01916252 and #NCT02406144.

Biological and clinical significance of dysplastic hematopoiesis in patients with newly diagnosed multiple myeloma.

Risk of developing myelodysplastic syndrome (MDS) is significantly increased in both multiple myeloma (MM) and monoclonal gammopathy of undetermined significance, suggesting that it is therapy independent. However, the incidence and sequelae of dysplastic hematopoiesis at diagnosis are unknown. Here, we used multidimensional flow cytometry (MFC) to prospectively screen for the presence of MDS-associated phenotypic alterations (MDS-PA) in the bone marrow of 285 patients with MM enrolled in the PETHEMA/GEM2012MENOS65 trial (#NCT01916252). We investigated the clinical significance of monocytic MDS-PA in a larger series of 1252 patients enrolled in 4 PETHEMA/GEM protocols. At diagnosis, 33 (11.6%) of 285 cases displayed MDS-PA. Bulk and single-cell-targeted sequencing of MDS recurrently mutated genes in CD34+ progenitors (and dysplastic lineages) from 67 patients revealed clonal hematopoiesis in 13 (50%) of 26 cases with MDS-PA vs 9 (22%) of 41 without MDS-PA; TET2 and NRAS were the most frequently mutated genes. Dynamics of MDS-PA at diagnosis and after autologous transplant were evaluated in 86 of 285 patients and showed that in most cases (69 of 86 [80%]), MDS-PA either persisted or remained absent in patients with or without MDS-PA at diagnosis, respectively. Noteworthy, MDS-associated mutations infrequently emerged after high-dose therapy. Based on MFC profiling, patients with MDS-PA have altered hematopoiesis and T regulatory cell distribution in the tumor microenvironment. Importantly, the presence of monocytic MDS-PA at diagnosis anticipated greater risk of hematologic toxicity and was independently associated with inferior progression-free survival (hazard ratio, 1.5; P = .02) and overall survival (hazard ratio, 1.7; P = .01). This study reveals the biological and clinical significance of dysplastic hematopoiesis in newly diagnosed MM, which can be screened with moderate sensitivity using cost-effective MFC.

Immunogenomic identification and characterization of granulocytic myeloid-derived suppressor cells in multiple myeloma.

Granulocytic myeloid-derived suppressor cells (G-MDSCs) promote tumor growth and immunosuppression in multiple myeloma (MM). However, their phenotype is not well established for accurate monitoring or clinical translation. We aimed to provide the phenotypic profile of G-MDSCs based on their prognostic significance in MM, immunosuppressive potential, and molecular program. The preestablished phenotype of G-MDSCs was evaluated in bone marrow samples from controls and MM patients using multidimensional flow cytometry; surprisingly, we found that CD11b+CD14-CD15+CD33+HLADR- cells overlapped with common eosinophils and neutrophils, which were not expanded in MM patients. Therefore, we relied on automated clustering to unbiasedly identify all granulocytic subsets in the tumor microenvironment: basophils, eosinophils, and immature, intermediate, and mature neutrophils. In a series of 267 newly diagnosed MM patients (GEM2012MENOS65 trial), only the frequency of mature neutrophils at diagnosis was significantly associated with patient outcome, and a high mature neutrophil/T-cell ratio resulted in inferior progression-free survival (P < .001). Upon fluorescence-activated cell sorting of each neutrophil subset, T-cell proliferation decreased in the presence of mature neutrophils (0.5-fold; P = .016), and the cytotoxic potential of T cells engaged by a BCMA×CD3-bispecific antibody increased notably with the depletion of mature neutrophils (fourfold; P = .0007). Most interestingly, RNA sequencing of the 3 subsets revealed that G-MDSC-related genes were specifically upregulated in mature neutrophils from MM patients vs controls because of differential chromatin accessibility. Taken together, our results establish a correlation between the clinical significance, immunosuppressive potential, and transcriptional network of well-defined neutrophil subsets, providing for the first time a set of optimal markers (CD11b/CD13/CD16) for accurate monitoring of G-MDSCs in MM.

