Effect of different promoters on expression of genes introduced into hematopoietic and marrow stromal cells by electroporation.

Electroporation is a simple and relatively efficient means of introducing genes into hematopoietic cells. However, achieving and maintaining high levels of gene expression in transfected hematopoietic progenitor cells remains problematic. In order to address this problem we examined the effect of different viral and cellular promoters on the transient expression of reporter genes transferred into K562, KG1a, and human marrow stromal cells. We found that although the Rous sarcoma virus long terminal repeat was most active in K562 cells in a transient expression assay, the murine cytomegalovirus immediate early promoter was strikingly more active than the other promoters in KG1a cells as well as in the marrow stromal cell population. Long-term stable gene expression was also demonstrated in stromal cells. We infer that the murine cytomegalovirus immediate early promoter may be highly active in human hematopoietic progenitor cells and that human marrow stromal cells may be an attractive vehicle for gene delivery.