目的：研究SD大鼠外周血单个核细胞（PBMNCs）的组成成分及其随年龄的变化，为大鼠PBMNCs相关 研究提供参考。方法：使用淋巴细胞分离液、不连续密度梯度离心法制备3、6、12 月龄雄性SD大鼠PBMNCs， 检测PBMNCs中细胞种类和含量、淋巴细胞和单核细胞含量随年龄的变化趋势；流式细胞术、免疫荧光技术检测 PBMNCs干/ 祖细胞含量及随年龄变化趋势。结果：使用淋巴细胞分离液，不连续梯度离心法制备PBMNCs，不 同细胞成分分层清晰，红细胞、粒细胞去除较完全，PBMNCs中淋巴细胞、单核细胞含量随年龄的增长下降趋势 明显； PBMNCs 中Nanog、OCT4、SOX2、SSEA4 四种干性标志物均有表达，Nanog 阳性表达量最低，SSEA4 表 达量最高，可达23.1% ；总体趋势均为6 月龄大鼠PBMNCs中干/ 祖细胞含量最高。结论：SD大鼠PBMNCs中干 / 祖细胞含量较高，动物实验治疗疾病的作用可能较人体应用的疗效好。进行SD大鼠PBMNCs移植治疗疾病的实 验研究，建议选用6 月龄以下大鼠为宜。

Objective ： To provide a reference for studies related to rat peripheral blood mononuclear cells （PBMNCs）， we investigated the composition and age-related changes in PBMNCs isolated from SD rats. Methods ： PBMNCs were isolated from male SD rats aged 3， 6， and 12 months using lymphocyte separation medium and discontinuous density gradient centrifugation. The types and numbers of cells in PBMNCs， as well as the agerelated changes in lymphocyte and monocyte content， were analyzed. Flow cytometry and immunofluorescence were utilized to quantify the number and assess the age-related trends of stem/progenitor cells within PBMNCs. Results ： The different cellular components of PBMNCs were clearly separated， and red blood cells and granulocytes were effectively removed. The number of lymphocytes and monocytes in PBMNCs decreased significantly with age. In SD rat PBMNCs， four stemness-related markers (Nanog， OCT4， SOX2， and SSEA4) were expressed. Among them， Nanog exhibited the lowest positive expression， while SSEA4 showed the highest， reaching 23.1%. Overall， the content of PBMNCs stem/progenitor cells in PBMNCs was highest in six-month-old rats. Conclusions ： SD rats have a higher content of stem/progenitor cells in their PBMNCs, which suggests that the therapeutic effect of animal experiments might be better than in human applications. For experimental studies involving the transplantation of SD rat PBMNCs for disease treatment, it is recommended to use rats younger than 6 months.