Endothelial identity not found - Beyond passage 38, commercial cardiac microvascular endothelial cells do not express CD31 and VE-cadherin.

Few immortalized cardiac microvascular endothelial cell (CMEC) lines are available, particularly mouse lines. We purchased the CLU510 mCMEC line (Cedarlane), isolated by fluorescence-activated cell sorting for CD31 and VE-cadherin. The cell line has been used in previous studies, although none report CD31 or VE-cadherin expression. We analyzed endothelial profile of two vials of passage 38 cells. CD31 and VE-cadherin mRNA were hardly expressed in mCMECs compared to primary mouse lung ECs. CD31 and VE-cadherin protein levels were also negligible compared to multiple EC lines. Thus, CLU510 mCMECs beyond P38 do not harbor an endothelial phenotype. Caution should be warranted when using commercial cells and journals should carefully consider the validity of results when essential characterization of cell lines is omitted.