Hematopoietic Stem Cell Mobilization for Gene Therapy: The Combination of G-CSF+Plerixafor in Patients with Beta-Thalassemia Major Provides High Yiel…

2015

Abstract Hematopoietic stem cell engineering is a promising therapy to cure b-thalassemia, in particular for patients who lack a suitable BM donor for allogeneic transplantation. Since the engrafted gene-corrected stem cells will not have any selective advantage over the unmodified ones, the effectiveness of the therapy in this setting largely depends on the infusion of high numbers of gene-modified cells and on the conditioning regimen. The quality of the infused cells is also crucial for the clinical outcome and the duration of the therapeutic effect. HSPCs mobilization, particularly when G-CSF and plerixafor are used in combination, has been proved to be the optimal approach to harvest a…

The Sea Urchin sns5 Insulator Protects Retroviral Vectors From Chromosomal Position Effects by Maintaining Active Chromatin Structure

2009

Silencing and position-effect (PE) variegation (PEV), which is due to integration of viral vectors in heterochromatin regions, are considered significant obstacles to obtaining a consistent level of transgene expression in gene therapy. The inclusion of chromatin insulators into vectors has been proposed to counteract this position-dependent variegation of transgene expression. Here, we show that the sea urchin chromatin insulator, sns5, protects a recombinant gamma-retroviral vector from the negative influence of chromatin in erythroid milieu. This element increases the probability of vector expression at different chromosomal integration sites, which reduces both silencing and PEV. By chr…

321. Sea Urchin sns Chromatin Insulator Prevents Silencing and Positional Effect Variegation of Oncoretroviral Vectors Transgene Expression in Murine…

2006

Silencing and position effect are considered significant obstacles to obtain a consistent level of transgene expression in viral gene therapy. Furthermore recent studies had shown that retroviruses tend to land on active genes with the potential consequence of insertional mutagenesis. The inclusion of elements, such as chromatin insulators, capable to insulate a gene from the surrounding chromatin effects at the integration site should improve both efficacy and safety of gene therapy vectors. We have previously characterized a 265 bp insulator element, termed sns, localized at the 3’ end of the early histone H2A gene of the sea urchin Paracentrotus lividus. This sequence contains three cis-…

The Challenge of Using CB-HSCs As Source for Gene Therapy: Lentiviral Vector Transduction, Phenotypic Characterization and Global Gene Expression Pro…

2015

Abstract Introduction: Genetic modification of autologous hematopoietic stem and progenitor cells (HSPC) is a promising clinical intervention to cure inherited monogenic diseases. Successful gene therapy trials have already been conducted using CD34+ cells from bone marrow and from mobilized peripheral blood. In this regard, cord blood (CB) represents an attractive source of HSCs due to its high concentration of high proliferative HSPC and increased susceptibility to be transduced by lentiviral vectors. Unfortunately, the major disadvantage is the limited number of HSC in the CB collection. Consequently, ex-vivo expansion of CB-HSC is desirable to extend clinical applications. Purposes: To …

Granulocyte–Colony Stimulating Factor plus Plerixafor in Patients with β-thalassemia Major Results in the Effective Mobilization of Primitive CD34+ C…

2017

Successful gene therapy for β-thalassemia requires optimal numbers of autologous gene-transduced hematopoietic stem and progenitor cells (HSPCs) with high repopulating capacity. Previous studies suggested superior mobilization in these patients by the combination of granulocyte–colony stimulating factor (G-CSF) plus plerixafor over single agents. We mobilized four adult patients using G-CSF+plerixafor to assess the intra-individual variation of the circulating CD34+ cells number and subtypes preand post-plerixafor administration. The procedure was well-tolerated and the target cell dose of ≥8×10 6 CD34+ cells/kg was achieved in three of them with one apheresis procedure. The addition of ple…

EFFECTIVENESS OF G-CSF+PLERIXAFOR MOBILIZATION IN β- THALASSEMIA PATIENTS AND WHOLE GENE EXPRESSION ANALYSIS OF THE HARVESTED CD34+ CELLS

2014

Non-primate lentiviral vectors and their applications in gene therapy for ocular disorders

2018

Lentiviruses have a number of molecular features in common, starting with the ability to integrate their genetic material into the genome of non-dividing infected cells. A peculiar property of non-primate lentiviruses consists in their incapability to infect and induce diseases in humans, thus providing the main rationale for deriving biologically safe lentiviral vectors for gene therapy applications. In this review, we first give an overview of non-primate lentiviruses, highlighting their common and distinctive molecular characteristics together with key concepts in the molecular biology of lentiviruses. We next examine the bioengineering strategies leading to the conversion of lentiviruse…

Functional characterization of the sea urchin sns chromatin insulator in erythroid cells.

