International Journal of Cell Cloning, Vol 9, 491-502, Copyright © 1991 by AlphaMed Press
Stimulation of retroviral vector infection of murine hematopoietic progenitors
FA Fletcher and JW Belmont
Institute for Molecular Genetics, Baylor College of Medicine, Houston, Texas 77030.
Conditioned media (CM) from a cloned murine marrow-derived stromal cell
line, AC6.21 (ALC), was shown to stimulate retroviral vector infection of
hematopoietic progenitors in culture. Inclusion of ALC CM during
cocultivation of normal murine bone marrow (BM) with vector-producing
fibroblasts improved infection efficiency of day 13 spleen colony- forming
cells (CFU-s) from 63% (15 provirus-positive spleen colonies/24 total),
without added growth factor, to 90% (36 provirus-positive colonies/40
total). In addition, stimulation of BM cells with ALC CM during
cocultivation improved retroviral infection of stem cells capable of
repopulating the hematopoietic system of irradiated recipient animals.
Because ALC CM was found to have 50 to 100 U/ml of IL-6 activity, purified
recombinant human IL-6 was tested for an effect in this system. Stimulation
with IL-6 alone increased retroviral infection efficiency of CFU-s from 15%
(17 colonies provirus- positive/111 total analyzed) without added growth
factor to 66% (97 provirus-positive colonies/148 total analyzed). These
experiments support and extend previous studies which have demonstrated the
necessity for growth factor stimulation in optimizing retroviral vector
transduction of hematopoietic precursors.