The Mechanism of Action of the Anti-CD38 Monoclonal Antibody Isatuximab in Multiple Myeloma.

PURPOSE: Knowledge about the mechanism of action (MoA) of monoclonal antibodies (mAb) is required to understand which patients with multiple myeloma (MM) benefit the most from a given mAb, alone or in combination therapy. Although there is considerable research about daratumumab, knowledge about other anti-CD38 mAbs remains scarce. EXPERIMENTAL DESIGN: We performed a comprehensive analysis of the MoA of isatuximab. RESULTS: Isatuximab induces internalization of CD38 but not its significant release from MM cell surface. In addition, we uncovered an association between levels of CD38 expression and different MoA: (i) Isatuximab was unable to induce direct apoptosis on MM cells with CD38 levels closer to those in patients with MM, (ii) isatuximab sensitized CD38hi MM cells to bortezomib plus dexamethasone in the presence of stroma, (iii) antibody-dependent cellular cytotoxicity (ADCC) was triggered by CD38lo and CD38hi tumor plasma cells (PC), (iv) antibody-dependent cellular phagocytosis (ADCP) was triggered only by CD38hi MM cells, whereas (v) complement-dependent cytotoxicity could be triggered in less than half of the patient samples (those with elevated levels of CD38). Furthermore, we showed that isatuximab depletes CD38hi B-lymphocyte precursors and natural killer (NK) lymphocytes ex vivo-the latter through activation followed by exhaustion and eventually phagocytosis. CONCLUSIONS: This study provides a framework to understand response determinants in patients treated with isatuximab based on the number of MoA triggered by CD38 levels of expression, and for the design of effective combinations aimed at capitalizing disrupted tumor-stroma cell protection, augmenting NK lymphocyte-mediated ADCC, or facilitating ADCP in CD38lo MM patients.See related commentary by Malavasi and Faini, p. 2946.

Flow cytometry for fast screening and automated risk assessment in systemic light-chain amyloidosis.

Early diagnosis and risk stratification are key to improve outcomes in light-chain (AL) amyloidosis. Here we used multidimensional-flow-cytometry (MFC) to characterize bone marrow (BM) plasma cells (PCs) from a series of 166 patients including newly-diagnosed AL amyloidosis (N = 94), MGUS (N = 20) and multiple myeloma (MM, N = 52) vs. healthy adults (N = 30). MFC detected clonality in virtually all AL amyloidosis (99%) patients. Furthermore, we developed an automated risk-stratification system based on BMPCs features, with independent prognostic impact on progression-free and overall survival of AL amyloidosis patients (hazard ratio: ≥ 2.9;P ≤ .03). Simultaneous assessment of the clonal PCs immunophenotypic protein expression profile and the BM cellular composition, mapped AL amyloidosis in the crossroad between MGUS and MM; however, lack of homogenously-positive CD56 expression, reduction of B-cell precursors and a predominantly-clonal PC compartment in the absence of an MM-like tumor PC expansion, emerged as hallmarks of AL amyloidosis (ROC-AUC = 0.74;P < .001), and might potentially be used as biomarkers for the identification of MGUS and MM patients, who are candidates for monitoring pre-symptomatic organ damage related to AL amyloidosis. Altogether, this study addressed the need for consensus on how to use flow cytometry in AL amyloidosis, and proposes a standardized MFC-based automated risk classification ready for implementation in clinical practice.

Flow Cytometry.

Multiparameter flow cytometry (MFC) is valuable in the diagnosis and monitoring of most hematological malignancies. Although the assessment of cellular infiltrates in Waldenström macroglobulinemia (WM) relies on morphology and immunohistochemistry grounds, there is evidence pointing to the clinical significance of MFC in this disease. Herein, the authors review immunophenotypic patterns of B-cell development, the antigen profile of the WM clone and its normal B-cell counterpart, the clinical applicability of MFC in the differential diagnosis of immunoglobulin M-secreting lymphoproliferative disorders and monoclonal gammopathies, and its potential role in detecting minimal residual disease and monitoring treatment efficacy in WM.

