Reliable approaches to extract high-integrity RNA from skin and other pertinent tissues used in pain research

Peter M LoCoco; Jacob T Boyd; Claudia M Espitia Olaya; Ashley R Furr; Dawn K Garcia; Korri S Weldon; Yi Zou; Erin Locke; Alejandro Tobon; Zhao Lai; Shivani B Ruparel; Nikita B Ruparel; Kenneth M Hargreaves

doi:10.1097/PR9.0000000000000818

Reliable approaches to extract high-integrity RNA from skin and other pertinent tissues used in pain research

Pain Rep. 2020 Mar 27;5(2):e818. doi: 10.1097/PR9.0000000000000818. eCollection 2020 Mar-Apr.

Authors

Affiliations

¹ Department of Endodontics, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
² University of Arizona Cancer Center, Tucson, AZ, USA.
³ Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
⁴ Department of Neurology, South Texas Veterans Health Care System, San Antonio, TX, USA.
⁵ Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.

Abstract

Introduction: Comprehensive mRNA sequencing is a powerful tool for conducting unbiased, quantitative differential gene expression analysis. However, the reliability of these data is contingent on the extraction of high-quality RNA from samples. Preserving RNA integrity during extraction can be problematic, especially in tissues such as skin with dense, connective matrices and elevated ribonuclease expression. This is a major barrier to understanding the influences of altered gene expression in many preclinical pain models and clinical pain disorders where skin is the site of tissue injury.

Objective: This study developed and evaluated extraction protocols for skin and other tissues to maximize recovery of high-integrity RNA needed for quantitative mRNA sequencing.

Methods: Rodent and human tissue samples underwent one of the several different protocols that combined either RNA-stabilizing solution or snap-freezing with bead milling or cryosectioning. Indices of RNA integrity and purity were assessed for all samples.

Results: Extraction of high-integrity RNA is highly dependent on the methods used. Bead-milling skin collected in RNA-stabilizing solution resulted in extensive RNA degradation. Snap-freezing in liquid nitrogen was required for skin and highly preferable for other tissues. Skin also required cryosectioning to achieve effective penetration of RNA-stabilizing solution to preserve RNA integrity, whereas bead milling could be used instead with other tissues. Each method was reproducible across multiple experimenters. Electrophoretic anomalies that skewed RNA integrity value assignment required manual correction and often resulted in score reduction.

Conclusion: To achieve the potential of quantitative differential gene expression analysis requires verification of tissue-dependent extraction methods that yield high-integrity RNA.

Keywords: Cryosectioning; RIN assignment; RNA extraction; RNA integrity assessment; RNA-sequencing; Skin.

Abstract

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