Do current bladder smooth muscle cell isolation procedures result in a homogeneous cell population? Implications for bladder tissue engineering

Tissue Engineering in Pediatric Bladder Reconstruction-The Road to Success

Several congenital disorders can cause end stage bladder disease and possibly renal damage in children. The current gold standard therapy is enterocystoplasty, a bladder augmentation using an intestinal segment. However, the use of bowel tissue is associated with numerous complications such as metabolic disturbance, stone formation, urine leakage, chronic infections, and malignancy. Urinary diversions using engineered bladder tissue would obviate the need for bowel for bladder reconstruction. Despite impressive progress in the field of bladder tissue engineering over the past decades, the successful transfer of the approach into clinical routine still represents a major challenge. In this review, we discuss major achievements and challenges in bladder tissue regeneration with a focus on different strategies to overcome the obstacles and to meet the need for living functional tissue replacements with a good growth potential and a long life span matching the pediatric population.

Towards non-invasive characterisation of coronary stent re-endothelialisation - An in-vitro, electrical impedance study

The permanent implantation of a stent has become the most common method for ameliorating coronary artery narrowing arising from atherosclerosis. Following the procedure, optimal arterial wall healing is characterised by the complete regrowth of an Endothelial Cell monolayer over the exposed stent surface and surrounding tissue, thereby reducing the risk of thrombosis. However, excessive proliferation of Smooth Muscle Cells, within the artery wall can lead to unwanted renarrowing of the vessel lumen. Current imaging techniques are unable to adequately identify re-endothelialisation, and it has previously been reported that the stent itself could be used as an electrode in combination with electrical impedance spectroscopic techniques to monitor the post-stenting recovery phase. The utility of such a device will be determined by its ability to characterise between vascular cell types. Here we present in-vitro impedance spectroscopy measurements of pulmonary artery porcine Endothelial Cells, Human Umbilical Vein Endothelial Cells and coronary artery porcine Smooth Muscle Cells grown to confluence over platinum black electrodes in clinically relevant populations. These measurements were obtained, using a bespoke impedance spectroscopy system that autonomously performed impedance sweeps in the 1kHz to 100kHz frequency range. Analysis of the reactance component of impedance revealed distinct frequency dependent profiles for each cell type with post confluence reactance declines in Endothelial Cell populations that have not been previously reported. Such profiles provide a means of non-invasively characterising between the cell types and give an indication that impedance spectroscopic techniques may enable the non-invasive characterisation of the arterial response to stent placement.

A simple, rapid, and efficient method for isolating detrusor for the culture of bladder smooth muscle cells

PURPOSE

To establish a simple and rapid method to remove serosa and mucosa from detrusor for the culture of bladder smooth muscle cells (SMCs).

METHODS

Fourteen New Zealand rabbits were randomly allocated to two groups. In the first group, pure bladder detrusor was directly obtained from bladder wall using novel method characterized by subserous injection of normal saline. In the second group, full thickness bladder wall sample was cut down, and then, mucosa and serosa were trimmed off detrusor ex vivo. Twelve detrusor samples from two groups were manually minced and enzymatically digested, respectively, to form dissociated cells whose livability was detected by trypan blue exclusion. Proliferative ability of primary culture cells was detected by CCK-8 kit, and purity of second-passage SMCs was detected by flow cytometric analyses. Another two detrusor samples from two groups were used for histological examination.

RESULTS

Subserous injection of normal saline combined with blunt dissection can remove mucosa and serosa from detrusor layer easily and quickly. Statistical analysis revealed the first group possessed higher cell livability, shorter primary culture cell doubling time, and higher purity of SMCs than the second group (P < 0.05). Histological examination confirmed no serosa and mucosa existed on the surface of detrusor obtained by novel method, while serosa or mucosa residual can be found on the surface of detrusor obtained by traditional method.

CONCLUSION

Pure detrusor can be acquired from bladder wall conveniently using novel method. This novel method brought about significantly higher purity and cell livability as compared to traditional method.

Effective combination of hydrostatic pressure and aligned nanofibrous scaffolds on human bladder smooth muscle cells: implication for bladder tissue engineering

Bladder tissue engineering has been the focus of many studies due to its highly therapeutic potential. In this regard many aspects such as biochemical and biomechanical factors need to be studied extensively. Mechanical stimulations such as hydrostatic pressure and topology of the matrices are critical features which affect the normal functions of cells involved in bladder regeneration. In this study, hydrostatic pressure (10 cm H(2)O) and stretch forces were exerted on human bladder smooth muscle cells (hBSMCs) seeded on aligned nanofibrous polycaprolactone/PLLA scaffolds, and the alterations in gene and protein expressions were studied. The gene transcription patterns for collagen type I, III, IV, elastin, α-SMA, calponin and caldesmon were monitored on days 3 and 5 quantitatively. Changes in the expressions of α-SMA, desmin, collagen type I and III were quantified by Enzyme-linked immuno-sorbent assay. The scaffolds were characterized using scanning electron microscope, contact angle measurement and tensile testing. The positive effect of mechanical forces on the functional improvement of the engineered tissue was supported by translational down-regulation of α-SMA and VWF, up-regulation of desmin and improvement of collagen type III:I ratio. Altogether, our study reveals that proper hydrostatic pressure in combination with appropriate surface stimulation on hBSMCs causes a tissue-specific phenotype that needs to be considered in bladder tissue engineering.