1,721,313 research outputs found
In Vivo Selection for Gene-Corrected HSPCs Advances Gene Therapy for a Rare Stem Cell Disease
No full textTwo recent papers (one by Román-Rodríguez et al., 2019 in this issue of Cell Stem Cell) highlight how the power of biological selection on hematopoietic stem cell fitness can facilitate gene therapies for Fanconi Anemia. A clinical trial using lentiviral gene replacement and a proof-of-concept targeted genome editing study show robust engraftment and expansion of gene-corrected cells at levels reaching therapeutic relevance
Cellular innate immunity and restriction of viral infection: Implications for lentiviral gene therapy in human hematopoietic cells
No full textHematopoietic gene therapy has tremendous potential to treat human disease. Nevertheless, for gene therapy to be efficacious, effective gene transfer into target cells must be reached without inducing detrimental effects on their biological properties. This remains a great challenge for the field as high vector doses and prolonged ex vivo culture conditions are still required to reach significant transduction levels of clinically relevant human hematopoietic stem and progenitor cells (HSPCs), while other potential target cells such as primary macrophages can hardly be transduced. The reasons behind poor permissiveness of primary human hematopoietic cells to gene transfer partly reside in the retroviral origin of lentiviral vectors (LVs). In particular, host antiviral factors referred to as restriction factors targeting the retroviral life cycle can hamper LV transduction efficiency. Furthermore, LVs may activate innate immune sensors not only in differentiated hematopoietic cells but also in HSPCs, with potential consequences on transduction efficiency as well as their biological properties. Therefore, better understanding of the vector-host interactions in the context of hematopoietic gene transfer is important for the development of safer and more efficient gene therapy strategies. In this review, we briefly summarize the current knowledge regarding innate immune recognition of lentiviruses in primary human hematopoietic cells as well as discuss its relevance for LV-based ex vivo gene therapy approaches
Gene therapy of lysosomal storage disorders by lentiviral vectors
No full textLysosomal storage disorders (LSDs) comprise a class of inherited diseases characterized by disruption of normal lysosomal function and the consequent accumulation of incompletely degraded substrates. Most LSDs are caused by loss of function of specific lysosomal acid hydrolases, which act to degrade complex substrates that have been targeted for degradation after endocytosis or autophagy. The degradation occurs by a stepwise pathway, and if one step in the process fails, further degradation often ceases and the partially degraded substrate accumulates. The ensuing substrate accumulation in lysosomes affects the architecture and function of cells, tissues, and organs. In some cases, the accumulated substrate itself (as in Galactocerebrosidosis) or the product of an alternative metabolic route, which is upregulated by the accumulated primary substrate (as in the case of psycosine in Globoid Cell Leukodystrophy), is cytotoxic and leads to cell dysfunction or death. In other cases, the actual molecular mechanism triggered by the accumulated metabolite and leading to cellular toxicity and tissue pathology remains elusive
Efficient gene delivery and targeted expression to hepatocytes in vivo by improved lentiviral vectors
No full textSafe and efficient genetic modification of liver cells could enable new therapies for a variety of hepatic and systemic diseases. Lentiviral vectors are promising tools for in vivo gene delivery. Previous data suggested that recruitment into the cell cycle was required for transduction of hepatocytes in vivo. We developed an improved vector design that enhanced nuclear translocation in target cells and significantly improved gene transfer performance. Using the new vector and a panel of internal promoters, we showed that rat hepatocytes were transduced ex vivo to high frequency without requirement for proliferation. On intravenous administration of vector into adult severe combined immunodeficient (SCID) mice, we found high levels (up to 30%) of transduction of parenchymal and nonparenchymal cells of the liver, integration of the vector genome in liver DNA and stable expression of the marker green fluorescent protein (GFP)-encoding gene without signs of toxicity. Coadministration of vectors and 5'-bromo-2'-deoxyuridine in vivo proved that cell cycling was not required for efficient transduction of hepatocytes. In addition to the liver, the spleen and the bone marrow were transduced effectively by systemic delivery of vector. GFP expression was observed in all these organs when driven by the cytomegalovirus promoter and by the phosphoglycerate kinase gene promoter. Using the promoter of the albumin gene, we could restrict expression to hepatocytes. By a single vector injection into the bloodstream of SCID mice, we achieved therapeutic-range levels of the human clotting factor IX, stable in the plasma for up to 1 year (the longest time tested), indicating the potential efficacy of improved lentiviral vectors for the gene therapy of hemophilias and other diseases
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