Denis Butnaru

The potential role of tissue-engineered urethral substitution: clinical and preclinical studies.

Urethral strictures and anomalies remain among the difficult problems in urology, with urethroplasty procedures being the most effective treatment options. The two major types of urethroplasty are anastomotic urethroplasty and widening the urethral lumen using flaps or grafts (i.e. substitution urethroplasty). However, no ideal material for the latter has been found so far. Designing and selecting such a material is a necessary and challenging endeavour, driving the need for further bioengineered urethral tissue research. This article reviews currently available studies on the potentialities of tissue engineering in urethral reconstruction, in particular those describing the use of both acellular and recellularized tissue‐engineered constructs in animal and human models. Possible future developments in this field are also discussed. Copyright

Memokath Stent Failure in Recurrent Bulbar Urethral Strictures: Results from an Investigative Pilot Stage 2a Study

OBJECTIVE To evaluate the efficacy of the Memokath stent in managing recurrent bulbar urethral strictures. MATERIALS AND METHODS This is an investigative pilot stage 2A study in patients with a recurrent bulbar urethral stricture who underwent a Memokath stent implant from January 2014 to January 2016 in a single high-volume center for urethral reconstruction. The Memokath stent (Pnn Medical A/S, Kvistgaard, Denmark) was manufactured from nitinol, a biocompatible alloy of nickel and titanium, which was endoscopically placed. It had a 24-Fr outside diameter and was preloaded on a disposable delivery device. When correctly positioned, the stent was anchored by a warm water (55°C) instillation, which expanded the proximal end of the stent from 24 to 42 Fr .The stent was provided in lengths of 3-7 cm in 1-cm increments. RESULTS Sixteen patients were included in the study. The median follow-up was 16 months. In 7 patients (43.7%), the stent was removed within 1 year. The main adverse events were pain, encrustations, stones, and recurrent strictures. Four patients (25%) were considered a success and 12 (75%) were failures. Study limitations include the small sample. CONCLUSION The Memokath stent was deemed to be not clinically helpful and had significant side effects, and therefore should not be considered a treatment option for men with bulbar urethral strictures.

Near-infrared fluorescence with indocyanine green for diagnostics in urology: initial experience.

Introduction Fluorescence imaging with indocyanine green is used in urology for the detection of sentinel lymph nodes and identification of prostate margins in radical prostatectomy for delineation of resection zone and selective clamping of vessels in partial nephrectomy; for identification and evaluation of length of ureteral strictures; for assessment of perfusion and viability of anastomoses during reconstructive stage of cystectomy. Safety of this technique is proven, while its diagnostic value and usefulness is still controversial. Methods This pilot study of using the SPY Elite Fluorescence Imaging System for diagnostics was performed in the I.M. Sechenov First Moscow State Medical University. Ten patients were enrolled: four patients underwent retropubic RP and lymph node dissection, five patients underwent partial nephrectomy, and one patient underwent ureteroplasty. Fluorophore was injected transrectally with TRUS guidance during RP in order to assess the lymph nodes. During partial nephrectomy, the compound was injected intravenously to differentiate the tumor from parenchyma by its blood supply. During ureteroplasty, the indocyanine green solution was injected into the renal pelvis to dye the ureter and locate the stricture. Results Sensitivity of this technique for visualization of sentinel lymph nodes was 100%, and specificity was 73.3%. In patients who underwent partial nephrectomy, all lesions were malignant and hypofluorescent when compared with healthy parenchyma. SPY allowed us to determine the location and extension of the stricture during ureteroplasty. No hypersensitivity reactions or complications were observed during injection of the compound.