Target Expression, Generation, Preclinical Activity, and Pharmacokinetics of the BCMA-T Cell Bispecific Antibody EM801 for Multiple Myeloma Treatment.

We identified B cell maturation antigen (BCMA) as a potential therapeutic target in 778 newly diagnosed and relapsed myeloma patients. We constructed an IgG-based BCMA-T cell bispecific antibody (EM801) and showed that it increased CD3+ T cell/myeloma cell crosslinking, followed by CD4+/CD8+ T cell activation, and secretion of interferon-γ, granzyme B, and perforin. This effect is CD4 and CD8 T cell mediated. EM801 induced, at nanomolar concentrations, myeloma cell death by autologous T cells in 34 of 43 bone marrow aspirates, including those from high-risk patients and patients after multiple lines of treatment, tumor regression in six of nine mice in a myeloma xenograft model, and depletion of BCMA+ cells in cynomolgus monkeys. Pharmacokinetics and pharmacodynamics indicate weekly intravenous/subcutaneous administration.

A simple flow-cytometry method to evaluate peripheral blood contamination of bone marrow aspirates.

Bone marrow (BM) aspirates used for flow-cytometry (FCM) studies are usually obtained from a second aspiration, as the primary aspirate is used for morphological assessment. For this reason, the FCM samples unavoidably contain some blood; although, good-quality samples contain only a small amount. It is of utmost importance to assess the quality of samples prior to FCM analysis; yet, contamination with peripheral blood (PB) is not evaluated in most laboratories, possibly because the methods available are either qualitative or too complex for daily practice. Here, we propose a simple FCM method to quantitatively evaluate PB contamination in BM aspirates, by analyzing the percentage of plasma cells and CD34+ cells - two cell populations nearly absent from PB - and CD10+ granulocytes, which comprise the majority of the PB granulocyte population. We analyzed these three populations in 122 BM aspirates from subjects without hematological disease, and identified samples with PB contamination by performing a hierarchical cluster analysis. A discriminant analysis yielded a function, which we named the PB contamination index (PBCI). This index value gives a quantitative indication about the degree of hemodilution of a given sample. A threshold was identified that discriminates low-quality samples. The method and the threshold proved to be useful in BM aspirates infiltrated with malignant cells, with the exception of cases where hematological disease altered two of the three parameters included in the index. We have easily implemented the PBCI calculation in our daily routine, and find it very helpful for an accurate interpretation of FCM results in a large proportion of BM specimens. Limitations of the technique are discussed.

First-line use of rituximab correlates with increased overall survival in late post-transplant lymphoproliferative disorders: retrospective, single-centre study.

This retrospective study evaluates the impact of rituximab on PTLD response and survival in a single-centre cohort. PTLD cases between 1984 and 2009, including heart, kidney, liver and lung transplant recipients, were included. Survival was analysed taking into account the type of PTLD (monomorphic vs. polymorphic), EBV infection status, IPI score, Ann Arbor stage and use of rituximab. Among 1335 transplanted patients, 24 developed PTLD. Median age was 54 yr (range 29-69), median time to diagnosis 50 months (range 0-100). PTLD type was predominantly late/monomorphic (79% and 75%), mostly diffuse large B-cell type. Overall response rate (ORR) was 62% (66% rituximab vs. 50% non-rituximab; P = 0.5). R-CHOP-like regimens were used most frequently (72% of patients treated with rituximab). Median overall survival was 64 months (CI 95% 31-96). OS was significantly increased in patients treated with rituximab (P = 0.01; CI 95% rituximab 58-79 months; non-rituximab 1-30 months). Post-transplant immunosuppression regimen had no effect on survival or time to PTLD, except for cyclosporine A (CyA), which associated with increased time to PTLD (P = 0.02). Rituximab was associated with increased survival in our single-centre series, and it should be considered as first-line therapy for PTLD patients. The possible protective effect of CyA for development of PTLD should be prospectively evaluated.

