[Development of motor neuron restorative therapy in amyotrophic lateral sclerosis using hepatocyte growth factor]

Amyotrophic lateral sclerosis (ALS) is an adult onset neurodegenerative disorder characterized by the death of upper and lower motor neurons. Approximately 20% of familial ALS cases are caused by mutations in the superoxide dismutase 1 (SOD1) gene. Mutations in the fused in sarcoma/translated in liposarcoma (FUS/TLS) gene have been recently discovered to be associated with familial ALS. We found FUS/TLS mutations in familial ALS cases in Japan. Even in Asian races, ALS with FUS/TLS mutations may have common characteristics of early onset, rapid progress, high penerence trait. We developed rats that express a human SOD1 transgene with two different ALS-associated mutations (G93A and H46R) develop striking motor neuron degeneration and paralysis. The larger size of this rat model as compared with the ALS mice will facilitate studies involving manipulations of spinal fluid (implantation of intrathecal catheters for chronic therapeutic studies; CSF sampling) and spinal cord (e.g., direct administration of viral- and cell-mediated therapies). Hepatocyte growth factor (HGF) is one of the most potent survival-promoting factors for motor neurons. To examine its both protective effect on motor neurons and therapeutic potential, we administered human recombinant HGF (hrHGF) by continuous intrathecal delivery to G93A transgenic rats at onset of paralysis for 4 weeks. Intrathecal administration of hrHGF attenuates motor neuron degeneration and prolonged the duration of the disease by 63%. Our results indicated the therapeutic efficacy of continuous intrathecal administration of hrHGF in ALS rats. In addition, HGF is capable of reducing astrocytosis and microglial accumulation, and thus supports the attention of a glial-dependent mechanism of ALS progression. These results should prompt further clinical trials in ALS using continuous intrathecal administration of hrHGF.