Transplantation and gene transfer of the human glucocerebrosidase gene into immunoselected primate CD34+Thy-1+ cells

Abstract

In an attempt to improve our gene transfer efficiency into hematopoietic stem cells and to evaluate the capacity of immunoselected CD34+Thy-1+(CDw90) cells to reconstitute hematopoiesis following myeloablation, bone marrow (BM) transplantation was performed using autologous, immunoselected CD34+Thy-1+ cells in rhesus macaques. BM samples were positively selected for cells that express CD34, further subdivided using high gradient immunomagnetic selection for cells that express Thy-1, and transduced using a 7-day supernatant transduction protocol with a replication-defective retroviral vector that contained the human glucocerebrosidase (GC) gene. Circulating leukocytes were evaluated using a semiquantitative polymerase chain reaction (PCR) assay for the human GC gene, with the longest surviving animal evaluated at day 558. Provirus was detected at all time points in both CD20+ B cells and CD2+ dim T cells, but long-term gene transfer was not observed in the granulocyte population. The CD2+ dim population was phenotypically identified as being CD8+ natural killer cells. By day 302 and day 330, both the CD2+ bright and dim cell populations and sorted CD4+ and CD8+ cells had detectable provirus. Vector-derived GC mRNA was detected by reverse transcriptase (RT)-PCR analysis as far out as day 588. Thus, CD34+Thy-1+ cells isolated using high gradient magnetic separation techniques can engraft, be transduced with a replication-defective retroviral vector, and contribute to CD20+ B lymphocytes, CD8+ T lymphocytes, and CD4+ T lymphocytes; making them a suitable cell population to target for gene therapies involving lymphocytes.