ABROGATION OF TGF-BETA ACTIVITY DURING RETROVIRAL TRANSDUCTION IMPROVES MURINE HEMATOPOIETIC PROGENITOR AND REPOPULATING CELL GENE-TRANSFEREFFICIENCY

Transforming growth factor-beta has complex activities on hematopoieti c cells. We have previously shown that murine long-term repopulating a ctivity is compromised by ex vivo culture in TGF-beta 1 and conversely is increased by abrogating endogenous TGF-beta activity with a neutra lizing antibody. In the current study, we investigated the effect of a brogation of autocrine or paracrine TGF-beta present during retroviral transduction on gene transfer efficiency to primitive hematopoietic c ells. Murine marrow cells were cultured and retrovirally transduced fo r 4 days in the presence of interleukin-3 interleukin-6 and stem cell factor, and either a neutralizing anti-TGF-beta antibody or an isotype control. Committed progenitor cells were analyzed for gene transfer e fficiency, and cells were also injected into W/W-v recipient mice for analysis of transduction of long-term repopulating cells. The progenit or (CFU-C) transduction efficiency in the presence of anti-TGF-beta wa s significantly greater Semiquantitative PCR analysis and Southern blo t 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 transduc tion in the presence of the anti-TGF-beta. Thus neutralization of TGF- beta activity during retroviral transduction allows more efficient gen e transfer into primitive murine hematopoietic cells and may prove ben eficial in future clinical gene transfer or therapy trials.