|The right combination of microRNAs and transcription factors turns human skin cells (top) into medium spiny neurons (bottom).--Courtesy of Yoo Lab/Washington U. in St. Louis|
Using a new programming method, researchers at Washington University in St. Louis (WUSTL) have converted human skin cells directly into a type of brain cell that is damaged by Huntington's disease.
The investigators hope to translate their technique to a therapy that could eventually be used to treat people with the debilitating neurodegenerative condition.
Adult human skin cells were chosen for their accessibility. Plus, if successfully converted, this opens up the possibility of using a patient's own cells for individualized treatments since the cells are not in danger of being rejected by a patient's immune system.
Placing the skin cells in an environment that closely mimics that of brain cells, scientists exposed the cells to two small molecules of RNA that are known for their ability to turn skin cells into a mix of different types of neurons.
In previous research, WUSTL professor Andrew Yoo and his colleagues identified these two microRNAs, miR-9 and miR-124, for their ability to alter the machinery that governs how DNA is packaged. Yoo and his team believe these microRNAs open up tightly packaged sections of DNA crucial to brain cells, allowing certain genes involved in the development and function of neurons to be expressed.
Yoo and his colleagues then tinkered with chemical signals, exposing the adult skin cells to different transcription factors known to exist in a part of the brain where medium spiny neurons are plentiful. Medium spiny neurons are important for movement control and are the primary cells affected by Huntington's disease. The transcription factors helped guide the skin cells into these specific kinds of neurons, which looked and behaved like native human medium spiny neurons.
The technique is described in the journal Neuron.
Next, the researchers plan to take skin cells from patients with Huntington's disease and reprogram them into medium spiny neurons using the same approach. After that, they will try injecting the reprogrammed cells into a mouse model of Huntington's disease to evaluate the effects the stem cells might have on symptoms.