title: Intraocular pressure changes: an important determinant of the biocompatibility of intravitreous implants.
abstract: BACKGROUND
  In recent years, research efforts exploring the possibility of using biomaterial nanoparticles for intravitreous drug delivery has increased significantly. However, little is known about the effect of material properties on intravitreous tissue responses.
  
  
  RESULTS
  To find the answer, nanoparticles made of hyaluronic acid (HA), poly (l-lactic acid) (PLLA), polystyrene (PS), and Poly N-isopropyl acrylamide (PNIPAM) were tested using intravitreous rabbit implantation model. Shortly after implantation, we found that most of the implants accumulated in the trabecular meshwork area followed by clearance from the vitreous. Interestingly, substantial reduction of intraocular pressure (IOP) was observed in eyes implanted with particles made of PS, PNIPAM and PLLA, but not HA nanoparticles and buffered salt solution control. On the other hand, based on histology, we found that the particle implantation had no influence on cornea, iris and even retina. Surprisingly, substantial CD11b+ inflammatory cells were found to accumulate in the trabecular meshwork area in some animals. In addition, there was a good relationship between recruited CD11b+ cells and IOP reduction.
  
  
  CONCLUSIONS
  Overall, the results reveal the potential influence of nanoparticle material properties on IOP reduction and inflammatory responses in trabecular meshwork. Such interactions may be critical for the development of future ocular nanodevices with improved safety and perhaps efficacy.
authors.affiliation: Joint Program in Bioengineering, University of Texas-Southwestern Medical Center at Dallas and The University of Texas at Arlington, Arlington, Texas, United States of America.
authors.forename: Ling
authors.initials: L
authors.lastname: Zou
authors.forename: Ashwin
authors.initials: A
authors.lastname: Nair
authors.forename: Hong
authors.initials: H
authors.lastname: Weng
authors.forename: Yi-Ting
authors.initials: YT
authors.lastname: Tsai
authors.forename: Zhibing
authors.initials: Z
authors.lastname: Hu
authors.forename: Liping
authors.initials: L
authors.lastname: Tang
mesh_terms: D000180:Acrylic Resins / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D039481:CD11b Antigen / Q000378:metabolism; D003315:Cornea / Q000187:drug effects / Q000473:pathology; D005137:Eye, Artificial; D016650:Fluorescein-5-isothiocyanate; D020007:Implants, Experimental; D007249:Inflammation / Q000473:pathology; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D058449:Intravitreal Injections; D007498:Iris / Q000187:drug effects / Q000473:pathology; D007668:Kidney / Q000187:drug effects / Q000473:pathology; D053758:Nanoparticles / Q000008:administration & dosage; D019919:Prosthesis Implantation; D011817:Rabbits; D014129:Trabecular Meshwork / Q000378:metabolism / Q000473:pathology; D014822:Vitreous Body / Q000187:drug effects* / Q000502:physiology*
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; D039481:CD11b Antigen; C052970:poly-N-isopropylacrylamide; D016650:Fluorescein-5-isothiocyanate