Macopharma (France)

BackgroundMuscular dystrophies (MDs) are inherited diseases in which a dysregulation of the immune response exacerbates disease severity and are characterized by infiltration of various immune cell types leading to muscle inflammation, fiber necrosis and fibrosis. Immunosuppressive properties have been attributed to mesenchymal stem cells (MSCs) that regulate the phenotype and function of different immune cells. However, such properties were poorly considered until now for adult stem cells with myogenic potential and advanced as possible therapeutic candidates for MDs. In the present study, we investigated the immunoregulatory potential of human MuStem (hMuStem) cells, for which we previously demonstrated that they can survive in injured muscle and robustly counteract adverse tissue remodeling.MethodsThe impact of hMuStem cells or their secretome on the proliferative and phenotypic properties of T-cells was explored by co-culture experiments with either peripheral blood mononucleated cells or CD3-sorted T-cells. A comparative study was produced with the bone marrow (BM)-MSCs. The expression profile of immune cell-related markers on hMuStem cells was determined by flow cytometry while their secretory profile was examined by ELISA assays. Finally, the paracrine and cell contact-dependent effects of hMuStem cells on the T-cell-mediated cytotoxic response were analyzed through IFN-γ expression and lysis activity.ResultsHere, we show that hMuStem cells have an immunosuppressive phenotype and can inhibit the proliferation and the cytotoxic response of T-cells as well as promote the generation of regulatory T-cells through direct contact and via soluble factors. These effects are associated, in part, with the production of mediators including heme-oxygenase-1, leukemia inhibitory factor and intracellular cell adhesion molecule-1, all of which are produced at significantly higher levels by hMuStem cells than BM-MSCs. While the production of prostaglandin E2 is involved in the suppression of T-cell proliferation by both hMuStem cells and BM-MSCs, the participation of inducible nitric oxide synthase activity appears to be specific to hMuStem cell-mediated one.ConclusionsTogether, our findings demonstrate that hMuStem cells are potent immunoregulatory cells. Combined with their myogenic potential, the attribution of these properties reinforces the positioning of hMuStem cells as candidate therapeutic agents for the treatment of MDs.

Yellow fever virus (YFV) is endemic to tropical and subtropical areas in South America and Africa, and is currently a major public health threat in Brazil. Transfusion transmission of the yellow fever vaccine virus has been demonstrated, which is indicative of the potential for viral transfusion transmission. An approach to manage the potential YFV transfusion transmission risk is the use of pathogen inactivation (PI) technology systems, such as THERAFLEX MB-Plasma and THERAFLEX UV-Platelets (Macopharma). We aimed to investigate the efficacy of these PI technology systems to inactivate YFV in plasma or platelet concentrates (PCs). YFV spiked plasma units were treated using THERAFLEX MB-Plasma system (visible light doses: 20, 40, 60, and 120 [standard] J/cm2 ) in the presence of methylene blue (approx. 0.8 μmol/L) and spiked PCs were treated using THERAFLEX UV-Platelets system (ultraviolet C doses: 0.05, 0.10, 0.15, and 0.20 [standard] J/cm2 ). Samples were taken before the first and after each illumination dose and tested for residual virus using a modified plaque assay. YFV infectivity was reduced by an average of 4.77 log or greater in plasma treated with the THERAFLEX MB-Plasma system and by 4.8 log or greater in PCs treated with THERAFLEX UV-Platelets system. Our study suggests the THERAFLEX MB-Plasma and the THERAFLEX UV-Platelets systems can efficiently inactivate YFV in plasma or PCs to a similar degree as that for other arboviruses. Given the reduction levels observed in this study, these PI technology systems could be an effective option for managing YFV transfusion-transmission risk in plasma and PCs.

