Proof‐of‐concept: neonatal intravenous injection of adeno‐associated virus vectors results in successful transduction of myenteric and submucosal neurons in the mouse small and large intestine

Abstract

Key MessagesThe efficiency of transduction of both myenteric and submucosal neurons in the mouse intestine after neonatal systemic delivery of vectors AAV8 and AAV9 was investigated.AAV8 and AAV9 are equally capable of transducing the ENS, although the transduction efficiency in the submucosal plexus is region-dependent.Manipulation of the ENS through gene delivery offers great potential in preclinical research and gene therapy. AbstractBackground Despite the success of viral vector technology in the transduction of the central nervous system in both preclinical research and gene therapy, its potential in neurogastroenterological research remains largely unexploited. This study asked whether and to what extent myenteric and submucosal neurons in the ileum and distal colon of the mouse were transduced after neonatal systemic delivery of recombinant adeno-associated viral vectors (AAVs). Methods Mice were intravenously injected at postnatal day one with AAV pseudotypes AAV8 or AAV9 carrying a cassette encoding enhanced green fluorescent protein (eGFP) as a reporter under the control of a cytomegalovirus promoter. At postnatal day 35, transduction of the myenteric and submucosal plexuses of the ileum and distal colon was evaluated in whole-mount preparations, using immunohistochemistry to neurochemically identify transduced enteric neurons. Key Results The pseudotypes AAV8 and AAV9 showed equal potential in transducing the enteric nervous system (ENS), with 25-30% of the

Systemic gene delivery transduces the enteric nervous system of guinea pigs and cynomolgus macaques

“…AAV9 targeted up to 57% of myenteric neurons from the stomach to the colon in mice following an intravenous AAV9 injection( 1 ). Similar transduction efficiency was also achieved in the murine submucosal plexus( 3 ).…”

“…Transgene expression in S100 positive enteric glial cells was rare but influenced by viral capsid and expression cassette( 1 ). These findings were largely replicated and furthered by showing transduction in the submucosal plexus in mice( 3 ). Here we demonstrate proof of concept that systemic delivery of AAV vectors can target the enteric nervous system in guinea pigs and non-human primates.…”

“…Here we demonstrate proof of concept that systemic delivery of AAV vectors can target the enteric nervous system in guinea pigs and non-human primates. Across our studies, mice and guinea pigs were given similar vector doses (~3x10 13 vg/kg) with ~16–20% of myenteric neurons targeted in mouse colon and 4–6% in guinea pigs( 1 , 3 ). At least for AAV8, this difference in efficiency is partially due to one AAV8 guinea pig not completing the study since a longer time post injection increases the accumulation of GFP and therefore the sensitivity of detection.…”

“…Gene delivery is an effective basic and translational tool to manipulate neurological behavior, inflammatory responses and degeneration that has only recently been explored for application to the enteric nervous system (ENS)( 1 – 3 ). Efficiency is enhanced with the use of viral or non-viral vectors to facilitate nucleic acid uptake and stability.…”

“…It was shown recently that direct injections of adeno-associated viruses (AAV) into the colon, small intestine or cecum of rats and mice showed capsid and dose dependent targeting of myenteric and submucosal neurons and glia near the injection site( 2 ). We and others have recently shown that widespread ENS transduction is achieved in mice following a one-time systemic delivery of AAV8 or 9( 1 , 3 ). AAV9 targeted up to 57% of myenteric neurons from the stomach to the colon in mice following an intravenous AAV9 injection( 1 ).…”