Biologists in China have published a study detailing how they transformed common cells found in human urine into neural stem cells that can be used to create neurons and glial brain cells. The find holds huge potential for the rapid testing and development of new treatments for neurodegenerative disorders.
The team, from the Guangzhou Institute of Biomedicine and Health, had announced in 2011 that it had successfully reprogrammed skin-like cells from the kidneys, found in urine, into induced pluripotent stem (iPS) cells. These iPS cells can be tweaked to become pretty much any human cell in the body; however the traditional technique prompting this transformation — inserting pluripotent genes into the blanket cells via a genetically engineered retrovirus — has its flaws. It seems the presence of the retrovirus leads to a destabilisation of the genome, rendering it unpredictable, susceptible to mutations and thus a liability.
Stem cell biologist Duanqing Pei and his team opted for another route, that they claim presents a safer, faster alternative. Having extracted kidney epithelial cells from the urine of three donors aged 10, 25 and 37, the team used vectors — a type of DNA molecule useful in transporting genetic information from cell to cell — to transport the information without having to integrate the new genes into the chromosome of the kidney cell, something that is presumed to be partly to blame for the aforementioned mutations.
In one experiment the pluripotent stem cells formed in Petri dishes after 12 days, which is about half the time it normally takes for them to form. These cultured cells soon took on the shape of neural rosettes and were deemed to be neural progenitor cells — a precursor to a fully blown neural cell. Eventually these neural progenitor cells were cultured to become neurons and astrocyte and oligodendrocyte glial cells.
Though the team did not definitively prove that the cells would have less mutations in the long run, it did suggest the method could provide a good alternative to using embryonic stem cells to build new neurons. In a 2007 study, when the embryonic stem cells began their transformation into neurons and were transplanted into the brain’s of rats suffering from an equivalent to Parkinson’s, they began to divide too quickly and tumours formed. This time around, however, when the neurons and astrocytes were transplanted into rat brains they appeared to still be thriving a month later, with no signs of abnormal cell division or tumour formation.
The technique is extremely promising for several reasons. For one, the material is readily available and no invasive extraction is necessary. “We work on childhood disorders,” commented University of Connecticut Health Centre geneticist Marc Lalande, not involved in the study, in Nature, “and it’s easier to get a child to give a urine sample than to prick them for blood.”
It’s also far better to be able to develop a cell derived from an individual’s own cells — they are less likely to prompt an immune response and rejection, which could be the case when using embryonic or umbilical cord stem cells to make iPS cells. The fact that it bypasses the ethical questions of using embryonic cells, and appears to take half the time to develop also provides researchers with a faster, more efficient way to help combat neurological diseases such as Alzheimer’s and Parkinson’s. And with millions suffering from these degenerative disorders worldwide, anything that can speed up research will be of huge benefit.
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