Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.
Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Hum Gene Ther. 2020 Jul;31(13-14):719-729. doi: 10.1089/hum.2020.023. Epub 2020 Jul 6.
Gene augmentation therapy based on subretinal delivery of adeno-associated viral (AAV) vectors is proving to be highly efficient in treating several inherited retinal degenerations. However, due to potential complications and drawbacks posed by subretinal injections, there is a great impetus to find alternative methods of delivering the desired genetic inserts to the retina. One such method is an intravitreal delivery of the vector. Our aim was to evaluate the efficacy of two capsid-modified vectors that are less susceptible to cellular degradation, AAV8 (doubleY-F) and AAV2 (quadY-F+T-V), as well as a third, chimeric vector AAV[max], to transduce photoreceptor cells following intravitreal injection in sheep. We further tested whether saturation of inner limiting membrane (ILM) viral binding sites using a nonmodified vector, before the intravitreal injection, would enhance the efficacy of photoreceptor transduction. Only AAV[max] resulted in moderate photoreceptor transduction following intravitreal injection. Intravitreal injection of the two other vectors did not result in photoreceptor transduction nor did the saturation of the ILM before the intravitreal injection. However, two of the vectors efficiently transduced photoreceptor cells following subretinal injection in positive control eyes. Previous trials with the same vectors in both murine and canine models resulted in robust and moderate transduction efficacy, respectively, of photoreceptors following intravitreal delivery, demonstrating the importance of utilizing as many animal models as possible when evaluating new strategies for retinal gene therapy. The successful photoreceptor transduction of AAV[max] injected intravitreally makes it a potential candidate for intravitreal delivery, but further trials are warranted to determine whether the transduction efficacy is sufficient for a clinical outcome.
基于腺相关病毒（AAV）载体的视网膜下递送来进行基因增强治疗，已被证明在治疗几种遗传性视网膜变性方面非常有效。然而，由于视网膜下注射可能带来的潜在并发症和缺点，人们迫切希望找到将所需遗传插入物递送到视网膜的替代方法。一种这样的方法是玻璃体内递送载体。我们的目的是评估两种衣壳修饰的载体的效力，这两种载体不易被细胞降解，分别是 AAV8（双 Y-F）和 AAV2（四 Y-F+T-V），以及第三种嵌合载体 AAV[max]，在绵羊中经玻璃体内注射后转导感光细胞。我们还进一步测试了在玻璃体内注射之前，使用非修饰载体使内界膜（ILM）病毒结合位点饱和是否会增强感光细胞转导的效力。只有 AAV[max]在玻璃体内注射后导致中度感光细胞转导。两种其他载体的玻璃体内注射均未导致感光细胞转导，ILM 在前玻璃体内注射时也未饱和。然而，在阳性对照眼中，这两种载体中的两种在视网膜下注射后有效地转导了感光细胞。之前在小鼠和犬模型中使用相同载体的试验分别导致了强大和中度的转导效力，这证明了在评估新的视网膜基因治疗策略时，利用尽可能多的动物模型的重要性。成功地将 AAV[max]玻璃体内注射后转导感光细胞，使其成为玻璃体内递送的潜在候选物，但需要进一步的试验来确定转导效力是否足以达到临床效果。
