Myostatin Overexpression and Smad Pathway in Detrusor Derived from Pediatric Patients with End-Stage Lower Urinary Tract Dysfunction

Cell therapies and tissue engineering approaches using smooth muscle cells (SMCs) may provide treatment alternatives for end-stage lower urinary tract dysfunction (ESLUTD). Myostatin, a negative regulator of muscle mass, is a promising target to improve muscle function through tissue engineering. The ultimate goal of our project was to investigate the expression of myostatin and its potential impact in SMCs derived from healthy pediatric bladders and pediatric ESLUTD patients. Human bladder tissue samples were evaluated histologically, and SMCs were isolated and characterized. The proliferation of SMCs was assessed by WST-1 assay. The expression pattern of myostatin, its pathway and the contractile phenotype of the cells were investigated at gene and protein levels by real-time PCR, flow cytometry, immunofluorescence, WES and gel contraction assay. Our results show that myostatin is expressed in human bladder smooth muscle tissue and in isolated SMCs at gene and protein levels. A higher expression of myostatin was detected in ESLUTD-derived compared to control SMCs. Histological assessment of bladder tissue confirmed structural changes and decreased muscle-to-collagen ratios in ESLUTD bladders. A decrease in cell proliferation and in the expression of key contractile genes and proteins, α-SMA, calponin, smoothelin and MyH11, as well as a lower degree of in vitro contractility was observed in ESLUTD-derived compared to control SMCs. A reduction in the myostatin-related proteins Smad 2 and follistatin, and an upregulation in the proteins p-Smad 2 and Smad 7 were observed in ESLUTD SMC samples. This is the first demonstration of myostatin expression in bladder tissue and cells. The increased expression of myostatin and the changes in the Smad pathways were observed in ESLUTD patients. Therefore, myostatin inhibitors could be considered for the enhancement of SMCs for tissue engineering applications and as a therapeutic option for patients with ESLUTD and other smooth muscle disorders.

Neurogenic Lower Urinary Tract Dysfunction in Spinal Dysraphism: Morphological and Molecular Evidence in Children

Spinal dysraphism, most commonly myelomeningocele, is the typical cause of a neurogenic lower urinary tract dysfunction (NLUTD) in childhood. The structural changes in the bladder wall in spinal dysraphism already occur in the fetal period and affect all bladder wall compartments. The progressive decrease in smooth muscle and the gradual increase in fibrosis in the detrusor, the impairment of the barrier function of the urothelium, and the global decrease in nerve density, lead to severe functional impairment characterized by reduced compliance and increased elastic modulus. Children present a particular challenge, as their diseases and capabilities evolve with age. An increased understanding of the signaling pathways involved in lower urinary tract development and function could also fill an important knowledge gap at the interface between basic science and clinical implications, leading to new opportunities for prenatal screening, diagnosis, and therapy. In this review, we aim to summarize the evidence on structural, functional, and molecular changes in the NLUTD bladder in children with spinal dysraphism and discuss possible strategies for improved management and for the development of new therapeutic approaches for affected children.

Improved contractile potential in detrusor microtissues from pediatric patients with end stage lower urinary tract dysfunction

Autologous cell-based tissue engineering has been proposed as a treatment option for end stage lower urinary tract dysfunction (ESLUTD). However, it is generally accepted that cells isolated from patient bladders retain the pathological properties of their tissue of origin and therefore need to be improved before they can serve as a cell source for tissue engineering applications. We hypothesize that human three-dimensional (3D) microtissues of detrusor smooth muscle cells (SMCs) are valuable ex vivo disease models and potent building blocks for bladder tissue engineering. Detrusor SMCs isolated from bladder wall biopsies of pediatric ESLUTD patients and healthy controls were expanded and cultured into 3D microtissues. Gene and protein analyses were performed to explore the effect of microtissue formation on SMC viability, contractile potential, bladder wall specific extracellular matrix (ECM) composition and mediators of ECM remodeling. Through microtissue formation, remodeling and intensified cell-cell interactions, the ESLUTD SMCs lost their characteristic disease phenotype. These microtissues exhibited similar patterns of smooth muscle related contractile proteins and essential bladder wall-specific ECM components as microtissues from healthy control subjects. Thus, the presented data suggest improved contractile potential and ECM composition in detrusor SMC microtissues from pediatric ESLUTD patients. These findings are of great relevance, as 3D detrusor SMC microtissues might be an appropriate cell source for autologous cell-based bladder tissue engineering.

Laparoscopic Ureteroureterostomy vs. Common Sheath Ureteral Reimplantation in Children With Duplex Kidney Anomalies

Purpose: Laparoscopic ureteroureterostomy (LUU) has been proposed as an alternative to common sheath ureteral reimplantation (CSUR) in children with symptomatic duplex kidneys. However, data is limited for LUU in the pediatric population. The aim of this study was to analyze our experience with LUU and to compare the results with those after CSUR to assess whether a less invasive surgical approach could be a valid alternative. Patients and methods: The data of all children with duplex kidneys who underwent either LUU or CSUR at our center from 2006 to 2018 were reviewed retrospectively. After parental counseling, the option of LUU was provided as an alternative to CSUR for unilateral procedures and in the absence of vesicoureteral reflux to the receiving ureter. Baseline characteristics, indication for surgery, hospitalization and operative times, and intraoperative, post-operative, and late complications were analyzed. Preoperative and 1-year post-operative sonographies were reviewed by a pediatric radiologist. Increasing renal pelvic diameter (Δ >5 mm) was regarded as a sign of ureteral obstruction. Results: Forty children were included in this study, with 16 children receiving LUU and 24 children receiving CSUR. The children had a mean age of 2.7 years (7 months-9.8 years) and were followed up in our outpatient clinic for an average of 3.9 years (3 months-10.6 years) after surgery. The median hospital stay was 2 days shorter after LUU. Initially, a considerably longer time was needed for LUU, but after more experience was gained, similar operative times were observed for both procedures. Complications were encountered in both groups. After LUU, two patients developed anastomotic leakage: one was managed conservatively, and one required temporary nephrostomy. In the CSUR group, one patient developed vesicoureteral obstruction during follow-up and required reoperation with LUU. The occurrence of post-operative urinary tract infections was similar in both groups. No complications related to the ureteral stump after LUU arose. Conclusion: LUU is a safe and efficacious treatment option for children with duplex kidney anomalies and can be used as an alternative to CSUR. All children receiving LUU showed a non-obstructive, patent anastomosis and no signs for stenotic compromise of the receiving ureter.