Clonality analysis after retroviral-mediated gene transfer to CD34+ cells from the cord blood of ADA-deficient SCID neonates

• Published in: Nature medicine Vol. 9; no. 4; pp. 463 - 468
• Main Authors: Schmidt, Manfred, Carbonaro, Denise A., Speckmann, Carsten, Wissler, Manuela, Bohnsack, John, Elder, Melissa, Aronow, Bruce J., Nolta, Jan A., Kohn, Donald B., von Kalle, Christof
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.04.2003; Nature Publishing Group
• Subjects: Adenosine Deaminase - genetics; Antigens, CD34; Biomedical and Life Sciences; Biomedicine; Cancer Research; Clone Cells; Fetal Blood; Gene Transfer Techniques; Genetic Vectors; Humans; Infant, Newborn; Infectious Diseases; Lymphocytes; Metabolic Diseases; Molecular Medicine; Neonates; Neurosciences; Polymerase Chain Reaction; Retroviridae - genetics; Severe Combined Immunodeficiency - therapy; T-Lymphocytes - metabolism; Transduction, Genetic
• ISSN: 1078-8956; 1546-170X
• DOI: 10.1038/nm844

A clinical trial of retroviral-mediated transfer of the adenosine deaminase (ADA) gene into umbilical cord blood CD34 + cells was started in 1993. ADA -containing peripheral blood mononuclear cells (PBMCs) have persisted in patients from this trial, with T lymphocytes showing the highest prevalence of gene marking 1 , 2 . To gain a greater understanding of the nature and number of the transduced cells that were engrafted, we used linear amplification–mediated PCR (LAM-PCR) to identify clonal vector proviral integrants 3 , 4 . In one patient, a single vector integrant was predominant in T lymphocytes at a stable level over most of the eight-year time span analyzed and was also detected in some myeloid samples. T-cell clones with the predominant integrant, isolated after eight years, showed multiple patterns of T-cell receptor (TCR) gene rearrangement, indicating that a single pre-thymic stem or progenitor cell served as the source of the majority of the gene-marked cells over an extended period of time. It is important to distinguish the stable pattern of monoclonal gene marking that we observed here from the progressive increase of a T-cell clone with monoclonal gene marking that results from leukemic transformation, as observed in two subjects in a clinical trial of gene therapy for X-linked severe combined immunodeficiency (SCID) 5 , 6 .