Intrathecal delivery of recombinant AAV1 encoding hepatocyte growth factor improves motor functions and protects neuromuscular system in the nerve crush and SOD1-G93A transgenic mouse models

Abstract

Amyotrophic lateral sclerosis (ALS) is a fatal neuromuscular disease resulting from motor neuron degeneration that causes muscle weakness, paralysis, and eventually respiratory failure. We investigated whether recombinant adeno-associated virus encoding human hepatocyte growth factor (rAAV-HGF) could generate beneficial effects in two mouse models with neuromuscular problems when intrathecally delivered to the subarachnoid space. We chose AAV serotype 1 (rAAV1) based on the expression levels and distribution of HGF protein in the lumbar spinal cord (LSC). After a single intrathecal (IT) injection of rAAV1-HGF, the protein level of HGF in the LSC peaked on day 14 and thereafter gradually decreased over the next 14 weeks. rAAV1-HGF was initially tested in the mouse nerve crush model. IT injection of rAAV1-HGF improved mouse hindlimb strength and rotarod performance, while histological analyses showed that the length of regenerated axons was increased and the structure of the neuromuscular junction (NMJ) was restored. rAAV1-HGF was also evaluated in the SOD1-G93A transgenic (TG) mouse model. Again, rAAV1-HGF not only improved motor performance but also increased the survival rate. Moreover, the number and diameter of spinal motor neurons (SMNs) were increased, and the shape of the NMJs restored. Data from in vitro motor cortical culture experiments indicated that treatment with recombinant HGF protein (rHGF) increased the axon length of corticospinal motor neurons (CSMNs). When cultures were treated with an ERK inhibitor, the effects of HGF on axon elongation, protein aggregation, and oxidative stress were suppressed, indicating that ERK phosphorylation played an important role(s). Taken together, our results suggested that HGF might play an important role(s) in delaying disease progression in the SOD1-G93A TG mouse model by reducing oxidative stress through the control of ERK phosphorylation. Electronic supplementary material The online version of this article (10.1186/s40478-019-0737-z) contains supplementary material, which is available to authorized users.

A Novel HGF/SF Receptor (MET) Agonist Transiently Delays the Disease Progression in an Amyotrophic Lateral Sclerosis Mouse Model by Promoting Neuronal Survival and Dampening the Immune Dysregulation

“…In the spinal cord, we found that the neuroprotection was accompanied by the activation (phosphorylation) of ERK but not AKT. This result complies with a recent study showing that intrathecal delivery of recombinant AAV1 encoding HGF/SF protected spinal motor neurons in SOD1G93A mice through an increase in phosphorylated ERK but no other signaling molecules of the HGF/SF-MET pathway such as STAT3, cJUN and GSK3b [ 15 ]. This highlights the importance of ERK activation in the rescue of motor neurons induced by HGF/MET signaling.…”

“…Interestingly, certain residual anterior horn cells from post-mortem ALS patients overexpressed both HGF/SF and MET in comparison with those of normal subjects [ 13 ]. Most importantly, transgenic overexpression or intrathecal delivery of the growth factor markedly delayed the progression of the disease in SOD1G93A transgenic mice and rats [ 14 , 15 ]. Hence, early clinical trials involving intramuscular administration of plasmid HGF/SF DNA [ 16 ] or intrathecal delivery of HGF/SF protein [ 17 ] in ALS patients have displayed adequate safety profiles and are now progressing to efficacy studies.…”

Impairment of peripheral nerve regeneration by insufficient activation of the HGF/c-Met/c-Jun pathway in aged mice

“…In recent studies, HGF has been reported to be involved in the regeneration of peripheral nerves, and supplementation with this gene shows therapeutic effects in various peripheral neuropathy models [ 3 , 4 , 8 , 11 ]. HGF promoted the differentiation of repair-type Schwann cells by inducing AP-1 transcription factors and accelerated the outgrowth of injured axons through c-Jun protein [ 3 , 5 ].…”

HGF and MET: From Brain Development to Neurological Disorders

“…Moreover, viral vector gene transfer has been tested pre-clinically and is more promising because it provides a more efficient transcription transfer than non-viral methods. Thus, gene therapy with viral vectors protects from neuronal death in animal models of ALS ( Lee et al, 2019 ) and cerebral ischemia ( Hayashi et al, 2001 ), promotes angiogenesis, and reduces apoptosis in SCI ( Kitamura et al, 2007 ). Moreover, HGF gene transfer with viral vectors reduces pain and inflammation in a neuropathic model ( Tsuchihara et al, 2008 ), promotes neurite extension, and increases synaptogenesis in a stroke model ( Shimamura et al, 2006 ).…”