title: [The study of effectiveness of polyhydroxyalkanoates based biodegradable stents in ureteropelvic segment pyeloplasty].
abstract: BACKGROUND
  Among urologic diseases, ureteropelvic segment stenosis with hydronephrosis is a common indication for instrumental or surgical correction. The restriction of urine flow with dilatation proximal to obstruction develops in 6.5-37% of cases at different times after the ureteral reconstruction. All this urges to develop and improve stents and search for effective ways to place stents and control their function.
  
  
  OBJECTIVE
  To investigate the effectiveness of polyhydroxyalkanoates based biodegradable stent compared with a commercial analogue in upper urinary tract drainage after ureteropelvic segment pyeloplasty.
  
  
  METHODS
  Morphological and functional changes in the stented ureter were investigated in 45 male rabbits of "Soviet chinchilla" breed weighing 4550-5200 g that underwent stenting of ureteropelvic segment (UPS). The study used polymeric stents based on poly-3-hydroxybutyrate, poly-4-gidroksibutirotom P (3GB/4GB) and a mixture of poly-3-hydroxybutyrate with polycaprolactone II (3GB)/PCL with the inclusion of PCL 75%; the control material was polyurethane stents. Morphologic evaluation was conducted on ureteral fragments and UPSs in the area of the stent placement at 7, 14 and 28 days after operation.
  
  
  RESULTS
  Throughout the experiment, excretory urography and spiral tomography in experimental groups showed no changes in the pelvicalyceal system after placing polymeric stents. The morphologic examination in the experimental group at day 28 after surgery revealed preserved longitudinal folding of ureteral mucosa and absence of muscle hypertrophy. Transitional epithelium had no signs of atrophy and desquamation, its mean thickness was 112.4+/-8.5 mm, whereas in the control group a productive inflammation resulting in sclerosis was found to develop.
  
  
  CONCLUSIONS
  We conducted a comparative study of morphologic and functional changes in rabbit ureters after stenting using polyurethane stents (control group) and polymeric stents made of poly-3-hydroxybutyrate, poly-4-hydroxybutyrate II (3GB /4GB) and a mixture of poly-3-hydroxybutyrate with polycaprolactone II (3Gb)/PCL (experimental group). Despite the difference in physical and mechanical properties of biodegradable PGA-based stents, the tissue response to both types of stent was comparable. Ureteral wall preserved longitudinal folds, there was no muscle layer hypertrophy, and mucous membrane had smooth contours with a uniform thickness of the transitional epithelium, whereas in the control group a productive inflammation resulting in sclerosis was found to develop.
authors.affiliation: Voino-Yasenetsky Krasnoyarsk State Medical University, Department of Urology, Andrology and Sexology, IPE, Krasnoyarsk, Russia.
authors.forename: M P
authors.initials: MP
authors.lastname: Myltygashev
authors.affiliation: Siberian Federal University, Krasnoyarsk, Russia.
authors.forename: A N
authors.initials: AN
authors.lastname: Boyandin
authors.affiliation: Siberian Federal University, Krasnoyarsk, Russia.
authors.forename: A A
authors.initials: AA
authors.lastname: Shumilova
authors.affiliation: Voino-Yasenetsky Krasnoyarsk State Medical University, Department of Urology, Andrology and Sexology, IPE, Krasnoyarsk, Russia.
authors.forename: F P
authors.initials: FP
authors.lastname: Kapsargin
authors.affiliation: Siberian Federal University, Krasnoyarsk, Russia.
authors.forename: E I
authors.initials: EI
authors.lastname: Shishatskaya
authors.affiliation: Voino-Yasenetsky Krasnoyarsk State Medical University, Department of Urology, Andrology and Sexology, IPE, Krasnoyarsk, Russia.
authors.forename: A K
authors.initials: AK
authors.lastname: Kirichenko
authors.affiliation: Institute of Biophysics, SB of the RAS, Laboratory Chemoautotrophic biosynthesis, Krasnoyarsk, Russia.
authors.forename: T G
authors.initials: TG
authors.lastname: Volova
mesh_terms: D000818:Animals; D063566:Biodegradable Plastics; D006885:Hydroxybutyrates; D007682:Kidney Pelvis / Q000601:surgery*; D008297:Male; D011091:Polyesters; D054813:Polyhydroxyalkanoates; D011817:Rabbits; D015607:Stents; D014513:Ureter / Q000473:pathology / Q000601:surgery*; D000094122:Polyhydroxybutyrates
chemical_list: D063566:Biodegradable Plastics; D006885:Hydroxybutyrates; D011091:Polyesters; D054813:Polyhydroxyalkanoates; C068056:poly(3-hydroxybutyrate-co-4-hydroxybutyrate); D000094122:Polyhydroxybutyrates; C016240:polycaprolactone; C003182:poly-beta-hydroxybutyrate
keywords: biodegradable stents; polyhydroxyalkanoates; ureter; ureteropelvic segment