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Purpose of the Study: After transplantation, cord blood (CB) hematopoietic stem and progenitor cells (HSPCs) are able to home to the bone marrow niche and to reconstitute the hematopoietic system. PET-CT imaging may be a useful method to monitor this parameter in different conditions. The aim of our study was to set up an efficient method for HSPC radiolabelling with [ 18 F] fluorodeoxyglucose ( 18 F-FDG) and to follow early HSPC homing through PET-CT in mice., Materials and Methods: Purified CB HSPCs were radiolabelled with 18 F-FDG at 37° C with various conditions of cell concentration, incubation time and radioactivity concentration in order to define the in vitro condition that allows both sufficient 18 F-FDG uptake to get high quality PET imaging, and preservation of HSPC viability and functional properties during 3h after radiolabelling. Then, 24h after 2.25Gy irradiation, eight NOD-scid/γc -/- mice were injected with 18 F-FDG-labelled HSPCs, the biodistribution of which was followed using micro-PET-CT., Results: The optimal incubation time was 45min with a stability of 48.3%±12.8% after 180min. The radio-uptake rate we obtained was 7.2%±1.7% with an activity of 5.6±2.1 MBq. Three hours after radiolabelling, viability was 96.7%±3.4%. Fifteen hours after radiolabelling, cell viability was 64.0%±2.3%, migration ability diminished from 51.0%±23.6% to 12.0%±9.1%, clonogenic capacity was null, and long-term engraftment in NSG mice also decreased compared to unlabelled cells. Micro-PET-CT experiments showed an accumulation of radiolabelled HSPCs for 2.5h after injection in the bone marrow and a slight elution of 18 F-FDG., Conclusion: The activity of the obtained 18 F-FDG-labelled HSPCs was sufficient to perform the micro-PET-CT imaging. Although the radiolabelling had a significant toxicity on HSPCs 15h after labelling, this technique allowed monitoring the beginning of HSPC homing into the bone marrow., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Gaucher disease (GD) is a lysosomal storage disorder due to glucocerebrosidase (GBA) deficiency. Mechanisms leading to the emergence of hematological and skeletal manifestations observed in GD are poorly explained. Bone marrow (BM) mesenchymal stem cells (MSCs) are multipotent progenitors that participate in the regulation of bone mass. MSCs should thus represent a cell population involved in the development or progression of bone disease in GD. In a chemical model of GD obtained with Conduritol β epoxide (CBE), a specific inhibitor of GBA activity, we functionally characterized BM MSCs and specifically analyzed their capacity to differentiate into osteoblasts. GBA deficiency obtained with CBE treatment, leads to a dramatic impairment of MSCs proliferation and to morphological abnormalities. Although the capacity of MSCs to differentiate into osteoblasts was not modified, the levels of several soluble factors that regulate bone metabolism were increased in MSCs treated with CBE, compared with untreated MSCs. Moreover, addition of conditioned media from CBE-treated MSCs on monocyte-derived osteoclasts cultured on bone matrix leads to an increase of resorption areas. These data suggested that, in GD, MSCs represents a stem cell population that is likely to be involved in bone pathogenesis.

Fanconi anemia (FA) is a rare condition due to the genetic inactivation of the FA/BRCA pathway. During childhood, most FA patients display progressive bone marrow failure (BMF), the mechanism of which has not been clarified to date. We analyzed BM mesenchymal stem cells (MSCs) from a series of 20 FA patients with BMF (patient median age 12.5 years old, range 7-34). Expression of FANCD2 and sensitivity to mitomycin C, differentiation capacities, and hematopoiesis-supporting abilities, as well as proliferation, cell senescence, and telomere length were assessed. FA MSCs demonstrated hypersensitivity to mitomycin C compared to control MSCs, as expected for FA cells. FA MSCs had normal immunophenotype, support long-term culture of hematopoietic stem cells (HSCs), and display normal differentiation capacities. Telomere loss during cell aging was similar for FA and control MSCs. However, FA MSCs showed reduced long-term proliferation ability, higher stem cell factor and interleukin-6 levels, and increased expression of senescent-associated beta-galactosidase compared to normal MSCs, suggesting a potential role of the BM microenvironment in long-term BMF.

Background The incidence and potential clinical consequences of bacterial contamination of autologous and allogeneic BM products remains open to question. We report our experience of bacterial contamination of BM grafts and adverse events that occurred after transplantation. Methods From January 2003 to February 2006, 257 BM harvests were processed and infused at our institution. Analysis of microbial contamination incidence before and after processing, sensitivity spectra of isolated bacteria and adverse events after graft infusion were analyzed. Results Nineteen of 257 BM (7.4%) were contaminated. Coagulase-negative Staphylococcus (n=9) and Propionibacterium acnes (n=6) were the most frequently isolated microorganisms. Two of nine coagulase-negative staphylococci were found to be resistant to erythromycin and two of six P. acnes to fosfomycin and gentamycin. The frequency and severity of immediate adverse events reported in patients receiving a contaminated graft were similar to those observed in patients receiving a non-contaminated product. No major adverse sequelae occurred after infusion of contaminated grafts. Finally, none of the patients transplanted with a contaminated graft developed bacteriemia that could have been related to the isolated microorganism. Discussion Microbial contamination of BM progenitor cell grafts does not induce severe clinical complications or infectious diseases after infusion. The vast majority of isolated pathogens were skin contaminants. [ABSTRACT FROM AUTHOR]