Diagnostic screening of paroxysmal nocturnal hemoglobinuria: Prospective multicentric evaluation of the current medical indications.

BACKGROUND: Although consensus guidelines have been proposed in 2010 for the diagnostic screening of paroxysmal nocturnal hemoglobinuria (PNH) by flow cytometry (FCM), so far no study has investigated the efficiency of such medical indications in multicentric vs. reference laboratory settings. METHODS: Here we evaluate the efficiency of consensus medical indications for PNH testing in 3,938 peripheral blood samples submitted to FCM testing in 24 laboratories in Spain and one reference center in Brazil. RESULTS: Overall, diagnostic screening based on consensus medical indications was highly efficient (14% of PNH+ samples) both in the multicenter setting in Spain (10%) and the reference laboratory in Brazil (16%). The highest frequency of PNH+ cases was observed among patients screened because of bone marrow (BM) failure syndrome (33%), particularly among those with aplastic anemia (AA; 45%) and to a less extent also a myelodysplastic syndrome (MDS; 10%). Among the other individuals studied, the most efficient medical indications for PNH screening included: hemolytic anemia (19%), hemoglobinuria (48%) and unexplained cytopenias (9%). In contrast, only a minor fraction of the patients who had been submitted for PNH testing because of unexplained thrombosis in the absence of cytopenia, were positive (0.4%). CONCLUSIONS: In summary, our results demonstrate that the current medical indications for PNH screening by FCM are highly efficient, although improved screening algorithms are needed for patients presenting with thrombosis and normal blood cell counts. © 2016 International Clinical Cytometry Society.

Utility of flow cytometry studies in the management of patients with multiple myeloma.

PURPOSE OF REVIEW: Although the input of multiparameter flow cytometry (MFC) into the clinical management of multiple myeloma patients has faced some reluctance, continuously growing evidence supports the utility of MFC in this disease. RECENT FINDINGS: MFC immunophenotyping of bone marrow and peripheral blood plasma cells affords cost-effective assessment of clonality, and provides prognostic information on the risk of progression in smoldering multiple myeloma, and the identification of active multiple myeloma patients with dismal outcome (e.g., high numbers of circulating tumor cells) or long-term survival despite suboptimal responses through the characterization of monoclonal gammopathy of undetermined significance-like phenotypes. Extensive data indicate that minimal residual disease (MRD) monitoring can be used as biomarker to evaluate treatment efficacy and act as surrogate for survival. The time has come to address within clinical trials the exact role of baseline risk factors and MRD monitoring for tailored therapy in multiple myeloma, which implies systematic usage of highly sensitive cost-effective, readily available, and standardized MRD techniques such as MFC. SUMMARY: Next-generation MFC should be considered mandatory in the routine evaluation of multiple myeloma patients both at diagnosis and after therapy, and represents an attractive technique to integrate with high-throughput DNA and RNA-seq methods to help in understanding the mechanisms behind dissemination and chemoresistance of multiple myeloma.

Transient Expression of Transgenic IL-12 in Mouse Liver Triggers Unremitting Inflammation Mimicking Human Autoimmune Hepatitis.

