Liquid Freezing – A Formaldehyde Alternative for Cell Fixation using CellCover

It is common for sample collection to occur days, weeks, or months before all downstream analysis is fully complete. Maintaining the integrity of samples for short- to long-term preservation and downstream analysis has long been a challenge for researchers.

Some may remember formaldehyde fixation from high school anatomy experiments – the distinct smell and warnings of its high toxicity certainly made an impact. Formaldehyde in aqueous solution is known as formalin. Specimen tissue is often formalin-fixed paraffin-embedded (FFPE) in order to preserve the tissue for transport and storage at room temperature prior to analysis. Like formaldehyde, formalin is still toxic, and FFPE samples are often difficult to use for downstream analysis due to molecular changes caused by the formalin.

Scientists have frozen samples for cell fixation as another means of preserving for quite some time, however this requires significantly more logistics than FFPE, as the sample would need to be fresh-frozen at the site of sample collection.

CellCover takes things one step further by essentially “liquid freezing” samples in the refrigerator (usually at 4°C), acting as a much more practical formaldehyde alternative and freezing alternative.

Cells grown on almost any substrate could be treated with CellCover (liquid freezing), maintaining in vivo morphology without chemical crosslinking of biomolecules during cell fixation. RNA degradation is inhibited, leading to great results in RNA sequencing or single cell sequencing experiments. Tissue destined for biobanking is kept without altering expression due to environmentally induced gene expression changes. Protein expression analysis has no limits. As a formaldehyde alternative, formalin sensitive epitopes are readily accessible for antibodies in immunohistochemical experiments.