RNA-sequencing transcriptomic analysis of scrapie-exposed ovine mesenchymal stem cells

In neurodegenerative diseases, including prion diseases, cellular models arise as useful tools to study the pathogenic mechanisms occurring in these diseases and to assess the efficacy of potential therapeutic compounds. In the present study, a RNA-sequencing analysis of bone marrow-derived ovine mesenchymal stem cells (oBM-MSCs) exposed to scrapie brain homogenate was performed to try to unravel genes and pathways potentially involved in prion diseases and MSC response mechanisms to prions. The oBM-MSCs were cultured in three different conditions (inoculated with brain homogenate of scrapie-infected sheep, with brain homogenate of healthy sheep and in standard growth conditions without inoculum) that were analysed at two exposure times: 2 and 4 days post-inoculation (dpi). Differentially expressed genes (DEGs) in scrapie-treated oBM-MSCs were found in the two exposure times finding the higher number at 2 dpi, which coincided with the inoculum removal time. Pathways enriched in DEGs were related to biological functions involved in prion toxicity and MSC response to the inflammatory environment of scrapie brain homogenate. Moreover, RNA-sequencing analysis was validated amplifying by RT-qPCR a set of 11 DEGs with functions related with prion propagation and its associated toxicity. Seven of these genes displayed significant expression changes in scrapie-treated cells. These results contribute to the knowledge of the molecular mechanisms behind the early toxicity observed in these cells after prion exposure and to elucidate the response of MSCs to neuroinflammation. Overall design: To discover genes and pathways potentially involved with prion disease mechanisms and to evaluate the potential of ovine mesenchymal stem cells as in vitro models of prion toxicity, we performed a RNA-sequencing analysis of oBM-MSCs. Two infection times (2 days and 4 days post-inoculation) and three conditions were studied (cells inoculated with scrapie-infected brain homogenate, cells inoculated with negative brain inoculum and non-inoculated controls) with 3 technical replicates per condition and time.