FIGURE 1.

In situ hybridization detecting severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) viral RNA and tissue factor (TF) RNA. A, Dual RNA in situ hybridization of SARS‐CoV‐2 (green color dots) and TF (red color dots) in coronavirus disease 19 (COVID‐19)‐acute respiratory distress syndrome (ARDS) and non‐‐COVID‐19 ARDS cases. B, Quantification of TF RNA expression from RNAscope (n = 6) using ImageJ program. C, Correlation of TF expression with SARS‐CoV‐2 expression (combined RNAscope [n = 6] and immunofluorescence ([n = 5]; R² = .66; P < .01). Staining of TF mRNA and immunofluorescence produced similar results, so the combined TF mRNA expression from five COVID‐19 patients and TF staining from six COVID‐19 patients were shown. D, Immunofluorescence assessment of lungs tissues from COVID‐19‐ARDS cases identifies higher TF expression associated with fibrin‐ and platelet factor 4 (PF4)‐positive thrombi. Immunostaining for TF (white), fibrin (green), and PF4 (red) of COVID‐19‐ARDS and non‐COVID‐19 ARDS as well as pathologically normal control lung tissues. Inset with white box and bottom panels showing magnified vessels/area with fibrin‐ and/or platelet‐rich thrombi. E, Quantification of TF expression