动员后外周血中CD34+细胞去除前后对改善肢体缺血疗效的研究

目的对动员的外周血单个核细胞（PBMNC）和动员的去除CD34^＋细胞的PBMNC移植治疗裸鼠下肢缺血的疗效进行比较，以探讨PBMNC的治疗机制。方法经过单采获得G-CSF动员的PBMNC后，一部分通过CD34磁珠抗体分选得到去除CD34^＋细胞的PBMNC。动员的PBMNC和动员的去除CD34^＋细胞的PBMNC荧光标记后按1×10^6细胞或相应体积的PBS分别局部肌肉注射移植到裸鼠缺血下肢。观察下肢血流灌注以及毛细血管密度。用ELISA法检测下肢肌肉的血管内皮生长因子（VEGF）表达，并进一步观察表达的VEGF是否由移植细胞分泌。结果PBMNC移植后缺血下肢血流明显恢复，毛细血管密度明显增加，但去除CD34^＋细胞的PBMNC移植组疗效有所下降。细胞移植后4周，PBMNC组的血流灌注由（20．3±4．2）％恢复为（96．4±5．6）％，对照组仅恢复为（71．3±4．4）％（P〈0．01），去除CD34^＋细胞组恢复为（83．8±5．2）％（P〈0．05）。PBMNC组血管密度为（521±47）／mm^2，去除CD34^＋细胞组为（3964-21）／mm^2（P〈0．05），但仍高于对照组（276±43）／mm^2]（P〈0．05）。在PBMNC组可以观察到移植的细胞整合到缺血的毛细血管壁。缺血肌肉VEGF的表达明显升高，其共表达VEGF和移植的单个核细胞。结论移植G-CSF动员的PBMNC不但可以通过干细胞整合到血管壁的机制促进血管生长，还可以通过提供细胞因子的机制促进血管生长。去除CD34^＋细胞削弱了动员的PBMNC移植治疗肢体缺血的血管新生效应。

The therapeutic efficacy for limb ischemia by transplantation of mobilized peripheral blood cells before and after CD34+ cell depletion

OBJECTIVE: To explore the mechanism of the therapeutic efficiency of mobilized peripheral blood mononuclear cells (PBMNCs) with and without CD34+ cell depletion in ischemia nude mice. METHODS: After femoral ligation of mice, 1 x 10(6) PBMNCs, CD34+ cell depletion PBMNCs, or PBS were intramuscularly injected into the ischemic limb. Blood perfusion, ischemia damage, and capillary density of the limb were observed. VEGF expression in ischemic limbs was assayed by ELISA and immunohistochemistry. RESULTS: PBMNCs transplant greatly improved the recovery of ischemic limbs. At day 28 after surgery, the blood perfusion rate of ischemic limbs recovered to (96.4 +/- 5.6)% from (20.3 +/- 4.2)% in PBMNCs transplanted group, compared with (71.3 +/- 4.4) % in PBS group (P <0.01). Depletion of CD34+ cells reduced the perfusion ratio to (83.8 +/- 5.2)% (P < 0.05). Capillary density in PBMNCs transplanted group was (521 +/- 47)/mm2, while in CD34+ cell-depleted group (396 +/- 21)/mm2] (P < 0.05). PBMNCs were found to incorporate into vascular network. VEGF was greatly up-regulated after transplantation of PBMNCs and was secreted in situ. CONCLUSION: Transplantation of mobilized PBMNCs augments neovascularization in ischemic limb via supply of stem/progenitor cells and angiogenic factors. Depletion of CD34+ cells impaired therapeutic efficacy for limb ischemia.