Abrogation of TGF-β activity during retroviral transduction improves murine hematopoietic progenitor and repopulating cell gene transfer efficiency

Abstract

Transforming growth factor-β has complex activities on hematopoietic cells. We have previously shown that murine long-term repopulating activity is compromised by ex vivo culture in TGF-β1 and conversely is increased by abrogating endogenous TGF-β activity with a neutralizing antibody. In the current study, we investigated the effect of abrogation of autocrine or paracrine TGF-β present during retroviral transduction on gene transfer efficiency to primitive hematopoietic cells. Murine marrow cells were cultured and retrovirally transduced for 4 days in the presence of interleukin-3, interleukin-6 and stem cell factor, and either a neutralizing anti-TGF-β antibody or an isotype control. Committed progenitor cells were analyzed for gene transfer efficiency, and cells were also injected into W/W^v recipient mice for analysis of transduction of long-term repopulating cells. The progenitor (CFU-C) transduction efficiency in the presence of anti-TGF-β was significantly greater. Semiquantitative PCR analysis and Southern blot analysis for the retroviral marker gene in the blood and bone marrow of recipient mice revealed a significant increase in the transduction efficiency of long-term repopulating cells after culture and transduction in the presence of the anti-TGF-β. Thus neutralization of TGF-β activity during retroviral transduction allows more efficient gene transfer into primitive murine hematopoietic cells and may prove beneficial in future clinical gene transfer or therapy trials.