Risk factors for urethral stricture and/or bladder neck contracture after monopolar transurethral resection of the prostate for benign prostatic hyperplasia:

Objective: To identify risk factors for urethral stricture and/or bladder neck contracture after transurethral resection of benign prostatic hyperplasia. Materials and methods: We performed a retrospective analysis of 402 patients, which underwent a monopolar transurethral resection of the prostate in the urology clinic of Sechenov First Moscow State Medical University for prostatic hyperplasia during the period 2011–2014. Urethral stricture and (or) bladder neck contracture in the postoperative period were diagnosed in 61 (15.27%) patients; 34 patients (8.6%) had urethral stricture, 20 (4.97%) bladder neck contracture, and 7 (1.7%) had a combination of urethral stricture and bladder neck contracture. In 341 of cases (84.73%), no late postoperative complications were observed. A total of 106 of the 341 patients met the inclusion criteria, hence, containing all the information necessary for analysis such as the volume of the prostate, the duration of the surgery, the size of the endoscope, data on concomitant diseases, analysis prostatic secretion, and so on. Thus, two groups were formed. Group 1 (106 patients) is the control group in which urethral strictures and/or bladder neck contractures did not occur in the long-term postoperative period and group 2 (61 patients), in which was observed the formation of these complications. To calculate the statistical significance of the differences for categorical data, Fisher criterion was used. For quantitative variables, in the case of normal data distribution, an unpaired t-test or one-way analysis of variance was used; for data having a distribution different from normal, a Mann–Whitney rank test was used. Results: Regression analysis established the significance of the influence of four factors on the development of scar-sclerotic changes of urethra and bladder neck: the tool diameter 27 Fr (p < 0.0001), presence of prostatitis in past medical history (p < 0.0001), prostate volume (p = 0.003), and redraining of the bladder (p = 0.0162). Conclusion: The relationship between the diameter of the instrument, presence of chronic prostatitis in anamnesis, increased volume of the prostate, and repeated drainage of the bladder using the urethral catheter with the risk of developing scar-sclerotic changes in the urethra and/or bladder neck are statistically reliable and confirmed as a result of regression analysis.

The clinical role of X-ray computed tomography to predict the clinical efficiency of extracorporeal shock wave lithotripsy

Aim: To evaluate the clinical efficiency of computed tomography for diagnostics of patients with urolithiasis and the choice of treatment strategy. Material and methods: The study was carried out at the Urological Clinic of I.M. Sechenov First Moscow State Medical University and included 1044 patients with urinary stones. The ultimate goal of this study was to predict the clinical efficiency of extracorporeal shock wave lithotripsy using a combination of computed tomography and densitometry. Extracorporeal shock wave lithotripsy was performed on “Siemens Lithostar Plus,” “Siemens Modularis Uro,” and “Dornier Gemini” lithotripters. Statistical analysis of clinical data included evaluation of individual sampling groups and calculation of weighted arithmetic mean (M). Results: The efficiency of extracorporeal shock wave lithotripsy has been determined primarily using X-ray analysis of the concrement outlines and the structure (homogeneous or heterogeneous) of its central zone. However, in terms of efficiency and repetition rate (the number of fragmentation procedures required for complete clearance) of extracorporeal shock wave lithotripsy, the mean density of the concrement along the whole length of its three-dimensional structure (expressed in Hounsfield units) appeared to be the most reliable and informative predictive index in this study. Conclusion: The combination of computed tomography with densitometry in the treatment of patients with urolithiasis allows one (1) to determine the exact localization, size, X-ray structure, and structural density of urinary stones and (2) to predict, on the basis of densitometric data histograms, the clinical efficiency and repetition rate of extracorporeal shock wave lithotripsy with due regard to the X-ray structure of peripheral and central zones, and mean density (in Hounsfield units) of urinary concrements.

Tissue-engineered construct for urethral reconstructive surgery

Abstract Nowadays, the common treatment of urethral stricture is substitute urethral reconstruction using a buccal mucosa graft or an acellular matrix. However, most studies showed that their use can cause the development of fibrosis, recurrent stricture, necrosis, and graft rejection (Atala et al., 2017). Therefore, this study aimed to fabricate a tissue-engineered urethral wall construct and test it in preclinical and clinical trials. We developed a system from mechanically strong hybrid matrix from collagen and glycolide and L-lactide fibers and spheroids from buccal epithelial cells. Epithelial cell in spheroids could save their phenotype and form epithelial lining on a matrix surface. The developed construct successfully passed preclinical trials (rabbits); and we have initiated its clinical trials (NCT03205670). Thus, this tissue-engineered construct is promising; and after ending trials, its use can be easily translated into clinical practice.