美国塔夫茨大学医学院的研究人员采用基因疗法治疗视网膜变性取得突破性进展。在动物实验中，研究人员用纳米颗粒将治疗视网膜变性的基因植入患病鼠的视网膜内，结果这些实验鼠在短期内视力出现恢复。该研究成果发表在《分子医学》（Molecular Therapy ）杂志上。

塔夫茨大学医学院的Rajendra  Kumar-Singh博士说：“这项研究显示，通过基因疗法来治疗视网膜变性是有可能取得成功的，因为纳米颗粒非常小，可以进入视网膜细胞，并且可以通过阻止细胞死亡来恢复视力。过去人们一般采用病毒载体来将基因运入细胞，但是病毒容易引发免疫系统反应从而导致炎症、癌症的发生甚至死亡，因此采取非病毒性载体的基因疗法更加安全。”

研究人员用纳米颗粒将携带胶质细胞源性神经营养因子（这种营养因子可以起到保护视网膜光感受器细胞的作用）的基因植入实验鼠的视网膜中，结果显示实验鼠的视网膜光感受器细胞的数量有明显恢复，植入7天后，实验鼠的视力有了明显的改善。

但是这种携带营养因子的纳米颗粒对视网膜的保护还不是永久性的，实验后14天，这些实验鼠的视力再次下降到接受治疗前的水平。Kumar-Singh博士说：下一步试验需要解决的问题，就是通过增加新的保护基因来延长这种治疗方法的有效时间。

视网膜色素变性是指视网膜光感受器细胞和色素上皮细胞变性，从而导致夜盲和进行性视野缺损的一种遗传性致盲眼病，患这类疾病的患者视觉会逐渐丧失，最终会导致失明。这类患者的年龄一般在60岁以上，这种病在美国的发病率一般为1/4000。

英文摘要：

Molecular Therapy  Received 14 January 2010; Accepted 12 July 2010; Published online 10 August 2010.

POD Nanoparticles Expressing GDNF Provide Structural and Functional Rescue of Light-induced Retinal Degeneration in an Adult Mouse
Sarah P Read1, Siobhan M Cashman1 and Rajendra Kumar-Singh1

1Department of Ophthalmology, Tufts University School of Medicine, Boston, Massachusetts, USA

Peptide for ocular delivery (POD) is a novel cationic cell-penetrating peptide (CPP) which, when conjugated with polyethylene glycol (PEG-POD), can deliver plasmid DNA to the retinal pigment epithelium (RPE) of adult murine retina. PEG-POD nanoparticles containing an expression cassette for glial cell line–derived neurotrophic factor (PEG–POD~GDNF) were investigated for their ability to inhibit light-induced photoreceptor apoptosis. PEG-POD~GDNF, control nanoparticles, or buffer were injected into the subretinal space of adult murine retina and retinal degeneration induced by blue light. Animals injected with PEG-POD~GDNF showed a significant reduction (3.9–7.7 fold) in apoptosis relative to control-injected animals. The thickness of the outer nuclear layer (ONL) of the superior retina of PEG-POD~GDNF-injected eyes was significantly greater (23.6–39.3%) than control-injected retina 14 days post-light treatment. PEG-POD~GDNF-injected eyes showed a 27–39% greater functional response relative to controls, as measured by electroretinogram (ERG) 7 days post-light treatment. This is one of only two studies demonstrating histological and functional rescue of a mouse model of retinal degeneration following nonviral administration of a transgene into adult retina. Although rescue is short lived for clinical application, this study represents an important step in the development of nonviral gene therapy for retinal diseases.