角质细胞生长因子在白血病小鼠异基因脐带血移植中的作用

目的 探讨角质细胞生长因子(KGF)在白血病小鼠异基因脐带血移植(UCBT)中的作用及机制.方法 C57BL/6胎鼠外周血作为脐带血移植物.BALB/c小鼠随机数字表法分为7组,每组12只.对照1组:单纯接种白血病;对照2组:全身辐射(TBI)前第4天(-4d)接种白血病,单纯TBI处理;对照3组:不接种白血病,TBI处理后输注2×106个脐带血总有核细胞数(TNC);对照4组:不接种白血病,自TBI-3 d起每日皮下注射磷酸盐缓冲液(PBS)连用7d,TBI后输注脐带血TNC,移植后第8天(+8 d)予输血小板支持;对照5组:TBI-4 d接种白血病,自TBI-3 d起每日皮下注射PBS连用7d,TBI后输注2×106个脐带血TNC,移植+8d予输血小板支持;实验1组:不接种白血病,自TBI-3 d起每日皮下注射KGF 1 mg/kg连用7d,TBI后输注脐带血TNC,移植+8d予输血小板支持;实验2组:接种白血病,自移植-3d起每日皮下注射KGF 1 mg/kg连用7d,TBI后输注脐带血TNC,移植+8d予输血小板支持.以生存期、病理组织学变化、脾脏淋巴细胞亚群、胸腺输出功能为观察指标并作组间比较.结果 对照1组,12只小鼠全部死于白血病,小鼠生存时间为(11.1±1.5)d;对照2组,小鼠单纯TBI处理后12只全部死于造血衰竭,生存时间为(11.5±2.5)d;对照3组,5只(5/12)小鼠生存期超过100 d,7只小鼠20 d内死于内脏出血;对照5组,白血病小鼠脐带血移植后4只(4/12)生存期超过100 d;实验2组,白血病小鼠9只(9/12)生存期超过100d.实验2组与对照5组白血病小鼠生存时间比较差异有统计学意义(Log-rank检验,x2=4.996,P=0.0254).移植后对照4组小鼠脾脏T、NK和B细胞数分别为(9.32 ±0.48)×106、(1.59 ±0.11)×106、(18.74±2.01)×106个;实验1组小鼠脾脏T、NK和B细胞数分别为(13.20±1.14)×106、(1.75±0.12)×106、(20.36±0.86)×106个,实验1组T细胞、NK细胞数均高于对照4组(均P＜0.05).实验1组信号结合T细胞受体删除DNA环(sjTREC)水平明显高于对照4组(228±24)拷贝/105脾细胞比(167±17)拷贝/105脾细胞,P =0.002].结论 足月胎鼠外周血富含造血干祖细胞.KGF输注减少小鼠异基因脐带血移植后白血病复发,其机制为促进胸腺输出功能恢复.

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

Objective To explore the actions of keratinocyte growth factor(KGF)in leukemic mice allogeneic umbilical cord blood cell transplantation(UCBT)and elucidate its mechanism.Methods 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 × 106 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.Results 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(x2 =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 l05 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).Conclusion 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.