SARS-CoV-2 is localized in cardiomyocytes: a postmortem biopsy case

Abstract

A 72-year-old patient was admitted to the intensive care unit due to acute respiratory distress syndrome caused by COVID-19. On day 20, the patient experienced shock. The electrocardiogram showed ST segment elevation in leads V3-V6 and severe left ventricular dysfunction with an ejection fraction of 35%-40%. The left ventricle showed basal hypokinesis and apical akinesis, while the creatine kinase level was normal, indicating Takotsubo cardiomyopathy. On day 24, the patient died of multiple organ failure. In post-mortem biopsy, SARS-CoV-2 antigen was detected in cardiomyocytes by immunostaining. Moreover, SARS-CoV-2 RNA was detected in heart tissue. We need to further analyse the direct link between SARS-CoV-2 and cardiomyocytes.

Keywords: SARS-CoV-2; cardiomyocyte; co-localization; immunostaining.

Figure 1

Localization of SARS-CoV-2 in heart tissue. (A, B) Haematoxylin and eosin (HE) staining and immunohistochemistry for SARS-CoV-2 in serial sections of the heart. SARS-CoV-2 is detected in myocardial cells. (C) In situ hybridization for SARS-CoV-2. Red signals are positive for SARS-CoV-2. (D-L) Double immunofluorescence assay in the heart. SARS-CoV-2 antigen is detected in HHF35 (muscle actin) antibody (Dako)-positive cells; however, it is rarely observed in CD68 (PGM1, macrophage)-positive cells and CD34 (endothelial cells)-positive cells. The red, green, and blue signals indicate Alexa 568, 468, and DAPI, respectively. SARS-CoV-2 proteins were labelled with Alexa 468 in panels (D-I) and Alexa 568 in panels (J-L).