Pathologic bladder microenvironment attenuates smooth muscle differentiation of skin derived precursor cells: implications for tissue regeneration

Not just fibrotic: endothelial-derived TGFβ maintains contractile function and lymphatic muscle phenotype during homeostasis

Cell-cell communication within the lymphatic vasculature during homeostasis is incompletely detailed. Although many discoveries highlight the pathological roles of transforming growth factor-beta (TGFβ) in chronic vascular inflammation and associated fibrosis, only a small amount is known surrounding the role of TGFβ-signaling in homeostatic lymphatic function. Here, we discovered that pharmacological blockade of TGFβ receptor 1 (TGFβR1) negatively impacts rat mesenteric lymphatic vessel pumping, significantly reducing vessel contractility and surrounding lymphatic muscle coverage. We have identified mesenteric lymphatic endothelial cells themselves as a source of endogenous vascular TGFβ and that TGFβ production is significantly increased in these cells via activation of a number of functional pattern recognition receptors they express. We show that a continuous supply of TGFβ is essential to maintain the contractile phenotype of neighboring lymphatic muscle cells and support this conclusion through in vitro analysis of primary isolated lymphatic muscle cells that undergo synthetic differentiation during 2-D cell culture, a phenomenon that could be effectively rescued by supplementation with recombinant TGFβ. Finally, we demonstrate that lymphatic endothelial production of TGFβ is regulated, in part, by nitric oxide in a manner we propose is essential to counteract the pathological over-production of TGFβ. Taken together, these data highlight the essential role of homeostatic TGFβ signaling in the maintenance of lymphatic vascular function and highlight possible deleterious consequences of its inhibition.NEW & NOTEWORTHY The growth factor TGFβ is commonly associated with its pathological overproduction during tissue fibrosis rather than its homeostatic functions. We expose the lymphatic endothelium as a source of endogenous TGFβ, the impact of its production on the maintenance of surrounding lymphatic muscle cell phenotype, and internally regulated mechanisms of its production. Overall, these results highlight the intricate balance of TGFβ-signaling as an essential component of maintaining lymphatic contractile function.

Inhibition of DNA methylation during chronic obstructive bladder disease (COBD) improves function, pathology and expression

Partial bladder outlet obstruction due to prostate hyperplasia or posterior urethral valves, is a widespread cause of urinary dysfunction, patient discomfort and also responsible for immense health care costs. Even after removal or relief of obstruction, the functional and pathologic aspects of obstruction remain as a chronic obstructive bladder disease (COBD). Epigenetic changes, such as DNA methylation, contribute to the persistent character of many chronic diseases, and may be altered in COBD. We tested whether candidate genes and pathways and the pathophysiology of COBD were affected by a hypomethylating agent, decitabine (DAC). COBD was created in female Sprague-Dawley rats by surgical ligation of the urethra for 6 weeks, followed by removal of the suture. Sham ligations were performed by passing the suture behind the urethra. After removal of the obstruction or sham removal, animals were randomized to DAC treatment (1 mg/kg/3-times/week intraperitoneally) or vehicle (normal saline). Bladder function was non-invasively tested using metabolic cages, both one day prior to de-obstruction at 6 weeks and prior to sacrifice at 10 weeks. Residual volume and bladder mass were measured for each bladder. Bladders were examined by immunostaining as well as qPCR. The effects of DNA methyltransferase (DNMT)-3A knockout or overexpression on smooth muscle cell (SMC) function and phenotype were also examined in bladder SMC and ex vivo culture. Residual volumes of the DAC treated group were not significantly different from the NS group. Compared to COBD NS, COBD DAC treatment helped preserve micturition volume with a significant recovery of the voiding efficiency (ratio of the maximum voided volume/maximum bladder capacity) by one third (Fig. 1, p > 0.05). Brain-derived neurotrophic factor (BDNF) variants 1 and 5 were upregulated by COBD and significantly reduced by DAC treatment. Deposition of collagen in the COBD bladder was reduced by DAC, but gross hypertrophy remained. In bladder SMC, DNMT3A overexpression led to a loss of contractile function and phenotype. In bladders, persistently altered by COBD, inhibition of DNA-methylation enhances functional recovery, unlike treatment during partial obstruction, which exacerbates obstructive pathology. The underlying mechanisms may relate to the gene expression changes in BDNF and their effects on signaling in the bladder.

Persistent myopathy despite release of partial obstruction: in vivo reversal of dysfunction and transcriptional responses using rapamycin

Current and potential medical therapy for obstruction-induced myopathic bladder dysfunction (from benign prostatic hyperplasia or posterior urethral valves) focuses on symptoms. The persistent tissue pathology and dysfunction after release of obstruction is often deemed irreversible without any systematic therapeutic approaches. As rapamycin can attenuate bladder smooth muscle hypertrophy and dysfunction during the genesis of partial obstruction in vivo, we tested whether rapamycin could improve persistent function after release of obstruction (de-obstruction or REL). Female Sprague-Dawley rat bladders were partially obstructed (PBO) by suturing around both the urethra and a para-urethral steel rod, then removing the rod. One day prior to release of obstruction (preREL), voiding parameters and residual urine volume of preREL+future rapa, preREL+future veh groups were recorded. Release of obstruction (REL) was performed by suture removal following 6 weeks of PBO. For 4 more weeks after the de-obstruction, REL animals were randomized to rapamycin (REL+rapa) or vehicle (REL+veh). PBO for 6 weeks were used as positive controls. In shams, the urethra was exposed, but no suture tied. Voiding parameters and residual urine volume were measured prior to sacrifice of sham and REL+veh or REL+rapa, and PBO. Rapamycin efficacy was tested by pair-wise comparison of changes in individual voiding data from preREL+future veh or preREL+future rapa versus REL+veh or REL+rapa, respectively, as well as by comparisons of REL+veh to REL+rapa groups. Bladders were weighed and processed for a high-throughput QPCR array, and histopathology. Bladder/body mass ratios with PBO increased significantly and remained higher in the release phase in REL+veh animals. REL+rapa versus REL+veh improved residual volumes and micturition fractions toward sham levels. Three genes encoding extracellular proteins, BMP2, SOD3, and IGFBP7, correlated with functional improvement by Pearson's correlations. The promoters of these genes showed enrichment for several motifs including circadian E-boxes. While obstruction and REL augmented CLOCK and NPAS2 expression above sham levels, rapamycin treatment during release significantly blocked their expression. This experimental design of pharmaco-intervention during the de-obstruction phase revealed a novel pathway dysregulated during the clinically relevant treatment phase of obstructive bladder myopathy.

