Prevention of Retinal Degeneration by Transgenic Autologous Stem Cells

描述(申请人提供)：婴儿晚期神经性蜡样脂褐素沉积症(LINCL，或CLN2)是一种进行性和致命性的儿童遗传性神经退行性疾病，其特征是脑萎缩和进行性视网膜变性导致视力丧失，最终导致失明。CLN2是由编码合成可溶性溶酶体酶三肽基肽酶-1(TPP1)的基因突变引起的。利用CLN2的犬模型，我们已经证明，定期向脑脊液(CSF)给予重组TPP1或向脑脊液单独给予AAV2-TPP1基因治疗可导致大部分脑区摄取活性TPP1，极大地抑制脑退行性变，并显著延缓疾病的神经体征的进展。基于我们对犬模型的研究，脑脊液的TPP1酶替代疗法正被用于2013年9月开始的人类临床试验。不幸的是，将TPP1输送到脑脊液并不能防止视网膜退化和由此导致的视力丧失，因为TPP1不能从脑脊液到达视网膜。为了实现TPP1持续输送到视网膜，我们建议从狗的自体骨髓来源的间充质干细胞(MSCs)中获得TPP1零突变的纯合子。骨髓间充质干细胞将被转导表达和分泌高水平的TPP1酶。然后，转基因细胞将被植入获得MSCs的同一只狗的玻璃体中，并将监测这些狗的存活和植入细胞的位置、视网膜TPP1水平以及视网膜结构和功能的保存。我们还将研究将AAV2-TPP1基因治疗直接应用于玻璃体的替代方法，以转导视网膜细胞合成TPP1蛋白。如果这些研究成功，它们将成为治疗慢性淋巴细胞性脑炎儿童的基础，这些儿童正在接受酶替代疗法，方法是将TPP1注入脑脊液或脑脊液TPP1基因疗法。在脑脊液治疗的基础上增加眼科治疗，有可能预防患有CLN2的儿童失明，他们正受益于脑部治疗。此外，这些研究将建立转基因细胞玻璃体内植入和直接基因治疗作为治疗许多其他视网膜退行性疾病的手段，包括遗传性视网膜退行性疾病、老年性黄斑变性和糖尿病视网膜病变。

DESCRIPTION (provided by applicant): Late-infantile neuronal ceroid lipofuscinosis (LINCL, or CLN2) is a progressive and fatal inherited neurodegenerative disease of children that is characterized brain atrophy as well as by progressive retinal degeneration resulting in vision loss that culminates in blindness. CLN2 results from a mutation in the gene that encodes synthesis of the soluble lysosomal enzyme tripeptidyl peptidase-1 (TPP1). Using a dog model of CLN2, we have demonstrated that periodic administration of recombinant TPP1 to the cerebrospinal fluid (CSF) or a single administration of AAV2-TPP1 gene therapy to the CSF results in uptake of active TPP1 by most brain regions, greatly inhibits brain degeneration, and substantially delays progression of neurological signs of the disease. Based on our studies with the canine model, TPP1 enzyme replacement therapy to the CSF is being employed in a human clinical trial that started in September of 2013. Unfortunately, delivery of TPP1 to the CSF does not prevent retinal degeneration and the resulting loss of vision because the TPP1 does not reach the retina from the CSF. To achieve continuous delivery of TPP1 to the retina, we propose to generate autologous bone marrow- derived mesenchymal stem cells (MSCs) from dogs that are homozygous for a null TPP1 mutation. The MSCs will be transduced to express and secrete high levels of TPP1 enzyme. The transgenic cells will then be implanted into the vitreous of the eyes of the same dogs from which the MSCs were obtained, and the dogs will be monitored for survival and location of the implanted cells, retinal TPP1 levels, and for preservation of retinal structure and function. We will also investigate the alternative approach o direct administration of AAV2-TPP1 gene therapy to the vitreous to transduce retinal cells to synthesize the TPP1 protein. If these studies are successful, they will serve as the basis for treating children with CLN2 who are receiving enzyme replacement therapy via infusion of TPP1 into the CSF or CSF TPP1 gene therapy. The addition of the eye treatment to the CSF treatments has the potential for preventing blindness in children with CLN2 who are benefiting from the brain treatments. In addition, these studies will establish intravitreal implantation of transgenic cells and direct gene therapy as means for treating many other retinal degenerative disorders, including inherited retinal degenerative diseases, age-related macular degeneration and diabetic retinopathy.