Markers of endothelial function in pediatric stem cell transplantation for acute leukemia

Endothelial cells and leukocytes intimately interact in inflammation and coagulation processes, so that dysregulation of their function may lead to both cellular damage and thrombosis, which may occur as complications of bone marrow transplantation (BMT). Partially conflicting evidence about endothelial markers and their relationships with clinical complications after BMT has been reported in the literature. Since almost all studies were carried out in adults, we evaluated some recent available markers of endothelial cell function in pediatric patients undergoing stem cell transplantation (SCT) for acute leukemia.

We studied the variation in circulating serum endothelial-selectin (ES), leukocyte-selectin (LS), thrombomodulin (TM), von Willebrand factor (vWF), nitrate + nitrite (NO(2) (-)/NO(3) (-)), endothelin-1 (EN), and tissue factor (TF) in 21 pediatric patients undergoing SCT for acute leukemia.

ES and LS significantly lowered following SCT and returned to pre-SCT levels 4 weeks after the procedure. NO(2) (-)/NO(3) (-) markedly increased following SCT. Also, TM and vWF increased, although such changes did not reach statistical significance. EN and TF did not appreciably change. A strong correlation was observed between white blood cell (WBC) count and both ES and LS, as well as between such selectins. TM significantly correlated with both selectins and NO(2) (-)/NO(3) (-). The pre-conditioning levels of TM and vWF in patients undergoing major complications, considered altogether, were significantly lower and higher, respectively, than in uncomplicated patients. NO(2) (-)/NO(3) (-) levels 3 and 4 weeks post-SCT were significantly lower in patients suffering from veno occlusive disease. Both selectins were significantly higher in allo- than in auto-transplanted patients 4 weeks after SCT.

Our data support the hypothesis of severe endothelial damage after conditioning and SCT, particularly allogeneic. However, the increase in TM, which has strong anticoagulant properties, and metabolites of NO, involved also in protective actions, may reflect regeneration of the anti-thrombotic endothelial function. This could take place after transitory functional impairment, rather than pure endothelial damage.