The etiopathogenesis of autoimmune hepatitis (AIH) remains poorly understood. In this study, we sought to develop an animal model of human AIH to gain insight into the immunological mechanisms driving this condition. C57BL/6 mice were i.v. injected with adeno-associated viral vectors encoding murine IL-12 or luciferase under the control of a liver-specific promoter. Organ histology, response to immunosuppressive therapy, and biochemical and immunological parameters, including Ag-specific humoral and cellular response, were analyzed. Mechanistic studies were carried out using genetically modified mice and depletion of lymphocyte subpopulations. Adeno-associated virus IL-12-treated mice developed histological, biochemical, and immunological changes resembling type 1 AIH, including marked and persistent liver mononuclear cell infiltration, hepatic fibrosis, hypergammaglobulinemia, anti-nuclear and anti-smooth muscle actin Abs, and disease remission with immunosuppressive drugs. Interestingly, transgenic IL-12 was short-lived, but endogenous IL-12 expression was induced, and both IL-12 and IFN-γ remained elevated during the entire study period. IFN-γ was identified as an essential mediator of liver damage, and CD4 and CD8 T cells but not NK, NKT, or B cells were essential executors of hepatic injury. Furthermore, both MHC class I and MHC class II expression was upregulated at the hepatocellular membrane, and induction of autoreactive liver-specific T cells was detected. Remarkably, although immunoregulatory mechanisms were activated, they only partially mitigated liver damage. Thus, low and transient expression of transgenic IL-12 in hepatocytes causes loss of tolerance to hepatocellular Ags, leading to chronic hepatitis resembling human AIH type 1. This model provides a practical tool to explore AIH pathogenesis and novel therapies.

Immune monitoring of immunosuppression withdrawal of liver transplant recipients.

UNLABELLED: Several studies have shown that some liver transplant recipients may tolerate immunosuppression withdrawal. Mechanisms and biomarkers of tolerance are not well known. METHODS: Twenty-four LT patients with immunosuppression side-effects underwent progressive immunosuppression withdrawal. Peripheral lymphocyte populations and secretion of cytokines were analyzed at baseline and during withdrawal until tolerance (n = 15) or rejection (n = 9), as well as 3 months after tolerance achievement or rejection resolution (as follow-up). Immunological markers were compared among groups. RESULTS: The percentages of CD3+CD4+ cells progressively decreased in both groups. CD3+CD8+ cells gradually increased in tolerant patients. B lymphocytes gradually decreased in tolerant and initially in non-tolerant patients, reverting at rejection. Regulatory T cells progressively increased until rejection in non-tolerants, decreasing to basal levels after renewing immunosuppression; no significant changes were found in tolerant patients. The percentages and absolute counts of natural killer cells significantly increased in both groups, being more evident in tolerant patients. The secretion of several cytokines was higher in non-tolerant patients when rejection was diagnosed. CONCLUSIONS: The greater increase of natural killer cells in tolerant patients suggests their potential role in the tolerance phenomenon.

GATA2 germline mutations impair GATA2 transcription, causing haploinsufficiency: functional analysis of the p.Arg396Gln mutation.

Germline GATA2 mutations have been identified as the cause of familial syndromes with immunodeficiency and predisposition to myeloid malignancies. GATA2 mutations appear to cause loss of function of the mutated allele leading to haploinsufficiency; however, this postulate has not been experimentally validated as the basis of these syndromes. We hypothesized that mutations that are translated into abnormal proteins could affect the transcription of GATA2, triggering GATA2 deficiency. Chromatin immunoprecipitation and luciferase assays showed that the human GATA2 protein activates its own transcription through a specific region located at -2.4 kb, whereas the p.Thr354Met, p.Thr355del, and p.Arg396Gln germline mutations impair GATA2 promoter activation. Accordingly, GATA2 expression was decreased to ∼58% in a patient with p.Arg396Gln, compared with controls. p.Arg396Gln is the second most common mutation in these syndromes, and no previous functional analyses have been performed. We therefore analyzed p.Arg396Gln. Our data show that p.Arg396Gln is a loss-of-function mutation affecting DNA-binding ability and, as a consequence, it fails to maintain the immature characteristics of hematopoietic stem and progenitor cells, which could result in defects in this cell compartment. In conclusion, we show that human GATA2 binds to its own promoter, activating its transcription, and that the aforementioned mutations impair the transcription of GATA2. Our results indicate that they can affect other GATA2 target genes, which could partially explain the variability of symptoms in these diseases. Moreover, we show that p.Arg396Gln is a loss-of-function mutation, which is unable to retain the progenitor phenotype in cells where it is expressed.

