Organ-specific change inDolichos biflorus lectin binding by myocardial endothelial cells during in vitro cultivation

Summary Endothelial cells of the NMRI mouse strain express a cell surface glycoprotein recognized by the lectinDolichos biflorus agglutinin (DBA). This study documents a marked organ-specific increase in DBA-specific lectin binding of myocardium-derived endothelial cells (MEC) of the NMRI/GSF mouse during in vitro cultivation. An up to 20-fold increase in DBA binding sites is observed in long-term culture, an increase not found in other NMRI-derived endothelial cell lines (e.g., brain, aorta). The increase appears restricted to DBA in that binding with other lectins (PNA, WGA) was unaltered. NMRI MEC cultures maintain typical endothelial cell attributes such as cobblestone morphology on confluence, expression of endothelial cell-specific surface markers, and production of angiotensin-converting enzyme. Cultures routinely become aneuploid within 4 passages, several passages before upregulation of the DBA binding site(s). Myocardial endothelial cells sorted to obtain DBA^hi and DBA^lo cell populations generally maintained their sorted phenotype for 3 to 4 passages. Limiting dilution cloning resulted in clones varying in DBA expression. Clones for DBA^hi expression maintained their DBA affinity for at least 10 passages (>30 doublings), whereas DBA^lo clones gave rise to varying numbers of DBA^hi cells within 2 to 4 passages. We hypothesize that the change in DBA affinity accompanies in vitro aging, that the change is independent of alterations in karyotype, and that the increase in DBA affinity may reflect a change in one or more other endothelial cell properties. Additional studies will be necessary to determine whether the in vitro changes are correlated with specific functional alterations and whether they accurately reflect progressive changes of MEC in vivo.