title: Supportive features of a new hybrid scaffold for urothelium engineering.
abstract: BACKGROUND
  Different clinical conditions can compromise the urinary bladder function and structure. Routine regenerative practices in urology for bladder augmentation have been associated with diverse side effects. The internal lining of the bladder, the urothelium, plays an integral role in normal bladder function. Tissue engineering has provided novel therapeutic strategies through scaffolding and cell transplantation. Nano-scale surface features of scaffolds are valuable parameters for enhancement of cell behavior and function.
  
  
  METHODS
  We fabricated a new hybrid scaffold of poly ɛ-caprolactone (PCL) and poly-L-lactide acid (PLLA) using an electrospinning system to exploit each polymer's advantages at nano-scale in the same scaffold. Dog urothelial cells were isolated, characterized by immunocytochemistry, and expanded for loading on the scaffold. Cell viability and proliferation on the scaffold surface were assessed by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Furthermore, cytoarchitecture, distribution and detailed morphology of cells, and expression of cell specific markers were examined using hematoxylin and eosin (H + E) staining, scanning electron microscopy (SEM), and immunohistochemistry, respectively.
  
  
  RESULTS
  According to MTT results, the scaffold did not exert any cytotoxic effect, and also supported cell proliferation and viability for 14 days of culture, which led to a significant increase in the number of cells. Scanning electron microscopy images revealed evenly distributed and normal appearing colonies of urothelial cells. A well-defined layer of cells was observed using H + E staining, which preserved their markers (pan-cytokeratin and uroplakin III) while growing on the scaffold.
  
  
  CONCLUSIONS
  Our findings confirmed favorable properties of PCL/PLLA regarding biocompatibility and applicability for upcoming new methods of bladder augmentation and engineering.
authors.affiliation: Urology and Nephrology Research Center (UNRC), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Naji
authors.affiliation: Urology and Nephrology Research Center (UNRC), Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Rasouli
authors.affiliation: Urology and Nephrology Research Center (UNRC), Shahid Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Nasser
authors.initials: N
authors.lastname: Shakhssalim
authors.affiliation: Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Dehghan
authors.affiliation: Tarbiat Modares University, School of Medical Science, Hematology Department and Stem Cell Technology Research Center, UNRC, Tehran, Iran.
authors.forename: Masoud
authors.initials: M
authors.lastname: Soleimani
keywords: hybrid scaffold; poly ɛ-caprolactone/poly-L-lactide acid; tissue engineering; urothelial cells