Preserved cells can be used as positive and process controls. In addition, they can be used as controls for instrument setup or standardization, reagent quality control, panel characterization, and in multi-instrument and multicenter longitudinal studies. Effective and stable control cells are, however, difficult to secure for cell-based assays. Current commonly used preservation methods such as cryopreservation and lyophilization often cause mechanical destruction of cells, resulting in deteriorated performance of cell markers.
Our newly developed air drying technology for cell preservation is designed to minimize the nonspecific binding of some problematic markers and maximize the stain resolutions for dim markers. Air-dried leukocytes and bone marrow maintain light scatter profiles comparable to fresh cells; More than 175 surface markers are consistently expressed on dried leukocytes including surface markers Kappa, Lambda, CD25, CD62L, CD11C and cytoplasmic markers cyCD3, cyCD79a and cyMPO. Dried leukocytes have a shelf life of 12 months at 2°C to 8°C. The aberrant and stem cells markers including CD34, CD117, and CD105 are consistently expressed on dried bone marrow cells. Having dried, rehydratable bone marrow for flow cytometric studies, promises for the first time to provide easily accessible control material directly from the biological source.
We demonstrate that dried cells can be used as flow cytometry process controls from staining through acquisition and analysis. We also demonstrate that dried cells can be used for flow cytometry longitudinal studies to standardize results across multiple instruments and locations.