Isolation and Characterization of Feline Neural Progenitor Cells and Transplantation to the Retina of the Abyssinian Cat With Hereditary Rod Cone Degeneration

Abstract

Abstract: : Purpose: To obtain feline neural progenitor cells for use as allogeneic donor cells in retinal transplantation studies into a large animal model of hereditary rod cone degeneration. Methods: Brains were removed from cat fetuses on gestational day 42. Tissue was dissociated and cells grown in medium containing EGF and bFGF. Cells used for transplantation were pre–labeled with BrDU and Hoechst dye. Using a 2–port partial vitrectomy, approximately 750,000 cells were injected subretinally in the superior nasal quadrant in one eye of a 2 yr–old male Abyssinian cat with moderately advanced retinal degeneration. Funduscopy and full–field flash ERGs were performed postoperatively. The cat was euthanised 4 weeks after surgery and the eyes immersion fixed in 4% paraformaldehyde for histological analysis. Results: Feline progenitor cultures grew as adherent cultures or suspended neurospheres and expressed nestin, Ki–67, Sox2, CXCR4, and vimentin by ICC. Subpopulations expressed A2B5, GFAP, or beta–III tubulin, suggesting lineage restriction. After surgery, areas of hyperpigmentation were seen in the injection area a few days post–op. ERG maximum scotopic b–wave amplitudes were reduced 25% in the injected eye 4 weeks after surgery. IHC revealed viable donor cells in the inner choroidal structures beneath Bruch’s membrane. GFAP was up–regulated in the retina of the treated eye. Conclusions: Neural progenitor cells can be obtained from fetal cat brain and transplanted subretinally in a cat model of retinitis pigmentosa. The allogenic neural progenitor cells survived for 4 weeks, despite their location outside the normal blood–retinal barrier, without evidence of tumor formation or immune reaction. Further refinement of this model is both indicated and worthwhile based on these initial data. The availability of rd feline recipients provides an important resource for development of retinal progenitor cell transplantation strategies.

Keywords: transplantation • plasticity • immunohistochemistry