Epicardial delivery of collagen patches with adipose-derived stem cells in rat and minipig models of chronic myocardial infarction.

Although transplantation of adipose-derived stem cells (ADSC) in chronic myocardial infarction (MI) models is associated with functional improvement, its therapeutic value is limited due to poor long-term cell engraftment and survival. Thus, the objective of this study was to examine whether transplantation of collagen patches seeded with ADSC could enhance cell engraftment and improve cardiac function in models of chronic MI. With that purpose, chronically infarcted Sprague-Dawley rats (n = 58) were divided into four groups and transplanted with media, collagen scaffold (CS), rat ADSC, or CS seeded with rat ADSC (CS-rADSC). Cell engraftment, histological changes, and cardiac function were assessed 4 months after transplantation. In addition, Göttingen minipigs (n = 18) were subjected to MI and then transplanted 2 months later with CS or CS seeded with autologous minipig ADSC (CS-pADSC). Functional and histological assessments were performed 3 months post-transplantation. Transplantation of CS-rADSC was associated with increased cell engraftment, significant improvement in cardiac function, myocardial remodeling, and revascularization. Moreover, transplantation of CS-pADSC in the pre-clinical swine model improved cardiac function and was associated with decreased fibrosis and increased vasculogenesis. In summary, transplantation of CS-ADSC resulted in enhanced cell engraftment and was associated with a significant improvement in cardiac function and myocardial remodeling.

Trial of complete weaning from immunosuppression for liver transplant recipients: factors predictive of tolerance.

Recipients of liver transplantation (LT) may develop immunological tolerance. Factors predictive of tolerance are not clearly understood. Transplant recipients with normal liver function tests and without active viral hepatitis or autoimmune disease who presented with side effects of immunosuppression or a high risk of de novo malignancies were selected to participate in this prospective study. Twenty-four patients fulfilled the inclusion criteria and, therefore, underwent a gradual reduction of immunosuppression. Tolerance was defined as normal liver function tests after immunosuppression withdrawal. Basal clinical and immunological characteristics, including lymphocyte counts and subpopulations (T, B, natural killer, CD4(+) , CD8(+) , and regulatory T cells) and the phytohemagglutinin stimulation index (SI), were compared for tolerant and nontolerant patients. Fifteen of the 24 patients (62.5%) were tolerant at a median of 14 months (interquartile range = 8.5-22.5 months) after complete immunosuppression withdrawal. Tolerant patients had a longer median interval between transplantation and inclusion in the study (156 for tolerant patients versus 71 months for nontolerant patients, P = 0.003) and a lower median SI (7.49 for tolerant patients versus 41.73 for nontolerant patients, P = 0.01). We identified 3 groups of patients with different probabilities of tolerance: in the first group (n = 7 for an interval > 10 years and an SI < 20), 100% reached tolerance; in the second group (n = 10 for an interval > 10 years and an SI > 20 or an interval < 10 years and an SI < 20), 60% reached tolerance; and in the third group (n = 7 for an interval < 10 years and an SI > 20), 29% reached tolerance. In conclusion, a high proportion of select LT recipients can reach tolerance over the long term. Two simple basal variables-the time from transplantation and the SI-may help to identify these patients.

Treatment of reperfused ischemia with adipose-derived stem cells in a preclinical Swine model of myocardial infarction.

