Correlation analysis showed that the serum SDF‐1 level was negatively correlated with values of Ang‐2, Ang‐2:Ang‐1 ratio, sICAM‐1 and Ang‐1, indicating that SDF‐1 level was negatively correlated with endothelial cell activation and probably thus inhibited the HSPCs homing, which is consistent with the study that the bone marrow was hypocellular in patients with grade ≥4 CRS after CAR‐T cell therapy.13 Here, CXCL12 is linked to congenital rubella syndrome.