Prevention of side effects by hemoglobin solutions; the selection of optimal test models, especially concerning thrombogenicity

Modification of hemoglobin (Hb) by crosslinking and polymerization results in an improved oxygen release capacity and a prolonged vascular retention time. Modification improves the efficacy and prevents certain side effects. Iteliminates leakage of Hb through the kidneys and accumulation in the tubuli. Another important issue is the degree of purification of Hb solutions. Traces of membrane fragments may cause immunogenic and thrombogenic side effects. To determine the contamination with erythrocyte membrane fragments, we developed assays for glycophorin-α and phospholipids. Special models were evaluated for testing the maximum allowable level of membrane contamination. As an in vitro model for thrombogenicity we used confluent monolayers of human umbilical vein endothelial cells. These cells were incubated with Hb solutions and subsequently tested on tissue factor (TF) procoagulant activity. TF was tested by the factor VII-catalyzed activation of factor X. The lower detection limit of this assay for endo...