Mechanistic target of rapamycin (MTOR) protein expression in the tumor and its microenvironment correlates with more aggressive pathology at cystectomy

BACKGROUND

The mechanistic target of rapamycin (mTOR) has been implicated in driving tumor biology in multiple malignancies, including urothelial carcinoma (UC). We investigate how mTOR and phosphorylated mTOR (pmTOR) protein expression correlate with chemoresponsiveness in the tumor and its microenvironment at final pathologic staging after neoadjuvant chemotherapy (NAC).

METHODS

A single-institution retrospective analysis was performed on 62 patients with cT2-4Nany UC undergoing NAC followed by radical cystectomy. Diagnostic (transurethral resection specimens, TURBT) and postchemotherapy radical cystectomy specimens were evaluated for mTOR and pmTOR protein expression using immunohistochemistry of the tumor, peritumoral stroma, and normal surrounding stroma. Protein expression levels were compared between clinical and pathologic stage. Whole transcriptome analysis was performed to evaluate mRNA expression relative to mTOR pathway activation.

RESULTS

Baseline levels of mTOR and pmTOR within TURBT specimens were not associated with clinical stage and response to chemotherapy overall. Nonresponders with advanced pathologic stage at cystectomy (ypT2-4/ypTanyN+) had significantly elevated mTOR tumor staining (P = 0.006) and a sustained mTOR and pmTOR staining in the peritumoral and surrounding normal stroma (NS). Several genes relevant to mTOR activity were found to be up-regulated in the tumors of nonresponders. Remarkably, complete responders at cystectomy (ypT0) had significant decreases in both mTOR and pmTOR protein expression in the peritumoral and normal stroma (P = 0.01-0.03).

CONCLUSIONS

Our results suggest that mTOR pathway activity is increased in tumor and sustained in its microenvironment in patients with adverse pathologic findings at cystectomy. These findings suggest the relevance of targeting this pathway in bladder cancer.

New Amniotic Membrane Based Biocomposite for Future Application in Reconstructive Urology

Objective

Due to the capacity of the amniotic membrane (Am) to support re-epithelisation and inhibit scar formation, Am has a potential to become a considerable asset for reconstructive urology i.e., reconstruction of ureters and urethrae. The application of Am in reconstructive urology is limited due to a poor mechanical characteristic. Am reinforcement with electrospun nanofibers offers a new strategy to improve Am mechanical resistance, without affecting its unique bioactivity profile. This study evaluated biocomposite material composed of Am and nanofibers as a graft for urinary bladder augmentation in a rat model.

Material and Methods

Sandwich-structured biocomposite material was constructed from frozen Am and covered on both sides with two-layered membranes prepared from electrospun poly-(L-lactide-co-E-caprolactone) (PLCL). Wistar rats underwent hemicystectomy and bladder augmentation with the biocomposite material.

Results

Immunohistohemical analysis (hematoxylin and eosin [H&E], anti-smoothelin and Masson’s trichrome staining [TRI]) revealed effective regeneration of the urothelial and smooth muscle layers. Anti-smoothelin staining confirmed the presence of contractile smooth muscle within a new bladder wall. Sandwich-structured biocomposite graft material was designed to regenerate the urinary bladder wall, fulfilling the requirements for normal bladder tension, contraction, elasticity and compliance. Mechanical evaluation of regenerated bladder wall conducted based on Young’s elastic modulus reflected changes in the histological remodeling of the augmented part of the bladder. The structure of the biocomposite material made it possible to deliver an intact Am to the area for regeneration. An unmodified Am surface supported regeneration of the urinary bladder wall and the PLCL membranes did not disturb the regeneration process.

Conclusions

Am reinforcement with electrospun nanofibers offers a new strategy to improve Am mechanical resistance without affecting its unique bioactivity profile.

Concise review: new frontiers in microRNA-based tissue regeneration

In recent years, the role of miRNAs in post-transcriptional gene regulation has come to the fore with strong evidence to indicate an important role for microRNAs (miRNAs) in the regulation of a wide range of fundamental biological processes. Notably, this includes the regulation of both endogenous tissue repair mechanisms and the growth and differentiation of stem cells (both adult and pluripotent). As a result, manipulation of miRNA signaling holds great promise for regenerative medicine, which aims to harness either endogenous or implanted cells to promote tissue repair. However, to fully realize this potential, it will be necessary to combine advances in our biological understanding with new technologies that allow precise spatiotemporal modulation of specific miRNA candidates. In this review, we highlight the role of miRNAs in tissue regeneration, discuss key challenges in translating this knowledge to the clinic, and outline recent technological advances that aim to address these issues. By combining a comprehensive knowledge of miRNA biology with cutting-edge delivery technologies, it is clear that miRNAs hold significant promise for tissue regenerative therapies in the future.