title: A long-term siRNA strategy regulates fibronectin overexpression and improves vascular lesions in retinas of diabetic rats.
abstract: OBJECTIVE
  A sustained gene modulatory strategy is necessary for regulating abnormal gene expression in diabetic retinopathy, a long-term complication. We investigated the efficacy of a small interference RNA (siRNA) strategy in mediating the long-term downregulatory effect of fibronectin (FN) overexpression in vivo.
  
  
  METHODS
  Streptozotocin-induced diabetic rats were intravitreally injected with 3 µM of FN-siRNA at six week intervals over a period of 4.5 months. Retinal FN protein expression, vascular basement membrane (BM) thickness, and retinal vascular cell loss were assessed by western blot, electron microscopy, and retinal trypsin digest, respectively.
  
  
  RESULTS
  Retinal FN expression and BM thickness were significantly increased in diabetic rat retinas compared to those in non-diabetic control rats (188±14.2% of control versus 100±7.4% of control, p<0.002; 72.5±5.0 nm versus 51.5±4.8 nm, p<0.001, respectively). FN-siRNA treatment reduced FN overexpression and BM thickening (145±19.9% of control and 56.4±2.8 nm, respectively) and significantly reduced the number of acellular capillaries (35%) and pericyte loss (55%) compared to those of untreated diabetic eyes.
  
  
  CONCLUSIONS
  These findings suggest that BM thickening is an important target for preventing vascular cell loss in a diabetic retina, and that the siRNA approach could be useful for long-term gene modulation in diabetic retinopathy.
authors.affiliation: Department of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA 02118, USA. sayon@bu.edu
authors.forename: Sumon
authors.initials: S
authors.lastname: Roy
authors.forename: Sigrid
authors.initials: S
authors.lastname: Nasser
authors.forename: Melissa
authors.initials: M
authors.lastname: Yee
authors.forename: Dana T
authors.initials: DT
authors.lastname: Graves
authors.forename: Sayon
authors.initials: S
authors.lastname: Roy
mesh_terms: D000818:Animals; D001485:Basement Membrane / Q000473:pathology / Q000648:ultrastructure; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight; D002196:Capillaries / Q000473:pathology / Q000648:ultrastructure; D003930:Diabetic Retinopathy / Q000097:blood / Q000473:pathology*; D005353:Fibronectins / Q000378:metabolism*; D006442:Glycated Hemoglobin / Q000378:metabolism; D058449:Intravitreal Injections; D008297:Male; D020286:Pericytes / Q000473:pathology / Q000648:ultrastructure; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000378:metabolism* / Q000473:pathology*; D013997:Time Factors
chemical_list: D001786:Blood Glucose; D005353:Fibronectins; D006442:Glycated Hemoglobin; D034741:RNA, Small Interfering