Introduction: One factor limiting the application of gene therapies to treat diseases of the central nervous system (CNS) is the lack of effective delivery systems. Batten disease is an inherited neurodegenerative disease caused by a mutation in the CLN2 gene resulting in decreased levels of TTP-1 enzyme. This results in lipofuscin accumulation in the brain causing progressive loss of cognitive, motor and sensory function, ultimately leading to death after the first decade of life. Here we describe a novel method for intra-arterial delivery of AAVrh.10 CLN2 following osmotic blood brain barrier (BBB) disruption in mice.
Methods: The left internal carotid arteries of naïve mice were catheterized using a 169 µm diameter microcatheter. After intra-arterial mannitol injection, one of four AAVrh.10 CLN2 doses (3.175 x 10^10 gc, 6.35 x 10^10 gc, 1.27 x 10^11 gc, 2.54 x 10^11 gc) were administered (n=3 for each group). Control groups included intra-arterial mannitol plus saline (n=3) or saline plus AAVrh.10 CLN2 (n=3). Animals were sacrificed at five weeks to assess the extent of TPP-1 production using immunohistochemistry (figures 1 and 2).
Results: At five weeks, all animals in treatment groups that received both mannitol and AAVrh.10 CLN2 showed TPP-1 production in left cerebral hemisphere by immunohistochemistry methods. Control animals receiving mannitol alone or AAVrh.10 CLN2 alone did not reveal any significant TPP-1 production. Qualitative assessment showed substantial increase in TPP-1 levels at higher AAVrh.10 CLN2 doses (figure 3).
Conclusions: In this study we demonstrate that co-administration of intra-arterial mannitol and AAVrh.10 CLN2 resulted in diffuse hemispheric TPP-1 production. Furthermore, TPP-1 was shown in both neurons and glial cells and was sustained at greater than 4 weeks after delivery. Intra-arterial gene therapy after osmotic disruption of the BBB may be a viable delivery method for viral-mediated gene therapy to the CNS.
Patient Care: Intra-arterial viral mediated gene therapy may potentially be used to treat a number of neurodegenerative diseases by provided an effective delivery system.
Learning Objectives: By the conclusion of this session, participants should be able to discuss the delivery of AAVrh.10 CLN2 gene therapy via intra-arterial injection after osmotic blood brain disruption in mice.