title: Modulation of TGF-β/BMP-6 expression and increased levels of circulating smooth muscle progenitor cells in a type I diabetes mouse model.
abstract: BACKGROUND
  Diabetic patients experience exaggerated intimal hyperplasia after endovascular procedures. Recently it has been shown that circulating smooth muscle progenitor cells (SPC) contribute to intimal hyperplasia. We hypothesized that SPC differentiation would be increased in diabetes and focused on modulation of TGF-β/BMP-6 signaling as potential underlying mechanism.
  
  
  METHODS
  We isolated SPC from C57Bl/6 mice with streptozotocin-induced diabetes and controls. SPC differentiation was evaluated by immunofluorescent staining for αSMA and collagen Type I. SPC mRNA expression of TGF-β and BMP-6 was quantified using real-time PCR. Intima formation was assessed in cuffed femoral arteries. Homing of bone marrow derived cells to cuffed arterial segments was evaluated in animals transplanted with bone marrow from GFP-transgenic mice.
  
  
  RESULTS
  We observed that SPC differentiation was accelerated and numeric outgrowth increased in diabetic animals (24.6 ± 8.8 vs 8.3 ± 1.9 per HPF after 10 days, p < 0.05). Quantitative real-time PCR showed increased expression of TGF-β and decreased expression of the BMP-6 in diabetic SPC. SPC were MAC-3 positive, indicative of monocytic lineage. Intima formation in cuffed arterial segments was increased in diabetic mice (intima/media ratio 0.68 ± 0.15 vs 0.29 ± 0.06, p < 0.05). In GFP-chimeric mice, bone marrow derived cells were observed in the neointima (4.4 ± 3.3 cells per section) and particularly in the adventitia (43.6 ± 9.3 cells per section). GFP-positive cells were in part MAC-3 positive, but rarely expressed α-SMA.
  
  
  CONCLUSIONS
  In conclusion, in a diabetic mouse model, SPC levels are increased and SPC TGF-β/BMP-6 expression is modulated. Altered TGF-β/BMP-6 expression is known to regulate smooth muscle cell differentiation and may facilitate SPC differentiation. This may contribute to exaggerated intimal hyperplasia in diabetes as bone marrow derived cells home to sites of neointima formation.
authors.affiliation: Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Westerweel
authors.forename: Cindy T J
authors.initials: CT
authors.lastname: van Velthoven
authors.forename: Tri Q
authors.initials: TQ
authors.lastname: Nguyen
authors.forename: Krista
authors.initials: K
authors.lastname: den Ouden
authors.forename: Dominique P V
authors.initials: DP
authors.lastname: de Kleijn
authors.forename: Marie Jose
authors.initials: MJ
authors.lastname: Goumans
authors.forename: Roel
authors.initials: R
authors.lastname: Goldschmeding
authors.forename: Marianne C
authors.initials: MC
authors.lastname: Verhaar
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D055418:Bone Morphogenetic Protein 6 / Q000235:genetics*; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000473:pathology / Q000503:physiopathology; D003922:Diabetes Mellitus, Type 1 / Q000473:pathology* / Q000503:physiopathology*; D004195:Disease Models, Animal; D005263:Femoral Artery / Q000293:injuries / Q000473:pathology; D049452:Green Fluorescent Proteins / Q000235:genetics; D006965:Hyperplasia; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000293:injuries / Q000473:pathology*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013234:Stem Cells / Q000473:pathology*; D016212:Transforming Growth Factor beta / Q000235:genetics*; D017539:Tunica Intima / Q000473:pathology
chemical_list: D055418:Bone Morphogenetic Protein 6; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D049452:Green Fluorescent Proteins