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Mesenchymal Stem Cells Inhibit Inflammatory and Fibrotic Markers and Prevent High Pressure Urine Storage after Partial Bladder Outlet Obstruction
Bridget Wiafe, BSc, MSc, Adetola Adesida, PhD., Thomas Churchill, PhD., Peter Metcalfe, MD, MSc, FRCSC.
University of Alberta, Edmonton, AB, Canada.

BACKGROUND: Partial Bladder Outlet Obstruction (pBOO) is a multi-factorial urological condition that affects over 1.1 billion people. Men with benign prostatic hyperplasia and children with congenital defects such as spina bifida and posterior urethral valves are most affected. pBOO is characterized by an initial inflammatory response which, can progress to smooth muscle hypertrophy and fibrosis. The resulting high urine storage pressure induces hypoxic changes and results in incontinence and, ultimately, a risk of renal failure. Current treatment modalities are burdensome and result in a high risk of morbidity. Mesenchymal stem cells (MSCs) are undifferentiated pluripotent adult cells with reparative, immunomodulatory, and anti-inflammatory capacities. MSCs have emerged as a promising source of therapy for tissue injury and fibrotic conditions in many organs. We recently reported the short term benefits of MSCs in mitigating inflammatory markers in rat model of pBOO. However, their longer-term effects on urodynamic properties and pro-fibrotic signalling pathways are not clearly understood. We hypothesize that intravenous injection of MSC after a surgically induced pBOO will result in the down-regulation of inflammatory and pro-fibrotic pathways, prevent smooth muscle hypertrophy, and mitigate the deleterious effects on bladder capacity and pressure.
METHODS: 20 Sprague Dawley rats were randomly assigned into 5 groups: unobstructed controls, pBOO -2wks, pBOO-4wks, pBOO+MSCs-2wks, pBOO+MSCs -4wks. pBOO was surgically induced followed by intravenous injection of 1x106 of bone marrow derived-MSCs. At the end of 2 or 4 weeks, cystometry was performed for bladder capacity and end-filling pressure. Bladders were harvested and snap frozen for analysis. RT-PCR and U-PLEX protein analysis was performed to study gene expression changes and protein quantities of major inflammatory and pro-fibrotic markers. Light microscopy was performed with H+E and Masson’ Trichrome, and immunohistochemistry performed for markers of hypoxia, fibrosis, and epithelial-mesenchymal transformation. RESULTS: pBOO resulted in an upregulation of TGFβ1, SMAD2, HIF 1α, HIF 3α, VEGF, TNFα, mTOR, p 70S6K, COL1, and COL3 expression in a time dependent manner. However, the injection of MSCs significantly reduced TNFα expression after 2 weeks and all the other markers after 4 weeks (p<0.05). The induction of pBOO led to a significant downregulation of IL-10 expression and the treatment of MSCs resulted in a significant upregulation after 2 and 4 weeks. H+E staining demonstrated a decrease in smooth muscle hypertrophy and fibrosis. Immunohistochemistry demonstrated a decrease in hypoxia, epithelial mesenchymal transformation, and fibrosis. Also, End filling pressure was significantly reduced after treatment with MSCs (p<0.05). CONCLUSIONS: Intravenous MSCs treatment potently mitigated the inflammatory, hypoxic, and profibrotic cell response to pBOO. Furthermore, significant improvement was seen in bladder histology and physiological parameters.

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