Purpose: Gene expression and protein analysis studies require high-quality human tissue which is a challenge and difficult to obtain through live human biopsies. Human postmortem lacrimal gland (LG) and submandibular gland (SMG) tissues have the potential to provide an invaluable source for studying the mechanisms involved in LG and SMG dysfunction. Therefore, we aimed to test the suitability of post-mortem LG and SMG for molecular, biochemical, and cell biological studies.
Methods: LG and SMG tissue from healthy donors was collected and immediately placed in RNAlater solution and then shipped overnight at 4 °C. After receipt, each gland was divided into three pieces for RNA, protein, and histological analysis, respectively. Total RNA isolated from each LG and SMG was analyzed for RNA integrity using an Agilent Bioanalyzer and reverse transcription-PCR (RT-PCR). For histology, tissues were embedded in paraffin and stained with hematoxylin and eosin. For protein analysis, lysates were prepared and processed for sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and western blotting.
Results: When the LG and SMG samples were preserved in RNAlater, the RNA integrity number (RIN) values from the LG and SMG were >7.0 from all three donors, while the RNAs from tissue not preserved in RNAlater were of poorer quality. The gene and/or protein expression of E-cadherin, aquaporin 5, alpha-smooth muscle actin (α-SMA), β-actin, and GAPDH was preserved in all samples. In addition, histological analyses showed normal tubuloacinar structures of all glands with serous and mucous producing acini within lobules interspersed with adipose fat.
Conclusions: In this study, we determined that RNA, protein, and histological sections obtained from postmortem human LG and SMG tissue preserved in RNAlater were of high quality. This would provide a viable source of human LG and SMG tissue suitable for studies of diseases that affect these glands, such as Sjögren's syndrome.