ENHANCED ENGRAFTMENT OF INTRAVENOUSLY TRANSPLANTED HEMATOPOIETIC STEM-CELLS INTO BONE-MARROW OF IRRADIATED MICE TREATED WITH ACSDKP

The effect of the tetrapeptide Acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) on in travenously transplanted hematopoietic stem cell engraftment into the bone marrow (BM) of irradiated mice was studied. When 5x10(4) marrow c ells were transplanted into lethally irradiated mice given 10 mu g AcS DKP, the survival of these animals 4 weeks posttransplantation increas ed markedly from 20.0 +/- 4.4% to 86.1 +/- 4.8%, the same result as th at obtained from mice transplanted with 5x10(5) cells without AcSDKP t reatment. Increased numbers of hematopoietic stem cells, including spl een colony-forming unit and colony-forming unit granulocyte-macrophage , were observed in the BM of AcSDKP-treated mice 1 and 8 days after tr ansplantation This finding suggested that AcSDKP influenced homing of hematopoietic stem cells into the BM of lethally irradiated animals. T his enhancing activity of AcSDKP was neutralized by the simultaneous a dministration of an anti-AcSDKP polyclonal antibody. Furthermore, reco very of leukocytes in peripheral blood occurred faster in AcSDKP-treat ed than in untreated transplanted mice. These findings may provide a b asis for the clinical use of AcSDKP in BM transplantation patients.