الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Many diseases affect the urinary bladder and urethra, which leads to deterioration of health and quality of life of patients at different ages and sexes. These diseases have high incidence and long-term impact causing increased burden on health systems all over the world.
These diseases necessitate the replacement of the involved organs and tissues. Moreover, rate of complications after cystectomy is estimated to be 25 - 35%. Shortages of organ donation, problems of immunosuppressants and complications associated with the use of non native tissues have urged clinicians and scientists to investigate new therapies, namely, tissue engineering.
Gastrointestinal segments are the most commonly used tissue for bladder replacement or repair. However; gastrointestinal tissues are designed to absorb specific solutes, whereas bladder tissue is designed for the excretion of the same solutes. As a result, when gastrointestinal tissue is placed within the urinary tract, multiple complications may occur. These include infection, metabolic disturbances, urolithiasis, perforation, increased mucus production and malignancy.
The current study was designed to compare the efficacy of reconstruction of urinary bladder defect using untreated SIS matrix versus seeded and unseeded decellularized SIS matrix.
This study included55 female albino rats. Forty adult rats of 6-8 months age and of average weight 150-200 grams were used in this experiment. In addition 10 young albino rats weighing 80-100 gm, 3-6 weeks age were used for preparation of AMSCs. Moreover 5 female albino rats weighing 200-250 gm aging 3-6 months were used to extract ileum for preparation of submucosal tissue matrix. The experimental rats were divided into three main groups:
group I: Control group: included 10 adult female albino rats.
group II: untreated SIS group: included 10 adult female albino rats. Urinary bladders were grafted using untreated SIS and was allowed to live for two weeks.
group III: acellular SISgroup: included 20 adult female albino rats. They were further subdivided into two subgroups, 10 rats each:
Subgroup IIIa:acellular SIS: Rat’s bladders were grafted with unseeded acellular SIS and were sacrificed two week after surgery.
Subgroup IIIB: acellular SIS seeded with AMSCs:Rat’s bladders were grafted by acellular SIS seeded with AMSCs and was allowed to live for two weeks after surgery then sacrificed.
Operative procedure was carried out to perform a 5 mm defect in the antero-superior aspect of the bladder. The defect was then grafted with untreated SIS or acellular SIS either unseeded or seeded with AMSCs. Post operative administration of antibiotics and analgesics were considered to prevent infection and reduce the pain. After two weeks postoperatively, all animals were sacrificed. Samples were processed for histological examination by light microscope using H & E, PAS with Alcian blue, Mallory’s trichrome and immunohistochemical stain for αSMA.Morphometric studies were performed to measure the mean area percentage of collagen fibers, the mean thickness of urothelium at the grafted area, mean thickness of muscle layer of musculosa at the grafted area and the mean area percentage of αSMA expression.
Examination the upper part of empty urinary bladder of control animals showed transitional epithelium appeared thrown into many folds, with underlying lamina propria. It appeared formed of 4-5 rows, which was seen formed of basal layer having small elongated nuclei mostly perpendicular to lamina propria, middle layers have larger cell with indented nuclei, and the largest cell is the superficial dome cell: they have abundant cytoplasm; some are binucleated.
While animals grafted by untreated SIS (group II) showed invagination of urothelium with sinus formation that occasionally form fistula. There were numerous intraepithelial cysts of variable sizes .Transitional epithelium appeared on the luminal and outer surface.Patches of stratified squamous epithelium were also observed. Moreover, in some specimen in the lumen of bladder there was acidophilic structure mostly protein rich exudates in the graft area.
In animal grafted by acellular SIS (subgroup IIIA) some specimen showed desquamated urothelium in the lumen.Urothelium was covering the lumen and extending to the lamina propria and muscle layer forming Brunn’s nest. Patches of disorganized hyperplastic epithelium and others of stratified squamous epithelium were also observed.
Moreover animals grafted by acellular SIS seeded with AMSCs (subgroup IIIB) showed that urothelium of grafted area was transitional epithelium formed of few layers, some cells are vacuolated, they lacked polarity but the top layer had rounded nuclei.
There was non significance difference in the mean urothelial thickness among different groups.
PAS with alcian blue stained sections of control, subgroup IIIA and IIIB revealed negative reaction. While group grafted by untreated SIS showed PAS positive cells within urothelium and lamina propria.
Lamina propria of control bladder was formed of loose connective tissue containing discontinuous smooth muscle bundles. While group grafted by untreated SIS showed lamina propria filled with congested dilated blood vessels, in addition to dilated congested blood vessels and lymphocytic infiltration vessels, lamina propria was seen formed of loose connective tissue with relatively few cells in contrast to lamina propria in animals grafted by acellular SIS which was highly cellular .
By Mallory trichrome: Control group showed collagen fibres in lamina propria and among muscle fibers. In group II There was increase in collagen fiber deposition in connective tissue of lamina propria and among muscle fibers in graft area. Collagen fibers were increased also in subgroup IIIA and subgroup IIIB.
As regarding muscle layer the control bladder showed smooth muscle layer running in different direction and covered from outside by serous membrane. α SMS stained sections demonstrated a positive immunoreaction in muscularis mucosa, lamina propria and muscle layer. While in animals grafted by untreated SIS there was interuption of muscle layer at the margin.This was obvious by α SMS that revealed significant decrease in the immune expression of α smooth muscle actin compared with other groups.In group grafted by acellular SIS muscle was ill developed irregularly arranged muscle fibers and some fibers showed vacuolation with deeply stained nuclei. On the contrary group grafted by acellular SIS seeded with AMSCsrevealed increase in the thickness of bladder wall in the graft area due to increase in the muscle layer and there was increased expression of α SMS.