Alveolus-on-a-chip: A Novel Tool for Modeling Lung Transplant Cold Storage Ischemia/Reperfusion Injury.

backgroundCurrent in vitro models used to investigate lung transplant cold storage (CS) ischemia/reperfusion injury (IRI) use single-cell lines in static culture. Although these models have informed our understanding of CS-IRI, they lack physiological complexity. We hypothesized that using a lung alveolus-on-a-chip model would facilitate the development of more physiologically relevant CS-IRI in vitro models.

methodsWe used the Emulate Organ-on-a-Chip 3-dimensional microfluidic air-liquid interface alveolus-on-a-chip model seeded with human primary alveolar epithelial cells and human lung microvascular endothelial cells. To simulate CS and IRI, alveolus chips were removed from the perfusion, and endothelial channels were perfused with Perfadex and stored at 4 °C for 6 h to recapitulate CS. Following CS, alveolar chips were reperfused under laminar media flow and stretch conditions for 24 h at 37 °C to simulate IRI. The impact of CS-IRI was compared with that of control alveolus chips using immunofluorescent staining for cellular markers, chemokine/adhesion molecule arrays to assess epithelial and endothelial injury/activation, and mRNA collected for NanoString analysis.

resultsBrightfield imaging and immunostaining indicated a loss of barrier function after CS-IRI. Assessment of chemokines and adhesion molecules demonstrated significant increases in markers of inflammation. NanoString analysis identified 42 human primary alveolar epithelial cell and 49 human lung microvascular endothelial cell genes that were significantly differentially expressed between the normal and CS-IRI groups ( P  < 0.01).

conclusionsHere, we report a novel CS-IRI model that incorporates physiological flow, stretch, and cell-cell interactions. We demonstrated key changes associated with IRI and hypothesized that future studies will provide novel insights into the pathophysiology of CS-IRI post-lung transplantation.