In chronic lymphocytic leukemia (CLL) the level of minimal residual disease (MRD) after therapy is an independent predictor of outcome. Given the increasing number of new agents being explored for CLL therapy, using MRD as a surrogate could greatly reduce the time necessary to assess their efficacy. In this European Research Initiative on CLL (ERIC) project we have identified and validated a flow-cytometric approach to reliably quantitate CLL cells to the level of 0.0010% (10−5). The assay comprises a core panel of six markers (i.e. CD19, CD20, CD5, CD43, CD79b and CD81) with a component specification independent of instrument and reagents, which can be locally re-validated using normal peripheral blood. This method is directly comparable to previous ERIC-designed assays and also provides a backbone for investigation of new markers. A parallel analysis of high-throughput sequencing using the ClonoSEQ assay showed good concordance with flow cytometry results at the 0.010% (10−4) level, the MRD threshold defined in the 2008 International Workshop on CLL guidelines, but it also provides good linearity to a detection limit of 1 in a million (10−6). The combination of both technologies would permit a highly sensitive approach to MRD detection while providing a reproducible and broadly accessible method to quantify residual disease and optimize treatment in CLL.

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The EuroFlow Consortium developed a fully standardized flow cytometric approach from instrument settings, through antibody panel, reagents and sample preparation protocols, to data acquisition and analysis. The Swiss Cytometry Society (SCS) promoted a study to evaluate the feasibility of using such standardized measurements of 8-color data across two different flow cytometry platforms - Becton Dickinson (BD) FACSCanto II and Beckman Coulter (BC) Navios, aiming at increasing reproducibility and inter-laboratory comparability of immunophenotypic data in clinical laboratories in Switzerland. The study was performed in two phases, i.e. a learning phase (round 1) and an analytical phase (rounds 2 and 3) consisting of a total of three rounds. Overall, 10 laboratories using BD FACSCanto II (n=6) or BC Navios (n=4) flow cytometers participated. Each laboratory measured peripheral blood samples from healthy donors stained with a uniform antibody panel of reagents - EuroFlow Lymphoid Screening Tube (LST) - applying the EuroFlow standardized protocols for instrument setup and sample preparation (www.EuroFlow.org). All data files were analyzed centrally and median fluorescence intensity (MedFI) values for individual markers on defined lymphocyte subsets were recorded; variability from reference MedFI values was assessed using performance scores. Data troubleshooting and discussion of the results with the participants followed after each round at SCS meetings. The results of the learning phase demonstrated that standardized instrument setup and data acquisition are feasible in routine clinical laboratories without previous experience with EuroFlow. During the analytical phase, highly comparable data were obtained at the different laboratories using either BD FACSCanto II or BC Navios. The coefficient of variation of MedFI for 7 of 11 markers performed repeatedly below 30%. In the last study round, 89% of participants scored over 90% MedFI values within the acceptance criteria (P-score), in line with the results of the EuroFlow quality assessment rounds performed by the EuroFlow expert laboratories(Kalina et al., 2015). Central analysis of data allowed identification of deviations from the standardized procedures and technical issues (e.g. failure to perform correct instrument setup and improper compensation). In summary, here we show that inter-laboratory cross-platform standardization of 8-color flow cytometric measurements in clinical laboratories is feasible and allows for fully comparable MedFI results across BD FACSCanto II and BC Navios instruments. However, adherence to standardized protocols is crucial. Thus, training of the laboratory personnel in the EuroFlow standardized procedures is highly recommended to prevent errors in instrument setup and sample preparation.

Pluripotent stem cell-seeded cardiopatches hold promise for in situ regeneration of infarcted hearts. Here, we describe a novel cardiopatch based on bone morphogenetic protein 2-primed cardiaccommitted mouse embryonic stem cells, embedded into biodegradable fibrin matrices and engrafted onto infarcted rat hearts. For in vivo tracking of the engrafted cardiac-committed cells, superparamagnetic iron oxide nanoparticles were magnetofected into the cells, thus enabling detection and functional evaluation by high-resolution magnetic resonance imaging. Six weeks after transplantation into infarcted rat hearts, both local (p < .04) and global (p < .015) heart function, as well as the left ventricular dilation (p < .0011), were significantly improved (p < .001) as compared with hearts receiving cardiopatches loaded with iron nanoparticles alone. Histological analysis revealed that the fibrin scaffolds had degraded over time and clusters of myocyte enhancer factor 2-positive cardiac-committed cells had colonized most of the infarcted myocardium, including the fibrotic area. De novo CD31-positive blood vessels were formed in the vicinity of the transplanted cardiopatch. Altogether, our data provide evidence that stem cell-based cardiopatches represent a promising therapeutic strategy to achieve efficient cell implantation and improved global and regional cardiac function after myocardial infarction. STEM CELLS TRANSLATIONAL MEDICINE 2012;1:248 -260