Exogenous gene expression and growth regulation of hematopoietic cells via a novel human artificial chromosome.

A number of gene delivery systems are currently being developed for potential use in gene therapy. Here, we demonstrate the feasibility of 21deltaqHAC, a newly developed human artificial chromosome (HAC), as a gene delivery system. We first introduced a 21deltaqHAC carrying an EGFP reporter gene and a geneticin-resistant gene (EGFP-21deltaqHAC) into hematopoietic cells by microcell-mediated chromosome transfer. These HAC-containing hematopoietic cells showed resistance to geneticin, expressed EGFP and retained the ability to differentiate into various lineages, and the EGFP-21deltaqHAC was successfully transduced into primary hematopoietic cells. Hematopoietic cells harboring the EGFP-21deltaqHAC could still be detected at two weeks post-transplantation in immunodeficient mice. We also showed effective expansion of hematopoietic cells by introducing the 21deltaqHAC containing ScFvg, a gp130-based chimeric receptor that transmits growth signals in response to specific-antigen of this receptor. All of these results demonstrate the usefulness of HAC in gene therapy.