Time course analysis of RNA quality in placenta preserved by RNAlater or flash freezing

Preservation of biospecimen quality is critical to accurately and reliably assessing genes and proteins. We evaluated the effect of preparation method and storage duration on RNA quality in placenta and decidua.

Aliquots of nine placentas and decidua were placed in RNAlater^® (RL) or flash frozen (FF) within 30 minutes of delivery. RNA was extracted immediately (baseline) and from matched samples stored at -80°C for 1 and 8-10 months. RNA Integrity Number (RIN) and housekeeping gene expression were quantified.

At both time points, RL placenta had RIN and housekeeping gene Ct values similar to baseline. However, FF placenta had significantly lower RIN and higher Ct values at 1 and 8-10 months. In RL and FF decidua, RIN was unchanged from baseline.

We found RNAlater more effectively and consistently preserved placenta, compared to flash freezing. However, for decidua, which is less dense than placenta, both modes yielded comparable RNA integrity over time.