title: Can autologous myoblasts be used as a potential bulking agent?
abstract: OBJECTIVE
  To investigate the behaviour of donor myoblasts at the vesico-ureteric junction (VUJ) and to evaluate their potential as an autologous bulking agent, as myoblast transplantation has been shown to regenerate damaged or degenerated tissue, and it was postulated that they could be used to treat vesico-ureteric reflux.
  
  
  METHODS
  Muscle biopsies were obtained from the lower limb muscles of 10 pigs. The quality of the cells was evaluated by electrophysiological and immunohistochemical tests. The cell membranes of myoblasts were labelled with PKH26, a fluorescent dye. Six weeks after taking of the muscle biopsies all pigs underwent cell transplantation; 30 x 10(6) cells suspended in transplantation medium (in 1-mL syringes) were injected at the VUJ, into the proximal urethra and the rhabdosphincter. At the VUJ volumes of 1 mL were injected, whereas in the urethra and rhabdosphincter small cell depots (0.1 mL) were injected. All the pigs were killed 8 weeks later, and the myoblasts and newly formed myofibres were identified using fluorescence microscopy, with a histological evaluation and investigation of potential local inflammatory reaction.
  
  
  RESULTS
  Two to three intact layers of autologous myoblasts were found in the outer aspects of the large cell depots in the VUJ. Immunohistochemistry further showed that the myoblasts were only viable at these outermost borders of the large bulking areas, whereas necrosis with red fluorescent cell detritus was visible in the remaining central aspects of the large bulk of cells. By contrast, cells survived and formed myotubes in the wall of the proximal urethra and the rhabdosphincter where the small cell depots had been injected.
  
  
  CONCLUSIONS
  In small depots, transplanted autologous myoblasts can survive and differentiate into myofibres, while in a large bulk of cells the vast majority of cells become necrotic. The present results show that myoblasts cannot be used for augmentation of large volumes of tissue or as a bulking agent.
authors.affiliation: Department of Urology, Medical University Innsbruck, Innsbruck, Austria. michael.mitterberger@i-med.ac.at
authors.forename: Michael
authors.initials: M
authors.lastname: Mitterberger
authors.forename: Rainer
authors.initials: R
authors.lastname: Marksteiner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schwaiger
authors.forename: Günther
authors.initials: G
authors.lastname: Klima
authors.forename: Christian
authors.initials: C
authors.lastname: Schwentner
authors.forename: Tilko
authors.initials: T
authors.lastname: Müller
authors.forename: Georg
authors.initials: G
authors.lastname: Bartsch
authors.forename: Christian
authors.initials: C
authors.lastname: Radmayr
authors.forename: Hannes
authors.initials: H
authors.lastname: Strasser
authors.forename: Josef
authors.initials: J
authors.lastname: Oswald
mesh_terms: D000818:Animals; D032446:Myoblasts / Q000637:transplantation*; D012038:Regeneration / Q000502:physiology*; D033581:Stem Cell Transplantation / Q000379:methods; D013536:Suture Techniques; D013552:Swine; D014182:Transplantation, Autologous; D014521:Urethra / Q000502:physiology*; D014718:Vesico-Ureteral Reflux / Q000628:therapy*