To study the expression level of lung sca-1⁺ CD31^- CD45^- cells in lung tissue of mice with acute respiratory distress syndrome (ARDS) .

10 C57BL/6 mice were divided into experimental group and the control group. The experimental group was established by intratracheal injection of lipopolysaccharide (LPS) to construct the mouse ARDS model, and intratracheal injection of PBS was used as the control group. Lung tissue of ARDS mouse model was treated with collagenase and heat digestion to obtain lung single cell suspension. Dual immunofluorescence staining was adopted to identify lung endogenous stem cells. Lung sca-1⁺ CD31^-CD45^- cells were sort by flow cytometry.

The ARDS model was successfully prepared by intratracheal injection of lipopolysaccharide; the total number of single cell suspensions prepared by whole lung tissue of 5 mice was 5×10⁷/ml, and the percentage of viable cells was 98﹪; Lung Endogenous stem cells include type Ⅱ alveolar epithelial cells, clara cells, and bronchoalveolar stem cells. The lung tissue type Ⅱ alveolar epithelial cells, clara cells, and bronchoalveolar stem cells were verified by double immunofluorescence staining of lung tissues. The number of lung endogenous stem cells in the control group and the experimental group accounted for a normal distribution of the number of single cell suspension cells, and the number of lung endogenous stem cells in the experimental group (10.73±10.65) ﹪ was significantly lower than that in the control group (12.23±0.73) ﹪ (t?= -3.405, P < 0.01) .

The proportion of lung sca-1⁺ CD31^-CD45^- cells in lung tissue of ARDS mice is significantly lower than that of the control group. It is not clear that the specific fate of these lung endogenous stem cells is reduced. It may participate in the repair and regeneration process of airway epithelial cells during acute inflammation in the body.