Mesenchymal stromal cells and hematopoietic stem cell transplantation.

Mesenchymal stromal cells (MSCs) comprise a heterogeneous population of multipotent cells that can be isolated from various human tissues and culture-expanded ex vivo for clinical use. Due to their immunoregulatory properties and their ability to secrete growth factors, MSCs play a key role in the regulation of hematopoiesis and in the modulation of immune responses against allo- and autoantigens. In light of these properties, MSCs have been employed in clinical trials in the context of hematopoietic stem cell transplantation (HSCT) to facilitate engraftment of hematopoietic stem cells (HSCs) and to prevent graft failure, as well as to treat steroid-resistant acute graft-versus-host disease (GvHD).

Clinical applications of gene therapy for primary immunodeficiencies.

Primary immunodeficiencies (PIDs) have represented a paradigmatic model for successes and pitfalls of hematopoietic stem cells gene therapy. First clinical trials performed with gamma retroviral vectors (γ-RV) for adenosine deaminase severe combined immunodeficiency (ADA-SCID), X-linked SCID (SCID-X1), and Wiskott-Aldrich syndrome (WAS) showed that gene therapy is a valid therapeutic option in patients lacking an HLA-identical donor. No insertional mutagenesis events have been observed in more than 40 ADA-SCID patients treated so far in the context of different clinical trials worldwide, suggesting a favorable risk-benefit ratio for this disease.

B-cell reconstitution after lentiviral vector-mediated gene therapy in patients with Wiskott-Aldrich syndrome.

Background: Wiskott-Aldrich syndrome (WAS) is a severe X-linked immunodeficiency characterized by microthrombocytopenia, eczema, recurrent infections, and susceptibility to autoimmunity and lymphomas. Hematopoietic stem cell transplantation is the treatment of choice; however, administration of WAS gene-corrected autologous hematopoietic stem cells has been demonstrated as a feasible alternative therapeutic approach.

Objective: Because B-cell homeostasis is perturbed in patients with WAS and restoration of immune competence is one of the main therapeutic goals, we have evaluated reconstitution of the B-cell compartment in 4 patients who received autologous hematopoietic stem cells transduced with lentiviral vector after a reduced-intensity conditioning regimen combined with anti-CD20 administration.

Combined gene/cell therapies provide long-term and pervasive rescue of multiple pathological symptoms in a murine model of globoid cell leukodystrophy.

Globoid cell leukodystrophy (GLD) is a lysosomal storage disease caused by deficient activity of β-galactocerebrosidase (GALC). The infantile forms manifest with rapid and progressive central and peripheral demyelination, which represent a major hurdle for any treatment approach. We demonstrate here that neonatal lentiviral vector-mediated intracerebral gene therapy (IC GT) or transplantation of GALC-overexpressing neural stem cells (NSC) synergize with bone marrow transplant (BMT) providing dramatic extension of lifespan and global clinical-pathological rescue in a relevant GLD murine model.

In vivo tracking of T cells in humans unveils decade-long survival and activity of genetically modified T memory stem cells.

A definitive understanding of survival and differentiation potential in humans of T cell subpopulations is of paramount importance for the development of effective T cell therapies. In particular, uncovering the dynamics in vivo in humans of the recently described T memory stem cells (TSCM) would be crucial for therapeutic approaches that aim at taking advantage of a stable cellular vehicle with precursor potential. We exploited data derived from two gene therapy clinical trials for an inherited immunodeficiency, using either retrovirally engineered hematopoietic stem cells or mature lymphocytes to trace individual T cell clones directly in vivo in humans.

Chemotherapy dose adjustment for obese patients undergoing hematopoietic stem cell transplantation: a survey on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation.

Background: Appropriate chemotherapy dosing for obese patients with malignant diseases is a significant challenge because limiting chemotherapy doses in these patients may negatively influence outcome. There is a paucity of information addressing high-dose chemotherapy in obese patients undergoing hematopoietic stem cell transplantation (HSCT).

