Could Stem Cell Therapy Treat Huntington’s Disease?
July 2019

What is Huntington’s Disease?

Huntington’s disease is a hereditary disease that causes degeneration of nerve cells in the brain, impacting a person’s ability to move and think, as well as causing psychiatric disorders, and ultimately progressive dementia. 

Most sufferers with Huntington’s Disease will begin to display motor and cognitive symptoms in their 30s and 40s, however that isn’t to say the disease won’t show up earlier or later in life. 

If a person is diagnosed in their 20s, the disease is known as Juvenile Huntington’s Disease and presents with a different set of symptoms to the typical Huntington’s Disease symptoms, and the disease has a faster progression. 

Presently a person with Huntington’s Disease can access therapies to manage the symptoms of the disease, but as yet there is no cure and there is no way to halt or prevent the onset of physical or mental decline that is symptomatic of Huntington’s Disease. 

Symptoms of Huntington’s Disease are wide and varied, and there is no set order in which the movement or mental disorders present, and with each patient the disorders will affect them differently.  

Huntington’s Disease is a monogenetic disorder, the result of one defect in a single gene. A person only needs one copy of the defective gene in order to get the disease (ordinarily a person will receive two copies of every gene, one from each parent, with the exception of sex chromosomes). 

Contracting Huntington’s Disease

The chances of contracting the disease are 50% as the parent with the disease may pass along an infected gene or a healthy one. There is no guarantee you will inherit the disease if it is in the family. 

For families affected with Huntington’s Disease there are the options available for genetic testing and family planning. Prenatal testing for the gene is one option, or couples could look to IVF using donor sperm or eggs, or even IVF combined with preimplantation genetic diagnosis to screen for healthy embryos, and only those which test negative for Huntington’s Disease are then implanted. 

How are stem cell and gene therapy a viable therapeutic option for Huntington’s Disease treatment?

With 5 out of every 100,000 people in the US, Europe and Australia affected with Huntington’s Disease and only therapies to help them manage symptoms at present, stem cell research is leading the way and providing new hope for sufferers that new treatments to cure the disease could be on the horizon. 

The monogenetic nature of Huntington’s Disease make it a suitable candidate for stem cell research and gene therapy. A recent study revealed that a combination of stem cell and gene therapy relieved symptoms in Huntington’s Disease infected mice. 

In the study, scientists demonstrated the effectiveness of the combined stem cell and gene therapy in Huntington’s Disease infected mice, using Rhesus Monkey neural progenitor cells, which had been established from induced pluripotent stem cells, as these cells are able to differentiate without tumour formation. 

Infected mice that received the stem cell and gene therapy showed a significantly improved lifespan in comparison to the infected mice that only received the placebo. The mice also demonstrated significantly improved motor functions, which were assessed via rotarod and grip strength tests. 

The challenges of stem cell and gene therapy as a viable therapeutic option for Huntington’s Disease treatment

  • An obvious major challenge to seeking a cure for Huntington’s Disease is that there are no approved stem cell treatments currently. Multiple studies have been conducted on neural stem cell transplants for treating patients with Huntington’s Disease, however they have yet to undergo clinical trials. 
  • Scientists are still researching ethical and reliable sources of neural stem cells. Setting aside the ethical reasons momentarily, neural stem cells must be predictable and uniform otherwise they could do more harm than good, causing cancer or other life threatening conditions in patients, where they weren’t there before. 
  • Gene therapy is coming an ever closer reality to curing currently incurable neurodegenerative diseases such as Huntington’s Disease. Early concerns with gene editing were that completely silencing the gene in people with Huntington’s Disease may cause brain cells to die if the toxic protein produced by the defective gene was completely removed. However this gene silencing therapy has legs and is one of the most promising gene therapies with regards curing Huntington’s disease, to date, by reducing or preventing the toxic protein from being made. Of course there is much further work required and improvements still to be made, but research is positive. 
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