Ocular Levels of Pigment Epithelium–Derived Factor (PEDF) After Repeated Intraocular or Periocular Injections of Adenovirus–Mediated PEDF.

Abstract

Abstract: : Purpose: To determine if repeated injections of AdPEDF can result in sustained increased levels of PEDF in the eye. Methods: Adult C57BL/6 mice were given periocular (5 x 10⁹ pu) or intravitreous (1 x 10⁹ pu) AdPEDF in the right eye. Mice were euthanized and PEDF levels were measured in ocular tissues at several time points. Repeat injections were performed in some mice on days 28 and 56. Results: (1) Periocular injections. Compared to uninjected mice (n=5), a single injection resulted in a significant increase in PEDF (pg PEDF/µg total protein) at day 3 in sclera (853 vs. 85; p=2x10^–6), choroid (623 vs. 64; p=8x10^–9) and retina (279 vs. 24; p=0.02). By day 14, increased PEDF levels were present in the sclera (135; p=0.008) and choroid (107; p=0.02), but not the retina (35; p= 0.15). Compared to uninjected mice, a 2^nd periocular injection of AdPEDF resulted in significant increase in PEDF at day 3 in sclera (158; p=0.002) and choroid (91; p=0.04), but not the retina (25; p=0.84). By day 14, increased PEDF levels were present only in sclera (368; p=0.002). Compared to uninjected mice, a 3^rd injection of AdPEDF resulted in a significant increase in PEDF at day 3 only in sclera (231; p=0.049). (2) Intravitreous injections. Compared to uninjected mice, a single intravitreous injection of AdPEDF resulted in a significant increase in PEDF at days 3 and 14 in sclera (610; 274; p<0.009), choroid (394; 248; p<0.006) and retina (279; 263; p<0.0001). Compared to uninjected mice, a 2^nd injection resulted in a significant increase in PEDF at day 3 in sclera (525; p=0.006), choroid (381; p=0.006) and retina (270; p= 0.01). By day 14 there was only a significant increase in retinal PEDF levels (43; p=0.048), but no difference from mice that received a single injection of AdPEDF (47 vs. 43; p=0.6). Compared to uninjected mice, a 3^rd injection resulted in a significant increase in PEDF at day 3 in the retina only (58; p=0.01), but no difference by day 14. Conclusions: Repeated intravitreous injections of AdPEDF cause a modest increase in duration of increased levels of PEDF in retina. Repeated periocular injections of AdPEDF do not sustain increased levels of PEDF in retina or choroid. Additional studies are needed to explore the feasibility of repeated injections of AdPEDF via these routes of administration.

Keywords: adenovirus • gene transfer/gene therapy • retina