Variable efficiency of retroviral-mediated gene transfer into early-passage cultures of fetal lamb epithelial,...

The relative efficiency of retroviral-mediated gene transfer into early-passage cultures of different tissues of fetal lamb was investigated. Monolayer cultures prepared by plating 1 x 10(6) cells were infected with the Moloney murine leukemia (MoMLV)-based vector pZIP Neo at a multiplicity of infection (moi) of approximately 1 pfu per 2 x 10(2) recipient cells prior to selection for neomycin resistance. At the low moi used, cells from different tissues showed marked differences in efficiency of colony formation in the descending order: brain > kidney > muscle, lung > skin. Brain cells were transduced at least an order of magnitude more efficiently than other cell types, despite the doubling time of brain cell cultures being five times as long. Cultures were analyzed by morphological and immunocytological criteria to determine whether any particular cell types were transduced. A wide variety of morphologically distinct neuron-like and glial-like brain cells were neomycin resistant. The majority of muscle cell colonies were myogenic. Approximately half of the large kidney colonies were epithelial-like. The majority of lung colonies consisted of fibroblasts. The results suggest that cells originating from the surface embryonic germ layer (ectoderm) and/or occupying positions near the fetal external surface have a markedly lower susceptibility to retroviral-mediated gene transduction.