Endoscopic atomization of mesenchymal stromal cells: in vitro study for local cell therapy of the lungs

Background aims: Cell-based therapies of pulmonary diseases with mesenchymal stromal cells (MSCs) are increasingly under experimental investigation. In most of these, MSCs are administered intravenously or by direct intratracheal instillation. A parallel approach is to administer the cells into the lung by endoscopic atomization (spraying). In a previous study, the authors developed a flexible endoscopic atomization device that allows administration of respiratory epithelial cells in the lungs with high survival. Methods: In this study, the authors evaluated the feasibility of spraying MSCs with two different endoscopic atomization devices (air and pressure atomization). Following atomization, cell viability was evaluated with live/dead staining. Subsequent effects on cytotoxicity, trilineage differentiation and expression of MSC-specific markers as well as on MSC metabolic activity and morphology were analyzed for up to 7 days. Results: MSC viability immediately after spraying and subsequent metabolic activity for 7 days was not influenced by either of the devices. Slightly higher cytotoxicity rates could be observed for pressure-atomized compared with control and air-atomized MSCs over 7 days. Flow cytometry revealed no changes in characteristic MSC cell surface marker expression, and morphology remained unchanged. Standard differentiation into osteocytes, chondrocytes and adipocytes was inducible after atomization. Conclusions: In the literature, a minimal survival of 50% was previously defined as the cutoff value for successful cell atomization. This is easily met with both of the authors’ devices, with more than 90% survival. Thus, there is a potential role for atomization in intrapulmonary MSC-based cell therapies, as it is a feasible and easily utilizable approach based on clinically available equipment.