Developing Cell Therapy Techniques for Respiratory Disease: Intratracheal Delivery of Genetically Engineered Stem Cells in a Murine Model of Airway Injury

Abstract

Interest has increased in the use of exogenous stem cells to optimize lung repair and serve as carriers of a therapeutic gene for genetic airway diseases such as cystic fibrosis. We investigated the survival and engraftment of exogenous stem cells after intratracheal injection, in a murine model of acute epithelial airway injury already used in gene therapy experiments on cystic fibrosis. Embryonic stem cells and mesenchymal stem cells were intratracheally injected 24 hr after 2% polidocanol administration, when epithelial airway injury was maximal. Stem cells were transfected with reporter genes immediately before administration. Reporter gene expression was analyzed in trachea-lungs and bronchoalveolar lavage, using nonfluorescence, quantitative, and sensitive methods. Enzyme-linked immunosorbent assay quantitative results showed that 0.4 to 5.5% of stem cells survived in the injured airway. Importantly, no stem cells survived in healthy airway or in the epithelial lining fluid. Using 5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside staining, transduced mesenchymal stem cells were detected in injured trachea and bronchi lumen. When the epithelium was spontaneously regenerated, the in vivo amount of engrafted mesenchymal stem cells from cell lines decreased dramatically. No stem cells from primary culture were located within the lungs at 7 days. This study demonstrated the feasibility of intratracheal cell delivery for airway diseases with acute epithelial injury.

Efficient intratracheal delivery of airway epithelial cells in mice and pigs

“…CELLS, cell delivery only; PDOCϩCELLS, cell delivery following lung pretreatment with PDOC. *P Ͻ 0.05. retention and are in good agreement with other previous studies (31).…”

“…Twenty-four hours following intratracheal administration of 2% PDOC into mouse lungs, the removal of surface epithelial cells in both the trachea and the airways was observed (Fig. 4, E-H), similar to what has been previously reported (5,31). GFP-labeled NHBE cells were then intratracheally delivered into mouse lungs.…”

“…It has been reported that transient lung injury enhances cell retention in lungs (10,31,44,54). We thus explored the effect of lung preinjury with PDOC on cell retention in mice.…”

“…Previous studies have shown that transient lung injury can improve the pulmonary retention of exogenous cells, including ESCs (31), bone marrow-derived stem cells (10,44), and alveolar epithelial type II cells (54). Among the different reagents used for inducing lung injury in animal models, polidocanol (PDOC) has been shown to temporarily remove the surface airway epithelial cells in mice and improve engraftment of stem cells or viral vectors (31,34).…”

“…Among the different reagents used for inducing lung injury in animal models, polidocanol (PDOC) has been shown to temporarily remove the surface airway epithelial cells in mice and improve engraftment of stem cells or viral vectors (31,34). In PDOC-treated lungs, the proliferation of normally quiescent epithelial cells was activated (5), probably in response to injury-induced cytokines (3).…”