Isolation of micronuclei: high yield by sucrose gradient versus maximum purity by cell sorting

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Micronuclei (MNC) are critical biomarkers for genotoxicity and chromosomal instability.
• Accurate DNA content characterization of MNC requires highly purified isolates.
• Existing isolation methods often face limitations in efficiency, purity, or cost.

Purpose of the Study:

• To develop and evaluate a novel, efficient method for isolating micronuclei (MNC) from L929 cells.
• To compare the developed method with cell sorting for purity, yield, and cost-effectiveness.
• To facilitate large-scale DNA isolation from MNC for downstream applications like gel electrophoresis.

Main Methods:

• Development of a novel isolation technique for MNC using sucrose gradient ultracentrifugation.
• Characterization of isolated MNC DNA content 72 hours post-irradiation (6 Gy) via gel electrophoresis.
• Comparative analysis with cell sorting for MNC isolation efficiency and purity.

Main Results:

• The sucrose gradient method achieved >99% purity and 80% recovery, isolating over 150 x 10^6 MNC daily.
• This method yielded 2000 times more MNC DNA compared to cell sorting.
• Cell sorting provided 100% purity but was time-consuming with low recovery (10%) and minimal DNA yield (<1 ng/day).

Conclusions:

• Sucrose gradient ultracentrifugation is a highly efficient, rapid, and cost-effective method for isolating large quantities of purified MNC.
• This technique avoids the need for sophisticated and expensive equipment like cell sorters.
• The developed method is superior to cell sorting for large-scale MNC DNA isolation required for analyses.