Arboviruses, such as dengue viruses (DENV) and chikungunya virus (CHIKV), pose a risk to the safe transfusion of blood components, including plasma. Pathogen inactivation is an approach to manage this transfusion transmission risk, with a number of techniques being used worldwide for the treatment of plasma. In this study, the efficacy of the THERAFLEX MB-Plasma system to inactivate all DENV serotypes (DENV-1, DENV-2, DENV-3, DENV-4) or CHIKV in plasma, using methylene blue and light illumination at 630 nm, was investigated. Pooled plasma units were spiked with DENV-1, DENV-2, DENV-3 DENV-4, or CHIKV and treated with the THERAFLEX MB-Plasma system at four light illumination doses: 20, 40, 60, and 120 (standard dose) J/cm(2) . Pre- and posttreatment samples were collected and viral infectivity was determined. The reduction in viral infectivity was calculated for each dose. Treatment of plasma with the THERAFLEX MB-Plasma system resulted in at least a 4.46-log reduction in all DENV serotypes and CHIKV infectious virus. The residual infectivity for each was at the detection limit of the assay used at 60 J/cm(2) , with dose dependency also observed. Our study demonstrated the THERAFLEX MB-Plasma system can reduce the infectivity of all DENV serotypes and CHIKV spiked into plasma to the detection limit of the assay used at half of the standard illumination dose. This suggests this system has the capacity to be an effective option for managing the risk of DENV or CHIKV transfusion transmission in plasma.

Five cases of variant Creutzfeldt-Jakob disease (vCJD) infections were attributed to infusion of contaminated blood components, turning to real the interhuman transmissibility of this prion disease from asymptomatic carriers. Preventive policies rely on exclusion from blood donation and benefit of leukoreduction initially implemented against leukotropic viruses. In the absence of available antemortem diagnostic tests, the updated prevalence of silent vCJD infections (1/2000 in the United Kingdom) urges the necessity to enforce blood safety with more efficient active measures able to remove the remaining infectivity. Several affinity resins were demonstrated to reduce high levels of brain-spiked infectivity from human leukoreduced red blood cells (L-RBCs). One was integrated in a device adapted to field constraints (volumes, duration) of human transfusion. We assessed here the ability of the resulting removal filter, termed P-Capt, to remove infectivity from human L-RBC units spiked with scrapie-infected hamster brain (≥10,000 infectious units/mL), through inoculation of hamsters with pre- and post-blood filtration samples. Incubation periods of recipient animals suggest around a 3-log removal of brain-derived prion infectivity by filtration through the P-Capt. On brain-derived spiked infectivity, the P-Capt filter provided a performance similar to the resin packed in columns used for initial proof-of-concept studies, suggesting an appropriate scale-up to efficiently remove infectivity from an individual human blood bag. According to the ability of resin to completely remove apparent endogenous infectivity from hamster leukoreduced blood, the implementation of such a filter, now commercially available, might seriously improve blood safety toward prions.

Lineage-priming is a molecular model of stem cell (SC) differentiation in which proliferating SCs express a subset of genes associated to the differentiation pathways to which they can commit. This concept has been developed for hematopoietic SCs, but has been poorly studied for other SC populations. Because the differentiation potential of human bone marrow mesenchymal stem cells (BM MSCs) remains controversial, we have explored the theory of lineage-priming applied to these cells. We show that proliferating primary layers and clones of BM MSCs have precise priming to the osteoblastic (O), chondrocytic (C), adipocytic (A), and the vascular smooth muscle (V) lineages, but not to skeletal muscle, cardiac muscle, hematopoietic, hepatocytic, or neural lineages. Priming was shown both at the mRNA (300 transcripts were evaluated) and the protein level. In particular, the master transactivator proteins PPARG, RUNX2, and SOX9 were coexpressed before differentiation induction in all cells from incipient clones. We further show that MSCs cultured in the presence of inducers differentiate into the lineages for which they are primed. Our data point out to a number of signaling pathways that might be activated in proliferating MSCs and would be responsible for the differentiation and proliferation potential of these cells. Our results extend the notion of lineage-priming and provide the molecular framework for inter-A, -O, -C, -V plasticity of BM MSCs. Our data highlight the use of BM MSCs for the cell therapy of skeletal or vascular disorders, but provide a word of caution about their use in other clinical indications.