Prestorage Leukoreduction Prevents Accumulation of Proinflammatory Matrix Metalloproteinases During Blood Storage

Walter L Biffl, Paul C. Frake, Hadley E. Smith, Lii F. Suen
Brown Medical School, Providence, RI

Objective: Proinflammatory effects of blood transfusions, including transfusion-related acute lung injury (ALI), become more pronounced as stored blood ages to 42 days. Matrix metalloproteinase (MMP)-2, MMP-9, and tissue inhibitor of MMP (TIMP)-1, have been implicated in basement membrane disruption in ALI. We hypothesized that levels of MMPs in red blood cell (RBC) plasma increase during storage and provoke proinflammatory (PMN) effects, and that prestorage leukoreduction (LR) prevents this effect.
Design: Prospective investigation.
Setting: Research laboratory.
Patients: Healthy volunteers.
Interventions: Units of blood were drawn from healthy volunteers. Half of each unit was filtered for LR, removing 99.9% of leukocytes. At biweekly intervals, aliquots were removed from RBC units and the plasma fraction separated from the RBCs. PMNs were isolated from separate healthy volunteers.
Main Outcome Measures: MMP-2 and -9 and TIMP-1 levels and activity were measured by ELISA. PMN apoptosis was assessed morphologically. Statistical significance was estimated by Student’s t-test (*p<0.05).
Results: There were time dependent increases in the concentrations of MMP-9 and TIMP-1, but not MMP-2 (Fig 1). The MMP-9 was active (not shown). This effect was abolished by LR (Fig 2). MMP-9 inhibition prevented plasma induced delayed PMN apoptosis (not shown).
Conclusions: Storage of RBCs for 14 days or more is associated with increases in MMP-9 and TIMP-1. Delayed PMN apoptosis with stored blood is due in part to MMP-9. Pre-storage LR prevents the accumulation of MMPs in stored RBCs.

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