生长抑素对人脐血CD34+细胞增殖能力的影响

Effects of somatostatin on proliferation ability of human CD34+ cells derived from umbilical cord blood*

目的探索生长抑素（SST）对造血干／祖细胞增殖能力的影响以及可能机制。方法采用免疫磁殊分选技术纯化人脐血CD34^＋细胞；SST孵育人CD34^＋细胞后，体外集落形成、扩增培养了解细胞增殖；ELISA测定细胞内外TNF-α、TGF-β水平；RT—PCR分析其受体亚型。结果在1×10^-6～1×10^-10mol／L浓度范围内，SST抑制人CD34^＋细胞集落形成及扩增倍数，其细胞集落形成抑制与SST浓度呈正相关（r=0．903，P〈0．01）。SST使CD34^＋细胞内、外TNF-α及TGF-β1浓度显著增加（P〈0．05）；人脐血CD34^＋细胞表达SST-3型受体。结论SST通过人脐血CD34^＋细胞上SST-3型受体介导，提高造血抑制因子TNF-α、TGF-β水平，抑制人CD34^＋细胞的增殖、维持其干细胞特性。

Objective To investigate the effects and mechanisms of somatostatin （SST） on proliferation ability of hematopoietie/ progenitor stem ceils （HSC）. Methods Mononuclear cell （MNC） derived from human cord blood was isolated by Ficoll, then MACS assay was used to purify human CD34^＋ cells from MNC; After treated with SST, colony forming unit （CFU） enumeration and amplification were clone to assess the effects on proliferation of human CD34^＋ cells;TNF-α and TGF-β in human CD34^＋ cells or its supernatant were measured with ELISA;reverse transcriptation polymerase chain reaction was used to quantify receptor for SST （SSTR） and detected its subtype. Results SST in concentration of1×10^-6～1×10^-10mol/L inhibite proliferation of human CD34^＋ cells. The inhibition of CFU forming bore a positive relation with the concentration of SST（r=0. 903,P〈0.01）. The concentrations of TNF-α or TGF-β1 in human CD34^＋ cells treated with SST were increased when compared to control group（P〈 0.05）. Human CD34^＋ cells expressed receptor for SST-3. Conclusion Mediated by SSTR-3 in Human CD34^＋ cells,SST inhibite proliferation of Human CD34^＋ cells due to increasing the intra cell concentrations of TNF-α and TGF-β, the inhibitive cytokines for hematopoiesis. SST tends to keep characteristics of Human CD34^＋ cells and inhibit the differentiation of Human CD34^＋ cells to granuloeyte-monocytes.