Perineural delivery of AAV2/9 in non-human primates is a safe and efficient route for gene therapy in Charcot-Marie-Tooth diseases

Abstract

AAV-based gene therapy represents an attractive treatment for hereditary peripheral neuropathies Charcot-Marie-Tooth diseases. We recently showed that AAV2/9 vector-expressing GFP, locally injected into mouse and rat sciatic nerves, transduced a large amount of myelinating Schwann cells (mSCs). The local delivery of a similar vector expressing a small hairpin RNA (shRNA) targeting PMP22 mRNA prevented CMT1A disease in a rat disease model. Here, we investigated the regional anesthesia standard perineural injection route in non-human primates using AAV2/9 expressing GFP and AAV2/9 expressing shRNA targeting human and monkey PMP22 mRNA. Injecting at multiple sites to cover the largest part of arm and leg nerves, we found that AAV2/9 easily crossed perineurium sheaths to transduce up to 90% of mSCs. Injections on 10 nerves in each animal did not generate any adverse effects. Injected nerves functioned properly, and fine motor dexterity remained unaffected. Enzymatic, metabolite, and blood cytometry were marginally affected, and no systemic inflammation was detected. Locally, we detected a slight to moderate perineural infiltration of monocytes only with vector-expressing GFP. Vector-expressing PMP22 shRNA decreased PMP22 expression in a dose-dependent manner and levels remained physiological. Perineural injections appear to be safe, well-tolerated, and efficient to deliver AAV2/9-based gene therapy vector to treat Charcot-Marie-Tooth diseases.