Decrease in Maximal Force Generation in the Neonatal Mouse Bladder Corresponds to Shift in Myosin Heavy Chain Isoform Composition

Alterations in the contractile phenotype of the bladder: lessons for understanding physiological and pathological remodelling of smooth muscle

The contractile properties of the urinary bladder are changed by the conditions of normal development and partial bladder outlet obstruction. This change in the contractile phenotype is accompanied by changes in the regulatory cascades and filaments that regulate contractility. This review focuses on such changes during the course of normal development and in response to obstruction. Our goal is to discuss the experimental evidence that has accumulated from work in animal models and correlate these findings with the human voiding phenotype.

Achieving urinary continence in children

Achievement of urinary continence is an important developmental step that most children attain with the assistance of their parents and caregivers. Debate continues as to the best time to toilet train; in some Asian and African cultures children are trained as infants, while training at age 2-3 years is more typical in Western cultures. Infant voiding is not merely a spinal reflex, as the sensation of bladder filling is relayed to the brain. However, the ability of the brain to inhibit bladder contractions, and to achieve coordinated bladder contraction with sphincter relaxation, matures over time. While there is a concern that later toilet training may be responsible for an increase in urinary incontinence in children, no controlled studies on early versus late toilet training exist to evaluate this hypothesis. A number of medical conditions such as spina bifida, posterior urethral valves, cerebral palsy and autism can cause incontinence and difficulties in toilet training. The decision to start toilet training a child should take into account both the parents' expectation of how independent the child will be in terms of toileting, and the child's developmental readiness, so that a realistic time course for toilet training can be implemented.

Towards control of smooth muscle cell differentiation in synthetic 3D scaffolds

A central tenant of tissue engineering is that cells should be able to recapitulate full functional tissue capability when placed within an appropriate architecture or scaffold. The aim of this study was to examine the effect of three-dimensional (3D) architecture on the differentiated phenotype of human smooth muscle cells derived from the stroma of the lower urinary tract. Stromal cell cultures were established from surgical specimens and the differentiated smooth muscle cell phenotype was monitored by gene expression, immunofluorescence and immunoblotting. Expression of contractile proteins, including smooth muscle myosin and smoothelin, was lost by cultures grown on two-dimensional (2D) tissue culture polystyrene, but was regained to some extent by the removal of serum and by the addition of TGFbeta1. Stromal cells were seeded onto plasma-coated electrospun polystyrene scaffolds to examine the influence of 3D architecture on smooth muscle cell phenotype, but differentiation was inhibited by serum proteins that adsorbed non-specifically onto the large surface area of the scaffold. Stromal cells failed to adhere to the scaffold in serum-free conditions, but laminin pre-coating of the scaffold prevented serum adsorption and promoted cell attachment and differentiation. The study highlights how non-specific factors, such as serum adsorption, may confound the development of materials for tissue engineering.