Question: What are the validated stopping points for sample storage in the Flex Gene Expression assay?
Answer: Fixed samples can be stored at multiple validated stopping steps within the Flex Gene Expression workflow (NextGEM and GEM-X Flex).
Sample Preparation:
Fixation of cells or nuclei suspensions: Cells and nuclei suspensions are fixed in a 4% formaldehyde fixative solution and then quenched following the Fixation of Cells & Nuclei Demonstrated Protocol. Fixed cell or nuclei suspensions can be stored short-term at 4°C for up to 1 week or long-term at -80°C for up to 12 months, after resuspending in appropriate reagents.
Fixation and dissociation of tissues: Fresh or flash frozen tissue samples are first fixed and then dissociated following the Tissue Fixation & Dissociation Demonstrated Protocol. Fixed tissue pieces and cell suspension derived from fixed dissociated tissues can be stored short-term at 4°C for up to 1 week or long-term at -80°C for up to 12 months, after resuspending in appropriate reagents.
Isolation of Cells from FFPE Tissue Sections: Cells isolated from formaldehyde fixed & paraffin embedded (FFPE) tissue sections can also be used for Flex Gene Expression following the Sample Preparation from FFPE Tissue Sections Demonstrated Protocol. Dissociated cells resuspended in appropriate buffer can be stored for short-term at 4°C for up to 1 week or long-term at −80°C for up to 12 months.
Post-Hybridization:
Samples can be optionally stored at two steps within the Flex Gene Expression workflow for up to 12 months at -80°C:
Post-Hybridization Pool & Wash Step: After completion of the post hybridization washes, the samples can be either stored at −80°C for up to 12 months after adding the appropriate reagents, or proceed immediately to the next step. If directly proceeding with the next step, the undiluted washed samples can be placed on ice and then stored later after GEM Incubation.
GEM Incubation: The remaining undiluted sample from Post-Hybridization Pool & Wash that has been stored on ice during GEM generation can be stored at −80°C for up to 12 months, after adding the appropriate reagents.
Please note: Samples may undergo a color change during storage (e.g. black, light gray, or green), however this will not impact assay performance.
Products: Flex Gene Expression