The effect of postmortem time on the RNA quality of human ocular tissues

Purpose: Profiling gene expression in human ocular tissues provides invaluable information for understanding ocular biology and investigating numerous ocular diseases. Accurate measurement of gene expression requires high-quality RNA, which often is a challenge with postmortem ocular tissues. Methods: We examined the effect of various death to preservation (DP) times on the RNA quality of ten different ocular tissues. We used 16 eyes from eight different human donors. The eyes were preserved immediately in RNAlater or preserved after initial storage at 4 degrees C to create a range of DP times from 2 to 48 h. Ten ocular tissues were dissected from each eye. After total RNA was extracted from each dissected ocular tissue, the RNA integrity number (RIN) was determined using an Agilent Bioanalyzer. Results: The RIN values from corneal and trabecular meshwork tissues were significantly (p<0.05) higher than those from the ciliary body at an earlier DP time (<6 h), but were not different among all tissues after 8 h. Interestingly, the RIN values from non-vascularized tissues were significantly (p= 0.0002) higher than those from vascularized ocular tissues at early DP times (<6 h). The RIN value from the cornea was significantly (p<0.05) higher at short DP times compared to longer DP times. The RIN values from corneal tissues were significantly correlated to DP time according to regression analysis (p<0.05). Conclusions: In this study, we determined RNA quality from postmortem ocular tissues with various DP times. Our results emphasize the need for rapid preservation and processing of postmortem human donor eye tissues, especially for vascularized ocular tissues.