ORGAN-SPECIFIC CHANGE IN DOLICHOS-BIFLORUS LECTIN-BINDING BY MYOCARDIAL ENDOTHELIAL-CELLS DURING IN-VITRO CULTIVATION

Endothelial cells of the NMRI mouse strain express a cell surface glyc oprotein recognized by the lectin Dolichos biflorus agglutinin (DBA). This study documents a marked organ-specific increase in DBA-specific lectin binding of myocardium-derived endothelial cells (MEC) of the NM RI/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 f ound in other NMRI-derived endothelial cell lines (e.g., brain, aorta) . The increase appears restricted to DBA in that binding with other le ctins (PNA, WGA) was unaltered. NMRI MEC cultures maintain typical end othelial cell attributes such as cobblestone morphology on confluence, expression of endothelial cell-specific surface markers, and producti on of angiotensin-converting enzyme. Cultures routinely become aneuplo id 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 phenot ype for 3 to 4 passages. Limiting dilution cloning resulted in clones varying in DBA expression. Clones for DBA(hi) expression maintained th eir 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 kary otype, and that the increase in DBA affinity may reflect a change in o ne 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 refle ct progressive changes of MEC in vivo.