A research team led by Dr Paul Tesar at Case Western Reserve University School of Medicine, Cleveland, USA, has transformed skin cells into a type of brain cells that is destroyed in neurodegenerative diseases, such as multiple sclerosis and cerebral palsy.
These cells - oligodendrocytes - produce a protective layer of fat called myelin around nerve cells, ensuring accurate transmission of brain impulses. Loss of myelin in neurodegenerative diseases can have a devastating impact. For example, in multiple sclerosis, poor coordination is an indication that brain signals fail to transmit properly due to lack of myelin.
There is currently no effective treatment to restore myelin in these patients, but over the past decade scientists have shown promising results by transplanting immature oligodendrocytes into genetically engineered mice that lacked myelin. As these transplanted cells matured, they wrapped themselves around naked nerve cells and produced myelin. Unfortunately, this technique relies on a very time-consuming procedure. "We started to question whether there would be a quicker approach in order for us to reprogram readily accessible cell types directly into oligodendrocytes," explains Dr Paul Tesar.
In a new Nature Biotechnology study, Dr Tesar's team describes a new method called 'cellular reprogramming' that converts skin cells into oligodendrocytes. This technique involves tweaking the levels of certain genes to turn fibroblasts, a type of skin cells, directly into functional immature oligodendrocytes, and bypassing the laborious intermediate steps used by previous methods.
Dr Tesar and colleagues integrated transformed brain cells into mice brains that lacked myelin. "We transplanted oligodendrocytes created from fibroblast cells into myelin-deficient mice and showed definitely that transplanted cells could produce myelin and function as normal oligodendrocytes," says Dr Tesar.
More tests are needed to check safety, efficacy and long-term functionality of these transformed oligodendrocytes, but the research team hopes to be able to translate this technology to human cells for therapeutic use. Calling this study "a major landmark", Dr Tesar predicts that "over the next few years we're going to see an explosion in the ability to control the identity and the fate of cells".
However, Dr Thomas Misgeld of the Institute of Neuroscience, Technical University of Munich, who was not involved in the study, advises caution. "Although the fact that it is possible to obtain such cells is quite remarkable, whether this will be of benefit in any specific condition, such as [multiple sclerosis], remains open, as the cause of the disease is likely inflammatory and damage extends beyond myelin, e.g. to nerve cells".