Effects of antemortem and postmortem variables on human brain mRNA quality: a BrainNet Europe study

Well-characterized and preserved human brain tissue that is prepared and stored in brain banks is an essential resource for research in neurological diseases. This study examined the quality of human brain postmortem tissue from multiple laboratories within the BrainNet Europe brain bank network to identify all possible confounding variables and determine how they may affect RNA quality. Antemortem and postmortem information was retrospectively collected for a large cohort of samples. Total RNA was isolated from anatomically defined brain regions using a standardized procedure; RNA quality was assessed using an Agilent 2100 Bioanalyzer. No significant difference in RNA quality was observed in 6 different brain regions. RNA quality deteriorated with increasing numbers of antemortem events such as hospitalization, coma, respiratory illness, and the use of artificial ventilation; accumulation of such events was associated with elevated hypoxia-inducible factor 1 alpha mRNA expression. Brain pH was found to be a good indicator of RNA quality. There was no correlation of postmortem delay with cerebrospinal fluid pH or RNA quality overall, but some individual RNAs decreased in quality with antemortem events and with postmortem delay. RNA quality did not affect total RNA yield. Determining the factors that are best predictors of RNA quality can help brain banks with selection criteria for storing high-quality brain tissue for research.