| 1. |
- Moscatelli, Ilana, et al.
(författare)
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Targeting NSG Mice Engrafting Cells with a Clinically Applicable Lentiviral Vector Corrects Osteoclasts in Infantile Malignant Osteopetrosis
- 2018
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Ingår i: Human Gene Therapy. - : Mary Ann Liebert Inc. - 1043-0342 .- 1557-7422. ; 29:8, s. 938-949
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Tidskriftsartikel (refereegranskat)abstract
- Infantile malignant osteopetrosis (IMO) is a rare, lethal, autosomal recessive disorder characterized by nonfunctional osteoclasts. More than 50% of the patients have mutations in the TCIRG1 gene, encoding for a subunit of the osteoclast proton pump. The aim of this study was to develop a clinically applicable lentiviral vector expressing TCIRG1 to correct osteoclast function in IMO. Two mammalian promoters were compared: elongation factor 1α short (EFS) promoter and chimeric myeloid promoter (ChimP). EFS promoter was chosen for continued experiments, as it performed better. IMO osteoclasts corrected in vitro by a TCIRG1-expressing lentiviral vector driven by EFS (EFS-T) restored Ca2+ release to 92% and the levels of the bone degradation product CTX-I to 95% in the media compared to control osteoclasts. IMO CD34+ cells from five patients transduced with EFS-T were transplanted into NSG mice. Bone marrow was harvested 9–19 weeks after transplantation, and human CD34+ cells were selected, expanded, and seeded on bone slices. Vector-corrected IMO osteoclasts had completely restored Ca2+ release. CTX-I levels in the media were 33% compared to normal osteoclasts. Thus, in summary, evidence is provided that transduction of IMO CD34+ cells with the clinically applicable EFS-T vector leads to full rescue of osteoclasts in vitro and partial rescue of osteoclasts generated from NSG mice engrafting hematopoietic cells. This supports the continued clinical development of gene therapy for IMO.
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| 2. |
- Rehn, Matilda, et al.
(författare)
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Hypoxic induction of vascular endothelial growth factor regulates erythropoiesis but not hematopoietic stem cell function in the fetal liver.
- 2014
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Ingår i: Experimental Hematology. - : Elsevier BV. - 1873-2399 .- 0301-472X. ; 42:11, s. 941-944
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Tidskriftsartikel (refereegranskat)abstract
- Hypoxia is an important factor in the hematopoietic stem cell (HSC) niche in the bone marrow, but whether it also plays a role in the regulation of fetal liver (FL) HSCs is unclear. Vascular endothelial growth factor A (VEGFA) is essential for adult HSC survival, and hypoxic induction of VEGFA in adult HSCs is required for proper function. Loss of hypoxia-regulated VEGFA expression increases the number of phenotypically defined hematopoietic stem and progenitor cells in the FL, but whether stem cell function is affected in FL HSCs has not, to our knowledge, been assessed. We show that fetal erythropoiesis is severely impaired when hypoxic induction of VEGFA is lacking. Fetal liver HSCs deficient for hypoxia-induced VEGFA expression have normal HSC function, arguing against a hypoxic FL HSC niche. However, after adaptation of FL HSCs to the bone marrow microenvironment, FL HSCs lose their function, as measured by serial transplantation.
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| 3. |
- Thudium, Christian Schneider, et al.
(författare)
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Regulation and Function of Lentiviral Vector-Mediated TCIRG1 Expression in Osteoclasts from Patients with Infantile Malignant Osteopetrosis : Implications for Gene Therapy
- 2016
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Ingår i: Calcified Tissue International. - : Springer Science and Business Media LLC. - 0171-967X .- 1432-0827. ; 99:6, s. 638-648
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Tidskriftsartikel (refereegranskat)abstract
- Infantile malignant osteopetrosis (IMO) is a rare, recessive disorder characterized by increased bone mass caused by dysfunctional osteoclasts. The disease is most often caused by mutations in the TCIRG1 gene encoding a subunit of the V-ATPase involved in the osteoclasts capacity to resorb bone. We previously showed that osteoclast function can be restored by lentiviral vector-mediated expression of TCIRG1, but the exact threshold for restoration of resorption as well as the cellular response to vector-mediated TCIRG1 expression is unknown. Here we show that expression of TCIRG1 protein from a bicistronic TCIRG1/GFP lentiviral vector was only observed in mature osteoclasts, and not in their precursors or macrophages, in contrast to GFP expression, which was observed under all conditions. Thus, vector-mediated TCIRG1 expression appears to be post-transcriptionally regulated, preventing overexpression and/or ectopic expression and ensuring protein expression similar to that of wild-type osteoclasts. Codon optimization of TCIRG1 led to increased expression of mRNA but lower levels of protein and functional rescue. When assessing the functional rescue threshold in vitro, addition of 30 % CB CD34+ cells to IMO CD34+ patient cells was sufficient to completely normalize resorptive function after osteoclast differentiation. From both an efficacy and a safety perspective, these findings will clearly be of benefit during further development of gene therapy for osteopetrosis.
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