Spraying Respiratory Epithelial Cells to Coat Tissue-Engineered Constructs

Applying cells in a spray can overcome current hurdles in coating tissue engineered constructs with a thin layer of endo- or epithelial cells. We report here a structured study on the influences of spray application with a medical spray device on vascular smooth muscle cells (vSMCs) and respiratory epithelial cells (RECs) with and without fibrin gel. Next to viability and cytotoxicity assays, the in vitro differentiation capacity after spray processing was analyzed. For vSMC, no influence of air pressures till 0.8 bar could be shown, whereas the viability decreased for higher pressures. The viability of RECs was reduced to 88.5% with 0.4 bar air pressure. Lactate dehydrogenase-levels in the culture medium increased the first day after spraying but normalized afterward. In the short term, no differences by means of morphology and expression-specific markers for vSMCs and RECs were seen between the control and study group. In addition, in a long-term study for 28 days with the air-liquid interface, RECs differentiated and built up an organized epithelial layer with ciliary development that was comparable to the control for cells sprayed without fibrin gel. When spraying within fibrin gel, ciliary development was lower at 28 days. Thus, spraying of vSMCs and RECs was proved to be a suitable method for tissue engineering. Especially for RECs, this application is of special significance when coating luminal structures or other unfavorable topographies.