| Chinese scientists have been able to reprogram kidney cells harvested from urine samples into neural cell progenitors--immature brain cells that can develop into various types of glial cells and neurons. This type of reprogramming has been done before, but not with cells gleaned from urine and not from a method this direct. The technique could prove extremely helpful to those pursuing treatments for neurodegenerative disorders like Parkinson’s and Alzheimer’s. |
Stem cells offer the hope of treating these debilitating diseases, but embryonic stem cells have always posed an ethical dilemma. It is now possible that cells taken from the adult human body can be made to revert to a stem cell-like pluripotent state and then transformed into virtually any other type of cell.
For instance, red blood cells have recently been used to create induced pluripotent stem cells (iPS), and researchers have been able to do the same with skin and other cells. Furthermore, grafts of patients' own cells do not elicit an immune response, so this approach may eventually lead to effective cell transplantation therapies. At this stage, the methods for generating iPS cells are not foolproof though – it appears that the reprogramming process destabilizes the genome and causes mutations, and that iPS cells potentially contain genetic defects that render them useless.
Last year, Duanqing Pei of the Chinese Academy of Sciences and his colleagues reported that human urine contains skin-like cells from the lining of the kidney tubules which can be efficiently reprogrammed, via the pluripotent state, into neurons, glia, liver cells and heart muscle cells. Now they have improved on the approach, making it quicker, more efficient and possibly less prone to errors.
In the new study, they isolated cells from urine samples given by three donors, aged 10, 25 and 37, and converted them directly into neural progenitors. They then grew these cells in Petri dishes and drove them to differentiate into mature neurons that can generate nervous impulses, and also into astrocytes and oligodendrocytes, two types of glial cell found in the human brain.
Finally, they transplanted the re-programmed neurons and astrocytes into the brains of newborn rats, and found that the cells had survived when they examined the brains a month later, but it remains to be seen if they can survive for longer, and if they integrate into the existing circuits to be become functional.
This isn't the first time that one type of cell has been converted into another without going through the pluripotent stage – in 2010, researchers from Stanford converted mouse connective tissue cells directly into neurons. The new technique does have a number of advantages, however.
Instead of using a virus to deliver the reprogramming genes, the researchers used a small circular piece of bacterial DNA which can replicate in the cytoplasm. This process is similar to Nuvilex's cell encapsulation technology, which is also called cell in a box. This not only speeds up the process, but also eliminates the need to integrate the reprogramming genes into the chromosome, which is one potential source of genetic mutation, but it's still not clear whether these cells contain fewer mutations than those reprogrammed using viruses.
Even so, the technique also makes the procedure of generating iPSCs far easier and non-invasive, as the cells can be obtained from a urine sample instead of a blood sample or biopsy. The next logical step will be to generate neurons from urine samples obtained from patients with Alzheimer's, Parkinson's, and other neurodegenerative diseases and to determine the the extent of any latent genetic alteration of the cells.
SOURCE The Guardian
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