羟乙基淀粉沉降法分离脐血过程的深入分析及条件优化

目的　进一步提高HES(羟乙基淀粉 )沉降法分离脐血单个核细胞的收率。方法　对比和分析对该沉降过程完成后上下层的白细胞数 ,并考察HES浓度、HES与脐血体积比、沉降距离对该过程白细胞收率的影响。结果　沉降过程存在因红细胞团向下沉降而推动白细胞向上运动的对流现象 ,该现象受到细胞占悬浮液总体积的比例和红细胞下降速度的影响 ,增加沉降距离能增加对流的作用距离 ,有利于提高白细胞的收率 ,提高HES与脐血的体积比也有利于提高白细胞收率。悬浮液中HES浓度 <0 .6 %时 ,细胞不能有效沉降 ,>3%时 ,会引起白细胞在红细胞中的夹带而影响收率。用 3%HES以 2∶1与脐血混合 ,在沉降距离为 2 5cm的沉降管中沉降 4 0min ,分离后白细胞收率达 94 .3%。结论　采用 3%HES溶液 ,并提高HES与脐血的体积比和增加沉降距离 ,可进一步提高HES沉降法分离脐血单个核细胞的收率

Optimization of cord blood separation process by Hydroxyethyl Starch (HES) sedimentation

Objective To improve the percent recovery of the white cells in the process of cord blood separation by HES sedimentation. Methods The effects of HES concentration, the volume ratio of HES to cord blood, and sedimentation length on the recovery were determined and analyzed. Results It was found that there was convection in this process that white cells moved upward caused by the fast downward settling of red cell pellets, and this convection was related to the velocity of red cell pellets and the ratio of cells to suspension volume. The longer sedimentation distance helped improve the recovery of white cells, since it prolonged the push up action distance. The white cell recovery also could be improved by enhancing the volume ratio of HES to cord blood. The red cells couldn't form pellet and settle efficiently if the HES concentration in the mixed suspension was less than 0.6%, and white cells were involved in the red cell pellets if HES concentration exceeded 3%. A 94.3% recovery of mononuclear cell could be obtained after sedimentation in a 25cm settler for 40 min, in which the volume ratio of 3%HES solution to cord blood was 2:1. Conclusion A higher recovery can be reached in a longer settler after HES concentration and the ratio of HES to cord blood are optimized