ACE2 Chromogenic Immunostaining Protocol Optimized for Formalin-fixed Paraffin Embedded Human Tissue Sections.

Angiotensin-converting enzyme 2 (ACE2) is a key cellular entry factor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Hence, identifying cell types that express ACE2 is important for understanding the pathophysiology of coronavirus disease 2019 (COVID-19). We performed extensive testing of multiple primary antibodies across various human tissue types. Here we describe an optimized protocol for immunostaining of ACE2 in formalin fixed paraffin embedded human (FFPE) pancreas, small intestine and kidney tissue sections obtained from organ donors and autopsies.