Korda, David

Subretinal and intravitreal injection of retinal gene therapy is associated with serious adverse events and poor efficacy. We sought to improve retinal gene therapy delivery by developing fibrin hydrogel encapsulated adeno-associated virus (FE-AAV). Here we investigate conditions for storage and stability for FE-AAV. FE-AAV containing 1.9 × 109 genome copies of AAV2/2-CMV-GFP was manufactured using fibrinogen reconstituted in 0.01 M sodium citrate, pH 7 (NaC) or phosphate-buffered saline containing 0.001% (v/v) Pluronic F68 (F68). Samples were stored at either −80 °C or 4 °C for up to 16 weeks. Changes in transduction efficiency, and mechanical and physical properties were evaluated. In vitro transduction was significantly (p < 0.05) reduced for FE-AAV manufactured with NaC. In contrast, we observed no change in transduction through 16 weeks for FE-AAV made with F68. Physical changes occurred in FE-AAV stored at −80 °C. In contrast to FE-AAV formulated with NaC, FE-AAV formulated with F68 and stored at 4 °C for 16 weeks was essentially equivalent to freshly made FE-AAV and retained the ability to transduce retinal pigment epithelial (RPE) cells in the pig eye. We conclude that FE-AAV formulated with F68 and stored at 4 °C is stable and shows potential for retinal gene therapy for at least 4 months following manufacture.

Death or dysfunction of retinal pigment epithelium (RPE) cells occurs in age-related macular degeneration (AMD) and certain inherited retinal dystrophies (IRDs). Induced-pluripotent stem cell (iPSC) derived-RPE have been used in early-stage clinical trials to treat AMD and IRDs by injecting them as a cell suspension or monolayers. While RPE transplant shows therapeutic potential, issues ranging from failure to repopulate the entire treatment area, clumping and monolayer folding, and a foreign body response to the support have been reported. We’ve shown that RPE can be grown on high concentration (&gt;30 mg/mL) degradable fibrin hydrogels, and that cell free fibrin hydrogels implanted in the subretinal space degrade without causing inflammation. Here we describe manufacture and surgical implantation of degradable fibrin hydrogels carrying iPSC-RPE into a porcine model of geographic atrophy (GA). Large (15.25 × 58.42 × 0.2 mm) fibrin gel blanks were produced by injection molding, and iPSC-RPE were grown on their surface. Using a mechanical punch, the blank was subdivided into 1.5 × 5.0 × 0.2 mm doses, which fit a custom tool used for storage and surgical placement. Following aseptic packaging, RPE and gels were stable at 37 °C for at least 7 weeks. When transplanted into a pig model of GA, the fibrin scaffold degraded in &lt;1 month and the iPSC-RPE provided partial rescue from GA as assessed by preservation of photoreceptors and blood flow in the choriocapillaris. We conclude that iPSC-RPE delivered on degradable fibrin hydrogels represent a potentially safe and effective approach to RPE transplantation.