title: Biocompatibility of different poly(lactide-coglycolide) polymers implanted into the subconjunctival space in rats.
abstract: OBJECTIVE
  Biomaterials are widely used in ophthalmology, and biodegradable polymers have been evaluated for use in surgery, tissue engineering and targeted drug delivery. We examined the tissue reactions attributable to 3 biodegradable polymers in the rat eye.
  
  
  METHODS
  Inion GTR™ membrane [a blend of 85:15 poly(L-lactide-coglycolide) and 70:30 poly(L-lactide-co-1,3-trimethylene carbonate) copolymers in a molar ratio of 70:30], a 50:50 molar ratio of poly(DL-lactide-coglycolide) (PDLGA 50:50), and a 85:15 molar ratio of poly(DL-lactide-coglycolide) (PDLGA 85:15) were surgically implanted into the subconjuctival space of rat eyes. Biocompatibility was evaluated by following the eyes clinically and with histo- and immunohistochemical techniques.
  
  
  RESULTS
  No clinical signs of inflammation were observed around the implants during follow-up. However, immunohistochemical sections revealed increased accumulation of magrophages around PDLGA 85:15 at 2 weeks and of myofibroblasts around GTR membrane material at 1 month. The order of the degradation time of the material was GTR membrane material > PDLGA 85:15 > PDLGA 50:50; Fourier transform infrared microscopy revealed some differences in the degradation behavior of the polymers. Immunohistochemical staining for plasma or cellular fibronectin was observed around all implants.
  
  
  CONCLUSIONS
  Despite the different decay times and influences on the expression levels of fibronectins, all polymers evoked rather similar tissue reactions during the observation period. This study provides new data on the biocompatibility of biomaterials in rat eyes. Our findings of the tissue decay of the implant and biomaterial-induced tissue reaction may help in the development of better biomaterials for eye surgery with optimal drug delivery properties.
authors.affiliation: Department of Ophthalmology, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland. Seppo.Ronkko@uef.fi
authors.forename: Seppo
authors.initials: S
authors.lastname: Rönkkö
authors.forename: Kai
authors.initials: K
authors.lastname: Kaarniranta
authors.forename: Giedrius
authors.initials: G
authors.lastname: Kalesnykas
authors.forename: Hannu
authors.initials: H
authors.lastname: Uusitalo
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage* / Q000737:chemistry; D003228:Conjunctiva / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004343:Drug Implants; D005353:Fibronectins / Q000378:metabolism; D005549:Foreign-Body Reaction / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D007150:Immunohistochemistry; D008264:Macrophages / Q000473:pathology; D008422:Materials Testing; D058628:Myofibroblasts / Q000473:pathology; D011098:Polyglactin 910 / Q000008:administration & dosage* / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D001672:Biocompatible Materials; D004343:Drug Implants; D005353:Fibronectins; D011098:Polyglactin 910