Plasmin therapy enhances mobilization of HPCs after G-CSF

The role of proteinases in the mobilization of hematopoietic progenitor cells (HPCs) after granulocyte colony-stimulating factor (G-CSF) remains unclear. Here we report that genetic loss of the plasminogen activator inhibitor Pai-1 or of the plasmin inhibitor alpha 2-antiplasmin increases HPC mobilization in response to G-CSF. Moreover, thrombolytic agents, such as tenecteplase and microplasmin, enhance HPC mobilization in mice and humans. Taken together, these findings identify a novel role for plasmin in augmenting HPC mobilization in response to G-CSF. (Blood. 2008; 112: 4048-4050)