-Original-

Amount of Green Fluorescent Protein in the Anterior Chamber after Intravitreal Injection of Triple-Mutated Self-Complementary AAV2 Vectors is Not Affected by Previous Vitrectomy Surgery

Kazuhisa Takahashi^1,2, Tsutomu Igarashi^1,2,4, Koichi Miyake¹, Maika Kobayashi^1,2, Yuko Katakai³, Hiromi Hayashita-Kinoh^1,5, Chiaki Fujimoto², Shuhei Kameya⁴, Hiroshi Takahashi² and Takashi Okada^1,5

¹Department of Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan
²Department of Ophthalmology, Nippon Medical School, Tokyo, Japan
³The Corporation for Production and Research of Laboratory Primates, Ibaraki, Japan
⁴Department of Ophthalmology, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan
⁵Division of Molecular and Medical Genetics, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan

Background: The adeno-associated virus (AAV) vector is a promising vector for ocular gene therapy. Surgical internal limiting membrane peeling before AAV vector administration is useful for efficient retinal transduction. However, no report has investigated localization of AAV vectors after administration into a post-vitrectomy eye. This study investigated the effects of vitrectomy surgery on intravitreal-injected AAV vector-mediated gene expression in the anterior segment and examined the presence of neutralizing antibodies (NAbs) in serum before and after AAV vector administration.
Methods: Of six eyes from three female cynomolgus monkeys, four were vitrectomized (Group VIT) and two were non-vitrectomized (Group IV). All eyes were injected with 50 μL of triple-mutated self-complementary AAV2 vector (1.9 × 10¹³ v.g./mL) encoding green fluorescent protein (GFP). NAbs in the serum were examined before administration and at 2 and 6 weeks after administration. GFP expression was analyzed at 19 weeks after administration.
Results: Immunohistological analysis showed no GFP expression in the trabecular meshwork in any eye. The GFP genome copy in two slices of the anterior segment was 2.417 (vector genome copies/diploid genome) in Group VIT and 4.316 (vector genome copies/diploid genome) in group IV. The NAb titer was 1:15.9 (geometric mean) before administration, 1:310.7 at 2 weeks after administration, and 1:669.4 at 6 weeks after administration.
Conclusion: Previous vitrectomy surgery did not affect gene expression in the anterior segment after intravitreal injection of AAV vectors.

J Nippon Med Sch 2021; 88: 103-108

Keywords
AAV vector, intravitreal, injection, vitrectomy, neutralizing antibodies (NAbs), trabecular meshwork

Correspondence to
Tsutomu Igarashi, MD, PhD, Department of Ophthalmology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan
tutomu@nms.ac.jp

Received, December 16, 2019
Accepted, February 26, 2020