Sixing Yang

Construction of Ureteral Grafts by Seeding Bone Marrow Mesenchymal Stem Cells and Smooth Muscle Cells Into Bladder Acellular Matrix

BACKGROUND Congenital or acquired abnormalities may cause an ureteral injury or defect. The main methods to reconstruct a long ureter often cause serious complications. In this study, we sought to construct a tissue-engineered graft by seeding bone marrow mesenchymal stem cells (MSCs) and smooth muscle cells (SMCs) into a bladder acellular matrix (BAM) for ureteral reconstruction. METHODS Isolated, proliferated, and in vitro identified rabbit bone marrow MSCs and SMCs were seeded into BAM as the experimental group. Grafts only seeding SMCs were the control group. Cell-seeded grafts were used to construct tissue-engineered tubular grafts (TETG) for transplantation into the rabbits omentum for 2 weeks before ureteral reconstruction. Evolutionary histology was performed at 2, 4, 8, and 16 weeks postoperatively. Renal function and ureteral obstruction were evaluated using intravenous urography at 16 weeks. RESULTS Flow cytometry demonstrated bone marrow MSCs to express CD29, CD44, CD90, but not CD34. Histological examination revealed consistent regeneration of TETG urothelium in the experimental group. At 8 and 16 weeks after TETG grafting in vivo, multilayer urothelium covered the entire lumen with visible neovascularization within the center. Organized smooth muscle bundles were observed. Intravenous urography demonstrated no ureteral stricture or hydronephrosis. The 5 rabbits were dead within 4 weeks postoperatively. Autopsy showed scar formation inside the graft with severe hydronephrosis. CONCLUSION We successfully constructed a TETG by seeding bone marrow MSCs and SMCs into BAM for ureteral reconstruction. Thus bone marrow MSCs can potentially promote urothelial regeneration to achieve a tissue-engineered ureter.

Urethral Reconstruction Using Bone Marrow Mesenchymal Stem Cell– and Smooth Muscle Cell–Seeded Bladder Acellular Matrix

BACKGROUND Congenital or acquired abnormalities may lead to a urethral defect that often requires surgical reconstruction. The traditional methods often lead to complications, including urethrocutaneous fistulae and strictures. In this study, we proposed to construct a tissue-engineered sheet graft (TESG) using a bone marrow mesenchymal stem cell (BMSC)- and smooth muscle cell (SMC)-seeded bladder acellular matrix (BAM) for urethral reconstruction. METHODS Rabbit BMSCs and SMCs were isolated, expanded, and identified in vitro before seeding into BAM as the experimental group, whereas BAM-only was the control group. The graft was used to construct TESG for implantation into the rabbit omentum for 2 weeks before urethral reconstruction. We divided 24 male rabbits into four experimental groups six each, and six other were the control group. Histological analysis was performed at 2 weeks, 4 weeks, 8 weeks, and 16 weeks postoperatively. Retrograde urethrography was performed at 16 weeks postoperatively. RESULTS All experimental rabbits survived to they were humanly killed. At 8 weeks, there was no difference between the graft and the normal urethra with no severe shrinkage. At 8 and 16 weeks after TESG grafting in vivo, multilayer urothelium covered the graft, neovascularization was visible within the center of TESG, and organized smooth muscle bundles were present. Retrograde urethrography failed to demonstrate diverticula formation or urethral stricture. Three control rabbits died within 4 weeks postoperatively. Autopsy showed their urethras to be almost completely blocked whereas another three hosts displays urethral strictures. CONCLUSION A TESG was constructed using a BMSC- and SMC-seeded BAM for urethral reconstruction.

Emergency Ureteroscopic Treatment for Upper Urinary Tract Calculi Obstruction Associated with Acute Renal Failure: Feasible or Not?

PURPOSE To determine the efficacy and safety of emergency ureteroscopy (URS) and holmium:yttrium-aluminum-garnet (Ho:YAG) laser lithotripsy for ureteral calculi that are associated with acute renal failure (ARF). PATIENTS AND METHODS We retrospectively evaluated a cohort of 49 patients who underwent URS from November 2005 to November 2008 for ARF that was caused by calculi obstruction of the upper urinary tract. The mean (maximal diameter) stone size was 1.48 cm. Acute renal failure was demonstrated by oliguria or anuria and marked increase in serum creatinine and blood urea nitrogen levels. All the patients were treated with URS and Ho:YAG laser lithotripsy emergently. Ureteral stent placement was performed in all cases after lithotripsy. A plain film of the kidneys, ureters, and bladder and abdominal ultrasonography were performed to evaluate efficacy of treatment on the first day postoperatively. Serum creatinine and blood urea nitrogen levels and urine volume were successively monitored until they returned to normal. All patients had postoperative imaging, including ultrasonography and excretory urography, to confirm stone clearance and exclude late obstructive complications 3 months after URS. RESULTS URS and laser lithotripsy were successfully performed in all patients. There were no major intraoperative complications, and no procedure was converted to open surgery. The mean operative time was 35 minutes. The successful fragmentation rate was 95.5%. The overall stone-free rate was 91.8%. Normal renal function returned in 46 (93.8%) patients within 7 days. No postoperative ureteral stricture occurred after 3 months. CONCLUSIONS URS and Ho:YAG laser lithotripsy represent an effective and safe modality for treating patients with ARF that is caused by calculi obstruction of the upper urinary tract in strictly selected situations.

