Proliferative vitreoretinopathy (PVR) is characterized by membranes that develop on the surface of the retina after rhegmatogenous retinal detachments (RRDs). Because PVR membranes exert tractional forces on the retina, they are the leading cause of failure after RRD surgery. Despite additional surgical interventions, the visual outcome still remains poor. Prevention of PVR during the initial RRD surgery is preferable and will avoid such recurrent retinal detachment or even blindness. Unfortunately, all previous attempts to prevent PVR formation using different pharmacologic agents have been unsuccessful. The two main pathological hallmarks of PVR membranes are proliferation and epithelial-mesenchymal transition (EMT) of retinal pigment epithelium (RPE) cells. RPE cells play a pivotal role in maintaining photoreceptor function and are normally differentiated and mitotically quiescent due to contact inhibition. RRDs allow RPE cells to be dispersed in the vitreous cavity and become exposed to growth factors (e.g., EGF, FGF, TGF-, VEGF and TNF-) and inflammatory cytokines (e.g., IFN-), which result in proliferation and EMT into fibroblasts or myofibroblasts. Our recent discovery provides insight into the mystery of how growth factors control the proliferation and EMT of RPE cells. Using post-confluent ARPE-19 cells in an in vitro model, we demonstrated that proliferation is coupled with EMT when contact inhibition is perturbed by EGTA followed by exposure to EGF and/or FGF-2, which activate canonical Wnt signaling. In contrast, proliferation ceases with full-blown EMT followed by exposure to TGF-1, which activates Smad/ZEB signaling. This baseline characterization establishes a framework for discovering new drugs which can prevent PVR by targeting both proliferation and EMT. Transplantation of cryopreserved amniotic membrane (AM) has become a standard surgical procedure for ocular surface reconstruction to deliver anti-inflammatory, anti-scarring and anti-angiogenic actions to promote wound healing. Recently, we have purified and characterized an active AM matrix component termed heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) complex, which retains AM's aforementioned therapeutic actions. In this SBIR Phase I application, we propose to prove the concept that HC-HA/PTX3 can inhibit both canonical Wnt signaling and TGF--induced Smad/ZEB signaling in RPE cells to inhibit proliferation and EMT, respectively. Successful completion of these aims will allow us to move to Phase II in order to gather critical pre-clinical safety and efficacy data for the IND submission to the FDA so that we may examine its therapeutic potential as a new class of biologics to prevent PVR in human patients.
Our published and preliminary studies support the hypothesis that the HC-HA/PTX3 complex, purified from human amniotic membrane, can suppress both proliferation and EMT of human RPE cells. In this Phase I application, we propose to prove the concept so that we may proceed with pre-clinical safety and efficacy studies in Phase II to gather critical data for the IND application to the FDA. Our ultimate goal is to develop HC- HA/PTX3 as a new class of biologics to prevent PVR in human patients. Furthermore, the success of achieving this product development program will pave the way to deploy HC-HA/PTX3 as a new class of biologics to treat inflammatory/scarring diseases in the eye and other parts of the body.
| He, Hua; Kuriyan, Ajay E; Su, Chen-Wei et al. (2017) Inhibition of Proliferation and Epithelial Mesenchymal Transition in Retinal Pigment Epithelial Cells by Heavy Chain-Hyaluronan/Pentraxin 3. Sci Rep 7:43736 |
