人胎儿血造血干/祖细胞的生物学特性及其移植实验

背景:造血干细胞来源目前包括骨髓干细胞、外周血干细胞和脐带血干细胞,寻找新的干细胞来源以满足临床移植需要一直是人们的希望。从妊娠第5周起,肝脏中发育成完善的血窦系统,此后造血干细胞就可以随血液流动迁移。目的:观察人胎儿血造血干/祖细胞的生物学特性并对其进行非肥胖糖尿病/重症联合免疫缺陷小鼠移植。设计:对照实验。单位:广西医科大学第一附属医院血液科。对象:①细胞来源:21例胎儿血标本取自胎龄为18～29周(24.2±3.2)周]死亡胎儿及21例足月脐带血标本取自广西医科大学第一附属医院产科2002-10/2003-02。所取的血标本均取得其家属的知情同意。②实验动物:非肥胖糖尿病/重症联合免疫缺陷小鼠12只,6～7周龄,雌性,无菌饲养于超净工作台中。方法:采用流式细胞术,检测胎儿血的造血干/祖细胞表面标志,包括CD34,CD38,HLA-DR及CD90,同时与21例足月儿脐血作比较。并将人胎血单个核细胞移植给6只经亚致死量照射的非肥胖糖尿病/重症联合免疫缺陷小鼠,5周后观察其植入情况,采用流式细胞术检测小鼠骨髓中人白细胞的含量,以及采用聚合酶链反应检测小鼠骨髓中的人Cart-1基因。主要观察指标:①胎血和脐血造血干/祖细胞表面标志的表达情况。②将胎血细胞移植给非肥胖糖尿病/重症联合免疫缺陷小鼠的植入情况。结果:①人胎血中CD34 细胞的百分率显著高于足月脐血(2.2588±0.7209)%,(1.5729±0.4783)%,P=0.0004],CD34 CD38-细胞和CD34 CD90 细胞的百分率也均显著高于足月脐血(1.2986±0.4706)%,(0.8710±0.4095)%,P=0.0016;(0.9300±0.4692)%,(0.5600±0.3658)%,P=0.0324]。②6例胎血中的4例可顺利重建经亚致死量照射的非肥胖糖尿病/重症联合免疫缺陷小鼠的造血,移植后5周在小鼠骨髓中仍可检测到人的白细胞和人Cart-1基因。结论:人胎儿血中有比足月脐血更高含量的造血干/祖细胞,其单个核细胞能植入非肥胖糖尿病/重症联合免疫缺陷小鼠骨髓,并重建髓、淋巴系全面造血。胎儿血有望成为多能造血干细胞来源。

Biological features and transplantation of human fetal blood hematopoietic stem/progenitor cells

BACKGROUND: Currently the hematopoietic stem cells can be obtained from bone marrow, peripheral blood and cord blood, so it is expected to search a new source of stem cells in order to satisfy the clinical transplantation needs. From the 5th week of pregnancy, the blood sinusoid system develops completely in liver, and then hematopoietic stem cells can move with blood flow. OBJECTIVE: To observe the biological features of human fetal blood hematopoietic stem/progenitor cells (HS/PCs), and their transplantation into non-obese diabetic/severe combined immunodeficiency disease (NOD/ SCID) mice. DESIGN: Control trial. SETTING: Department of Hematology, First Affiliated Hospital of Guangxi Medical University. MATERIALS:①Cell resource: Twenty-one fetal blood samples were from dead fetus gestational age of 18-29 weeks, mean (24.2±3.2) weeks] and twenty-one full-term cord blood samples were provided from the Department of Obstetrics, First Affiliated Hospital of Guangxi Medical University between October 2002 and February 2003, with the consent of their relatives.②Experimental animal: Twelve NOD/SCID female mice of 6-7 weeks old were bred in sterility and super-clean operation board. METHODS: Flow cytometer was used to assess cell surface markers of HS/PCs including CD34, CD38, HLA-DR and CD90 in 21 human fetal blood samples, and their expressions were compared with 21 human cord blood samples. Moreover, human fetal blood mononuclear cells (MNCs) were transplanted into 6 NOD/SCID mice irradiated sublethally. After 5 weeks, human leukocytic content was also detected in bone marrow of mice with flow cytometer while human Cart-1 gene in recipients' bone marrow was sensed with polymerase chain reaction (PCR).MAIN OUTCOME MEASURES: ① Expressions of HS/PCs surface markers in fetal blood and cord blood. ②Implantation of fetal blood cells into NOD/SCID mice.RESULTS: ①The percentage of CD34+ cells in fetal blood was significantly higher than that of full-term cord blood (2.258 8±0.720 9)%,(1.572 9±0.478 3)%, P=0.000 4]. The percentages of CD34+CD38- cells and CD34+CD90+ cells in fetal blood were also higher than those of fullterm cord blood (1.298 6±0.470 6)%, (0.871 0±0.409 5)%, P=0.001 6;(0.930 0±0.469 2)%, (0.560 0±0.365 8)%, P=0.032 4].②Four cases (4/6)of human fetal blood MNCs smoothly transplanted the hematopoiesis of sublethally irradiated NOD/SCID mice. Five weeks after the transplantation, human leukocyte and Cart-1 gene could still be detected in marrow cells of NOD/SCID mice.CONCLUSION: Human fetal blood contains more HS/PCs than cord blood. Human fetal blood MNCs can engraft bone marrow of NOD/SCID mice and reconstitute general hemopoiesis of marrow and lymph systems.Human fetal blood is a new possible source of pluripotential hematopoietic stem cell.