Comparison of Droplet Digital PCR versus qPCR Measurements on the International Scale for the Molecular Monitoring of Chronic Myeloid Leukemia Patients.

BACKGROUND: BCR-ABL1/ABL1 p210 measurement by quantitative polymerase chain reaction (qPCR) is used worldwide to monitor the molecular response in chronic myeloid leukemia (CML) patients. Droplet digital polymerase chain reaction (ddPCR) seems to show a greater sensitivity than qPCR, probably due to the high number of replicates analyzed in ddPCR for the comparison. Additionally, in a recently published comparison, ddPCR measurements were not adequately transformed into International Scale (IS). METHOD: We have analyzed 50 CML patients and ten non-CML donors in parallel by qPCR and ddPCR. To the best of our knowledge, this is the first study comparing both techniques under similar conditions, with BCR-ABL1/ABL1 measurements performed via both techniques transformed into IS. RESULTS: Qualitative and quantitative comparisons showed excellent results. The qualitative correlation showed a Kappa index of 0.94 (95% confidence interval [CI] 0.90-0.98) (P < 0.001). In the quantitative comparison, the absolute intra-class correlation coefficient was 0.868 (95% CI 0.734-0.937; P < 0.001), and Lin's concordance correlation coefficient was 0.863. The Passing-Bablock test indicated a slight proportional difference between qPCR and ddPCR. A quantitative and qualitative subanalysis including 40 patients with a molecular response of 3.0 or deeper showed similar results in every test. In addition, the proportional difference in the Passing-Bablock test disappeared. There were no differences in the sensitivity for BCR-ABL1 detection between qPCR and ddPCR (McNemar test, P = 0.5). CONCLUSIONS: In conclusion, our results show very good quantitative and qualitative correlations between BCR-ABL1/ABL1 p210 results obtained by qPCR and by ddPCR and confirm previous scarce data regarding the lack of an increase in sensitivity of ddPCR over qPCR in this setting.

Mesenchymal stem cells: biological properties and clinical applications.

IMPORTANCE OF THE FIELD: In the last decade, knowledge of mesenchymal stem cells (MSCs) has evolved rapidly; their immunomodulatory properties and paracrine interactions with specific cell types in damaged tissues and promising results in some clinical applications have made these cells an attractive option for the treatment of certain diseases. AREAS COVERED IN THIS REVIEW: We present some relevant methodological issues and biological properties of MSCs, as well as clinical applications of MSC therapies with particular emphasis in the treatment of graft versus host disease (GVHD), complex perianal fistula and refractory metastatic neuroblastoma. Other topical aspects relevant to the application of cellular therapies such as biosafety studies and cellular production of MSCs are also discussed in this review. WHAT THE READER WILL GAIN: The growing optimism regarding MSCs research is based on the promising results obtained in in vitro and in vivo studies. The rapid translational research with MSCs necessitated standardization of methodology and terminology and greater focus on other aspects such as biosafety and cellular production, especially for clinical use of MSCs. TAKE HOME MESSAGE: Much has been learned about the biology and applications of MSCs and much remains to be learned.