Are you flushing away brain cells? How urine cells can give rise to neurons

in Article, News
March 7th, 2013

Uh-oh, urine trouble! Well, now that that’s out of my system (ahem), how would you feel if you learned that you’ve been flushing away potential brain cells? I’m not talking about the copious amount of hours you’ve logged online or kicked back in front of the television just this past month. On a daily basis, you’re expelling 1-2 liters of a possible source of neurons in a way you’ve never expected – through urinating.

Back in 2009, stem-cell biologist Duanqing Pei demonstrated that kidney epithelial cells, a common component of urine, could be converted into induced pluripotent stem (iPS) cells, which have the ability to differentiate into any cell type found in the body. Recently, Pei and his colleagues at China’s Guangzhou Institutes of Biomedicine and Health took this technique a step further by converting iPS cells into functioning neurons.

Researchers like those at Guangzhou Institutes often utilize a process known as cell reprogramming to create iPS cells. In this process, adult cells, such as blood or skin cells, are reprogrammed by introducing genes that allow cells to differentiate into specialized cells, just like embryonic stem cells. Instead of utilizing blood of skin cells, Pei and his team formed iPS cells from human urine cells, giving them the same potential to differentiate into neurons that embryonic stem cells have.

However, Pei and his team are making it apparent that iPS cells can be far more advantageous than using embryonic stem cells. Compared to embryonic stem cells, which are derived from a 4-5 day old human embryo, iPS cells converted from urine cells are much more feasible considering the accessibility of urine. Furthermore, these iPS cells don’t pose the risk of developing tumors when transplanted into a living organism.

After forming iPS cells from urine cells, Pei and colleagues formed neural progenitor cells by introducing them to a neuron growth medium. These neural progenitor cells, or NPCs, are what give rise to neurons, and Pei’s team successfully cultivated functioning neurons in vitro with these NPCs.

a) Bright-field image of differentiated cells originated from NPCs made from human urine cells. From ““Generation of integration-free neural progenitor cells from cells in human urine.”

Their research points towards promising ends, and the Guangzhou Institute team has high hopes for future applications of their work. In their study, “Generation of integration-free neural progenitor cells from cells in human urine”, published at the end of last year in Nature Methods, Pei and his colleagues envisioned that their “protocols can be further applied to Human Urine Cells isolated from patients with neural disorders such as Parkinson’s disease, Alzheimer’s disease or other neurodegenerative diseases.” It seems possible that their vision could be realized, as the team has discovered that the iPS cells reprogrammed from urine developed at twice the speed of iPS cells made from blood or skin cells. Combined with the relative simplicity of collecting a urine sample from a patient, the use of human urine cells in therapies for neurodegenerative disease could become highly viable.

The most compelling piece of evidence, however, is what happened when the China-based team took their homegrown neurons and implanted them into a living specimen. Neurons that the team cultivated from human epithelial kidney cells were transplanted into the brain of a newborn rat, and these cells continued to function and differentiate. After four weeks, the cells maintained the signs of functioning neurons, without displaying any markers of tumor formation.

With a potentially safer, more abundant, and more personalized source of neurons, therapies for neurodegenerative diseases could be revolutionized in coming years, and its beginning to look like Pei and his team have stumbled upon a “gold rush” of their own.

Brain cells made from urine -Nature Methods

Differentiation of hUiNPCs in vitro -Nature Methods

How to make a human neuron -Nature Methods

Alternative stem cell sources – University of Notre Dame, Initiative on Adult Stem Cell Research & Ethics

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