Gene expression profiling of tissue and hMSC xenografts in a rat postpartum urinary injury model

Periurethral human mesenchymal stem cell (hMSC) injections are associated with functional improvement in animal models of post-partum stress urinary incontinence (SUI). However, limited data exists on the role of hMSCs in modulating gene expression in tissue repair after urethral injury. We quantified temporal gene expression modulation in hMSCs, and injured rat urethral tissue, using RNA seq in an animal model of SUI, over a 3-day time period following urethral injury, and local hMSC therapy. We injected PKH fluorescent-labeled human hMSC into the periurethral space of rats, following a 4h vaginal distention (3 rats per time point). Control rats underwent vaginal distention injury only, and were sacrificed at 12h, 24h, 36h, 72h post injury. Rat urethral and vaginal tissues were frozen and sectioned. Fluorescent labeled hMSCs were distinguished from adjacent, unlabeled rat urethral tissue. RNA was prepared from urethral tissue obtained by laser dissection of frozen tissue sections and sequenced on an Illumina HiSeq 2500. Differentially expressed genes (DEGs) over 72h were evaluated using a 2-group t-test (p<0.05). Our transcriptional analyses identified candidate genes involved in tissue injury, that were broadly sorted by injury and exposure to hMSC, throughout the first 72h of acute phase of injury. DEGs in treated urethra, compared with untreated urethra, were functionally associated with tissue repair, angiogenesis, neurogenesis, and oxidative stress suppression. DEGs included a variety of cytokines, extracellular matrix stabilization and regeneration genes, cytokine signaling modification, cell cycle regulation, muscle differentiation and stabilization. Moreover, our results revealed DEGs changes in the hMSCs (PKH-labelled), which were harvested from injured urethra. The expressions are related to DNA damage repair, transcription activation, stem cell regulation, cell survival, apoptosis, self-renewal, cell proliferation, migration and injury response.