The aim of the study was to determine the long-term effect of transplantation of adipose-derived stromal cells (ADSCs) in a preclinical model of ischemia/reperfusion (I/R). I/R was induced in 28 Goettingen minipigs by 120 min of coronary artery occlusion followed by reperfusion. Nine days later, surviving animals were allocated to receive transendocardial injection of a mean of 213.6 ± 41.78 million green fluorescent protein (GFP)-expressing ADSCs (n = 7) or culture medium as control (n = 9). Heart function, cell engraftment, and histological analysis were performed 3 months after transplantation. Transplantation of ADSCs induced a statistically significant long-lasting (3 months) improvement in cardiac function and geometry in comparison with control animals. Functional improvement was associated with an increase in angiogenesis and vasculogenesis and a positive effect on heart remodeling with a decrease in fibrosis and cardiac hypertrophy in animals treated with ADSCs. Despite the lack of cell engraftment after 3 months, ADSC transplantation induced changes in the ratio between MMP/TIMP. Our results indicate that transplantation of ADSCs, despite the lack of long-term significant cell engraftment, increases vessel density and prevents adverse remodeling in a clinically relevant model of myocardial infarction, strongly suggesting a paracrine-mediated effect. ADSCs thus constitute an attractive candidate for the treatment of myocardial infarction.

Predictive value of the Luminex single antigen panel for detecting flow cytometry cross-match positivity.

Anti-human leukocyte antigen (HLA) antibodies are a major cause of allograft loss. Solid-phase immunoassays, notably Luminex technology, have lately begun to replace traditional techniques for detecting these antibodies. This platform, however, carries some restrictions in the type of antibodies it detects. For this reason, results using these new technologies must be correlated with results using traditional techniques that have proven clinical significance. We have correlated flow cytometry cross-match (FCXM) outcomes with results from Luminex assays. Serum samples from patients awaiting transplantation who had known anti-HLA antibodies as detected by Luminex were incubated with lymphocytes expressing (a) 1 of the HLA antigens detected by the sera or (b) several of them. Of the 169 T-cell FCXMs we performed, in 92 cases the target cell expressed only 1 of the HLA antigens detected by the serum. The results obtained correlated well with Luminex data (r = 0.84). A cutoff mean fluorescence intensity value of 6,500 for the Luminex single antigen assay yielded a sensitivity of 85% and specificity of 82% for detecting a positive FCXM. In the other 77 cases, the target cell expressed 2 or more of the HLA antigens detected by the serum. In this situation, the same cutoff proved a useful tool for differentiating negative from positive FCXMs.

Adipose stromal vascular fraction improves cardiac function in chronic myocardial infarction through differentiation and paracrine activity.

Fresh adipose-derived cells have been shown to be effective in the treatment of acute myocardial infarction (MI), but their role in the chronic setting is unknown. We sought to determine the long-term effect of the adipose derived-stromal vascular fraction (SVF) cell transplantation in a rat model of chronic MI. MI was induced in 82 rats by permanent coronary artery ligation and 5 weeks later rats were allocated to receive an intramyocardial injection of 10(7) GFP-expressing fresh SVF cells or culture media as control. Heart function and tissue metabolism were determined by echocardiography and (18)F-FDG-microPET, respectively, and histological studies were performed for up to 3 months after transplantation. SVF induced a statistically significant long-lasting (3 months) improvement in cardiac function and tissue metabolism that was associated with increased revascularization and positive heart remodeling, with a significantly smaller infarct size, thicker infarct wall, lower scar fibrosis, and lower cardiac hypertrophy. Importantly, injected cells engrafted and were detected in the treated hearts for at least 3 months, directly contributing to the vasculature and myofibroblasts and at negligible levels to cardiomyocytes. Furthermore, SVF release of angiogenic (VEGF and HGF) and proinflammatory (MCP-1) cytokines, as well as TIMP1 and TIMP4, was demonstrated in vitro and in vivo, strongly suggesting that they have a trophic effect. These results show the potential of SVF to contribute to the regeneration of ischemic tissue and to provide a long-term functional benefit in a rat model of chronic MI, by both direct and indirect mechanisms.