Bone Marrow as a Source of Hematopoietic Stem Cells for Human Gene Therapy of β-Thalassemia

Abstract

β-Thalassemia is a severe inherited anemia caused by insufficient production of β-globin chains. Allogeneic hematopoietic stem cell (HSC) transplantation is currently the only cure, and is limited by donor availability and regimen-related toxicity and mortality. Gene therapy is a promising therapeutic tool for all thalassemic patients lacking a compatible donor and potentially provides transfusion independence in the absence of transplant-related complications, such as graft rejection and graft-versus-host disease. The issue of HSC procurement is critical in this setting because of the specific features of thalassemic syndromes, which include bone marrow (BM) expansion, ineffective erythropoiesis, and splenomegaly. Little is known about the efficiency of CD34(+) cell yield from steady-state BM harvests from thalassemic patients. We have collected data on safety and cell yield from 20 pediatric patients with β-thalassemia who underwent autologous BM harvest before allogeneic HSC transplantation, and from 49 age-matched sibling donors who also underwent BM harvest. The procedure was safe, as no significant adverse events occurred. In terms of cell yield, no difference was found between patients and normal donors in the number of CD34(+) cells and total nucleated cells harvested. Most importantly, no difference was found in the proportion of myeloid and erythroid progenitors, suggesting a similar repopulating capacity. On the basis of these results, we conclude that steady-state BM can be used as a safe and efficient source of HSC for gene therapy of β-thalassemia.

Artificial Niche Combining Elastomeric Substrate and Platelets Guides Vascular Differentiation of Bone Marrow Mononuclear Cells

“…Frittoli et al reported that bone marrow aspirated from human iliac crest contains *10-20 million BMNCs per mL. 31 Therefore, 10 mL of bone marrow aspirate is sufficient to construct a 10 cm graft with a 5 mm internal diameter according to the cell seeding density in the present study. Obtaining 10 mL bone marrow aspirates from human is highly feasible.…”

Harvesting autologous stem cells from a patient with red blood cell abnormalities of β‐thalassemia intermedia

“…Splenic enlargement and rupture in healthy donors has been reported after administration of G‐CSF . This risk needs to be assessed in patients with β‐thalassemia and other hemoglobinopathies, since some of the patients have splenomegaly before G‐CSF administration . G‐CSF also increases the risk of thrombotic events in otherwise healthy donors due to coagulation and endothelial cell activation related to G‐CSF .…”

“…4 More recent developments in genetic therapy have led to the collection of autologous stem cells, which are then genetically corrected and reinfused to the patient to treat hemoglobinopathies. 5 Additionally, improved treatment modalities in this patient population have resulted in extended life spans but with a concomitant increased incidence of hematologic malignancies. 6-10 A recent case report featured a patient with Hb SC disease who underwent an autologous stem cell transplant for MM.…”

“…15 This risk needs to be assessed in patients with β-thalassemia and other hemoglobinopathies, since some of the patients have splenomegaly before G-CSF administration. 5 G-CSF also increases the risk of thrombotic events in otherwise healthy donors due to coagulation and endothelial cell activation related to G-CSF. [16][17][18] This complication has a higher risk in patients with β-thalassemia because they are in a persistent hypercoagulable state.…”

Safe mobilization of CD34+ cells in adults with β-thalassemia and validation of effective globin gene transfer for clinical investigation

“…22,23 In a clinical case report, peripheral blood marking levels were initially low before a single clone expanded and eventually compensated for overall low transduction efficiency. 24 Here, we demonstrate for the first time that we can achieve globin gene transfer in thalassemic G-CSF mobilized HPCs in the range of 0.4 to 0.6 VC/cell under cGMP conditions.…”