Goal-Oriented Monitoring of Cyclosporine Is Effective for Graft-versus-Host Disease Prevention after Hematopoietic Stem Cell Transplantation in Sickle Cell Disease and Thalassemia Major.

Graft-versus-host disease (GVHD) is an important challenge and a major cause of morbidity and mortality in children after hematopoietic stem cell transplant (HSCT). Herein we report our institution's experience of goal-oriented Bayesian monitoring for cyclosporine (CsA) used alone as GVHD prophylaxis during the post-transplant period in pediatric patients with thalassemia major (TM) or sickle cell anemia (SCA) undergoing HLA-matched HSCT. We also studied evolution of chimerism. Twenty-six consecutive patients (SCA, 14; TM, 12) underwent matched sibling donor (MSD) HSCT from 2004 to 2014. All patients received a myeloablative conditioning regimen. GVHD prophylaxis consisted of 20 mg/kg antithymocyte globulin in the conditioning regimens and then CsA alone in the post-transplant period. Target CsA trough blood concentration (TBC) was 150 ± 20 ng/mL. At last follow-up, all patients were alive and free of disease, even in cases of mixed chimerism. Engraftment occurred in all patients. No patient developed grades II to IV acute GVHD, 4 patients developed acute grade I skin GVHD, and only 1 presented with chronic pulmonary GVHD. A better control of GVHD and immunosuppression by a strict monitoring of CsA TBC as described herein is promising and could play a crucial role. Further investigations are required, but this study opens new perspectives to improve survival and safety of HSCT from alternative donors in TM and SCA to levels compatible with that obtained with MSDs.

Correlation between genetic and geographic structure in Europe.

Understanding the genetic structure of the European population is important, not only from a historical perspective, but also for the appropriate design and interpretation of genetic epidemiological studies. Previous population genetic analyses with autosomal markers in Europe either had a wide geographic but narrow genomic coverage [1, 2], or vice versa [3-6]. We therefore investigated Affymetrix GeneChip 500K genotype data from 2,514 individuals belonging to 23 different subpopulations, widely spread over Europe. Although we found only a low level of genetic differentiation between subpopulations, the existing differences were characterized by a strong continent-wide correlation between geographic and genetic distance. Furthermore, mean heterozygosity was larger, and mean linkage disequilibrium smaller, in southern as compared to northern Europe. Both parameters clearly showed a clinal distribution that provided evidence for a spatial continuity of genetic diversity in Europe. Our comprehensive genetic data are thus compatible with expectations based upon European population history, including the hypotheses of a south-north expansion and/or a larger effective population size in southern than in northern Europe. By including the widely used CEPH from Utah (CEU) samples into our analysis, we could show that these individuals represent northern and western Europeans reasonably well, thereby confirming their assumed regional ancestry.

[Chimerism analysis after hematopoietic cell transplantation: Guidelines from the Francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC)]. / Étude du chimérisme après allogreffe de cellules hématopoïétiques : recommandations de la Société francophone de greffe de moelle et de thérapie cellulaire (SFGM-TC).

Chimerism analysis is an important step for the patient follow-up after hematopoietic stem cell transplantation. It is used to quantify the donor and the recipient part of a cell population issued from blood or bone marrow sample. In addition to hemogram, this technique is necessary to appreciate the quality of engraftment. The aim of this article is to propose some recommendation about methods, result analysis and therapeutic decision in hematopoietic stem cell transplantation for malignant or non-malignant diseases.

Lymphodepletive effects of rabbit anti-pig thymocyte globulin in neonatal swines.

Lymphodepletive agents play important role in different clinical applications or experimental transplant studies. In order to facilitate preclinical pediatric transplant studies, we have developed the rabbit anti-pig thymocyte globulin (pATG) and studied its effects in neonatal swines. In vitro assays showed that pATG can bind to lymphocytes and neutrophils in a dose-dependent manner and lyse peripheral blood mononuclear cells by apoptosis and complement-dependent cytotoxicity. In vivo, pATG as a monotherapy was administered at different doses (2.5, 5, 20, 40 and 80mg/kg) in newborn pigs. Results showed that pATG induced a dose-dependent but transient T-cell depletion in peripheral blood. Lymphodepletion was also observed in lymph nodes, spleen and thymus. Pharmacokinetic studies showed dose-related cell-bound pATG on lymphocytes, as well as the presence of free pATG in the serum. Both cell-bound and free pATG levels decreased gradually after administration. Interestingly, adjuvant mycophenolate mofetil (MMF) given at 1g/m2/day for 1week successfully maintained pATG-induced T-cell depletion. In conclusion, pATG administration can cause transient T-cell depletion in neonatal pigs and this effect can be maintained by MMF. Therefore, we have developed an original immunosuppressive regimen that can be used for transplantation studies in swine model.

An evaluation of the genetic-matched pair study design using genome-wide SNP data from the European population.

Genetic matching potentially provides a means to alleviate the effects of incomplete Mendelian randomization in population-based gene-disease association studies. We therefore evaluated the genetic-matched pair study design on the basis of genome-wide SNP data (309,790 markers; Affymetrix GeneChip Human Mapping 500K Array) from 2457 individuals, sampled at 23 different recruitment sites across Europe. Using pair-wise identity-by-state (IBS) as a matching criterion, we tried to derive a subset of markers that would allow identification of the best overall matching (BOM) partner for a given individual, based on the IBS status for the subset alone. However, our results suggest that, by following this approach, the prediction accuracy is only notably improved by the first 20 markers selected, and increases proportionally to the marker number thereafter. Furthermore, in a considerable proportion of cases (76.0%), the BOM of a given individual, based on the complete marker set, came from a different recruitment site than the individual itself. A second marker set, specifically selected for ancestry sensitivity using singular value decomposition, performed even more poorly and was no more capable of predicting the BOM than randomly chosen subsets. This leads us to conclude that, at least in Europe, the utility of the genetic-matched pair study design depends critically on the availability of comprehensive genotype information for both cases and controls.