While many new therapeutic molecules for treatment of ocular diseases have become available over the past decade, one of the major problems facing their effective application in clinic has been drug delivery. Often bioactive molecules have a short half-life in vivo and require repeated administration. In the case of intraocular administration this often means poor patient compliance and high cost. As such, controlled release of therapeutic molecules over a period of months to years is expected to have a significant impact in patient care and in the treatment of ocular disease. The focus of this proposal is to investigate micro and nanoscale polymer fibers for the intraocular delivery of therapeutic molecules. Fibers have an advantage over other nano and microscale delivery vectors in that they can be moved or removed if complications arise. One of the primary targets implicated in several ocular diseases is Transforming Growth Factor - beta (TGF-?). These diseases include corneal scarring, scarring following cataract and glaucoma surgery, as well as proliferative vitreoretinopathy. Decreasing TGF-? expression and its effect through use of antisense oligonucleotides, aptamers and other small molecule drugs has shown some success in treatment of these diseases. While delivery of siRNA against TGF-? has also been demonstrated to be effective, siRNA is limited as a long term therapy due to its susceptibility to ubiquitous RNAses as well as the need to have a large number of molecules for effective knockdown in vivo. In this study we propose to examine delivery of DNA which codes for the siRNA to knockdown TGF-? expression. Delivery of DNA addresses issues of stability since DNA is much more stable than RNA, and addresses issues of drug amount since a single DNA molecule can be transcribed into many siRNAs. The objective of the proposed research is to develop a microscale drug delivery platform which can easily be implanted to treat a wide range of ocular diseases. Specifically the hypothesis of this study is that the proposed therapeutic DNA can be incorporated and released from polymer nanofibers, and that released DNA can result in expression knockdown in ocular cell models. The hypothesis will be tested in three specific aims: 1) Evaluate the bioactivity of DNA released from nanofibers formed by electrospinning, 2) In a destabilized GFP model evaluate effect of released DNA in knocking down expression, and 3) In a human corneal fibroblast model evaluate the effect of released DNA in knockdown of TGF-? expression. This ocular model was chosen due to the investigators'familiarity with it. However, a drug delivery platform which can successfully deliver therapeutic DNA against one disease could rapidly be applied toward treatment of other diseases, such as VEGF knockdown in wet-type macular degeneration, or in diabetic retinopathy.
This proposal is critically concerned with the issue of public health in that its long term goal is to provide a drug delivery platform for providing sustained release of molecules to treat intraocular diseases. The short term goal is whether polymer nanofibers can deliver DNA to knock down expression of TGF-? in cell culture models of intraocular scarring disorders including corneal scarring, post-surgical scarring, and proliferative vitreoretinopathy.