Methods: The Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (EBMT) designed an electronic survey to assess current practice of dose adjustment of chemotherapy in obese patients undergoing HSCT.

VISPA: a computational pipeline for the identification and analysis of genomic vector integration sites.

The analysis of the genomic distribution of viral vector genomic integration sites is a key step in hematopoietic stem cell-based gene therapy applications, allowing to assess both the safety and the efficacy of the treatment and to study the basic aspects of hematopoiesis and stem cell biology. Identifying vector integration sites requires ad-hoc bioinformatics tools with stringent requirements in terms of computational efficiency, flexibility, and usability. We developed VISPA (Vector Integration Site Parallel Analysis), a pipeline for automated integration site identification and annotation based on a distributed environment with a simple Galaxy web interface.

Cyclosporin a and rapamycin relieve distinct lentiviral restriction blocks in hematopoietic stem and progenitor cells.

Improving hematopoietic stem and progenitor cell (HSPC) permissiveness to HIV-derived lentiviral vectors (LVs) remains a challenge for the field of gene therapy as high vector doses and prolonged ex vivo culture are still required to achieve clinically relevant transduction levels. We report here that Cyclosporin A (CsA) and Rapamycin (Rapa) significantly improve LV gene transfer in human and murine HSPC. Both compounds increased LV but not gammaretroviral transduction and acted independently of calcineurin and autophagy.

Dual-regulated lentiviral vector for gene therapy of X-linked chronic granulomatosis.

Regulated transgene expression may improve the safety and efficacy of hematopoietic stem cell (HSC) gene therapy. Clinical trials for X-linked chronic granulomatous disease (X-CGD) employing gammaretroviral vectors were limited by insertional oncogenesis or lack of persistent engraftment. Our novel strategy, based on regulated lentiviral vectors (LV), targets gp91(phox) expression to the differentiated myeloid compartment while sparing HSC, to reduce the risk of genotoxicity and potential perturbation of reactive oxygen species levels.

Clinical features and follow-up in patients with 22q11.2 deletion syndrome.

Objective: To investigate the clinical manifestations at diagnosis and during follow-up in patients with 22q11.2 deletion syndrome to better define the natural history of the disease.

Study Design: A retrospective and prospective multicenter study was conducted with 228 patients in the context of the Italian Network for Primary Immunodeficiencies.

B-cell development and functions and therapeutic options in adenosine deaminase-deficient patients.

Background: Adenosine deaminase (ADA) deficiency causes severe cellular and humoral immune defects and dysregulation because of metabolic toxicity. Alterations in B-cell development and function have been poorly studied. Enzyme replacement therapy (ERT) and hematopoietic stem cell (HSC) gene therapy (GT) are therapeutic options for patients lacking a suitable bone marrow (BM) transplant donor.

Therapeutic benefit of lentiviral-mediated neonatal intracerebral gene therapy in a mouse model of globoid cell leukodystrophy.

Globoid cell leukodystrophy (GLD) is an inherited lysosomal storage disease caused by β-galactocerebrosidase (GALC) deficiency. Gene therapy (GT) should provide rapid, extensive and lifetime GALC supply in central nervous system (CNS) tissues to prevent or halt irreversible neurologic progression. Here we used a lentiviral vector (LV) to transfer a functional GALC gene in the brain of Twitcher mice, a severe GLD model.

Muscle regeneration by bone marrow-derived myogenic progenitors.

Growth and repair of skeletal muscle are normally mediated by the satellite cells that surround muscle fibers. In regenerating muscle, however, the number of myogenic precursors exceeds that of resident satellite cells, implying migration or recruitment of undifferentiated progenitors from other sources. Transplantation of genetically marked bone marrow into immunodeficient mice revealed that marrow-derived cells migrate into areas of induced muscle degeneration, undergo myogenic differentiation, and participate in the regeneration of the damaged fibers.