Modification of Antitumor Immunity and Tumor Microenvironment by Resveratrol in Mouse Renal Tumor Model

Abstract Renal cell carcinoma (RCC) microenvironment plays critical roles in antitumor immune response. Resveratrol exhibits a direct antitumor effect in various tumor models. However, the immunomodulatory effect of resveratrol on RCC microenvironment is unknown. In this study, we found that administration of low dose of resveratrol inhibits Renca tumor growth and its inhibition effect depends on CD8+ T cells. Moreover, the proportion of regulatory T cells is decreased, while the proportion of myeloid-derived suppressor cells does not alter after resveratrol treatment. More importantly, massive amount of activated CD8+ T cells accumulates in tumor microenvironment in the resveratrol-treated group and shows increased cytotoxicity, as indicated by a higher expression of Fas ligand. We also found that resveratrol switches the expression of T-helper (Th) 2 cytokines such as interleukin (IL)-6 and IL-10 to Th 1 cytokines with dominance of interferon (IFN)-γ, which increases the expression of Fas in Renca cells. Furthermore, we found resveratrol down-regulates angiogenesis along with decreased level of vascular endothelial growth factor in tumor microenvironment. Our results strongly suggest that resveratrol might be used for RCC immunotherapy through modulating tumor microenvironment.

Reconstructing Full-length Ureteral Defects Using a Spiral Bladder Muscle Flap With Vascular Pedicles

INTRODUCTION This study investigates the efficacy of ureteral reconstruction using a spiral bladder muscle flap with vascular pedicles (ie, the superior vesical arteries) to repair full-length ureteral defects and explores a surgical approach for repairing long ureteral defects (>20 cm) using a bladder muscle flap. TECHNICAL CONSIDERATIONS The characteristics of the ureteral reconstruction surgery include the following: (1) Surgeons fully expose the bladder in the retroperitoneal space. (2) While dissecting the superior vesical arteries, the integrities of the blood vessel trunk and the primary branches are maintained as much as possible. (3) While preparing the bladder muscle flap, the surgeons make an S-shaped cut along the route of the superior vesical arteries along the bladder. In general, the basal width of the muscle flap is approximately 2-3 cm in length, and the total length is approximately 1-2 cm longer than the defective ureter. (4) During the surgery, kidney descent and fixation and psoas hitch are performed to reduce end-to-end anastomotic tension. (5) The addition of a submucosal tunnel to prevent postoperative ureteral reflux is unnecessary. (6) A pedicled greater omentum graft is transferred to cover the reconstructed ureter to enhance blood supply when necessary. CONCLUSION Ureteroplasty using a spiral bladder muscle flap with vascular pedicles (ie, the superior vesical arteries) is an ideal treatment to repair full-length ureteral defects. Moreover, this technique is particularly useful for ureteral defects longer than 20 cm. This procedure should be strongly promoted.

Long-Term Culture and Transplantation of Spermatogonial Stem Cells from BALB/c Mice

Development of a culture system that supports self-renewal and proliferation of spermatogonial stem cells (SSCs) is enormously valuable for experimental research and potential treatment for male infertility. Although several research groups had reported their successes in SSC isolation and culture, the two current accepted culture systems are different in cell enrichment methods, serum and growth factors. Previous researches also indicated SSCs from different mouse strains required different culture conditions. Here we report for the first time that SSCs from BALB/c mice could be cultured in an improved culture system for 3 months. The modified culture system consisted of an improved enzymatic procedure, the enrichment of undifferentiated spermatogonia by differential adherence selection of isolated SSCs, mouse embryonic fibroblast feeder cells, StemPro-34 SFM medium supplemented with glial cell line-derived neurotrophic factor (GDNF), basic fibroblast growth factor and GDNF-family receptor α1 (GFRα1). The improved digestion method increased the viability and enrichment efficiency of isolated testis cells. Furthermore, basal culture medium with 10% fetal bovine serum as selected medium could increase the number of germ cell colonies in the initiation stage of culture. Cultured SSCs were characterized morphologically and formed typical colonies. Immunocytochemical staining and RT-PCR showed that cultured SSCs expressed Oct-4, GFRα1, Sox2 and several other special genes resembling undifferentiated spermatogonia. Spermatogonia transplantation further confirmed that cultured SSCs were functionally normal and could restore complete spermatogenesis. The culture methods described here could serve as a paradigm to establish conditions for the culture of SSCs from other species, allowing identification of universal factors necessary for proliferation of SSCs.

