Oral Presentation ABNA - Biobanking: Shaping the Future Together

Evaluating Nucleic Acid Stability in Brain Tissue: Insights from a Pilot Study on PMI (#47)

Samara Bray 1 2 3 , Kaylee O'Brien 1 3 4 , Megan Clarke 1 3 5 , Xiajie Zhang 2 6 , Simon King 1 5 , Deb Kerr 1 2 3 , Cassandra Griffin 1 3 4
  1. Hunter Cancer Biobank – University of Newcastle, New Lambton Heights, NSW, Australia
  2. School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, NSW, Australia
  3. Hunter Medical Research Institute, Newcastle, NSW, Australia
  4. School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia
  5. NSW Health Pathology, Department of Anatomical Pathology, John Hunter Hospital, Newcastle, NSW, Australia
  6. NSW Health Pathology, Department of Molecular Medicine, John Hunter Hospital, Newcastle, NSW, Australia

Despite decades of research, advances in the treatment options for brain cancer have remained stagnant over the last 19 years[1] due largely to an incomplete understanding of brain tumour biology and scares access to high-quality biological samples for research [2]. The Mark Hughes Foundation Biobank is an invaluable resource of post-mortem brain tumour samples stored as both FFPE and fresh frozen tissues. Evidence regarding the best practice for the collection of whole brain specimens is conflicting, with post-mortem interval (PMI) – the time between death and cryopreservation of tissue - being identified as having one of the largest impacts on sample integrity [2] but no clear correlation between PMI and sample quality. [3][4].

In this pilot study we aimed to isolate and analyse both DNA and RNA from fresh frozen brain tissue to explore the relationship between PMI and nucleic acid integrity. At the time of autopsy fresh frozen sections were sliced from whole brain then quickly snap frozen in liquid nitrogen and transported to a -80 freezer for long term storage. Samples were taken from 12 patients and divided into the PMI groups: 0-4hrs, 7-10hrs and >24 hrs. These samples were then assessed for DNA and RNA concentration and integrity (DIN and RIN). Initial results did not detect a correlation between DNA or RNA results and PMI, with samples from the >24 hour group having yields RNA yields as high as 4 and samples from the <4 hours group yields as low as 1.7. Additional factors specific to a brain cancer context such as hypoxia, agonal state, systemic temperature, and systemic pH may explain these results and were not controlled for in this setting.[1]

While this pilot study did not identify a correlation between PMI and nucleic acid quantity/quality, further work with a much greater sample size is required to confirm these results. Furthermore, future studies could also include assessment of protein as an additional indicator of quality.

 

 

 

 

 

 

References:

  1. Sandmann, T., et al., Patients With Proneural Glioblastoma May Derive Overall Survival Benefit From the Addition of Bevacizumab to First-Line Radiotherapy and Temozolomide: Retrospective Analysis of the AVAglio Trial. J Clin Oncol, 2015. 33(25): p. 2735-44.
  2. Griffin, C.P., et al., Postmortem brain donations vs premortem surgical resections for glioblastoma research: viewing the matter as a whole. Neurooncol Adv, 2022. 4(1): p. vdab168.
  3. Durrenberger, P.F., et al., Effects of Antemortem and Postmortem Variables on Human Brain mRNA Quality: A BrainNet Europe Study. Journal of Neuropathology & Experimental Neurology, 2010. 69(1): p. 70-81.
  4. Sele, M., et al., Optimization of ultrastructural preservation of human brain for transmission electron microscopy after long post-mortem intervals. Acta Neuropathologica Communications, 2019. 7(1): p. 144.