2005

Abstract Chromatin insulators are regulatory elements that determine domains of genetic functions. We have previously described the characterization of a 265 bp insulator element, termed sns, localized at the 3′ end of the early histone H2A gene of the sea urchin Paracentrotus lividus. This sequence contains three cis-acting elements (Box A, Box B, and Box C + T) all needed for the enhancer-blocking activity in both sea urchin and human cells. The goal of this study was to further characterize the sea urchin sns insulator in the erythroid environment. We employed colony assays in human (K562) and mouse (MEL) erythroid cell lines. We tested the capability of sns to interfere with the communi…

Wharton's Jelly Mesenchymal Stromal Cells as a Feeder Layer for the Ex Vivo Expansion of Hematopoietic Stem and Progenitor Cells: a Review

2016

In recent years, umbilical cord blood (UCB) has been widely used as an alternative source to bone marrow (BM) for transplantation of hematopoietic stem and progenitor cells (HSPCs) in a variety of hematological and non-hematological disorders. Nevertheless, the insufficient number of UCB-HSPCs for graft represents a major challenge. HSPCs ex vivo expansion prior to transplantation is a valid strategy to overcome this limit. Several attempts to optimize the expansion conditions have been reported, including the use of mesenchymal stromal cells (MSCs) as feeder layer. Wharton's Jelly (WJ), the main component of umbilical cord (UC) matrix, is especially rich in MSCs, which are considered ideal…

The Sea Urchin sns5 Chromatin Insulator Shapes the Chromatin Architecture of a Lentivirus Vector Integrated in the Mammalian Genome.

2016

Lentivirus vectors are presently the favorite vehicles for therapeutic gene transfer in hematopoietic cells. Nonetheless, these vectors integrate randomly throughout the genome, exhibiting variegation of transgene expression due to the spreading of heterochromatin into the vector sequences. Moreover, the cis-regulatory elements harbored by the vector could disturb the proper transcription of resident genes neighboring the integration site. The incorporation of chromatin insulators in flanking position to the transferred unit can alleviate both the above-mentioned dangerous effects, due to the insulator-specific barrier and enhancer-blocking activities. In this study, we report the valuable …

Wharton’s Jelly Mesenchymal Stromal Cells Support the Expansion of Cord Blood–derived CD34+Cells Mimicking a Hematopoietic Niche in a Direct Cell–cel…

2018

Wharton’s jelly mesenchymal stromal cells (WJ-MSCs) have been recently exploited as a feeder layer in coculture systems to expand umbilical cord blood–hematopoietic stem/progenitor cells (UCB-HSPCs). Here, we investigated the role of WJ-MSCs in supporting ex vivo UCB-HSPC expansion either when cultured in direct contact (DC) with WJ-MSCs or separated by a transwell system or in the presence of WJ-MSC–conditioned medium. We found, in short-term culture, a greater degree of expansion of UCB-CD34+cells in a DC system (15.7 ± 4.1-fold increase) with respect to the other conditions. Moreover, in DC, we evidenced two different CD34+cell populations (one floating and one adherent to WJ-MSCs) with …

The Sea Urchin sns5 Chromatin Insulator Improves the Likelihood of Lentiviral Vectors in Erythroid Milieu By Organizing an Independent Chromatin Doma…

2015

Abstract Retroviral vectors are currently the most suitable vehicles for therapeutic gene transfer in hematopoietic stem cells. However, these vectors are known to integrate rather randomly throughout the genome, suffering the so called chromosomal position effects (PE). Such a critical occurrence most probably depends upon the ability of heterochromatin to spread in the inserted vector sequences. Moreover, the use of transgenes imply genotoxicity effects, since the cis-regulatory sequences harbored by the vector can disturb the proper transcription of the resident genes neighboring the integration site, potentially leading to malignant transformation. Due to their enhancer blocker activity…