The influence of age on in vitro plasmin generation in the presence of fibrin monomer.
OBJECTIVE
The components of the fibrinolytic system interact to generate plasmin from its zymogen form, plasminogen. At birth, all the components of the fibrinolytic system are present but with differing plasma concentrations. The present study was undertaken to explore the effect of physiological, age-dependent factors of the fibrinolytic system during childhood on the capacity to generate plasmin.


METHODS
Total plasmin generation was measured in venous plasma from umbilical cords and adults, on plastic and cell surfaces, in the presence of fibrin monomer, Desafib. Plasminogen, its inhibitors alpha2-antiplasmin and plasminogen activator inhibitor type 1, and plasmin-alpha2-antiplasmin complex in the time samples were assayed by enzyme-linked immunosorbent assay. The effect of addition of plasminogen on the plasmin generation in cord plasma and the effect of lipoprotein on adult and cord plasmin generation were measured.


RESULTS
On the surface of human umbilical vein endothelial cells, onset of plasmin generation was earlier (40 min) compared to plastic (60 min) but total plasmin generation was similar on both surfaces. The addition of plasminogen to cord plasma increased plasmin generation. Supplementation of lipoprotein in adult plasma had an inhibitory effect, but there was no significant effect in cord plasma.


CONCLUSIONS
Plasmin generation is reduced in newborn compared to adult plasma. Decreased plasmin generation in cord plasma is likely due to decreased plasminogen concentration. The antifibrinolytic effect of lipoprotein is more pronounced in adults as compared to newborns due to the presence of higher plasminogen concentration.
Pediatric Thrombosis and Hemostasis Program, The Hospital for Sick Children, Toronto, Canada.
Nagina
N
Parmar
Lesley G
LG
Mitchell
Leslie R
LR
Berry
Maureen
M
Andrew
Anthony K C
AK
Chan
D000328:Adult; D000367:Age Factors; D001780:Blood Coagulation Tests / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005312:Fetal Blood / Q000378:metabolism*; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis*; D005341:Fibrinolysin / Q000032:analysis*; D005343:Fibrinolytic Agents / Q000032:analysis / Q000494:pharmacology; D006801:Humans; D007231:Infant, Newborn; D010958:Plasminogen / Q000032:analysis / Q000494:pharmacology; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood; D000979:alpha-2-Antiplasmin / Q000032:analysis
D005338:Fibrin Fibrinogen Degradation Products; D005343:Fibrinolytic Agents; D017395:Plasminogen Activator Inhibitor 1; C051321:SERPINE1 protein, human; D000979:alpha-2-Antiplasmin; C011468:fibrinmonomer; D010958:Plasminogen; D005341:Fibrinolysin