Actions of keratinocyte growth factor in leukemic mice allogeneic umbilical cord blood cell transplantation

Abstract

To explore the actions of keratinocyte growth factor (KGF) in leukemic mice allogeneic umbilical cord blood cell transplantation (UCBT) and elucidate its mechanism. Peripheral blood drawn from the litters of C57BL/6 females was used as umbilical cord blood (UCB) graft. BALB/c mice were randomly divided into 7 groups (n = 12 each). The grouping was as follows. Control group 1, inoculated with leukemia. Control group 2, inoculated with leukemia at -4 d and total body irradiation (TBI) treatment. Control group 3, TBI treatment and reconstituted with 2 × 10(6) UCB-TNCs. Control group 4, injected with PBS subcutaneously, TBI treatment and reconstituted with UCB-TNCs with platelet transfusion. Control group 5, inoculated with leukemia, injected with PBS subcutaneously, TBI treatment and reconstituted with UCB-TNCs with platelet transfusion. Experiment group 1, injected with KGF subcutaneously, TBI treatment and reconstituted with UCB-TNCs with platelet transfusion. Experiment group 2, inoculated with leukemia, injected with KGF subcutaneously, TBI treatment and reconstituted with UCB-TNCs with platelet transfusion. The survival status, pathohistological changes, splenic lymphoid cell subsets and thymic output post-UCBT were compared between groups. The survival time of control group 1 was (11.1 ± 1.5) days and all died of leukemia. The survival time of control group 2 was (11.5 ± 2.5) days and all died of aplasia. Five of 12 mice of control group 3 survived for 100 days and 7 mice died of visceral hemorrhage. Four of 12 mice of control group 5 survived for 100 days and 8 mice died of leukemia with a survival rate of 33.3%. Nine of 12 mice of experiment group 2 survived for 100 days and 3 mice died of leukemia with a survival rate of 75.0%. The survival was prolonged in experiment group 2 mice as compared with that of control group 5 mice (χ² = 4.996, P = 0.0254). The splenic T, NK and B cell counts in control group 4 mice at +35 d were (9.32 ± 0.48) × 10⁶, (1.59 ± 0.11) × 10⁶ and (18.74 ± 2.01) × 10⁶ respectively. While in group 6 mice at +35 d were (13.20 ± 1.14) × 10⁶, (1.75 ± 0.12) × 10⁶ and (20.36 ± 0.86) × 10⁶ respectively. The counts of T cell and NK cell of group 6 were higher than those of group 4 (both P < 0.05). The level of signal joint T-Cell receptor excision circles (sjTRECs) in control group 4 mice was (167 ± 17) copies per 10⁵ cells while that of experiment group 1 mice (228 ± 24) copies per 10⁵ cells. They were higher than that of control mice (P = 0.002). Hematopoietic stem/precursor cells are abundant in full-term murine fetal peripheral blood. The infusion of KGF reduces the post-UCBT relapse of leukemia through the enhancement of thymic output.