Genetic correction of cultured T cells from an adenosine deaminase-deficient patient: characteristics of non-transduced and transduced T cells

MLV-10A1 retrovirus pseudotype efficiently transduces primary human CD4+ T lymphocytes

BACKGROUND

Previously, we showed that retroviral vectors pseudotyped with the envelope of the amphotropic murine leukemia virus 10A1 (MLV-10A1) more efficiently transduce primary human CD8+ T lymphocytes when compared with other A-MLV, gibbon ape leukemia virus (GaLV) and feline endogenous retrovirus (RD114) vector pseudotypes. For the success of several gene therapeutic approaches (ADA, HIV) it is important to effectively transduce primary human CD4+ T lymphocytes.

METHODS

We have used retroviral vectors encoding the enhanced green fluorescent protein (EGFP) as a marker gene and carrying envelopes of MLV-10A1, A-MLV and GaLV and have analyzed the transduction efficiency of both human CD4+ T cell lines (CEM, H9, HUT78, J16) and primary human CD4+ T lymphocytes using a RetroNectin-assisted transduction protocol and virus-containing supernatant.

RESULTS

In CD4+ T cell lines the MLV-10A1 vector pseudotype was most effective and infected up to 85% of cells which then stably expressed GFP over time. MLV-10A1 was also superior and infected approximately 32% of primary human CD4+ T lymphocytes in comparison to GaLV (18%) and A-MLV (12%). The superior efficiency of MLV-10A1 for the transduction of CD4+ T cells correlates with the longer half-life of this pseudotype in comparison to A-MLV and, as previously shown by interference analysis, with the usage of both the A-MLV (Pit2) and the GaLV receptor (Pitl) for cell entry.

CONCLUSIONS

MLV-10A1 is a suitable vector for transferring genes with high efficacy into primary human CD4+ T lymphocytes. The use of MLV-10A1 pseudotyped vectors should make it easier to obtain a sufficient number of gene-modified T lymphocytes for an adoptive transfer.

High-efficiency gene transfer into normal and adenosine deaminase-deficient T lymphocytes is mediated by transduction on recombinant fibronectin fragments

Primary human T lymphocytes are powerful targets for genetic modification, although the use of these targets in human gene therapy protocols has been hampered by low levels of transduction. We have shown previously that significant increases in the transduction of hematopoietic stem and progenitor cells with retroviral vectors can be obtained by the colocalization of the retrovirus and target cells on specific fibronectin (FN) adhesion domains (H. Hanenberg, X. L. Xiao, D. Dilloo, K. Hashino, I. Kato, and D. A. Williams, Nat. Med. 2:876-882, 1996). We studied the transfer of genes into primary T lymphocytes by using FN-assisted retroviral gene transfer. Activated T lymphocytes were infected for three consecutive days on the recombinant FN fragment CH-296 with a retroviral vector encoding the murine B7-1 protein. Transduced lymphocytes were analyzed for murine B7-1 expression, and it was found that under optimal conditions, 80 to 89% of the CD3+ lymphocytes were transduced. Gene transfer was predominantly augmented by the interaction between VLA-4 on the T lymphocytes and the FN adhesion site CS-1. Adenosine deaminase (ADA)-deficient primary T lymphocytes transduced on CH-296 with a retrovirus encoding murine ADA (mADA) exhibited levels of mADA activity severalfold higher than the levels of the endogenous human ADA protein observed in normal human T lymphocytes. Strikingly, the long-term expression of the transgene was dependent on the activation status of the lymphocytes. This approach will have important applications in human gene therapy protocols targeting primary T lymphocytes.

A murine model for B-lymphocyte somatic cell gene therapy

Mature primary B lymphocytes represent a potentially important cellular target for somatic cell gene therapy, which could prove advantageous for the treatment of certain metabolic and immunologic disorders. Their capacity to serve as antigen-presenting cells could be utilized for triggering and/or potentiating immune responses to tumors and viruses. Alternatively, B cells expressing an autoantigen could be manipulated to induce antigen-specific unresponsiveness for treatment of autoimmune diseases. Efficient expression of an exogenous gene product in long-lived B lymphocytes could be particularly useful for providing a corrected gene product in the bloodstream. Despite these advantages, efficient gene transfer into mature primary B cells has not been reported. One reason for this is that current protocols for retroviral vector-mediated gene transfer into lymphocytes rely on in vitro expansion and/or drug selection. This precludes the use of mature primary B cells as targets, since they cannot be readily cultured for long periods of time. In this report, we describe an efficient and rapid protocol for the introduction of exogenous genes into primary B cells without the need for drug selection. We have used retroviral vectors containing the human adenosine deaminase gene as a marker gene, since the biological activity of this enzyme is easy to measure and is readily distinguishable from that of the endogenous mouse adenosine deaminase. Upon adoptive transfer into SCID mice, infected B cells continuously expressing one to three copies of the human adenosine deaminase gene could be found in the spleens of recipient animals for at least 3 months.

Retrovirus-mediated gene transfer into rhesus monkey hematopoietic stem cells: the effect of viral titers on transduction efficiency

We have generated a cell line, designated POAM-P1, shedding amphotropic recombinant retroviruses carrying the human adenosine deaminase (hADA) gene. It exhibits a 1 log increased retrovirus titer on NIH-3T3 cells and a five-fold more efficient transduction of human ADA-deficient T lymphocytes, as compared to the previously generated cell line POC-1 which produces the same recombinant hADA retrovirus. To study whether the titer of retrovirus-producing cell lines influences the transduction efficiency of hematopoietic stem cells in a co-culture setting, we compared the POAM-P1 and POC-1 cell lines with respect to their gene transfer efficiency on rhesus monkey bone marrow. Following co-cultivation of rhesus monkey bone marrow with POAM-P1 cells, successful transduction could be demonstrated in approximately 10% of myeloid progenitor colonies (CFU-C) and 0.1% of peripheral blood mononuclear cells (PBMC) and granulocytes in vivo until > 1 year after autologous transplantation. In addition, the presence of functional hADA enzyme was detected in red blood cells, PBMC, and granulocytes. Monkeys receiving POC-1 co-cultured bone marrow carried transduced blood cells for > 2 years after transplantation. Despite the higher retrovirus titer of POAM-P1 cells as compared to POC-1 cells, no difference was observed in gene transfer efficiency into CFU-C and long-term repopulating stem cells. This shows that in our co-cultivation procedure the retrovirus titer was not limiting the transduction efficiency of primate hematopoietic stem cells.