Downregulation of miR-193a-3p inhibits cell growth and migration in renal cell carcinoma by targeting PTEN

Although miR-193a-3p has been found to be dysregulated in variety of human tumors, little is known about its role in renal cell carcinoma. This study was designed to investigate the function and underlying mechanism of miR-193a-3p in human renal cell carcinoma tissues and cell lines. Here, we demonstrated that the expression of miR-193-3p was increased in renal cell carcinoma tissues and cell lines. In addition, knockdown of miR-193a-3p significantly inhibited cell proliferation and colony formation and induced cells into G1 phase arrest. Meanwhile, the migration potential of 786-O cells was also decreased compared to control group. Furthermore, we identified PTEN as a direct and functional target of miR-193a-3p, at least partly responsible for promoting tumor effect of miR-193a-3p in renal cell carcinoma. Taken together, the findings indicated for the first time that miR-193a-3p functions as a tumor-promoting microRNA by directly targeting PTEN in renal cell carcinoma.

Seeding Homologous Adipose-Derived Stem Cells and Bladder Smooth Muscle Cells Into Bladder Submucosa Matrix for Reconstructing the Ureter in a Rabbit Model

BACKGROUND Congenital or acquired abnormalities may result in ureteral malformation, trauma, or defect. Traditional reconstructive methods are often associated with numerous complications. Tissue engineering technology may provide an alternate avenue for ureteral reconstruction. In this study, we constructed tissue-engineered tubularized grafts (TETGs) by seeding homologous adipose-derived stem cells (ADSCs) and bladder smooth muscle cells (SMCs) into bladder submucosa matrix (BSM) for ureteral reconstruction in rabbit models. METHODS ADSCs and bladder SMCs were seeded onto 2 sides of the BSM, respectively. Then the grafts were used to construct TETGs of 4.0 cm length and 8.0 mm diameter and were transplanted into the omentum of rabbits for 2 weeks before ureteral reconstruction. The 4.0-cm segment of the ureter was replaced by the TETG. Evolutionary formation of tissue structures and degree of epithelization were evaluated with the use of histologic and immunohistochemical techniques at 2, 4, 8, and 16 weeks after implantation. RESULTS All of the rabbits were alive until they were killed. Histologic and immunohistochemical analyses showed consistent regeneration of mature and functional urothelium. At 16 weeks after TETG implantation, multilayered urothelium covered the entire lumen, with visible neovascularization in the center and formation of organized smooth muscle bundles. CONCLUSIONS We successfully constructed a tissue-engineered transplanted graft by seeding ADSCs and SMCs onto the BSM for ureteral repair and reconstruction in a rabbit model.

Tissue-engineered tubular substitutions for urinary diversion in a rabbit model

Clinically, autologous gastrointestinal segments are traditionally used for urinary diversion. However, this procedure often causes many serious complications. Tissue engineering may provide an alternative treatment method in urinary diversion. This research aims to produce tissue-engineered tubular substitutions by using homologous adipose-derived stem cells, smooth muscle cells, and bladder acellular matrix in developing urinary diversion in a rabbit model. Adipose-derived stem cells and smooth muscle cells of rabbit were obtained and cultured in vitro. These cultured adipose-derived stem cells and smooth muscle cells were seeded onto the two sides of the bladder acellular matrix and then incubated for seven days. The cell-seeded matrix was used to build tissue-engineered tubular substitutions, which were then implanted and wrapped into the omentum in vivo for two weeks to promote angiogenesis. In the experimental group, the bladder of 20 rabbits was totally resected, and the above tissue-engineered tubular substitutions were used for urinary diversion. In the control group, bladder acellular matrix tubular substitutions with unseeded cells were implanted into the omentum and were used as urinary diversion on another five rabbits with the same process. The implants were harvested, and histological examination was conducted at 2, 4, 8, and 16 weeks after operation. Intravenous urography assessment was performed at 16 weeks postoperatively. All the rabbits were alive in the experimental group until they were sacrificed. Histological analysis of the construct displayed the presence of multilayer urothelial cells on the luminal side and organized smooth muscle tissue on the other side, and different diameters of neovascularization were clearly identified in the substitutions obtained. No leakage, stricture, or obstructions were noted with intravenous urography assessment. All the animals in the control group died within two weeks, and urine leakage, scar formation, and inflammation were detected through autopsy. This study demonstrates the feasibility of tissue-engineered tubular substitutions constructed using homologous adipose-derived stem cells, smooth muscle cells, and bladder acellular matrix for urinary diversion in a rabbit model.

Efficacy and functional outcome of flexible ureteroscopy for renal stones in patients with a solitary kidney

The aim of the present study was to evaluate the efficacy and functional outcome of flexible ureteroscopy (fURS) for renal stones in patients with a solitary kidney.