Objective To investigate the influence of Exo-1 gene deletion on the engraftment of hematopoietic stem cell(HSC) transplantation by different methods into the telomerase knockout mice.Methods Bone marrow cells or KSL((c-kit +,Sca-1 +,lineage-) cells were isolated from CD45.1 mice,and then injected into recipients,which were telomer-ase gene knockout or Exo-1 and telomerase gene double knockout mice with or without irradiation.At 1 month later,pe-ripheral blood was collected and analyzed by flow cytometry.Re...