*Image of neurons courtesy of Tilo Kunath, Edinburgh University.

Dr Malin Parmar and colleagues recently published an article in Cell Reports showing that their method of ‘direct neural conversion’ creates new neurons in the brains of mice that integrate and signal with neurons already in the brain. These results suggest that direct neural conversion may be a valuable tool for developing future treatments to replace neurons lost by patients with Parkinson’s (PD) and other diseases that destroy neurons. 

In 1987 researchers in Lund, Sweden were the first to attempt replacing neurons destroyed by PD in two patients' brains using a method called a ‘foetal cell transplant’. These two patients showed substantial improvements prompting more clinical trials around the globe. However, the trials had very mixed results due to mismatched methodologies and outcomes. Researchers have since studied the results of these different transplants, reassessed the methodologies and have designed the present TRANSEURO project, a new phase 1 clinical trial funded by the European Union.

Although foetal brain cell transplants are a promising treatment for PD, they carry several ethical and technical problems. Ethical issues over using aborted foetuses for medical and research purposes are widely debated. This aside, the availability of foetal brain cells and standardising the quality of these cells in each treatment (cells from different foetuses may behave differently) are two big obstacles to making the treatment widely available. Dr Parmar and colleagues point out in their short review that renewable and abundant sources of cells that do not rely on foetuses are ‘an absolute necessity’.

A new technology called ‘direct neural conversion’ is giving researchers new ideas and options for treating diseases like PD. Direct neural conversion can turn any cell from a patient directly into a neuron. These ‘induced neurons’ potentially avoid some of the risks pluripotent stem cells have. Dr Parmar’s laboratory and several other research groups have even used this method to make new neurons inside the brains of living mice. The exciting part is that researchers are able to convert a type of brain cell already in the brain, called ‘glial cells’, into the new neurons, so no transplant is needed. Dr Parmar and colleagues show in their 'Cell Reports' article that their direct neural conversion method creates functional neurons that receive signals and successfully integrate into the brain’s network of neurons. There’s lots of work to be done before this method will ever be tested in people, but it certainly is a new and promising approach for developing future PD treatments.

This article includes excerpts taken from the website: www.eurostemcell.org written by Ryan Lewis, edited by Jan Barfoot, reviewed by Malin Parmar.