What do you think of rapid immunophenotyping your cell product on a chip? A group of Japanese researchers described a modified method for high-throughput immunophenotyping of mesenchymal stromal cells (MSC). They used cell binding antibody array with various MSC surface markers and validated it against conventional flow cytometry. The method was described for the first time 10 years ago – it entails:
Antibody arrays are fabricated by displaying different antibodies on a micropatterned, glass-based chip in a site-addressable manner. The expression pattern of surface markers can be attained by inspecting cell adhesion on every antibody spots for assessing simultaneously reactivity of multiple surface antigens with surface-immobilized antibodies.
The following antibodies were used in array: CD11b, CD31, CD44, CD45, CD51, CD73, CD90, CD105, and CD254. The authors tested different cell concentrations, seeded onto array and different concentrations of antibodies. Bound cell number became constant at antibody concentration of 125 μg/mL and at seeding cell concentration of 2000 cells/mm2. Data between antibody array and flow cytometry were “fairly comparable”. Slight difference was noted in CD90 expression, where flow cytometry showed 2 subpopulations with high and low expression. Three different cell culture harvest methods were tested. After cell seeding, array was incubated for 15 min at 37C. Unbound cells were eliminated by inversion of the plate before readout.
Importantly, “It was further found that the density of cells attached to antibody spots was correlated to the mean fluorescent channel recorded in flow cytometry.” So, assay could be used as quantitative.
It seem to me, antibody array could be a good alternative to flow cytometry. It requires fluorescent microscope for assay readout and less training than flow cytometry. The authors specifically discuss pros and cons of the method in comparison with flow cytometry:
Importantly, antibody arrays provide a high-throughput method that enable us with analyzing the expression of multiple surface markers at once. This is not always straightforward by flow cytometry even if the latest multicolor flow cytometer is used, although simultaneous expression of multiple markers on an identical cell can be analyzed by flow cytometry. Besides this, compare to flow cytometry, the antibody array-based method has several advantages: Analysis can be performed using smaller number of cells per surface marker and does not require analysts’ proficiency in data interpretation as well as an expensive cytometer. To increase the throughput of analysis, it may be practical to automate some of the analytical process such as determination of bound cell densities.
What do you think? Will antibody array chips be used in cell products quality control? Will it replace flow cytometry for some applications?