An in Vitro Stopped Flow Method of Microdialysis Sampling for Cytokines

by Herbaugh, Anthony; Stenken, Julie A.

Cytokines have been highly studied for their roles in directing various immunol. functions. Microdialysis sampling offers a means to collect cytokines in an in vivo setting. However quant. sampling by microdialysis of cytokines is difficult because of their low concns. and small aq. diffusion coeff. limiting the amt. of cytokine that can be recovered. A stopped flow method was developed to det. if recovery of these important proteins could be improved. For a linear style probe, the perfusion fluid was stopped for 30 min and 1 h between each collected sample. A perfusion flow rate of 5 µL/min with a sample collection time of 10 min was then applied. Using this approach with the analyte MCP-1, samples collected under stopped flow conditions achieved an av. of 15% to 20% relative recovery. There was no significant difference in the relative recovery between samples that had the flow stopped for 30 min vs 1 h. In comparison with the stopped flow approach, samples were also collected using continuous flow at 0.5 and 1 µL/min. These samples had av. relative recovery values between 5 and 8%. Ongoing work will compare the linear vs. cannula style microdialysis geometry for other cytokines. Addnl., the use of heparin-immobilized beads that can capture cytokines will be compared in the stopped-flow approach. This work was supported by NIH EB 001441 and the Arkansas Biosciences Institute.