Inflamed site-specific gene delivery using bone marrow-derived CD11b+CD18+ vehicle cells in mice

We report a novel technique that may allow site-specific gene delivery into inflamed tissues. Bone marrow cells from DBA/2 mice were incubated for 7 days in L-929 cell-conditioned medium containing elements that favor the development of mononuclear cells, such as colony-stimulating factors. Flow cytometric analysis revealed that 99.1 +/- 0.9% of the subcloned cells were positive for CD11b and CD18, both of which are ligands of the intercellular adhesion molecule 1 (ICAM-1). These vehicle cells were labeled with a fluorescent lipophilic probe and returned intravenously to the DBA/2 mice. The mice then received, for 1 week, intraperitoneal injections of either lipopolysaccharide (LPS) to enhance ICAM-1 expression in the glomerulus, or saline as a control. In the LPS-treated mice, labeled vehicle cells were detected within the glomerulus cross-section (gcs) 24 hr after the first injection (0.73 +/- 0.10/gcs). The number of labeled vehicle cells within the glomerulus gradually increased for 1 week (1.47 +/- 0.19/gcs) and decreased after discontinuation of the LPS injections. However, in the saline-treated control group, only a negligible number of vehicle cells could be detected in the glomerulus (0.05 +/- 0.03/gcs). A second administration of LPS 4 weeks after injection of the vehicle cells was also able to promote accumulation in the glomerulus. Furthermore, immunohistochemical analysis revealed that the kinetics of the vehicle cell recruitment into the glomerulus corresponded to the level of ICAM-1 expression. On the assumption that the LPS-induced ICAM-1 expression may regulate the site and timing of the delivery of vehicle cells into the glomerulus, vehicle cells were transduced with human glucocerebrosidase (GC) gene, using an adenovirus vector, and reintroduced into the mice. The basal expression of GC gene in the isolated glomeruli of vehicle cell-treated mice rose by 1.7-fold compared with endogenous activity, whereas the GC activity was enhanced 3.2-fold by LPS treatment. Polymerase chain reaction designed to detect human GC-specific sequence revealed that isolated glomeruli of vehicle cell-treated mice contained exclusively the vehicle cell-oriented GC. This indicates that vehicle cells can be used to carry a certain gene to a specific inflamed site. Injection of vehicle cells, with or without LPS, had small effect on urinary protein excretion or serum creatinine levels. These findings suggest that our novel method allows site-specific gene delivery into inflamed glomeruli through interaction of adhesion molecules.