Gene therapy could treat Parkinson's at the source

Japanese researchers are looking to develop a novel treatment for the millions of people who suffer from Parkinson’s disease (PD) — a neurodegenerative disease that can strike at any age, though it is most common in those aged over 60. While not fatal in and of itself, the progressive neurodegeneration that is characteristic of PD can often cause secondary effects that lead to death — so the new research, published in the journal Scientific Reports, provides a ray of hope for patients.

The exact cause of PD is still a mystery, but researchers believe that both genetics and the environment are likely to play a part. Importantly, though, all PD patients show a loss of dopaminergic neurons in the brain and increased levels of a protein called α-synuclein, which accumulates in Lewy bodies. Lewy bodies are a pathological feature of both familial and sporadic forms of the disease, as well as some types of dementia.

With this in mind, a research team led by Osaka University focused on α-synuclein as a target for a novel PD treatment. As explained by lead author Takuya Uehara, “Although there are drugs that treat the symptoms associated with PD, there is no fundamental treatment to control the onset and progression of the disease. Therefore, we looked at ways to prevent the expression of α-synuclein and effectively eliminate the physiological cause of PD.”

To do this, the researchers designed short fragments of DNA that are mirror images of sections of the α-synuclein gene product. The constructs were stabilised by the addition of amido-bridging. The resulting fragments, called amido-bridged nucleic acid-modified antisense oligonucleotides (ASOs), bind to their matching mRNA sequence, preventing it from being translated into protein. After screening 50 different ASOs, the researchers settled on a 15-nucleotide sequence that decreased α-synuclein mRNA levels by 81%.

“When we tested the ASO in a mouse model of PD, we found that it was delivered to the brain without the need for chemical carriers,” said Chi-Jing Choong, co-lead author on the study. “Further testing showed that the ASO effectively decreased α-synuclein production in the mice and significantly reduced the severity of disease symptoms within 27 days of administration.”

“Our results showed that gene therapy using α-synuclein-targeting ASOs is a promising strategy for the control and prevention of PD,” added senior author Hideki Mochizuki. “We expect that in the future, this method will be used to not only successfully treat PD, but also dementia caused by α-synuclein accumulation.”

Image credit: ©stock.adobe.com/au/viperagp

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