Long-term storage of samples for flow cytometric DNA analysis

Area of Science:

• Biotechnology
• Cell Biology
• Analytical Chemistry

Background:

• Accurate DNA analysis in cells is crucial for research and diagnostics.
• Current methods for cell preservation can limit experimental design and sample throughput.
• Long-term storage solutions are needed to standardize flow cytometric DNA analysis.

Purpose of the Study:

• To develop and validate a simple, reliable method for long-term storage of cells for flow cytometric DNA analysis.
• To assess the impact of the storage method on cell cycle phase distribution.
• To evaluate the potential of the method for improving accuracy and enabling large-scale studies.

Main Methods:

• Cells were stored as single cells, fine-needle aspirates in citrate buffer with dimethylsulfoxide (DMSO), or small tissue blocks.
• Storage was performed at -80 degrees C for up to one year.
• DNA content and cell cycle phases were analyzed using flow cytometry and deconvolution of DNA histograms.

Main Results:

• The storage method preserved cell cycle phase fractions without significant changes after one year of freezing.
• Intraday and interday variations were observed, suggesting that analyzing different aliquots on separate days enhances accuracy.
• The method facilitated large-scale experiments, multi-institutional tumor sample analysis, and full flow cytometer utilization.

Conclusions:

• Simple freezing at -80 degrees C is a viable method for long-term cell storage for flow cytometric DNA analysis.
• This storage technique improves analytical accuracy by enabling day-to-day comparisons and facilitates complex experimental designs.
• The method is essential for standardizing DNA content determination and advancing flow cytometry applications in research and clinical settings.