¹¹¹In-oxine leukocyte labeling: Intraindividual comparison of leukocyte isolation methods: Conventional versus automated microfluidic chip

Objectives To compare conventional hydroxyethyl starch augmented gravity sedimentation/centrifugation, with an automated microfluidic chip for leukocyte (WBC) isolation in preparation for radiolabeling.

Methods 25 pts. referred for ¹¹¹InWBC imaging were prospectively investigated. 60 mL blood was withdrawn & divided into 40mL (Group 1) & 20 mL (Group 2) aliquots. Group 1 WBCs underwent conventional isolation. Group 2 WBCs were isolated with an automated microfluidic chip process using size based sorting where whole blood is displaced through a microfluidic chip by a syringe pump. Within the chip, the larger WBCs are isolated from smaller RBCs & platelets, & collected for labeling. Isolated WBCs in both groups were labeled with 27.8 MBq ¹¹¹In-oxine using standard methods. Labeling efficiency, cell viability & label stability were determined. An automated cell analyzer was used to determine WBC, RBC & platelet retention in the final InWBC preparation.

Results Labeling efficiency was similar in Groups 1 & 2. InWBC stability, viability & retention were significantly higher & RBC & platelet retention significantly lower in Group 2 (table).

Conclusions These data indicate that the microfluidic chip method provides superior WBC isolation & retention & less RBC & platelet contamination. Microfluidically isolated WBC quality was comparable or superior to that of conventionally isolated WBC’s in terms of labeling efficiency, viability, & label stability. In addition to advantages of automation & decreased personnel contact with blood, reduced RBC & platelet concentrations provided by the microfluidic process potentially could improve image quality/test accuracy.

Research Support This work was supported in part by National Institute Of Biomedical Imaging and Bioengineering Award P41EB002503 to BioMeMs Resource Center at Massachusetts General Hospital

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Comparison performed using two tailed paired t- test (α = 0.05; p values < 0.05 denote statistical difference in the methods)