title: Morphology, phenotype and ultrastructure of fibroblastic cells from normal and neuropathic human detrusor: absence of myofibroblast characteristics.
abstract: OBJECTIVE
  Fibroblasts are functionally diverse and fibroblastic cells with smooth muscle-like characteristics (myofibroblasts) regulate smooth muscle activity in certain tissues. The presence of myofibroblasts has been reported in the bladder with important implications for normal function and detrusor overactivity. We assessed fibroblastic cell characteristics to discern features suggesting a myofibroblast phenotype in normal or neuropathic human detrusor.
  
  
  METHODS
  A total of 25 control samples were obtained from cadaveric organ donors or patients with a mean age of 42.3 years investigated for hematuria and compared with samples from 18 patients with a mean age of 37.4 years with neurogenic detrusor overactivity. Morphology, phenotypic expression of various markers and the ultrastructure of each fibroblastic cell visible in multiple sections from each specimen was evaluated by 2 independent assessors.
  
  
  RESULTS
  Fibroblastic cells were observed throughout the smooth muscle and connective tissue. They were located peripherally on muscle fascicles and had a polar stellate appearance with processes ramifying in interfascicular planes and muscle. They possessed vimentin-like immunoreactivity and weak c-kit-like immunoreactivity but not desmin or alpha-smooth muscle actin-like immunoreactivity. Ultrastructurally they showed dilated rough endoplasmic reticulum with a moderately electron dense amorphous content and prominent golgi complexes. Nuclei had clumped peripheral heterochromatin. There were extensive flattened processes that lacked basal laminae. There was no specific contact with nerve fibers or smooth muscle. Neuropathic bladder samples did not differ overtly from those of controls.
  
  
  CONCLUSIONS
  The detrusor possesses an extensive network of fibroblastic cells and processes. No evidence of myofibroblast differentiation was discerned in normal or neuropathic detrusor, although a minority subpopulation or regional variability in cellular phenotype could not be excluded.
authors.affiliation: Tyne Micturution Research Group, School of Surgical Sciences, University of Newcastle, United Kingdom.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Drake
authors.forename: Petter
authors.initials: P
authors.lastname: Hedlund
authors.forename: Karl-Erik
authors.initials: KE
authors.lastname: Andersson
authors.forename: Alison F
authors.initials: AF
authors.lastname: Brading
authors.forename: Iqbal
authors.initials: I
authors.lastname: Hussain
authors.forename: Clare
authors.initials: C
authors.lastname: Fowler
authors.forename: David N
authors.initials: DN
authors.lastname: Landon
mesh_terms: D000328:Adult; D000368:Aged; D003238:Connective Tissue / Q000473:pathology; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D009122:Muscle Hypertonia / Q000473:pathology*; D009130:Muscle, Smooth / Q000473:pathology*; D010641:Phenotype; D001743:Urinary Bladder / Q000473:pathology; D001750:Urinary Bladder, Neurogenic / Q000473:pathology*